tag:theconversation.com,2011:/global/topics/mating-strategy-192/articlesMating strategy – The Conversation2023-02-16T19:17:54Ztag:theconversation.com,2011:article/2000622023-02-16T19:17:54Z2023-02-16T19:17:54ZAustralian humpback whales are singing less and fighting more. Should we be worried?<figure><img src="https://images.theconversation.com/files/510471/original/file-20230216-26-s6g586.jpeg?ixlib=rb-1.1.0&rect=23%2C29%2C3858%2C2555&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Cetacean Ecology Group, University of Queensland.</span>, <span class="license">Author provided</span></span></figcaption></figure><p>As eastern Australian humpback whale populations have recovered over the years, males have adapted their mating strategy in a highly strategic way, new research finds. </p>
<p>I analysed 123 days’ worth of data on Australian humpbacks (<em>Megaptera novaeangliae</em>), collected from 1997 to 2015, and found male humpbacks sang less and fought more as the whale population ballooned.</p>
<p>We think this shift in behaviour is a result of not wanting to attract other males to a potential mate, as we explain in <a href="https://www.nature.com/articles/s42003-023-04509-7">research published</a> today in Communications Biology. </p>
<h2>Rapid growth, rapid adaptation</h2>
<p>Humpbacks have recovered magnificently since 1965, when the species became <a href="https://www.dcceew.gov.au/environment/marine/marine-species/cetaceans/whaling#">globally protected</a>.</p>
<p>One population off Australia’s east coast grew from less than 500 in the 1960s and is estimated to contain at least 30,000 today. This population has provided experts a rich dataset. The males in particular are great subjects thanks to their striking song broadcasts. </p>
<p><audio preload="metadata" controls="controls" data-duration="424" data-image="" data-title="Whale Song from 2003" data-size="7010245" data-source="Rebecca Dunlop" data-source-url="" data-license="Author provided" data-license-url="">
<source src="https://cdn.theconversation.com/audio/2746/whale-song.mp3" type="audio/mpeg">
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Whale Song from 2003.
<span class="attribution"><span class="source">Rebecca Dunlop</span>, <span class="license">Author provided</span><span class="download"><span>6.69 MB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/2746/whale-song.mp3">(download)</a></span></span>
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<p>Carrying on work started by University of Queensland Professor <a href="https://researchers.uq.edu.au/researcher/1028">Michael Noad</a> in the ’90s, we set out to investigate exactly how the eastern humpbacks have adapted to the growth numbers.</p>
<p>Luckily for us these whales migrate close to the coastline, so we were able to establish a land-based observation station at Peregian Beach, a small coastal town on the Sunshine Coast.</p>
<p>Volunteers onshore helped us track individual whales as they moved down the coast, while an acoustic array moored offshore recorded the whales’ song and tracked singing whales. This method (which Professor Noad first established) allowed us to pinpoint the exact location of a particular whale in real time. </p>
<p>A trend emerged when our data were coupled with those collected by Professor Noad’s team. As the eastern humpback population grew, males weren’t singing as much as they used to. Instead they were increasingly opting to quietly find a female to mate with, or fighting off other male competition.</p>
<p>Specifically, the proportion of singing males decreased from two in ten in 2003–2004, to only one in ten by 2014–2015. Data from 2003–2004 also show males were less likely to sing when they had a higher proportion of males in their social circle. </p>
<p>And it seems the change in tactics led to a change in results. In 1997 singing males were almost twice as likely as their counterparts to be seen joining with a female and escorting her, likely to attempt to mate. But by 2014-2015, non-singing males were almost five times more likely to be seen joining a group with a female. </p>
<p>That said, we can’t say for sure when joining a group actually results in mating with the female and fathering a calf. That’s another piece of this puzzle: how many of the males that join groups (singing or otherwise) actually end up mating and then fathering a calf?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large humpback whales head is seen sticking out from the ocean's surface, with a second small fin peeking out nearby" src="https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510473/original/file-20230216-26-m2nvrg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Megaptera novaeangliae</em> is one of three subspecies of the humpback whale.</span>
<span class="attribution"><span class="source">Cetacean Ecology Group/University of Queensland.</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>What’s driving males to fight?</h2>
<p>A species will carry out a behaviour for as long as the benefits outweigh the costs. If something changes, and the costs start to outweigh the benefits, they will stop. It’s a basic principle, but it goes a long way towards explaining our findings. </p>
<p>In the early years of data collection, when there were fewer whales around, a male could sing and broadcast himself to nearby females quite comfortably – not having to worry about hordes of other males wanting his neck. </p>
<p>Now, with a more than burgeoning population, the same tactic attracts the risk of being interrupted by other males. As a male humpback, you’re better off spending the breeding season quietly seeking a female to mate with and not attracting the attention of other males.</p>
<p>Or, if you fancy yourself a big, tough guy, you might take the chance to fight other males to become the “primary escort” of a group. And this relates to one of our working theories about why singing among the eastern humpbacks has diminished through time, and fighting has increased.</p>
<p>Until it was banned, whaling was likely <a href="https://www.nature.com/articles/s41598-022-09570-6">targeting larger</a> mature adults. This could have left an immature population, full of young whales less equipped to fight. Coupled with a sudden decrease in competition overall, this may help explain why whales in the early years preferred singing as a mating tactic. </p>
<p>By the same token, once these same males started to mature and grow large in later years, they may have tended more towards fighting off competition. </p>
<p>We have observed some of these bigger and more assertive whales, the “primary escorts”, on the breeding grounds. They move from group to group, displacing other males – always maintaining their alpha status. </p>
<h2>Are whales losing their song?</h2>
<p>Despite what our research has observed, we don’t think whales are at risk of losing their song. The eastern humpback whales have simply changed their behaviour to improve their chances of mating. As researchers working out in the field, we still hear whales singing, so we’re not worried.</p>
<p>But we do have questions moving forward.</p>
<p>For one thing, we don’t know how the population dynamics in the eastern humpback may have changed in the past seven years. The dataset used in our study ended in 2015 (and the population has since grown). It would be interesting to know if the trend we observed from 1997 to 2015 is ongoing or has stabilised.</p>
<p>We also want to better understand the factors that drive a male whale’s choice to sing. Is it age, or size, a combination of both, or something else? </p>
<p>Until then, we can safely conclude one thing: whales are incredibly socially complex creatures – and our findings indicate they can adapt remarkably to the social pressures around them. </p>
<p>By the same logic, however, any species under threat that can’t adapt to changing population dynamics stands to lose out. Humpbacks have managed to bounce back, but what about the other precious animals in the world?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tail of a humpback whale is seen above the water's surface, with water splashing around it." src="https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510476/original/file-20230216-28-1fialx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Adult humpback whales can grow up to 17 metres in length.</span>
<span class="attribution"><span class="source">Cetacean Ecology Group/University of Queensland.</span>, <span class="license">Author provided</span></span>
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Read more:
<a href="https://theconversation.com/humpback-whales-may-have-bounced-back-from-near-extinction-but-its-too-soon-to-declare-them-safe-157232">Humpback whales may have bounced back from near-extinction, but it's too soon to declare them safe</a>
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<img src="https://counter.theconversation.com/content/200062/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rebecca Dunlop currently receives funding from Living Marine Resources Programme, Office of Naval Research, U. S., and has received past funding from the U.S. Office of Naval Research, the Australian Defence Science and Technology Organisation and the Australian Marine Mammal Centre) and the Joint Industry Program E&P Sound and Marine Life. </span></em></p>We’ve noticed a clear trend away from singing as a mating tactic among male humpbacks. But it’s probably a pretty good strategy.Rebecca Dunlop, Senior Lecturer in Physiology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1947932022-11-21T13:15:49Z2022-11-21T13:15:49ZPeople don’t mate randomly – but the flawed assumption that they do is an essential part of many studies linking genes to diseases and traits<figure><img src="https://images.theconversation.com/files/496010/original/file-20221117-25-slwoe3.jpg?ixlib=rb-1.1.0&rect=110%2C96%2C4690%2C2134&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Statistical pitfalls in GWAS can result in misleading conclusions about whether some traits (like long horns or spotted skin, in the case of dinosaurs) are genetically linked.</span> <span class="attribution"><span class="source">@meanymoo</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The idea that <a href="https://doi.org/10.1002/0471667196.ess0209.pub2">correlation does not imply causation</a> is a fundamental caveat in epidemiological research. A classic example involves a hypothetical link between ice cream sales and drownings – instead of increased ice cream consumption causing more people to drown, it’s plausible that a third variable, summer weather, is driving up an appetite for ice cream and swimming, and hence opportunities to drown.</p>
<p>But what about correlations involving genes? How can researchers be sure that a particular trait or disease is truly genetically linked, and not caused by something else?</p>
<p>We are <a href="https://www.richardborder.com">statistical</a> <a href="https://scholar.google.com/citations?user=SPXgieEAAAAJ&hl=en">geneticists</a> who study the genetic and nongenetic factors that influence human variation. In our <a href="https://www.science.org/doi/10.1126/science.abo2059">recently published research</a>, we found that the genetic links between traits found in many studies might not be connected by genes at all. Instead, many are a result of how humans mate.</p>
<h2>Genome-wide association studies try to link genes to traits</h2>
<p>Because the genes you inherit from your parents remain unchanged throughout your life, with rare exception, it makes sense to assume that there is a causal relationship between certain traits you have and your genetics.</p>
<p>This logic is the basis for <a href="https://www.genome.gov/about-genomics/fact-sheets/Genome-Wide-Association-Studies-Fact-Sheet">genome-wide association studies, or GWAS</a>. These studies collect DNA from many people to identify positions in the genome that might be correlated with a trait of interest. For example, if you have certain forms of the <a href="https://www.cancer.gov/about-cancer/causes-prevention/genetics/brca-fact-sheet"><em>BRCA1</em> and <em>BRCA2</em> genes</a>, you may have an increased risk for certain types of cancer.</p>
<p>Similarly, there may be gene variants that play a role in whether or not someone has schizophrenia. The hope is to learn something about the complex mechanisms that link variation at the molecular level to individual differences. With a clearer understanding of the genetic basis of different traits, scientists would be better able to determine risk factors for related diseases. </p>
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<figcaption><span class="caption">GWAS studies seek to find genetic associations between individual traits.</span></figcaption>
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<p>Researchers have run <a href="https://doi.org/10.1093/nar/gky1120">thousands of GWAS to date</a>, identifying genetic variants associated with myriad diseases and disease-related traits. In many instances, researchers have identified genetic variants that affect more than one trait. This form of biological overlap, in which the same genes are thought to influence several apparently unrelated traits, is known as <a href="https://doi.org/10.1186/s13073-016-0332-x">pleiotropy</a>. For example, certain variants of the <a href="https://medlineplus.gov/genetics/gene/pah"><em>PAH</em> gene</a> can have <a href="https://medlineplus.gov/genetics/condition/phenylketonuria/">several distinct effects</a>, including altering skin pigmentation and causing seizures.</p>
<p>One way scientists assess pleiotropy is through <a href="https://doi.org/10.1038/ng.3604">genetic correlation analysis</a>. Here, geneticists investigate whether the genes associated with a given trait are associated with other traits or diseases by statistically analyzing large samples of genetic data. Over the past decade, genetic correlation analysis has become the primary method for assessing potential pleiotropy across fields as diverse as <a href="https://doi.org/10.1038/ng.3406">internal medicine</a>, <a href="https://www.thessgac.org">social science</a> and <a href="https://doi.org/10.1017/s0033291717002318">psychiatry</a>. </p>
<p>Scientists use the findings from genetic correlation analyses to figure out the potential shared causes of these traits. For instance, if <a href="https://doi.org/10.1126/science.aap8757">genes associated with bipolar disorders</a> also predict anxiety disorders, perhaps the two conditions may partially involve some of the same neural circuits or respond to similar treatments.</p>
<h2>Assortative mating and genetic correlation</h2>
<p>However, just because a gene is correlated with two or more traits doesn’t necessarily mean it causes them.</p>
<p>Virtually all the statistical methods researchers commonly use to assess genetic correlations <a href="https://doi.org/10.1046/j.1439-0388.2002.00356.x">assume that mating is random</a>. That is, they assume that potential mating partners decide who they will have children with based on a roll of the dice. In reality, many factors likely influence who mates with whom. The simplest example of this is geography – people living in different parts of the world are less likely to end up together than people living nearby.</p>
<p>We wanted to find out how much the assumption of random mating affects the accuracy of genetic correlation analyses. In particular, we focused on the potential confounding effects of <a href="https://doi.org/10.1038/s41562-018-0476-3">assortative mating</a>, or how people tend to mate with those who share similar characteristics with them. Assortative mating is a widely documented phenomenon seen across a broad array of traits, interests, measures and social factors, including <a href="https://doi.org/10.1002/ajhb.22917">height</a>, <a href="https://doi.org/10.2307/2095670">education</a> and <a href="https://doi.org/10.1016/j.biopsych.2019.06.025">psychiatric conditions</a>.</p>
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<figcaption><span class="caption">Humans do not mate randomly – rather, people tend to gravitate toward certain traits.</span></figcaption>
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<p>In <a href="https://doi.org/10.1126/science.abo2059">our study</a> we examined cross-trait assortative mating, whereby people with one trait (for example, being tall) tend to mate with people with a completely different trait (for example, being wealthy). From our database of 413,980 mate pairs in the U.K. and Denmark, we found evidence of cross-trait assortative mating for many traits – for instance, an individual’s time spent in formal schooling was correlated not only with their mate’s educational attainment, but also with many other characteristics, including height, smoking behaviors and risk for different diseases.</p>
<p>We found that taking into consideration the similarities across mates could strongly predict which traits would be considered genetically linked. In other words, just based on how many characteristics a pair of mates shared, we could identify around 75% of the presumed genetic links between these traits – all without sampling any DNA.</p>
<h2>Genetic correlation does not imply causation</h2>
<p>Cross-trait assortative mating shapes the genome. If people with one heritable trait tend to mate with people with another heritable trait, then these two distinct characteristics will become genetically correlated to each other in subsequent generations. This will happen regardless of whether or not these traits are truly genetically linked to each other.</p>
<p>Cross-trait assortative mating means that the genes you inherit from one parent will be correlated with those you inherit from the other. How people mate is not random, violating the key assumption behind genetic correlation analyses. This inflates the genetic association between traits that aren’t truly linked together by genes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of dinosaurs with and without long horns or spiked backs." src="https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">If dinosaurs with long horns preferentially mate with dinosaurs with spiked backs, genes for both of these traits can become associated with each other in subsequent generations even though the same gene doesn’t code for them.</span>
<span class="attribution"><span class="source">Aaqilah M</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>Recent studies corroborate our findings. Earlier this year, researchers computed genetic correlations using a method that examines the association between the <a href="https://doi.org/10.1038/s41588-022-01062-7">traits and genes of siblings</a>. The genetic links between traits influenced by cross-trait assortative mating were substantially weakened.</p>
<p>But without accounting for cross-trait assortative mating, using genetic correlation estimates to study the biological pathways causing disease can be misleading. Genes that affect only one trait will appear to influence multiple different conditions. For example, a genetic test designed to assess the risk for one disease may incorrectly detect vulnerability for a broad number of unrelated conditions.</p>
<p>The ability to measure variation across individuals at the genetic and molecular level is truly a feat of modern science. However, genetic epidemiology is still an observational enterprise, subject to the same caveats and challenges facing other forms of nonexperimental research. Though our findings don’t discount all genetic epidemiology research, understanding what genetic studies are truly measuring will be essential to translate research findings into new ways to treat and assess disease.</p><img src="https://counter.theconversation.com/content/194793/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Border receives funding from the National Institutes of Health.</span></em></p><p class="fine-print"><em><span>Noah Zaitlen receives funding from the NIH, NSF, DoD, and CZI. </span></em></p>People don’t randomly select who they have children with. And that means an underlying assumption in research that tries to link particular genes to certain diseases or traits is wrong.Richard Border, Postdoctoral Researcher in Statistical Genetics, University of California, Los AngelesNoah Zaitlen, Professor of Neurology and Human Genetics, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1594312021-06-07T04:20:05Z2021-06-07T04:20:05ZThe sex life aquatic: how moving from land to water led to the surprisingly touchy courtship of sea snakes<figure><img src="https://images.theconversation.com/files/403537/original/file-20210531-27-1xf8j0d.JPG?ixlib=rb-1.1.0&rect=19%2C19%2C4294%2C2851&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Claire Goiran</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Although sea snakes aren’t usually associated with intimate interactions, our new research is revealing their “sensitive” side.</p>
<p>In a study <a href="https://academic.oup.com/biolinnean/article-lookup/doi/10.1093/biolinnean/blab069">published today</a> in the Biological Journal of the Linnaean Society, my colleagues and I detail the enlarged touch receptors which evolved in the male turtle-headed sea snake (<em>Emydocephalus annulatus</em>). </p>
<p>We suspect these curious sensory organs help the males keep up with their female counterparts underwater.</p>
<h2>As I headed to sea</h2>
<p>The sun rises over the calm water of Baies des Citrons in Nouméa, New Caledonia. I don my wetsuit and snorkel out in search of turtle-headed sea snakes. </p>
<p>Once I slip into the water it doesn’t take long to spot one; a yellow and black banded male swims with purpose along the rocky reef. It’s the winter breeding season.</p>
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<figcaption><span class="caption">A banded male turtle-headed sea snake swims along the reef, looking for females.</span></figcaption>
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<p>During mating season, a male will search frantically for females and approach nearly everything that moves, including my flippers! </p>
<p>When he does find a female, he begins a curious courtship behaviour — undulating his body over hers, while repeatedly prodding his head into her back. </p>
<p>The female swims to the surface to breathe as the smaller-bodied male rushes to keep up. As she dives back down, he becomes disorientated and swims in the opposite direction. Realising he has lost her, the male erratically circles their last place of contact. She may be metres away, but he’ll probably never find her again. </p>
<p>This is a common story for this species. <a href="https://link.springer.com/article/10.1007/s00265-004-0897-z">One study</a> found up to 60% of males will lose contact with females they encounter. </p>
<h2>Sea sense: how do sea snakes find their mates?</h2>
<p>On land, snakes use tongue-flicking to sense and follow sex pheromones left by other snakes. In the water, however, these chemicals are diluted. </p>
<p>Turtle-headed sea snakes also can’t see very clearly underwater and have been known to court anything long and dark, including sea cucumbers. To make matters worse, once a female is found, the male must overcome buoyancy force so he doesn’t float away from his potential mate. </p>
<p>Given the challenges of living underwater, my colleagues and I hypothesised male turtle-headed sea snakes might have an enhanced sense of touch, to maintain contact with females during close courtship. </p>
<h2>Underwater tactile foreplay</h2>
<p>Most snakes have a dusting of thousands of touch receptors that look like freckles all over their face. These touch receptors are much larger in sea snakes, potentially so they can sense vibrations made by swimming prey and predators.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A comparison of scale receptors in a land snake (<em>Pseudonaja textilis</em>) and sea snake (<em>Hydrophis schistosus</em>).</span>
<span class="attribution"><span class="source">xx</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>One of the largest touch receptors on any snake is found on turtle-headed sea snakes. And when we took a closer look at museum specimens, we discovered males have larger touch receptors than females overall. </p>
<p>We also found mature males have enlarged scale structures on their snout, chin and their cloaca (which is an all-purpose hole used for reproduction and excretion). The positioning of these enlarged receptors over the body hints at the role they play in sea snake courtship.</p>
<p>The touch receptors on the chin of males (referred to as “genial knobs”) have the same specialised cells as those on the face, but the outer bump is four times larger. </p>
<p>Their position on the underside of the head gives sensory feedback to the male as he swims above females, helping him orient towards the direction of her swimming. </p>
<p>The touch receptors on his anal scales (or “anal knobs”) provide feedback to align both snakes’ cloacae, which is necessary for sex. Genital alignment may seem like a trivial task, but for tube-shaped limbless snakes, touch receptors on the cloaca are essential. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=367&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=367&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=367&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comparison of male and female turtle-headed sea snakes. Males have rostral spines (RS) and enlarged genial knobs (GK) and anal knobs (AK). Males also have larger scale receptors (SS). H = hemipene, which is a male reproductive organ.</span>
<span class="attribution"><span class="source">Chris Jolly</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Males also have a tapered scale on their snout known as the “rostral spine”. While courting the female, the male will prod the female’s back with this hardened scale. </p>
<p>We investigated the micro-structure of the rostral spine and found it is made of thickened layers of skin with no specialised sensory cells. As such, we think it may play a role in stimulating female interest in mating. </p>
<p>However, it provides relatively less feedback for the male, especially compared to the touch receptors on his chin and cloaca.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=567&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=567&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=567&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=713&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=713&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=713&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Positioning of the scale structures on a male turtle-headed sea snake. RS = rostral spine and GK = genial knob.</span>
<span class="attribution"><span class="source">Photo of full snake by Max Jackson; photos of tactile receptors by Chris Jolly</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A similar form of “tactile foreplay” has been observed in species of boas and pythons. These snakes have hard claws known as pelvic spurs near their cloaca, which are vestigial remnants of legs lost through evolution! </p>
<p>During courtship, males will scratch and pry at the female’s scales during mating. Such sinuous courtship can stimulate beneficial hormonal changes and receptive behaviours in females, such as “cloacal gaping” which increase mating success for both sexes.</p>
<p>Could the rostral spine in turtle-headed sea snakes play a similar role in stimulating females? </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1ygIGg6XMQA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The mating begins.</span></figcaption>
</figure>
<h2>Evolutionary transitions</h2>
<p>Sea snakes <a href="https://doi.org/10.1098/rsob.160054">evolved from land snakes</a> some 20 million years ago. Most live their entire lives at sea. </p>
<p>Decades of research have revealed their remarkable morphological adaptations to aquatic life, including paddle-shaped tails, salt-excreting glands and the ability to breathe through their skin. Now, our research is beginning to uncover the importance of touch for social behaviours in sea snakes.</p>
<p>While sea snakes are not typically appreciated for their sensitive side, our discovery suggests an enhanced sense of touch evolved to improve communication within members of a species. This is especially crucial in aquatic environments, where other sensory signals such as vision and pheromones are diminished.</p>
<p>As our work continues, sea snakes are becoming a fantastic example of how evolution can create opportunity from constraint.</p><img src="https://counter.theconversation.com/content/159431/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jenna Crowe-Riddell received funding for this study from an Australian Government Research Training Program Scholarship and a New Caledonia University Scientific Exchange Program Grant. </span></em></p>During mating season, a male turtle-headed sea snake will often lose sight of the female before mating can happen. The female may be metres away, but the male won’t ever find her again.Jenna Crowe-Riddell, Postdoctoral research fellow, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1610812021-05-19T19:57:31Z2021-05-19T19:57:31ZMen are from Mars, women are from… Mars? How people choose partners is surprisingly similar (but depends on age)<figure><img src="https://images.theconversation.com/files/401542/original/file-20210519-19-1psbexl.jpg?ixlib=rb-1.1.0&rect=41%2C17%2C3952%2C1479&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>As behavioural scientists, we have a keen interest in how people make decisions, and particularly how these decisions incorporate a range of emotional, cognitive and psychological factors.</p>
<p>Choosing a life partner is arguably one of the most important decisions a person can make. And <a href="https://www.abc.net.au/news/2019-11-26/australia-talks-national-survey-where-to-find-a-partner/11692170">research</a> <a href="https://news.stanford.edu/2019/08/21/online-dating-popular-way-u-s-couples-meet/">has shown</a> the most common way to do this these days is to go online.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=951&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=951&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=951&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1195&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1195&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1195&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">John Gray’s famous 1992 book purports that men and women have innately different natures.</span>
<span class="attribution"><span class="source">Wiki</span></span>
</figcaption>
</figure>
<p>As increasing numbers of people wade cautiously through the digital dating market, many still subscribe to stereotypical ideas about what men and women find attractive in a partner.</p>
<p>Our latest research, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0250151">published</a> today in PLOS One shows the truth, as ever, is more nuanced. </p>
<p>Using survey data from 7,325 heterosexual users of dating websites, aged 18 to 65, we show there is no absolute difference between the preferences of men and women when it comes to choosing a mate. Both essentially desire the same qualities, but prioritise them slightly differently.</p>
<h2>The democratisation of dating?</h2>
<p>Dating in the 21st century is <a href="https://theconversation.com/sex-bots-virtual-friends-vr-lovers-tech-is-changing-the-way-we-interact-and-not-always-for-the-better-159427">a truly unique experience</a>. For millennia, the human search for companionship had been constrained by access, distance and resources. Most people had to find a partner through close or extended family, or religious, cultural or social organisations.</p>
<p>Today, online dating allows seemingly unrestrained and “<a href="https://www.cs.ubc.ca/%7Ekevinlb/teaching/cs322%20-%202005-6/Lectures/lect32.pdf">nonsequential</a>” decision-making.</p>
<p>Imagine if you met someone at a bar and told them to wait around for two hours, just in case you managed to find someone better. It sounds bizarre, but that’s what <a href="https://medium.com/@therealnair/tinder-and-cognitive-overload-5c7650f5fe00">online dating allows</a>. You can search through thousands of people and never have to make a decision. </p>
<p>This is good news for researchers of human behaviour. With such a vast and growing pool of data, we can study mating choices in a way we never could before.</p>
<h2>Pressure to play the evolutionary game</h2>
<p>Obviously, a huge part of sexual attraction comes down to personal preference regarding what makes someone “sexy”. That said, there are many stereotypes relating to what heterosexual men and women find sexy. </p>
<p>It’s often assumed women favour more emotional, personality, intelligence and commitment-based traits in men, while men are often said to prefer physical attractiveness. </p>
<p>From an evolutionary psychology angle, these stereotypes aren’t unfounded. In the game of life, the main aim is to pass on your genes — and once you do, to ensure your offspring achieve the same success. </p>
<p>Naturally, men and women play different roles in the reproduction process. From an evolutionary standpoint, it makes sense for women to seek a man with traits that will benefit her offspring in both the short and long term, as women bear a bigger reproductive cost than men. </p>
<p>They have internal gestation for nine months and then must successfully give birth, all while facing discomfort and risk. They will then continue to nurse and care for the child. </p>
<figure class="align-center ">
<img alt="Mother and child place their hands atop each other's" src="https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Throughout the evolution of our species, mothers on average have had a far greater parenting responsibility across their offspring’s lives.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Men, at its simplest, need only to invest time into copulation to have offspring. Theoretically, then, the specific selection pressures on men and women to pass on their genes should be observable in the characteristics of the mates they choose.</p>
<p>Many of these assumptions fall under a school of thought called “<a href="https://www.sciencedirect.com/topics/neuroscience/parental-investment">parental investment theory</a>”, developed in the early 1970s by evolutionary biologist Robert Trivers. </p>
<p>More recent theories in gender studies and social and evolutionary psychology have countered the notion of absolute differences. They demonstrate men and women are far more similar in their preferences than previously thought.</p>
<p>Our research reinforces one such theory, referred to as “<a href="https://www.pnas.org/content/106/Supplement_1/10001">mutual mate choice</a>”. We found both men and women essentially desire the same qualities in a partner, differing only in the relative emphasis placed on each trait at different life stages.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-i-stay-or-should-i-go-here-are-the-relationship-factors-people-ponder-when-deciding-whether-to-break-up-153707">Should I stay or should I go? Here are the relationship factors people ponder when deciding whether to break up</a>
</strong>
</em>
</p>
<hr>
<h2>If men are from Mars, women are too</h2>
<p>We asked survey participants to rate from 0 to 100 the importance they placed on nine traits when looking for a mate. They fell into three categories: </p>
<ul>
<li><strong>aesthetics</strong>, such as age, attractiveness and physical features</li>
<li><strong>resources</strong>, such as intelligence, education and income</li>
<li>and <strong>personality</strong>, such as trust, openness and emotional connection.</li>
</ul>
<p>Both genders rated aesthetics as highly important, along with all three personality traits, while income was much less important. </p>
<hr>
<p><iframe id="ScLiU" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/ScLiU/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<hr>
<p>Women, however, rated factors including age, education, intelligence, income, trust and emotional connection about 9 to 14 points higher than men. Men placed relatively more emphasis on attractiveness and physical build.</p>
<p>Importantly, the way both genders prioritised traits changed with age. Both cared less about physical attractiveness as they got older, whereas emphasis on personality increased. This makes sense, considering we require different things from a partner at different life stages. </p>
<p>Our findings reinforce that both men and women tend to give similar emphasis to certain traits, depending on their individual needs at a particular stage in life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Older couple" src="https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">On dating apps, users can at times be spoilt for choice. This may result in us not placing as much emphasis on the actual search for a partner that older generations historically did.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Men and women can both be very picky</h2>
<p>One interesting revelation came when we grouped participants’ preference data together. </p>
<p>Of those individuals who said one specific trait was very important to them, it turned out the majority of traits were very important to them. On the other hand were respondents who said they didn’t have a strong preference for any particular trait at all. </p>
<p>So while some people were happy to go with the flow, many of the participants actually cared <em>a lot</em> about <em>a lot</em> of different factors. For men, the likelihood of having such stringent preferences was most common between ages 20 and 40. Among women it was more likely between the ages of 35 and 50. </p>
<h2>Personal circumstance and preference is key</h2>
<p>The bottom line is there is no single unified theory of mate choice. Attractiveness matters to everyone to some extent. Resources and intelligence matter to everyone to some extent. </p>
<p>Beyond human biology and evolution, it’s likely our individual personal constraints — such as employment, education, family and social circle — still have a huge impact on how we choose a mate, even if we are dating online.</p>
<p>While dating apps and websites may come with an element of “cognitive overload”, they are ultimately just conduits for human communication. They let people search far and wide for a mate who will help them achieve their own relationship goals.</p>
<p>And our relationship goals, just as is the case with the importance we place on our preferences, change over time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-one-could-dna-tests-find-our-soulmate-we-study-sex-and-sexuality-and-think-the-idea-is-ridiculous-158533">The One: could DNA tests find our soulmate? We study sex and sexuality — and think the idea is ridiculous</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/161081/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Brooks receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Benno Torgler, Ho Fai Chan, and Stephen Whyte do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Each year, more and more people are looking to dating apps to find a partner. And a trove of data from these users is finally revealing what men and women really want.Stephen Whyte, Deputy Director, Centre for Behavioural Economics, Society and Technology, Queensland University of TechnologyBenno Torgler, Professor, Business School, Queensland University of TechnologyHo Fai Chan, Postdoctoral Research Fellow, Queensland University of TechnologyRob Brooks, Scientia Professor of Evolutionary Ecology; Academic Lead of UNSW's Grand Challenges Program, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1517272021-01-12T19:00:30Z2021-01-12T19:00:30ZBirds sniff out potential mates who are genetically different<figure><img src="https://images.theconversation.com/files/377856/original/file-20210108-15-tbqm61.jpg?ixlib=rb-1.1.0&rect=15%2C22%2C5097%2C3380&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scent plays an important role in how birds choose their mates.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>I’ll never forget the heady scent of Cindy, my first major crush. Sometimes, I catch a whiff of her Hawaiian Ginger Body Mist perfume and I’m transported 15 years back in time and straight into a darkened club. <a href="https://www.youtube.com/watch?v=8yjGPgs0_S0">Calgon, take me away</a>.</p>
<p>Many of us have experienced the power of a <a href="https://www.bustle.com/p/why-some-smells-make-you-feel-nostalgic-according-to-science-7685224">nostalgic scent</a> triggering our memories. Of course, our sense of smell doesn’t only serve to remind us of our long-lost loves. Smell can inform us of the presence of enticing food nearby, or it can warn us of dangerous toxins in the environment. We can even <a href="https://www.nationalgeographic.com/news/2018/01/smell-sickness-parkinsons-disease-health-science">smell when our companions are ill</a>. </p>
<p>Our body odour is affected by many factors. The <a href="https://doi.org/10.1016/j.appet.2015.11.001">food we eat</a>, our <a href="https://doi.org/10.1007/s10646-020-02171-x">stress levels</a>, if we are healthy <a href="https://doi.org/10.1093/jb/mvr090">or sick</a>, the <a href="https://doi.org/10.1098/rstb.2019.0269">bacteria</a> and fungi that naturally live on our bodies and even our <a href="https://doi.org/10.1098/rspb.2012.2889">genetic makeup</a> can all affect the way we smell.</p>
<h2>Avian body scent</h2>
<p>But what does this have to do with birds?</p>
<p>Much like the phrase “blind as a bat” (<a href="https://www.livescience.com/55986-are-bats-really-blind.html">bats can see quite well, thank you</a>), there is a persistent myth that birds can’t smell. In the 1820s, <a href="https://www.smithsonianmag.com/science-nature/john-james-audubon-americas-rare-bird-97819781/">artist and ornithologist John James Audubon</a> wrongly claimed that <a href="https://baynature.org/article/comes-smell-turkey-vulture-stands-nearly-alone/">vultures use sight over smell to find food</a>. Audubon’s <a href="https://doi.org/10.1093/icb/7.3.415">conclusions were flawed</a>, but the myth lingers on.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of two vultures with the head of a calf." src="https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ornithologist John James Audubon’s illustration of two black vultures. Audubon conducted experiments that falsely indicated that vultures relied on sight rather than smell.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Illustration_from_Birds_of_America_(1827)_by_John_James_Audubon,_digitally_enhanced_by_rawpixel-com_106.jpg">(National Gallery of Art)</a></span>
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<p>Researchers have shown that birds use smell to do all sorts of things, like <a href="https://www.audubon.org/magazine/january-february-2014/birds-can-smell-and-one-scientist">find food</a>, <a href="https://doi.org/10.1111/j.1365-2435.2007.01361.x">avoid predators</a>, <a href="https://doi.org/10.1007/s00442-009-1418-6">protect their nests</a>, <a href="https://doi.org/10.1016/j.anbehav.2012.06.014">distinguish relatives from nonrelatives</a> and <a href="https://doi.org/10.1038/s41598-017-13110-y">identify their parents</a>.</p>
<p>Our feathered friends have a special preen gland at the base of their tail. When birds rub the gland with their beak, it releases preen oil, which they groom themselves with. Preen oil helps waterproof and protect feathers from damage, but it is also a major source of bird body odour. </p>
<p>Does a bird’s body odour have a purpose? I wanted to know whether birds feel attracted to each other because of how they smell, like I did with Cindy’s perfume. </p>
<p>By gently squeezing the preen gland, I collected preen oil from a common North American bird called the song sparrow (<em>Melospiza melodia melodia</em>), brought them in to captivity, and gave them a choice between preen oil from males and females. Males spent more time with preen oil from females, and females spent more time with preen oil from males, suggesting that <a href="https://doi.org/10.1016/j.anbehav.2019.06.035">birds prefer the smell of the opposite sex</a>. This is probably because the sparrows were looking for mates to start a family with.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sparrow preening on a beach" src="https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Birds groom themselves by rubbing preen oil over their feathers with their beaks.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Smell the difference</h2>
<p>Birds, like humans, are more likely to raise a healthy family if their mate is genetically unrelated to them. But how can we assess whether a potential partner is a good genetic match? </p>
<p>Our B.O. may hold the key. </p>
<p>Believe it or not, in the 1990s, researchers convinced a group of women to rate their preferences for the smell of men’s dirty shirts. This “<a href="https://www.nytimes.com/1998/06/09/science/studies-explore-love-and-the-sweaty-t-shirt.html">sweaty t-shirt experiment</a>” showed that women prefer the B.O. of men who are genetically different from themselves. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-smelly-truth-about-romantic-relationships-and-health-131171">The smelly truth about romantic relationships and health</a>
</strong>
</em>
</p>
<hr>
<p>More recently, researchers showed that there is a <a href="https://doi.org/10.1098/rspb.2016.1966">link between bird scent and bird genes</a>, suggesting that genetically dissimilar birds smell different than genetically similar birds. </p>
<p>I wanted to know whether birds, like humans, prefer the odour of genetically dissimilar partners, so I designed my own sweaty t-shirt experiment. I gave female song sparrows a choice between preen oil from males who were more or less genetically similar to themselves. Just like in the human study, <a href="https://doi.org/10.1016/j.anbehav.2019.10.005">female birds preferred the smell of genetically dissimilar males</a>. </p>
<p>What’s more, I gave male birds the same test and got the same result: males preferred the smell of genetically dissimilar females. </p>
<p>Birds and humans both prefer the scent of a genetically different partner. This can help us ensure our offspring are healthy and able to fight off harmful pathogens.</p><img src="https://counter.theconversation.com/content/151727/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leanne Grieves receives funding from the Natural Sciences and Engineering Research Council of Canada (NSERC). </span></em></p>Birds use body odour to smell out potential mates, and partners who are genetically unrelated to them smell more attractive.Leanne Grieves, McCall MacBain Postdoctoral Fellow, Dept. of Psychology, Neuroscience & Behaviour, McMaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1210722019-07-29T15:48:33Z2019-07-29T15:48:33ZBelligerent beetles show that fighting for mates could help animals survive habitat loss<figure><img src="https://images.theconversation.com/files/286026/original/file-20190729-43145-1p8sarc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">En garde!</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rhinoceros-beetle-on-wood-forest-243404500?src=x3wJuQTOXK6isXUv-_Gwog-1-1&studio=1">BaLL LunLa/Shutterstock</a></span></figcaption></figure><p>Animals around the world are seeing their environments change. <a href="https://theconversation.com/animals-will-struggle-to-adapt-fast-enough-to-cope-with-climate-change-study-finds-120857">Climate change</a> is causing heating and changes to weather patterns, the oceans are becoming <a href="https://theconversation.com/the-worlds-shellfish-are-under-threat-as-our-oceans-become-more-acidic-103868">more acidic</a>, and previously undisturbed habitats are being <a href="https://theconversation.com/habitat-loss-doesnt-just-affect-species-it-impacts-networks-of-ecological-relationships-117687">altered and degraded</a> by human activities.</p>
<p>If we want to understand how these changes will affect animals around the world, we need a better understanding of how their biology might determine how well they survive these changes. My colleagues and I have just <a href="https://doi.org/10.1111/ele.13358">published research</a> that demonstrates how important an animal’s mating system is to this. We found that species whose males compete for mates are more likely to survive damaging changes to their environment.</p>
<p>In many species, males try to woo females <a href="https://theconversation.com/strut-your-stuff-how-rockstars-and-peacocks-attract-the-ladies-29045">with signals</a> like calls, colouration or long tails, or they try to monopolise access to females by fighting other males with weaponry like horns or antlers. This competition for mates helps drive the evolution of these species, in a process called <a href="https://theconversation.com/why-men-are-not-biologically-useless-after-all-42012">sexual selection</a>. The most attractive or most aggressive mates are more likely to pass on their genes to the next generation and produce more offspring with their attractive features or aggressive nature. </p>
<p>There are many reasons to think competitive mating could affect the resilience of a species to environmental change. First, the signals and weapons that often evolve in those species where competition is more intensive are costly to grow and to carry. They can make animals more conspicuous to predators, and both contests with rival males and extravagant displays to females can use enormous amounts of energy. So these strongly sexually selected species could be less able to cope with environmental change because of these costs.</p>
<p>On the flip side, strong competition between males for mates means that only a few particularly strong, healthy or energetic males “win” and father the majority of the next generation. If the environment is changing, then males that are genetically best suited to the new environment are likely to be in the best condition. If these males end up as the winners in the competition for mating then their well-adapted genes will spread very rapidly. So strong sexual selection could make animal populations <a href="https://mast.queensu.ca/%7Etday/pdf/Lorchetal03.pdf">adapt faster to new environments</a>, making them more resilient in the face of it changing.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Peacocking is a costly mating strategy.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/indian-male-peacock-1147396844?src=8jEkBHVkTbTf6jxsFJXBGw-1-4&studio=1">Kandarp/Shutterstock</a></span>
</figcaption>
</figure>
<p>So which process is more important in influencing species survival? A <a href="https://www.nature.com/articles/s41467-019-10074-7">series of lab studies</a> have consistently found that strong sexual selection improves outcomes for animal species when the environment shifts from their optimum. But studies of animals in the field have often found either no effect of sexual selection or the opposite. For example, when birds have been introduced to islands <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.1998.00199.x">such as New Zealand</a>, then the species that are more sexually selected are less likely to become established.</p>
<p>One possible reason for this disparity is that the field studies have often concentrated on very small populations of animals. It’s possible that the effects of sexual selection on a population’s resilience vary with its size. </p>
<p>Very small populations living in a certain location might not have enough genetic variety to produce individuals that are very well adapted to its particular environment. In which case, the costs of sexual selection could make them more likely to go extinct. Whereas large populations are more likely to have the genetic variety that will produce “winning” males even when the environment is unfriendly.</p>
<p>What was needed was a field study of sexual selection and persistence in larger populations. To that end, my colleagues and I conducted a study, published in <a href="https://doi.org/10.1111/ele.13358">Ecology Letters</a>, of how dung beetles respond to environmental change in the rainforest of Sabah in Malaysian Borneo.</p>
<h2>Horny beetles</h2>
<p>Dung beetles are fascinating animals for many reasons, one of which is the diversity of their sex lives. Males from the familiar ball-rolling species do compete for matings. But there are also many species of dung beetle that don’t roll, instead burying dung directly under where they find it, and these species show much greater variability. Some species have <a href="https://www.sciencenewsforstudents.org/article/little-beetle-big-horns">males with horns</a>, which they use in <a href="http://hs.umt.edu/dbs/labs/emlen/documents/Emlen%20Publications/BRCLososEmlenFINALlowres.pdf">fights with other males</a>, whereas others are less strongly sexually selected, with hornless males who are less aggressive in their pursuit of mates.</p>
<p>Using an existing large-scale study called the <a href="https://www.safeproject.net/">SAFE Project</a>, we followed 34 species of beetle found in untouched “old growth” forest. We looked at how they fared in lightly-logged and heavily logged forest and then oilpalm plantation where the original forest was largely removed. </p>
<p>We found that those species with horns were more likely to survive in all these cases. Strikingly, all 11 remaining species in the most disturbed plantation environment carried horns. </p>
<p>We also compared species with relatively small horns against those with big horns for their size. We found that beetle species with big horns are not only more likely to survive in disturbed environments, but they also tend to have larger remaining population sizes.</p>
<p>This tells us that – in some particular cases at least – we should think about sexual selection as well as other aspects of an animal’s biology if we want to predict or to manage population sizes in the face of environmental change. Sexual selection is a ubiquitous and powerful force driving evolution in the animal kingdom and has been intensively studied by behavioural and evolutionary biologists. Maybe now it’s time ecologists and wildlife management specialists started to think about it as well.</p><img src="https://counter.theconversation.com/content/121072/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Knell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New evidence boosts the idea that species with males who compete for mates adapt faster to changing circumstances.Rob Knell, Reader in Evolutionary Ecology, Queen Mary University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1174462019-05-21T11:27:22Z2019-05-21T11:27:22ZBonobo mothers meddle in their sons’ sex lives – making them three times more likely to father children<figure><img src="https://images.theconversation.com/files/275668/original/file-20190521-23845-8784pd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-male-bonobo-walking-jungle-pan-407331436?src=HRiuQClsLfiopLQg60UEMg-1-29">Sergey Uryadnikov/Shutterstock</a></span></figcaption></figure><p>Dating is never easy, for any of us. Scenarios play over in our heads, classic questions and worries bombard us. Will she like me? Does he share the same interests? Will my mum be watching us have sex? Thankfully, that last question isn’t actually one we humans have to deal with. But <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(19)30338-0?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982219303380%3Fshowall%3Dtrue">new research</a> shows that for bonobos, sex really is often a family affair. What’s more, rather than being an embarrassing hindrance, motherly presence greatly benefits bonobo sons during the deed.</p>
<p>Along with chimpanzees (<em>Pan troglodytes</em>), bonobos (<em>Pan paniscus</em>) are our closest living relatives. Restricted to a 500,000 km² thickly-forested zone of the <a href="http://pin.primate.wisc.edu/factsheets/entry/bonobo">Congo Basin</a>, these endangered great apes were only formally discovered in 1928, which until <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(17)31245-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982217312459%3Fshowall%3Dtrue">2017</a> made them the most recently-described living great ape species.</p>
<p>Operating in female-led social <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/evan.21501">systems</a>, bonobos are capable of showing a wide range of what were long held as human-specific feelings and emotions, such as <a href="https://www.amazon.co.uk/Bonobo-Forgotten-Ape-Frans-Waal/dp/0520216512">sensitivity</a>, patience, compassion, kindness, <a href="https://science.sciencemag.org/content/336/6083/874">empathy</a> and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051922">altruism</a>.</p>
<p>They’re also perhaps the most promiscuous non-human species on the planet. While chimpanzee sex is tied closely to reproduction, up to <a href="https://www.jstor.org/stable/pdf/24980375.pdf?casa_token=qcSO4qG6HUsAAAAA:mCt3dYZWsLAZhDUYEfyokaEzhunqHZ7mv9zjoXTSo-LSC8x4XhSKoUfjCDZGzFsHAIYSsDpA0bf6VcI23IeyaVUEvjDd8xDltIDwJo5pEQNKim6VlkM">75%</a> of bonobo sexual behaviour is purely for pleasure. From saucy greetings and social bonding to conflict <a href="https://brill.com/view/journals/beh/152/3-4/article-p313_4.xml">resolution</a> and post-conflict <a href="https://www.scientificamerican.com/article/bonobos-use-sex-to-cool-tempers/?redirect=1">make-up sex</a>, sex serves <a href="https://www.jstor.org/stable/pdf/24980375.pdf?casa_token=qcSO4qG6HUsAAAAA:mCt3dYZWsLAZhDUYEfyokaEzhunqHZ7mv9zjoXTSo-LSC8x4XhSKoUfjCDZGzFsHAIYSsDpA0bf6VcI23IeyaVUEvjDd8xDltIDwJo5pEQNKim6VlkM">hugely important</a> functions in most aspects of bonobo social behaviour. Even the mere discovery of a new food source or feeding ground is enough to <a href="https://www.jstor.org/stable/pdf/24980375.pdf?casa_token=l7hL1eK07SIAAAAA:W3G87V0eoyDVR8kzXwz6EnY0LvAjP1l5cy2OgiKynIb5V3FqiE2NsfY43EEsOZ3gL_m1CNey9-tSw6uYlh4FqPShhUVXvALumo5X_it0dZwnNIPJA7c">spark a wave</a> of communal sexual activity.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=522&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=522&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275492/original/file-20190520-69169-72tucs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=522&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bonobo sex isn’t generally a private affair.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bonobo-love-lola-ya-democratic-republic-60692260?src=-kZ0IxjEn9RlXeiiG0dXjQ-1-4">Sergey Uryadnikov/Shutterstock</a></span>
</figcaption>
</figure>
<p>It seems that the number of reasons for a bonobo to have sex is surpassed only by the number of forms in which they do it. Indiscriminate of sex and <a href="https://www.nature.com/articles/srep16135#ref4">age</a>, the only combination strictly off limits in bonobo society is between a mother and her mature son. In addition to standard penetrative encounters, they frequently engage in manual genital massage and <a href="https://www.scientificamerican.com/article/bonobos-use-sex-to-cool-tempers/">oral</a> sex. These positionally creative apes are also the only animal (other than us) to practice tongue-on-tongue <a href="https://link.springer.com/article/10.1023%2FA%3A1026395829818">kissing</a> or <a href="https://www.scientificamerican.com/article/bonobos-use-sex-to-cool-tempers/?redirect=1">face-to-face</a> penetrative sex. The prominence of bonobos’ sexual behaviour in social life has led researchers to brand bonobos as the <a href="https://www.amazon.co.uk/Bonobo-Forgotten-Ape-Frans-Waal/dp/0520216512">“make-love-not-war apes”</a>.</p>
<h2>Meddling mothers</h2>
<p>Bonobo mothers, however, seem to make a war out of seeing their sons successfully make love. They’ve frequently been <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2010.1572">observed</a> to form coalitions with their sons to help them acquire and maintain high dominance rank, protect their sons’ mating attempts from interference by other males and even interfere in the mating attempts of other, unrelated males.</p>
<p>The <a href="https://www.eurekalert.org/pub_releases/2019-05/cp-bmw051519.php">new research</a>, published in Current Biology, shows that these strategies pay off. Males who had a mother present in their social group engaging in these behaviours were about three times more likely to produce offspring than males whose mothers were no longer part of the group.</p>
<p>Mothers of successful bonobo fathers were present more than twice as frequently during conception than in chimpanzees, a species in which males are socially dominant, and in which maternal presence provided no benefit to sons. Thus, it appears that the dominance of females in bonobo social systems allows mothers to exert behavioural influence to boost the sexual fitness of their sons.</p>
<p>This elevated female social power doesn’t just let bonobo mums get involved in their families’ sex lives, but is likely responsible for a host of peaceful and progressive traits rarely seen in the mammal world. Females practice sex even when <a href="https://link.springer.com/article/10.1007%2FBF02734089">not ovulating</a>, male-male competition is much <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ajp.22641">reduced</a>, and the species is remarkably tolerant to bonobos from outside of their social <a href="https://link.springer.com/article/10.1007/s10764-018-0058-2">group</a>. Perhaps us humans ought to take note of how positively society can change when females are in positions of influence. It’s probably better if we keep our sex lives parent-free, though.</p><img src="https://counter.theconversation.com/content/117446/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Garrod does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Bonobos may be the most promiscuous species on the planet. From meddling mothers to feeding ground excitement, their sex lives are unique in the animal world.Ben Garrod, Professor of Evolutionary Biology and Science Engagement, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1169502019-05-14T23:02:22Z2019-05-14T23:02:22ZBoredom in the mating market: Guppies demonstrate why it’s good to stand out<figure><img src="https://images.theconversation.com/files/274414/original/file-20190514-60537-xe3zd3.png?ixlib=rb-1.1.0&rect=12%2C161%2C1636%2C742&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A male guppy looks good when he looks different.</span> <span class="attribution"><span class="source">Mitchel Daniel</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>If you’re looking for love, it pays to stand out from the crowd. Or at least that’s how it works in some parts of the animal kingdom. Scientists have found that in several species – <a href="https://doi.org/10.1093/beheco/arn059">green swordtail</a> fish, <a href="https://doi.org/10.1006/anbe.1999.1225">Trinidadian guppies</a>, <a href="https://doi.org/10.1098/rspb.2013.1691">fruit flies</a>, <em><a href="https://doi.org/10.1038/sj.hdy.6800386">Poecilia parae</a></em> fish – ladies overwhelmingly go for the guy that looks different from the rest.</p>
<p>But the reason for this attraction to novelty has remained a mystery. So <a href="https://scholar.google.com/citations?hl=en&user=8eVrCPUAAAAJ&view_op=list_works&sortby=pubdate">my colleagues</a> <a href="https://scholar.google.com/citations?user=t2ybLKcAAAAJ&hl=en">and I</a> used the Trinidadian guppy to <a href="http://dx.doi.org/10.1098/rspb.2019.0435">investigate the psychology behind why</a> many females have an affinity for the unusual.</p>
<h2>Male features that attract females</h2>
<p>The guppy has long been a workhorse for biologists like me who are interested in understanding the mating decisions that animals make and the evolutionary forces behind those decisions. Male guppies attempt to woo females using courtship dances that show off the elaborate color patterns adorning their bodies. The females of the species are color pattern connoisseurs, carefully <a href="https://doi.org/10.1111/j.1558-5646.1987.tb05766.x">choosing among their suitors</a> based, in large part, on their visual appeal. This tendency has made the guppy an excellent model for studying mate choice.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UaVTzOK7IbQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Male guppies showcase their colors during their courtship dances.</span></figcaption>
</figure>
<p>Many types of animals exhibit what evolutionary biologists call directional preferences, an attraction to more of a certain thing – think <a href="https://doi.org/10.1016/j.anbehav.2018.02.004">bigger antlers</a>, a <a href="https://doi.org/10.1038/299818a0">longer tail</a> or <a href="https://doi.org/10.1111/j.1439-0310.1989.tb00511.x">brighter color spots</a>. And there are evolutionary theories that help make sense of these preferences. If a male can grow more extreme features, that can be a sign that he is in <a href="https://doi.org/10.1086/512046">good physical condition</a>, has <a href="https://doi.org/10.1098/rspb.1999.0607">good genes</a>, or would make a <a href="https://doi.org/10.1006/anbe.1996.0156">good parent</a>.</p>
<p>What’s less clear, though, is why females should value unusualness in a mate. </p>
<p>When puzzling over why this mating preference arose, it occurred to me that attraction to novelty fits with a simple kind of learning called <a href="https://doi.org/10.1016/j.nlm.2008.09.012">habituation</a>. Psychologists have long known that when an animal is repeatedly exposed to some stimulus – be it a sound, a touch or in this case a visual pattern – it responds to the stimulus less and less. This occurs because the nervous system starts to “tune out” repetitive information. Since repetitive information is usually unimportant, habituation helps to free up the animals attention for other more important things.</p>
<p>What’s interesting about habituation is that it’s pervasive: Virtually every animal species, including human beings, can <a href="https://doi.org/10.1016/j.nlm.2008.07.011">habituate to a wide range of things</a>. It’s the reason why the noise from the air conditioning unit seems loud and distracting when it first turns on, but before long you barely notice it.</p>
<p>I wondered if this might be happening in guppies. If females are tuning out the color patterns they commonly see, then a male with a different-looking pattern is going to have a huge advantage attracting mates.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=194&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=194&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=194&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=244&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=244&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274416/original/file-20190514-60545-1gyqqlf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=244&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Why does new colorful flair pay off with the ladies?</span>
<span class="attribution"><span class="source">Mitchel Daniel</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Testing whether habituation is what’s happening</h2>
<p>To test this idea, I had to determine whether preference for novel-looking males meets four key <a href="https://doi.org/10.1016/j.nlm.2008.09.012">criteria of habituation</a>.</p>
<p>First I needed to see whether repeated exposure to a stimulus – like the noisy air conditioner, or a particular color pattern – made the animals less interested in that thing. Scientists call this “responsiveness decline.” To test it, I took a group of female guppies and exposed them to a series of males that looked alike. Then, I observed how the females behaved toward a male with the now-familiar pattern.</p>
<p>Male guppies are persistent suitors, and females mostly ignore their courtship dances. But when a male catches their fancy, females will turn and <a href="https://press.princeton.edu/titles/6156.html">approach the male</a>, which can lead to copulation. The effect of exposure to males was striking: Females already familiar with the pattern responded about half as often to male courtship compared to females that had never seen any male color patterns before. I also found it took just 12 minutes of exposure to reduce female responsiveness, which shows that female interest is fleeting.</p>
<p><iframe id="s7TuY" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/s7TuY/1/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Next, I had to show whether isolating females from the stimulus causes their responsiveness to increase again, something called “spontaneous recovery.” This would be like the air conditioning unit turning off for a while, and then being noticeable again when it flips back on. I found that isolating females for a short period after exposure made them more responsive when I observed their behaviors with the familiar-looking male, meeting this criterion.</p>
<p>The third criterion is called dishabituation: After responsiveness to a stimulus has declined, exposure to a different stimulus should cause responsiveness to increase again. For instance, hearing the siren of a passing police car would make you notice the droning of the air conditioner again. And yes, showing females a different-looking male before observing their behavior towards the familiar-looking male caused them to show more mating interest, demonstrating dishabituation.</p>
<p>The fourth criterion is that exposure to one stimulus – like the familiar pattern – should not reduce interest in another stimulus – such as a different-looking pattern. This is why getting used to the noisy air conditioner doesn’t prevent you from noticing that passing siren. I tested this by exposing females to males that looked alike, as before, but this time I observed how they behaved towards males with a different-looking pattern. As expected, they showed the same level of interest as other females that had never seen any male color patterns before, meeting this criterion.</p>
<p>These results ticked all four of the habituation boxes. Female guppies do habituate to male color patterns, explaining their attraction to novelty. This means females tune out familiar-looking males, so that when a male with a new pattern shows up it really turns their heads. Females grow bored of males that look like all the rest, giving an edge to the distinctive.</p>
<p>It was exciting to discover the why of this behavior because while habituation has been extensively studied by psychologists, no one had linked it to attraction to unusual mates. Our study reveals the psychology behind this preference, and shows how ideas from other fields can help to explain biological phenomena.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/274469/original/file-20190514-60554-rzx43l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Something different stands out against the backdrop of what you’re used to.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/one-different-board-game-pawn-individuality-675370507">Tero Vesalainen/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Everyone notices the next new thing</h2>
<p>These results also provide clues about why attraction to novelty evolved. </p>
<p>There are a lot of reasons why habituation can be advantageous. The environment is constantly bombarding our senses with information, much of which is repetitive and unimportant. For example, when trying to meet an urgent deadline at work, you don’t want to be distracted by the lingering smell of the lunch you ate earlier. So when your brain keeps getting this same information, it starts to filter it out. By shifting your attention away from repetitive information, <a href="https://doi.org/10.1016/j.nlm.2008.07.011">habituation frees you up</a> to focus on what matters. Habituation can benefit guppies, too, helping them to notice an approaching predator, or a new food source.</p>
<p>Habituation probably evolved because it helps animals navigate these aspects of the environment, which are unrelated to choosing mates. Attraction to novel mates could therefore be a byproduct of the evolutionary forces that favored habituation in these other contexts. In other words, preference for unusual-looking mates might just reflect a general evolutionary advantage of habituation.</p>
<p>Because habituation is found in many species, preference for novel-looking mates may be a common and underappreciated force shaping mating decisions. Indeed, there is evidence that we humans <a href="https://doi.org/10.1098/rsbl.2013.0958">find novel-looking features attractive</a>. The mating habits of these tiny, colorful fish may be revealing something broader about the animal kingdom, and perhaps even our own desires.</p><img src="https://counter.theconversation.com/content/116950/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mitchel Daniel receives funding from Florida State University. Funding for this study was also provided by the National Science Foundation (IOS-1354775 and DEB 1740466). </span></em></p>The mating habits of these tiny, colorful fish may be revealing something broader about the animal kingdom, and perhaps even our own desires.Mitchel Daniel, Postdoctoral Fellow in Ecology and Evolution, Florida State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/921842018-03-11T09:02:16Z2018-03-11T09:02:16ZSex: birds do it, bees do it - and fungi do it too. Here’s how, and why it matters<figure><img src="https://images.theconversation.com/files/209695/original/file-20180309-30958-1w7hmly.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sweet-smelling, fluffy white fungus, _Huntiella moniliformis_, engaging in sexual reproduction in the lab.</span> <span class="attribution"><span class="source">Author supplied</span></span></figcaption></figure><p>Sex is an essential part of life. You, me and almost every other living organism on this planet are only here because two individuals got together at some point in the past to have their genes represented in the next generation. </p>
<p>For many species on earth – especially humans – that’s a pretty inflexible process. There are strict requirements: for instance, having two partners of the opposite sex tends to be indispensable for the production of offspring. </p>
<p>But there are a number of exceptions to this rigidity. Some of the most beautiful and interesting are exemplified by certain species of fungi.</p>
<p>Fungi play a variety of roles in our lives. Some are food sources, like button mushrooms; some are used in the production of cheese, wine, beer and bread. Others have provided humans with antibiotics for almost a century. And still others can cause great harm, wiping out trees by the hectare – or even killing humans.</p>
<p>And of course, like most species, fungi have sex lives. I study the sexual behaviour of <em>Huntiella moniliformis</em>, a sweet-smelling and fluffy white fungus that’s found in plantations all over the world. It’s fairly unique in that it’s unisexual – able to reproduce completely alone. </p>
<p>This makes it potentially very dangerous: even if it’s the only fungus in, say, an entire forest, it can keep mating and reproducing. It gets all the evolutionary benefits of sex, without having to go through all the trouble of finding a mating partner. </p>
<p>If we understand its sex life, we can come up with ways to control, manage or even stop it. That’s important in the case of species like <em>Huntiella moniliformis</em>, because they can infect damaged trees and cause disease. </p>
<h2>Fungal mating strategies</h2>
<p>In humans and most other mammals there is only one way to produce sexual offspring: sexual intercourse between a male and a female. Reptiles and birds often also reproduce heterosexually. </p>
<p>Fungi, meanwhile, can utilise one or more of six different sexual strategies. These range from the fungal equivalent of heterosexuality to changing their mating type as necessary.</p>
<p><strong><a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.1949.tb00582.x/pdf">Heterothallism</a></strong>: is like heterosexuality in humans and requires two partners. In humans, having two X chromosomes makes you female; having an X and a Y chromosome makes you male. Some fungi use a similar system but instead of a whole chromosome they use single genes. A fungus with the <em>MAT1</em> gene is of the MAT1 mating type; having the <em>MAT2</em> gene means its mating type is MAT2. </p>
<p>For sex to take place, MAT1 and MAT2 partners need to get together. This means that out of everyone you meet, only half are sexually compatible with you. This severely limits the number of successful partners a fungus can meet in its search for a mate.</p>
<p>So how do they find each other? Smell. Or, at least, something similar: pheromones. These are small molecules that let a MAT1 individual know that a MAT2 individual is close, and vice versa. This ensures that no one wastes time and energy slowly growing towards an incompatible partner. </p>
<p><strong>Primary homothallism:</strong> is when a single fungus has sex completely alone. Instead of having either the <em>MAT1</em> or the <em>MAT2</em> gene, they have both. In this way a single individual can make both pheromones and recognise itself as a partner. There are other forms of self-sex too. Two of these include the ability to change mating type. These systems mimic those of some fish that can switch between male and female, depending on what partners are available. The third relies on having two genomes and is functionally very similar to heterothallism. </p>
<p>The fourth lonely sexual strategy completely changed the way we think about sex in fungi. <strong>Unisexuality</strong> occurs in individuals we would classically have thought to be either MAT1 or MAT2. We would have expected them to need a partner, but they don’t.</p>
<p>My PhD research at the <a href="https://www.fabinet.up.ac.za/">Forestry and Agricultural Biotechnology Institute</a> in South Africa has revealed that unisexual reproduction is possible in <em>H. moniliformis</em>. My supervisors and I have recently <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0192517">shown</a> that MAT2 individuals are able to secrete both pheromones, despite the absence of the <em>MAT1</em> gene. </p>
<p>This means that a single mating type can recognise itself as a compatible partner and respond appropriately. We are currently working on understanding how this system evolved and whether related species could be manipulated to employ the same strategy.</p>
<h2>Why does this matter?</h2>
<p>There are obvious evolutionary benefits to species having sex. The most obvious is because it ensures a species’ longevity. But there are downsides – not for <em>H. moniliformis</em>, in this case, but for forestry plantations. </p>
<p>Sex combines genes from different individuals and produces genetically unique offspring. In disease causing fungi this has been shown to enable host jumping – the movement from a susceptible host species such as a Pine tree in a plantation, to a previously resistant species, like an indigenous tree in a natural forest. </p>
<p>This means that hosts previously thought to be immune to infection could get infected in the future, and can cause serious disease outbreaks that are difficult to control. </p>
<p>The other downside to sex in fungi like <em>H. moniliformis</em> is that it produces easily dispersible spores. These are often the agent that enhances fungal spread and infection. </p>
<p>Understanding these processes, and the sex lives of fungi like <em>H. moniliformis</em>, can help us find answers to how to control the spread of diseases. This will ultimately mean keeping plantations – and humans – safer.</p><img src="https://counter.theconversation.com/content/92184/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andi Wilson receives funding from the National Research Foundation (NRF). </span></em></p>Understanding the sex lives of fungi can help in finding answers about disease control.Andi Wilson, PhD: Genetics Candidate, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/719032017-01-27T13:00:38Z2017-01-27T13:00:38ZFish show cheating can be better than playing by the rules in the mating game<figure><img src="https://images.theconversation.com/files/154546/original/image-20170127-30394-514ou6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The males of some species go to extraordinary lengths to attract females – but some simply cheat. Take African cichlid fish. Many males build underwater “sandcastle” structures that the females use to judge the quality of their potential mates. But, as my colleagues and I found out during a <a href="http://www.nature.com/articles/srep41128">recent study</a>, some males don’t bother with this show of construction prowess, and instead are able to father offspring by engaging in “sneaky mating”.</p>
<p>There are hundreds of species of colourful cichlid fish in Lake Malawi, Africa, and about two hundred of these build pit- or volcano-shaped structures known as “bowers” out of sand. Each species builds a slightly different type of sand bower, and they function as a signal of male quality, both to <a href="https://www.researchgate.net/profile/Martin_Genner/publication/228646881_A_role_for_male_bower_size_as_an_intrasexual_signal_in_a_Lake_Malawi_cichlid_fish/links/55846dbc08ae7bc2f4483742.pdf">other males</a>, and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1558-5646.2010.00984.x/full">to females</a>.</p>
<p>The females are what are known as <a href="http://www.cichlid-forum.com/articles/mouthbrooders.php">mouthbrooders</a>. After courtship with their male partners, which takes place on top of the bower, the females lay eggs and pick them up in their mouths. The males then fertilise the eggs while they are still in the females’ mouths.</p>
<p>The females then carry the eggs for about three weeks until they hatch into baby fish known as “fry”. The male contributes no parental care, nothing but his genetic material. So the females need to ensure they choose high quality males, and they use the shape of his bower to do this.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QGtCFgNcdJY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The males even help the females to do this by congregating in breeding arenas <a href="https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=0ahUKEwiWjoysm-LRAhXMDMAKHVWuAw8QFggxMAI&url=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2FBF00005175&usg=AFQjCNGuqsCgnrKZR42iP-5xSTQK5BGnaw">called “leks”</a>. The females can then visit a lek and judge a large number of males at once, usually laying only a handful of eggs with each chosen male. The ability to build and defend a bower in this hotbed of male activity is thought to demonstrate the quality of the male to the females. It takes two to three weeks for each male to build his bower and he has to work hard to maintain it over a breeding season of several weeks.</p>
<h2>No bower needed</h2>
<p>But we wondered whether there was another way that male cichlids could father offspring without building a bower. Trying to find this out in the wild would be very difficult, so we recreated a mini-version of their habitat for a breeding population of fish in <a href="http://www2.hull.ac.uk/science/biologicalbiomedicalenvironmen/facilities/aquaria.aspx">our aquarium system in Hull</a>. We then implanted tiny tracking microchips into the fish, similar to those often implanted into pets, and allowed the males to form a lek in a large tropical pond.</p>
<p>We also put microchip readers on to the bowers as they were built so we would know which males had built and were defending a bower and which weren’t. We then waited until a number of females were brooding and then DNA paternity-tested their offspring to find out which males had been most successful.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mine’s the biggest.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We found that bower-owning males were considerably more successful than non-bower owning ones, which makes evolutionary sense given the considerable effort and investment it requires. But a small number of non-bower holding males still fathered offspring, showing that an alternative strategy can be successful. Male cichlids spend a lot of time chasing away rivals. This suggests that some non-territorial males attempt to sneak past the bower holders and distract the females, persuading them to hedge their bets and mate again. </p>
<p>There’s still a lot we don’t know about these fish. How did so many species evolve in such a short evolutionary <a href="http://news.stanford.edu/news/2014/september/fish-genome-fernald-092214.html">time scale</a>? What is the genetic basis for their behaviour? What determines female preference and why? How do changes in the environment affect their ability to attract mates?</p>
<p>Studying these questions provides a wider insight into the evolution of complex behaviours and the way that female choice can shape evolution. Males who build impressive sandcastles are favoured by females, and this has driven their evolution. But it’s possible that being sneaky could also be a viable strategy for evolutionary success.</p><img src="https://counter.theconversation.com/content/71903/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Domino Joyce has received funding from the Leverhulme Trust, and NERC. </span></em></p>Some fish build sandcastles to attract a mate but others just use sneaky tactics.Domino Joyce, Senior Lecturer in evolutionary biology, University of HullLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/703122016-12-14T00:03:34Z2016-12-14T00:03:34ZHow penis bones help primates win the mating game – and why humans might have lost theirs<figure><img src="https://images.theconversation.com/files/149963/original/image-20161213-1600-15vpl5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">All shapes and sizes.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Armand_de_Montlezun_Baculum_Ursus_arctos.jpg">Didier Descouens</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>One of the most weird and wonderful products of evolution is the penis bone, or baculum. The baculum is an extra-skeletal bone, which means it is not attached to the rest of the skeleton but instead floats daintily at the end of the penis. Depending on the animal, bacula range in size from under a millimetre to nearly a metre long, and in shape, varying from needle-like spines to fork like prongs. </p>
<p>The <a href="http://qi.com/infocloud/penises">walrus baculum</a>, which could easily be mistaken for a 2ft-long club, is around a sixth of its body length, whereas the diminutive centimetre-long baculum of the ring-tailed lemur is only around a 40th of its body length.</p>
<p>Bacula are found in certain species of mammal, but not all. Most primate males have a baculum, so humans are rather an oddity in that they don’t have one. In a handful of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3650806/">extraordinary circumstances</a> human males have formed bones in the soft tissue at the end of their penises, but this is a rare abnormality, rather than a baculum.</p>
<p>In a new study, published in <a href="http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2016.1736">Proceedings of the Royal Society B</a>, my colleague Kit Opie and I examined how the baculum developed in mammals by studying how it is distributed across different species in light of their pattern of descent (known as phylogenetics).</p>
<p>We showed that the baculum first evolved after placental and non-placental mammals split, around 145m years ago, but before the most recent common ancestor of primates and carnivores evolved, around 95m years ago. Our research also shows that the common ancestor of primates and carnivores had a baculum. This means that any species in these groups without a baculum, such as humans, must have lost it over the course of evolution.</p>
<p>So, why on earth would an animal need a bone in their penis in the first place? Scientists have come up with a few theories as to why a baculum might be handy. In certain species, such as cats, a female’s body doesn’t release its eggs until she mates, and some argue that the baculum may help to stimulate females and <a href="http://onlinelibrary.wiley.com/doi/10.1002/ar.1090580302/abstract">trigger ovulation</a>. Another, somewhat colourfully named, theory is the <a href="http://jmammal.oxfordjournals.org/content/49/1/32.abstract">vaginal friction hypothesis</a>. This essentially argues that the baculum acts as a shoehorn, enabling a male to overcome any friction and squeeze himself into a female.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149885/original/image-20161213-1608-oyatfu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Is that it?</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Finally, it has been proposed that the baculum helps prolong intromission, otherwise known as vaginal penetration. Far from simply being a nice way to spend an afternoon, prolonging intromission like this is a way for a male to prevent a female from sneaking off and mating with anyone else before his sperm have had a chance to work their magic. This theory brings a whole new meaning to the term “cock-blocking”.</p>
<p>We found that, over the entire course of primate evolution, having a baculum was linked to longer intromission durations (anything over three minutes). On top of this, males of primate species with longer intromission durations tend to have far longer bacula than males of species where intromission is short.</p>
<p>Another interesting discovery was that males of species facing high levels of sexual competition for females have longer bacula than those facing lower levels of sexual competition.</p>
<p>But what about humans? If the penis bone is so important in competing for a mate and prolonging copulation, then why don’t we have one? Well, the short answer to that is that humans don’t quite make it into the “prolonged intromission” category. The average duration from penetration to ejaculation for human males is <a href="http://onlinelibrary.wiley.com/doi/10.1002/ajpa.1330060119/abstract">less than two minutes</a>.</p>
<p>But bonobos only copulate for about 15 seconds at a time and they still have a baculum, even if it is very small (about 8mm). So what makes us different? It’s possible that this comes down to our mating strategies. Human males (generally) have minimal sexual competition as females typically only mate with one male at a time. Perhaps the adoption of this mating pattern, in addition to our short intromission duration, was the last straw for the baculum.</p>
<p>Scientists are only just beginning to piece together the function of this most unusual bone. What seems to be clear is that changes in the primate baculum are driven, at least partly, by a species’ mating strategy. The picture that seems to be emerging is that, under high levels of sexual competition, bigger is better when it comes to the penis bone.</p><img src="https://counter.theconversation.com/content/70312/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matilda Brindle receives funding from the London NERC DTP (NE/L002485/1). </span></em></p>New research uncovers the role of the primate baculum and may explain why humans don’t have one.Matilda Brindle, PhD candidate on the London NERC DTP, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/513272015-12-01T21:21:02Z2015-12-01T21:21:02ZThe spectacular peacock spider dance and its strange evolutionary roots<figure><img src="https://images.theconversation.com/files/103837/original/image-20151201-26546-190yro8.JPG?ixlib=rb-1.1.0&rect=1016%2C729%2C3065%2C2126&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Look at me! They're not called peacock spiders for nothing.</span> <span class="attribution"><span class="source">Maddie Girard</span>, <span class="license">Author provided</span></span></figcaption></figure><p>With their flamboyant dress, and fabulous song and dance routines, tiny <a href="https://en.wikipedia.org/wiki/Maratus_volans">peacock spiders</a> have <a href="http://www.livescience.com/51740-peacock-spider-dances.html">captivated the hearts</a> of the internet.</p>
<p>Many species have courtship displays, but few are as complex as that of the peacock spider. But why does this little Casanova put on such a spectacular show, particularly when we’d expect evolution to favour simplicity?</p>
<p>We set up an <a href="http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2015.2222">elaborate experiment</a> to find out. But before we raise the curtain on that, we need to set the scene.</p>
<h2>What’s in a signal?</h2>
<p>Imagine a high school suitor picking up his date for the prom, and we might picture him exiting a limousine wearing a tux with bouquet in hand. We’d argue (and he’d likely agree) that each of these things improves his chances of impressing his date. </p>
<p>But what kind of information is his date gleaning from these signals? Is he trying to make sure that his date notices that he can afford extravagance, and therefore, he’s signalling his wealth and success? Or does the car signal his wealth, his tux his desire to look good, and his flowers his love for nature? If so, then these aspects work together to signal his overall suitability as a mate.</p>
<p>Regardless of what motivated his signals, we’d probably all agree that that this wide-eyed youngster is trying to impress his date. But is this true? Isn’t it just as likely that this extravagance is signalling to other males that they should stay away? Or is it just the social norm to appear in a limo with a tux and flowers, otherwise he’d look out of place?</p>
<p>This is the problem biologists have faced when trying to explain the existence of complex courtship that uses multiple traits: what is driving a male’s improved dress and his desire to impress? </p>
<p>The answer has escaped biologists because single, simple traits are generally the norm. Sometimes we have species that use multiple traits, like the colourful plumage and elaborate dances of some birds, but the use of multiple traits is very rare. </p>
<p>Biologists’ favourite example of courtship complexity is the <a href="http://animals.nationalgeographic.com.au/animals/birds/bird-of-paradise/">birds of paradise</a>. </p>
<p>With 39 different species, there is a diversity of vocal signalling, extreme variation in colouration and dances that accompany both. But despite our desire to explain this diversity as a result of female preference, there is no such evidence. Until now.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YTR21os8gTA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The extreme variation in courtship found in birds of paradise, and the difficulty in observing them.</span></figcaption>
</figure>
<h2>Along came a spider</h2>
<p>Peacock spiders (<em><a href="http://bie.ala.org.au/species/Maratus%20volans">Maratus volans</a></em>) are a group that is unique to Australia. With more than 40 documented species, and likely many more to discover, it is an example where <a href="https://www.facebook.com/PeacockSpider/">citizen science</a> is helping us understand the diversity in this group.</p>
<p>It is this diversity, abundance and their extroverted courtship behaviour in the lab that really allows us to explore why such complexity exists and what it means.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103804/original/image-20151130-26574-wtho8y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">You can see the camera above the mating arena surrounded with acetate to provide a safe habitat for them to court. The laser virbrometer is just behind Maddie Girard.</span>
<span class="attribution"><span class="source">Maddie Girard</span></span>
</figcaption>
</figure>
<p>So to explore peacock spider courtship, we collected 128 male and female spiders from around Sydney and brought them back into the lab. Then by creating a courtship arena consisting of nylon stretched over a wooden frame and naturalising it with some leaves, we were able to record the behaviours using a video camera and the vibrational songs that males produce using a laser vibrometer. </p>
<p>What we found was rather interesting. We discovered that males use several different aspects to court a female.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/sUypt5lMYUo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A video of a different components of the courtship males use to court a female.</span></figcaption>
</figure>
<p>Males use vibrations early on to gain a females attention. When they are sure she’s watching, they begin to escalate courtship by waving their front legs and showing off their fan. If the female begins ignoring the male, they change their strategy and begin vibrating more. </p>
<p>We found that there was a very low success rate: only 16 of the 64 males were successful! And it was visual signalling effort that best predicted success – so the tux was more effective than the serenade. It was the males that were best able to show off their fans while ensuring that females were constantly watching. </p>
<p>Our other interesting finding was that females were very clear about what they didn’t like. During courtship, if a female signalled her displeasure by waving their abdomen back and forth, there was a low chance of success. Males therefore received feedback to their performance. So it seems that being attentive pays off.</p>
<p>The low success rate when courting virgin females (and potential death), coupled with the fact that none of our mated females re-mated suggests that success is very low in nature and only the males that best show off their stuff succeed.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103806/original/image-20151201-26559-1liufc5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A displeased female Maratus volans that’s taken it out on her suitor.</span>
<span class="attribution"><span class="source">Maddie Girard</span></span>
</figcaption>
</figure>
<h2>What we can learn from little spiders</h2>
<p>Female peacock spiders are picky, and it’s this scrupulous behaviour that has likely led to the strong selection for the complexity of male courtship.</p>
<p>Understanding this is important because it provides us with insight into the evolution of traits as signals and the situations necessary for such complexity to evolve. These answers have eluded biologists so far because natural variation in the success of courting males is extremely difficult to observe.</p>
<p>The next step is to explore whether the species that show increased complexity have even pickier females. </p>
<p>But for know, we can learn from these little Aussie wonders and say that if you’re strutting your stuff on the dance floor or through virtual interactions on the internet, pay attention to what the female has to say. Perhaps you may increase your chances as you’ll know where to put your effort.</p>
<p><em>Check out the video below to learn more about Maddie and some of the diversity in courtship from other species.</em></p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/mq-r20mlGes?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The diversity of courtship from other species of Maratus produced by SciFri.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/51327/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Kasumovic receives funding from the ARC in the form of a fellowship and received funding from the Hermon Slade Foundation to perform this research.</span></em></p><p class="fine-print"><em><span>Damian Elias receives funding from the NSF for his research on communication and multimodal signalling and received funding from the Hermon Slade Foundation to perform this research.</span></em></p><p class="fine-print"><em><span>Madeline Girard received funding from the NSF GROW program to support her PhD research.</span></em></p>Biologists, along with most of the internet, have been puzzled as to why peacock spiders have such flamboyant courtship displays. So we decided to find out.Michael Kasumovic, Evolutionary Biologist, ARC Future Fellow, UNSW SydneyDamian Elias, Assistant Professor in Evolutionary Biology, University of California, BerkeleyMadeline Girard, PhD student in evolutionary biology, University of California, BerkeleyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/370102015-02-12T07:17:25Z2015-02-12T07:17:25ZForget opposites attract – to be happy, find someone like you<figure><img src="https://images.theconversation.com/files/71643/original/image-20150210-24679-164g4he.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Yin and yang or two peas in a pod? </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Relationships are often interpreted as the outcome of an exchange of goods and services. Common knowledge says that the sexes want different things from a partner. </p>
<p>These preferences are often reduced to shallow, one-dimensional demands – beauty for men and resources for women. “Opposites attract,” they say. No one asks, “Why did that beautiful, young woman marry that old, old man?” because they already know the answer. He had something she wanted and she had something he wanted. </p>
<p>This <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=6734712&fileId=S0140525X00023992">exchange view of relationships</a> is constantly reinforced – from Shakespearean sonnets and modern romantic comedies to a mother’s advice – and the conclusion seems self-evident. Men and women are two sides of a coin, the yin to the other’s yang. And all any of us are doing is attempting to get the <a href="http://www.ncbi.nlm.nih.gov/pubmed/20006552">most out of a partner</a> for what we’re offering on the mating market. </p>
<p>The only problem is it’s wrong, according to the latest research. </p>
<h2>Why we think opposites attract</h2>
<p>The prevalent view that opposites attract and it’s all about an exchange is in line with <a href="http://www.jstor.org/stable/2091961?seq=1#page_scan_tab_contents">decades of research</a> in the mate choice literature. The argument, rooted in basic sex differences, is that males and females engage in fundamentally different strategies to ensure their ability to survive and reproduce. Because males invest less than females do in reproduction, they benefit more from <a href="http://www.anthro.utah.edu/PDFs/trivers1972.pdf">taking multiple partners</a> than do females. </p>
<p>Thus, males assess indicators of a partner’s reproductive ability. This assessment is particularly acute for our species because women’s window of fertility is quite short relative to a man’s. So men place a greater importance on the physical attractiveness of a potential partner because it serves as an indicator of fertility. </p>
<p>Females, on the other hand bear the brunt of reproductive costs and so access to resources becomes central to raising successful young. Thus women, who have some of the most expensive children in the animal kingdom, are quite interested in a partner’s ability to invest. Women desire indicators of a man’s ability to acquire and provide resources. Thus, our opposite preferences are, at their simplest, due to our basic sex differences. </p>
<h2>Likes attract</h2>
<p>But more recent work challenges this simple “opposites attract” approach. <a href="http://rsos.royalsocietypublishing.org/content/2/1/140402">For example</a>, while men are often labeled as preferring multiple partners, these preferences are inappropriately assumed. Many men are quite averse to short-term uncommitted relationships and instead desire long-term relationship commitment with a single partner. </p>
<p>Increasingly, findings from cross-cultural studies of mate choice run counter to Western notions of “opposites attract.” For example, in some cases men are the ones who desire an <a href="http://www.sciencedirect.com/science/article/pii/S1090513808000081">investing partner</a> and in others women show a clear preference for <a href="https://www.youtube.com/watch?v=Dm1tN3SmDWs">male beauty</a> and <a href="http://www.pnas.org/content/111/40/14388.abstract">feminine traits</a>. So should we just dismiss this as a Western quirk, and just chalk up another explanation to “cultural differences?”</p>
<p>Not so fast. A body of theory in reproductive decision making referred to as <a href="http://www.britannica.com/EBchecked/topic/39494/assortative-mating">assortative mating</a> has recently been building up an <a href="http://mitpress.mit.edu/books/adapting-minds">impressive body of support</a>. Central to theoretical expectations is that those individuals who are more alike will end up together. This should be thought of as antitheses to claims of “opposites attract” and referred to as a “likes attract” approach. </p>
<p>For example, “likes attract” research finds that partner preferences are strongly influenced by how, for example, <a href="http://www.pnas.org/content/100/15/8805.abstract">individuals rate themselves</a>. That is, people who rate themselves high as a mate are generally more demanding of a high quality mate. More specifically, if an individual rates him/herself high on a trait (such as physical attractiveness, education, trustworthy, etc) they desire a partner that also scores high on that trait as well. </p>
<h2>It all comes down to partner matching</h2>
<p><a href="http://asr.sagepub.com/content/early/2014/05/29/0003122414536391.abstract">Recent work</a> exploring this approach using US data finds that yes, as is commonly expected, physically attractive women often desire high status men, and high status men want physically attractive women. However, if the data is analyzed from a “likes attract” approach, it is clear that attractive women want attractive men and high status men want high status women. Like for like. </p>
<p>Thus, relationships don’t seem to be about an exchange of goods and services but instead about partner matching. Therefore the apparent robustness of sex differences in preferences may largely be an artifact of the focus on sex at the expense of other more meaningful variables.</p>
<p>But why do see this pattern? Why do we want someone like us? Well, if we look across the animal kingdom it’s easy to see that humans are unusual creatures. Monogamy among animals is <a href="http://www.ncbi.nlm.nih.gov/pubmed/20006552">extremely rare</a>. Even more unusual is paternal care. And because our children take a long time to develop and require the help of a dad, <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0089539#pone.0089539-Ellis1">long-term stable relationships</a> are likely in the best interest of both parents. Thus, pairing based on similar traits and evaluations as a mate possibly make for more enduring pair-bonds over time. </p>
<p>In conclusion, most of us desire to one day find our soul mate. We pine for that one perfect somebody whose sole purpose for existence is to be found by us. But, if we are all seeking our other half, the one who completes us, why do most relationships end in failure? Why is love so full of heartache? Possibly because an “opposites attract” approach to a relationships is doomed from the beginning. If you want to be happy it would seem that you need to be realistic about yourself. Who makes the best mate for you is not some cultural or societal ideal, but someone who matches you.</p><img src="https://counter.theconversation.com/content/37010/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Schacht does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Relationships are often interpreted as the outcome of an exchange of goods and services. Common knowledge says that the sexes want different things from a partner. These preferences are often reduced to…Ryan Schacht, Postdoctoral Fellow in Anthropology, University of UtahLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/363762015-02-02T07:01:19Z2015-02-02T07:01:19ZWhy do groundhogs emerge on February 2 if it’s not to predict the weather?<p>According to legend, if the groundhog sees his shadow on February 2nd, there will be six more weeks of winter; if not, an early spring is predicted. </p>
<p>Of course groundhogs – also known as woodchucks – don’t emerge at this time just to be furry weather predictors. So what’s the real reason? Research into groundhog biology shows they have other priorities in early February than mingling with the people of Punxsutawney, Pennsylvania. </p>
<h2>It’s Groundhog Day!</h2>
<p>Groundhog Day appears to have <a href="http://www.cambridge.org/us/academic/subjects/life-sciences/animal-behaviour/marmot-biology-sociality-individual-fitness-and-population-dynamics">European roots</a>. Early February is midway between the winter solstice and the spring equinox, and throughout history this seasonal crossroads has been celebrated. The ancient Greeks and Romans observed a mid-season festival on February 5th in anticipation of spring. In the Celtic tradition, this period was celebrated as the festival of Imbolog to mark the beginning of spring. Early Christians in Europe embraced this tradition and celebrated Candlemas Day on February 2nd, to commemorate the purification of the Virgin Mary. Customarily on this day, clergy would bless candles and distribute them to the people in the dark of winter in anticipation of spring.</p>
<p>In northern Europe, farmers needed some indication when to start spring planting. They looked for the emergence of hibernators, such as the hedgehog or badger, to signal the coming of spring. Since their emergence occurred in early February, it was believed that if Candlemas Day was sunny, and the hibernator saw its shadow, more wintry weather was ahead. But if it rained or snowed on Candlemas Day, the rest of the winter would be mild.</p>
<p>This tradition was brought to America by the Germans who migrated to eastern Pennsylvania. They found groundhogs in profusion in many parts of the state and decided this mammal was a perfect replacement for the hibernators they’d left behind in Europe. Thus, the tradition continued in America.</p>
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<a href="https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=581&fit=crop&dpr=1 754w, https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=581&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/70035/original/image-20150126-24541-1ji5h11.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=581&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Female groundhog emerging from her burrow in late January.</span>
<span class="attribution"><span class="source">Stam Zervanos</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Hibernation helps survival</h2>
<p>In my study area in southeastern Pennsylvania, the average date groundhogs emerge from their burrows is February 4. This fits the folklore and the timing of Groundhog Day. However, predicting the weather is not their objective.</p>
<p>The real reason is related to Darwinian fitness – a measure of an organism’s ability to contribute its genes to the next generation. The process defines natural selection and is based on an organism’s ability to survive and to reproduce successfully. High Darwinian fitness suggests an individual will pass on its genes to many healthy offspring.</p>
<p>Hibernation contributes to Darwinian fitness value. It enhances survival by <a href="http://dx.doi.org/10.1086/367950">saving energy</a> during times of limited food availability. The ability to hibernate is found in several mammalian groups, including all marmots, many species of ground squirrels, chipmunks, hamsters, badgers, lemurs, bats and even some marsupials and echidnas. Curled up in their burrows, they pass the winter months, when food would be hard to come by. </p>
<h2>Hibernation: alternating torpor and arousal</h2>
<p>Hibernation is characterized by a significant drop in body temperature and metabolic function. This process is commonly called torpor. During torpor, body functions including heart rate, breathing rate, and brain activity are reduced. The overall benefit for the animal is saving metabolic energy at a time when it isn’t eating.</p>
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<a href="https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/70051/original/image-20150126-24531-1dnzd7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This Maine groundhog had 17 torpor bouts where body temperature went up and down.</span>
<span class="attribution"><span class="source">Stam Zervanos</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>However, for some still unexplained reason, hibernators arouse periodically during their hibernating season. These arousals come at a great energy cost. Therefore, arousing must be critical to survival in some way or animals wouldn’t waste the energy on it. Some <a href="http://dx.doi.org/10.1152/physrev.00008.2003">possibilities</a> include maintaining cellular functions or disposing of bodily wastes.</p>
<p>In Pennsylvania, these bouts of torpor and arousal continue throughout the hibernation season, starting on average in mid-November and ending by the beginning of March; a total of about 110 days. In <a href="http://dx.doi.org/10.1093/icb/ict100">one study,</a> an average of 15 bouts of torpor occurred during this period, with arousals in between. Groundhogs aroused for about 41 hours and then returned to torpor for about 128 hours for males and 153 hours for females. </p>
<p>In a 2010 study, we determined that the hibernation periods for groundhogs <a href="http://dx.doi.org/10.1086/648736">increase in length with increasing latitude</a>. The hibernation period matches winter’s duration. The celebration of Groundhog Day would need to change by latitude in order to perfectly match groundhog emergence.</p>
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<figcaption>
<span class="caption">Male groundhog (on the right) greeting a female groundhog for the first time after they emerge from their separate burrows.</span>
<span class="attribution"><span class="source">Stam Zervanos</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>It all boils down to sex</h2>
<p>One of the drawbacks of hibernation is the reduced time available for reproduction. Thus, hibernators have developed mating strategies to maximize reproductive success. Groundhog <a href="http://www.jstor.org/stable/1931796">mating strategies</a> involve temporary emergence in early February, mating in early March during during their final arousal, and giving birth in early April. This behavior enhances reproductive success because young are born as early as possible (but not too early) and are able to start feeding in May when lots of food is available. That way they have enough time to gain sufficient weight to survive their first winter hibernation.</p>
<p>But why do groundhogs emerge in February, when mating won’t occur until next month? The answer lies in their <a href="http://www.jstor.org/stable/1383202">social structure</a>. Most of the year, male and female groundhogs are solitary and antagonistic against each other. They aggressively maintain a feeding territory around their burrows and rarely have any contact with each other. February is used to <a href="http://dx.doi.org/10.1093/icb/ict100">reestablish the bonds</a> necessary for mating and ensures that mating can then proceed without delay in early March. </p>
<p>So for the animals themselves, Groundhog Day is more like Valentine’s Day. On February 2nd, groundhogs don’t emerge to predict the weather, but to predict whether their own mating season will be a success!</p><img src="https://counter.theconversation.com/content/36376/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stam Zervanos does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It’s all about mating success.Stam Zervanos, Emeritus Professor of Biology, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/361042015-01-14T10:29:37Z2015-01-14T10:29:37ZMating market theory: the math of one-night stands and long-term relationships<figure><img src="https://images.theconversation.com/files/68913/original/image-20150113-28446-6fe3pu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sex ratio in your community may affect what you're looking for in a relationship.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-228645016/stock-photo-people-dating-and-finding-love-large-crowd-of-people-in-the-shape-of-hearts.html">Hearts image via www.shutterstock.com.</a></span></figcaption></figure><p>Popular wisdom and established evolutionary science hold that the sexes seek fundamentally different relationships: men want short-term, no-strings-attached relationships whereas women value longer-term, loyal partnerships. </p>
<p>The explanation generally comes down to biological differences between men and women. Because women invest more in reproduction than men do – think pregnancy, morning sickness and stretchmarks – being picky becomes important because choosing poorly can be costly, even devastating. However, for men, reproduction may only entail a brief sexual liaison and a bit of sperm – there are potentially no long-term costs. This calculus has been <a href="http://www.bradley.edu/dotAsset/165805.pdf">built into our psychology</a>, many argue.</p>
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<a href="https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68867/original/image-20150113-28452-vkqe66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sorry sweetie, there are too many fish in the sea.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Paradise_fish_femail_and_male_01.jpg">A-kun--a</a></span>
</figcaption>
</figure>
<p>Think about it more carefully, though. Where do all the women sleeping with these guys come from? Shouldn’t it be difficult for men to find so many willing partners? As theorist <a href="http://www.sciencedirect.com/science/article/pii/S0169534703000090">Hanna Kokko noted</a>, it takes two to tango. </p>
<p>If we go by the numbers, in a group with an equal number of both sexes, it is impossible, on average, for men to have more partners than women. So why do we expect male psychology to be so hellbent on one-night stands? And why, clearly in opposition to this notion, are many men often so devotedly paternal? </p>
<p>Here’s where an established body of literature in sociology and demography – called <a href="http://www.sagepub.com/books/Book902">mating market theory</a> (MMT) – can help out. According to MMT, relationship preferences are expected to follow not simply from these fixed biological propensities, but also to be heavily influenced by partner availability. </p>
<p>If we think of the number of men and women in market terms, namely supply and demand, the rarer sex has more bargaining power in the market place. Individuals of the less numerous sex are more likely to get their way because they are awash with options. In theory, they can, if not pleased with a relationship, or terms therein, easily replace a disappointing partner. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68855/original/image-20150113-28440-1namzt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Step out on me, maybe I’ll step out on you.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Mandarin_Pair.jpg">Francis C. Franklin</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The more abundant sex, by contrast, has fewer outside options and must cater to the preferences of the rarer sex. For example, when there are extra women, men face a favorable market and can behave promiscuously, offering little parental investment to their mates. However, when women are in short supply, they can demand relationship faithfulness and commitment – with men responding because female partners are rare and therefore a valued resource. And if he’s out on the prowl, so may she be!</p>
<p>In order to evaluate these ideas empirically, we worked with an Amerindian population in southwestern Guyana, the Makushi. The Makushi offer striking juxtapositions of the traditional and modern world. Bows line a house’s walls and arrows are stuck into the thatched roof, ready to be pulled out at a moment’s notice to make a meal of a passing deer or peccary, while round the back a group of villagers are transfixed by the village’s lone TV and DVD player, powered by an old car battery.</p>
<p>While the Makushi traditionally relied on processing the bitter tuber cassava, fishing and hunting to feed their families, recent access to the market economy has led to differing numbers of men and women leaving communities in search of paid labor. This migration produces quite strong sex-ratio variation across communities. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68925/original/image-20150113-28449-15z7o7u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Conducting an interview, including use of a nonverbal response card.</span>
<span class="attribution"><span class="source">Ryan Schacht</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>We selected eight communities of varying sex ratios and interviewed 300 men and women. One set of questions specifically targeted relationship preferences with questions like ‘how many partners have you had in the last year?’ and ‘do you enjoy casual sex?’ These are sensitive inquiries, but we administered them only after developing rapport through living in the villages of study and, of course, using same-sex interviewers.</p>
<p>Two findings emerged from <a href="http://rsos.royalsocietypublishing.org/lookup/doi/10.1098/rsos.140402">our analysis</a>. First, if we simply look to differences between men and women, we find support for biological expectations. On average, men were more interested in uncommitted sexual relationships than women were.</p>
<p>But if we look to how the responses of men and women are influenced by the sex ratio, some interesting patterns emerged. When women were abundant, men were the cads we often expect them to be. They had many sexual partners, and yet still wanted more!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/68912/original/image-20150113-28437-gtw4m1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Local cowboys in one of the more male-biased communities.</span>
<span class="attribution"><span class="source">Ryan Schacht</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>However, as the sex ratio became more male-biased, men’s interest in short-term relationships waned. In fact, in the communities with the most surplus men, men’s and women’s preferences were indistinguishable - both men and women desired long-term, committed relationships with a single partner. In these places, we saw no evidence of simple, biological sex differences – when women were rare, men’s preferences were indistinguishable from women’s. So in some communities sex wasn’t a useful predictor of behavior and in fact told us nothing about a person’s preferences! </p>
<p>The evolutionary social sciences have only recently begun exploring the effects of frequency-dependent dynamics on reproductive decision-making, and here we show the usefulness of moving away from simple biological models of behavior. </p>
<p>The take home point is this: context matters. Yes, men and women likely employ different strategies to find partners because of biological differences, but these strategies are strongly affected by partner availability. </p>
<p>Yes, women do face steeper reproductive costs than men and this may constrain their willingness to engage in short-term relationships. However, men may also face steep reproductive costs that may constrain their interest in a casual fling because if they were to do so, they could lose what they have at home. </p>
<p>Just looking to sex does not adequately explain the rich tapestry of factors that influence reproductive decision making – in Makushi society and closer to home too. Different US regions are also home to variable sex ratios. Generally speaking, both rural areas and western states have <a href="https://stuff.mit.edu/afs/sipb/user/fustflum/images/singles-map.jpg">more men than women</a>. These male biased-sex ratios are associated with higher rates of marriage and relationship stability, and lower rates of female-headed households and children born out of wedlock. These <a href="http://dx.doi.org/10.1016/j.tree.2014.02.001">findings</a>, along with our Makushi study, all point to the strong commitment men make to relationships when partners are scarce, challenging simple sexual stereotypes.</p><img src="https://counter.theconversation.com/content/36104/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Schacht receives funding from the University of Utah and this research was funded by NSF and Wenner-Gren</span></em></p><p class="fine-print"><em><span>Monique Borgerhoff Mulder receives funding from UC Davis</span></em></p>Research among the Makushi of southwestern Guyana shatters stereotypes about men wanting casual sex and women wanting relationships.Ryan Schacht, Postdoctoral Fellow in Anthropology, University of UtahMonique Borgerhoff Mulder, Professor of Anthropology, University of California, DavisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/245722014-04-11T01:54:38Z2014-04-11T01:54:38ZTiny male spiders can get a leg over – as long as they’re picky<figure><img src="https://images.theconversation.com/files/45844/original/gh4ym88d-1396935053.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Male orb-web spiders are dwarfed by their female counterparts, but they can maximise success if they don't mate indiscriminately.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/briangratwicke/2725185345">Brian Gratwicke/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Males will mate with anything. Well, that is the general view, one that exists because of a simple biological underpinning: females are reproductively limited by costly gestation, while males are only limited by their number of partners. </p>
<p>As a result, if males want to increase their number of offspring, they should mate with anything, right? The problem with this line of thought is that it assumes that all males have equal access to all females – an assumption any high school student could tell you is false. </p>
<p>In a <a href="http://www.jstor.org/discover/10.1086/675755?uid=3737536&uid=2134&uid=2&uid=70&uid=4&sid=21103965317623">study</a> published in American Naturalist this week, <a href="http://www.alexjordan.org/">Alex Jordan</a>, <a href="http://biology.anu.edu.au/hosted_sites/kokko/">Hanna Kokko</a> and I explored the understudied factors that limit male access to females to determine how they affect male mate choice in golden orb-web spiders. </p>
<p>We show that males are choosy because they are forced to be by rivals. But through their choices, they’re behaving rationally: males perfectly balanced the intensity of competition with a female’s quality allowing them to maximise their success.</p>
<h2>Preference versus choice</h2>
<p>Whether it’s a knight riding a valiant steed or simply someone who is able to clean after themselves <em>and</em> remember your birthday, we all have traits that we value in a prospective partner. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/45851/original/hh6nxyrr-1396936594.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jdhancock/5968448601">JD Hancock/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Our preferences aren’t static and the relative importance of specific traits changes in response to internal factors such as the <a href="http://www.tandfonline.com/doi/abs/10.1300/J056v12n03_01#.UyozaYU0mEw">type of relationship</a> we are looking for or our <a href="http://www.pnas.org/content/100/15/8805.long">personality</a>.</p>
<p>But there is an obvious disconnect between what we prefer in a partner and what we end up choosing. In studies of mate choice, researchers often ignore one of the strongest factors likely to shift choice away from preference: intrasexual competition. </p>
<p>Visiting a nightclub on a busy night can shed some light on the importance of competition in real time. </p>
<p>Certain individuals attract more attention, and therefore, competition. As the evening progresses, the pool of potential mates shrinks faster than a <a href="https://www.youtube.com/watch?v=DtS39go966o">photoshopped waistline</a> due to individuals partnering up. This changes the mating market – those waiting too long will have very little to choose from and will likely leave with a mate that wouldn’t have been their first choice.</p>
<p>To really understand mate choice, especially in males, thus requires examining how competition affects choice. To do so, my colleagues and I decided to work with one of Australia’s iconic animals, the golden orb-web spider.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EuTPY12kLS4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<h2>Ladies good enough to die for</h2>
<p>Step into any Australian backyard and you’re likely within arm’s reach of a golden orb-web spider (genus <em>Nephila</em>). Their golden webs decorate parks and backyards, and to the dismay of runners, encroach on paths.</p>
<p>Apart from their golden webs, what’s most noticeable is the large female sitting in the centre surrounded by diminutive suitors. These males need to wait patiently until the female is occupied with prey before they make any sexual advances – otherwise they will be courting death rather than a receptive female.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/44353/original/48kb9sy5-1395284973.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A tiny male golden orb-web spider waiting for an opportunity to mate.</span>
<span class="attribution"><span class="source">Michael Kasumovic</span></span>
</figcaption>
</figure>
<p>A male’s position on this web tells us a lot about his competitive ability and <a href="https://theconversation.com/incy-wincy-spider-dont-fret-you-can-still-get-the-girl-12316">potential success</a>. Males closer to females are better competitors and are able to mate first, allowing them to father more offspring. </p>
<p>What we knew was that males generally prefer larger females as they produce more offspring. What we didn’t understand was why some males chose smaller females when larger ones were available.</p>
<p>To examine what alters a male’s choice, we collected hundreds of males and females and marked them to allow individual identification. We then built a 16m<sup>3</sup> enclosure and allowed 12 females to settle naturally. </p>
<p>The next day, we released 12 marked males into the enclosure and followed where each of them settled to determine their initial preference. Under this moderate level of competition, we found that males preferred the largest females. And just like previous results, larger males were settled closer to the female.</p>
<p>The next day, we doubled the intensity of competition by adding 12 new males and then monitored what the initial males did. Like a high school cafeteria after the return of the popular kids, we found that males reorganised themselves. </p>
<p>But it was how this reorganisation occurred which was really interesting.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/44355/original/k5tnbr4r-1395287151.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The screened-in enclosure used to examine female settlement and male mate choice.</span>
<span class="attribution"><span class="source">Michael Kasumovic</span></span>
</figcaption>
</figure>
<p>The previous males at the lower end of the hierarchy were displaced by larger rivals that also preferred the larger females. These smaller males then left. But rather than simply searching for the next nearest female, males targeted smaller females with fewer suitors. </p>
<p>Although these females were initially less preferred, males could sit higher up on the totem pole. These “loser” males thus ensured they lost no fitness by increasing their mating order with a lower quality female. In this manner, males perfectly balanced a female’s reproductive output with the intensity of competition. </p>
<h2>What’s love got to do with it?</h2>
<p>We expect females to be choosy simply because the costs of making a bad choice are so high. </p>
<p>Our results show that males are choosy too, but for completely different reasons. Choice is a consequence of being forced away from what they prefer rather than the concern about mating with the wrong mate.</p>
<p>Our results also help to explain another biological conundrum — the existence of competitively inferior males. We show that their genes are propagated in populations because they choose to mate with less preferred females. </p>
<p>This mating strategy can be applied to males of all species. Back to the night club, individuals that recognised they stood a poor chance would benefit from aiming lower. This may allow them to leave with someone a little closer to their preference. </p>
<p>It seems we can all learn something from our eight-legged neighbours.</p><img src="https://counter.theconversation.com/content/24572/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Kasumovic receives funding from the Australian Research Council for his research exploring the evolution of mate choice and mating strategies. </span></em></p>Males will mate with anything. Well, that is the general view, one that exists because of a simple biological underpinning: females are reproductively limited by costly gestation, while males are only…Michael Kasumovic, Lecturer, ARC DECRA Fellow, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/123132013-02-22T00:47:39Z2013-02-22T00:47:39ZHow deep is your cheep? Why songbirds sing their size<figure><img src="https://images.theconversation.com/files/20459/original/vcs8g6rw-1361334865.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bigger male purple-crowned fairy-wrens can sing their 'trill song' at a lower pitch than smaller males.</span> <span class="attribution"><span class="source">Michelle Hall</span></span></figcaption></figure><p>The melodious beauty and elaborate complexity of <a href="http://esciencenews.com/articles/2012/12/18/birdsong.bluster.may.dupe.strange.females.it.wont.fool.partners">birdsong</a> has long inspired poets, writers, and musicians – as well as behavioural ecologists! </p>
<p>But besides appreciating the aesthetics of birdsong, we are interested in why birds sing, and what they “say” with their songs.</p>
<p>Our research was conducted by myself and my colleagues <a href="http://monash.edu/science/about/schools/biological-sciences/staff/peters/index.html">Dr Anne Peters</a> (Monash University) and <a href="http://www.uea.ac.uk/biological-sciences/People/Research+Associate/Sjouke+Kingma">Dr Sjouke Kingma</a> (University of East Anglia, UK), and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056717">published today</a> in PLOS ONE.</p>
<p>We found that, although the pitch of the lowest frequencies male <a href="http://www.australianwildlife.org/Wildlife-and-Ecosystems/Wildlife-Profiles/Birds/Purple-crowned-Fairy-wren.aspx">purple-crowned fairy-wrens</a> could produce depended on their size, the average pitch of all a male’s different song types did not depend on his body size.</p>
<p>So, what are some of the important questions we attempted to answer by conducting this study?</p>
<h2>Fighting and flirting</h2>
<p>The most common reason birds sing is to compete with rivals and <a href="https://theconversation.com/birds-and-boasting-honest-when-mating-dishonest-when-dating-11520">attract mates</a>. Much of the complexity of song seems designed to intimidate or appeal. </p>
<p>This often happens by way of revealing something about the singer to the listener. The quality of a bird’s singing can reveal its age to listeners because birds have to learn their songs, and their performance often improves with practice. Youngsters that haven’t yet perfected their art are not as intimidating to rivals, or as attractive to prospective mates.</p>
<p>There are sound theoretical reasons for believing that song can also reveal the size of the singer.</p>
<h2>Deep voices, honest signals</h2>
<p>The <a href="http://www.studyphysics.ca/newnotes/20/unit03_mechanicalwaves/chp141516_waves/lesson49.htm">physical properties of sound</a> (low-pitched sounds have long wavelengths) mean that only big bodies can produce low-pitched sounds (think of the deep rumbles of elephants versus the high-pitched squeaks of mice). </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=950&fit=crop&dpr=1 600w, https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=950&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=950&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1193&fit=crop&dpr=1 754w, https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1193&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/20458/original/26g3xwyw-1361334864.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1193&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Male purple-crowned fairy-wrens sing trill songs in response to predator calls.</span>
<span class="attribution"><span class="source">Michelle Hall</span></span>
</figcaption>
</figure>
<p>In principle, this makes a deep voice an unbluffable sign of a big body. This kind of honest signal is known as an <a href="http://clas.mq.edu.au/animal_communication/index.html">“index” signal</a> because it is intrinsically linked to some property of the signaller, and can’t be faked. </p>
<p>Low-pitched calls are a textbook example of an index signal of body size, and there is <a href="http://beheco.oxfordjournals.org/content/11/2/169.full">good evidence</a> from frogs that the calls of bigger males are lower-pitched than those of smaller males. </p>
<p>In the case of frogs, listening males know to steer clear of calls that are lower-pitched than their own, while females might find the lower-pitched calls more attractive. </p>
<p>So what about birds?</p>
<h2>Bigger birds sing lower pitched songs</h2>
<p>Surprisingly, until our recent study, there was no evidence that the pitch of birdsong revealed the singer’s size to rivals and potential mates. </p>
<p>Our work demonstrates that bigger male fairy-wrens sing certain song types in their repertoire at a lower pitch than smaller males. Such songs therefore provide listeners with reliable information about the size of the singer.</p>
<iframe width="100%" height="166" scrolling="no" frameborder="no" src="https://w.soundcloud.com/player/?url=http%3A%2F%2Fapi.soundcloud.com%2Ftracks%2F80003237"></iframe>
<p><em>(Example of a trill song. Audio credit to Michelle Hall, University of Melbourne)</em></p>
<p>Why is this the first time a correlation between pitch and size has been shown in a songbird, when it has been shown in so many frog species?</p>
<p>Frog calls are simple, and it is the very complexity of birdsong that has caused the relationship between size and song frequency predicted by theory to be overlooked. Birds can have large repertoires of song types that span a wide frequency range, and potentially communicate many messages.</p>
<p>Some birds may not use song to signal their size, while others may signal their size along with many other messages in their songs. </p>
<p>The key to our study was that we focused on the low end of the full frequency range, where body size is expected to impose a constraint. </p>
<p>Needless to say, what we discovered was music to our ears. </p><img src="https://counter.theconversation.com/content/12313/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michelle Hall does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The melodious beauty and elaborate complexity of birdsong has long inspired poets, writers, and musicians – as well as behavioural ecologists! But besides appreciating the aesthetics of birdsong, we are…Michelle Hall, Research Fellow, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/123162013-02-20T19:36:38Z2013-02-20T19:36:38ZIncy wincy spider? Don’t fret – you can still get the girl<figure><img src="https://images.theconversation.com/files/20464/original/vzq3x3pv-1361337479.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For golden orb spiders, it seems size doesn't matter when it comes to finding a mate.</span> <span class="attribution"><span class="source">Michael Kasumovic</span></span></figcaption></figure><p>Whether it’s two lions fighting over a pride or two butterflies fighting over a sunny spot, decades of nature shows have led the average watcher to conclude that bigger, stronger males win competitions. </p>
<p>But despite <a href="http://www.davidattenborough.co.uk/">David Attenborough’s</a> confident and assuring voice, research demonstrates it’s common to find smaller males out-competing larger males. In fact, the larger and more similar in size the combatants, the less of an accurate predictor size is.</p>
<p>But if it size isn’t the reliable predictor we always assumed, what other traits are important? My colleague <a href="http://sydney.edu.au/science/biology/about_us/academic_staff/seebacher_frank/">Frank Seebacher</a> and <a href="http://www.michaelkasumovic.com">I</a> – in <a href="http://rsbl.royalsocietypublishing.org/content/9/2/20121164.abstract">research that was published today</a> in Biology Letters – found that when male spiders were similar in size, a male’s success depended more on his physiological capacity than his size. </p>
<h2>Along came a spider …</h2>
<p>Just like the underlying differences in physiology between sprinters, marathon runners and the average individual, it seems that a spider’s internal physiology plays an important role in winning a mate.</p>
<p><a href="http://australianmuseum.net.au/Golden-Orb-Weaving-Spiders">Golden orb web spiders</a> are part of an Australian summer. When walking or hiking along paths, it is common to find groups of females’ webs in aggregations and males jockeying for the closest position. </p>
<p>Proximity to a female on her web is extremely important for these males as the closest males have the first opportunity to mate - first in, best-dressed really does ensure more offspring for males.</p>
<p>Although competition for position is intense, a male’s size doesn’t always declare him a winner. So, we collected 210 males and 12 females and decided to examine what they did. We released three females within an artificial 2.5m<sup>3</sup> screened-in enclosure in a glass house at <a href="http://www.bees.unsw.edu.au/">UNSW</a> and released 12 individually marked, similarly sized males. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=802&fit=crop&dpr=1 600w, https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=802&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=802&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1008&fit=crop&dpr=1 754w, https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1008&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/20427/original/x24kk3wm-1361316776.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1008&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A female golden orb web spider at the hub of the web.</span>
<span class="attribution"><span class="source">Michael Kasumovic</span></span>
</figcaption>
</figure>
<p>After an hour, we returned and collected the closest and furthest males on each female’s web and examined how physiologically capable they were.</p>
<p>By sealing males in airtight containers and using an oxygen meter, we could examine how quickly males were consuming oxygen when at rest. We then compared this to a male’s active metabolic rate by forcing males to exercise. </p>
<p>We did this by using a spinning magnetic bar to activate their natural prey-catching behaviour. Males that consumed more oxygen while exercising indicated a superior metabolic capacity.</p>
<p>Along with measuring their metabolic rate, we examined three different biochemical pathways to examine whether differences in metabolic rates could be attributed to differential energy production.</p>
<p>After collecting information on 36 spiders, we compared the winners against the losers and found some interesting results.</p>
<h2>It’s what’s inside that counts</h2>
<p>The winners and losers did not differ in their resting metabolic rate. But males that were physically closer to females had a significantly higher active metabolic rate. What this means is that winning males were able to ramp up their performance to a higher level when in competition. </p>
<p>We further found that this extra energy production was a result of an increased density of <a href="http://biology.about.com/od/cellanatomy/ss/mitochondria.htm">mitochondria</a> – the energy powerhouses of the cell.</p>
<p>Our results demonstrated a strong link between an individual spider’s internal physiology and his potential fitness: a difficult connection to make. The male spiders that were closest to females were more like sprinters than marathon runners as they had the physiological capacity for burst activity that provides them with a competitive, and therefore fitness, advantage. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/20426/original/cpkskd78-1361315822.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Michael Kasumovic</span></span>
</figcaption>
</figure>
<p>But unlike sprinters that need to train to improve their physiology, these differences may be determined during development. Male golden orb web spiders are <a href="http://www.esajournals.org/doi/abs/10.1890/08-1540.1">developmentally plastic</a>, which means they alter how they look in response to specific environmental triggers. </p>
<p>When developing around a high density of available females, males mature smaller and more quickly which allows them to locate and mate with females earlier. In contrast, when males are developing around more rival males, they take longer to mature larger to have the capacity to out-compete males. </p>
<p>Our new results suggest sexual selection has also shaped plasticity in underlying physiological traits. But we’ll have to complete more manipulative experiments to determine this conclusively. </p>
<p>For now, we’re happy to know we’ve eased the collective minds of all the little spiders (and maybe humans) out there.</p><img src="https://counter.theconversation.com/content/12316/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Kasumovic receives funding from the Australian Research Council for his research.</span></em></p>Whether it’s two lions fighting over a pride or two butterflies fighting over a sunny spot, decades of nature shows have led the average watcher to conclude that bigger, stronger males win competitions…Michael Kasumovic, Lecturer, ARC DECRA Fellow, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/49422012-02-05T19:33:15Z2012-02-05T19:33:15ZNo food, no love: female fish prefer well-nourished males<figure><img src="https://images.theconversation.com/files/7380/original/n5wtkxpf-1328244993.jpg?ixlib=rb-1.1.0&rect=58%2C469%2C2848%2C2188&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How do you get the girl? That's a nom-brainer.</span> <span class="attribution"><span class="source">Yann Audras</span></span></figcaption></figure><p>“Finish your dinner or there’ll be no dessert for you!” – it’s a cry heard at dinner tables around the world, as mothers battle to convince their sons about the importance of eating properly. Sorry lads: mum’s right on this one.</p>
<p>A poor nutritional upbringing has been shown to have all sorts of long-term consequences in myriad species – humans included. And now, research by myself and colleagues at the Research School of Biology at ANU has shown that a good start to life can also make you more attractive to the ladies – if you’re a mosquitofish that is.</p>
<h2>Playing catch-up</h2>
<p>The natural world is a variable one – levels of available food rise and fall with the level of competition, the seasons change, the weather varies from day to day. In this way it’s not unusual for animals to face challenging conditions early in life.</p>
<p>How are these unlucky individuals meant to compete with their luckier rivals?</p>
<p>Well, one option to compensate for a bad start in life is to delay entry into a future developmental stage (that is, sexual maturity) until they are as big as their rivals. Alternatively, individuals might show compensatory growth – a dramatic increase in their growth rate when food does become available. This allows them to quickly catch up to where they should’ve been. </p>
<h2>Costly compensation?</h2>
<p>While it’s easy to see how such responses are favoured by natural selection, the existence of compensatory growth raises a big question: if animals <em>can</em> grow so fast when food is plentiful, why don’t they do it all the time?</p>
<p>One possible answer is that rapid growth actually imposes costs of its own – rapidly grown bones may be more fragile, for instance. Indeed, studies have found that compensatory growth negatively impacts a range of traits such as survival, longevity and fecundity (or fertility) in numerous species.</p>
<p>Thus, it only makes sense to grow this fast when you’re already lagging behind.</p>
<p>The question <a href="http://www.anu.edu.au/BoZo/jennions/">my colleagues and I</a> asked was: does a poor start in life, followed by compensatory growth, affect adult sexual attractiveness?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/7087/original/7n4vs6qw-1327288740.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Hunter Desportes</span></span>
</figcaption>
</figure>
<h2>Mosquitofish: from meals to mating</h2>
<p>We studied this question in the introduced pest species mosquitofish (<em>Gambusia holbrooki</em>), a relative of guppies and swordtails. </p>
<p>In mosquitofish, males do not actively court females – instead they incessantly try to copulate coercively. So the closest a female can get to “choosing” her partner is to avoid males she doesn’t like the look of.</p>
<p>We separated pairs of brothers at birth and subjected one brother to a three-week period of severe food limitation before returning him to the continuous, abundant diet enjoyed throughout by his brother.</p>
<p>Males on the restricted diet displayed compensatory growth – but couldn’t completely catch up, so they also slightly delayed maturation. Therefore, on average, brothers reached the same final size and looked indistinguishable, at least to us.</p>
<p>Surprisingly though, when we gave females the choice between the two brothers, they were able to distinguish between the two and actively avoided the male who had suffered a bad start to life.</p>
<h2>How and why?</h2>
<p>Why would females shun these unfortunate males? Well, the possible reasons are two-fold. First, males that have suffered a period of poor nutrition may be more susceptible to parasites and diseases, which could be passed directly to the female if she got too close.</p>
<p>Second, perhaps a male’s ability to get enough food when he’s young is heritable in the wild. If this were the case, it would make sense for females to choose well-fed males because it would increase their offspring’s chances of feeding themselves.</p>
<p>So how do the females tell the males apart? Well, we don’t know that yet. We suspect it has something to do with locomotor ability – the way they swim. Compensatory growth has previously been shown to negatively impact swimming performance in a related species: the green swordtail.</p>
<h2>Less than meets the eye</h2>
<p>One of the more interesting aspects of our findings is that if you were to put a pair of males in a tank together, you wouldn’t be able to tell which one had undergone which feeding regime. But the female mosquitofish could.</p>
<p>This highlights an important lesson for those researching mate choice – animals’ ideas of attractiveness might often go beyond our simple proxies (body length, in the case of the mosquitofish).</p>
<p>Still, and this shouldn’t really come as a surprise, most individuals do have a “type”; but when it comes to picking a partner the most important thing is often a little chemistry and a touch of <em>je ne sais quoi</em>.</p><img src="https://counter.theconversation.com/content/4942/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Kahn receives funding from the Australian National University.</span></em></p>“Finish your dinner or there’ll be no dessert for you!” – it’s a cry heard at dinner tables around the world, as mothers battle to convince their sons about the importance of eating properly. Sorry lads…Andrew Kahn, PhD Candidate in Evolution, Ecology & Genetics, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/5272011-04-18T21:08:51Z2011-04-18T21:08:51ZAll about the girl: the mating game and how (not) to win it<figure><img src="https://images.theconversation.com/files/563/original/1635483220_be1974194b_b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A guy walks into a cafe … but what happens next depends on strategy.</span> <span class="attribution"><span class="source">nathancolquhoun/Flickr</span></span></figcaption></figure><p>Long before men asked themselves “What’s the meaning of life?”, they were scratching their heads and wondering “How do I get the girl?”</p>
<p>And it’s not just humans who have been consumed with this question. Working out how to get the girl has been top priority for our animal relatives all the way down the tree of life.</p>
<p>But if everyone is asking the same question, are they all getting the same answer? Are there simple rules in the mating game? Or is something more complex happening – are males tailoring their sexual strategy in subtle ways?</p>
<h2>Sexual selection</h2>
<p>Wherever sexual reproduction occurs in the natural world, competition for mates is never far behind. That’s because every individual has one mother and one father – assuming there is a balanced sex ratio this means that, for every male that successfully mates with more than one female, there will be another male that misses out.</p>
<p>This highly competitive sexual environment, where males try to out-do each other for the attentions of females, has led to some of the most extraordinary, beautiful and bizarre character traits seen in nature. </p>
<p>The meticulously tended <a href="http://www.youtube.com/watch?v=SFek6zyRXD4">blue nests of bower birds</a>, the colourful tail-fins of male guppies and branch-like antlers on deer are all the result of males competing for sexual advantage.</p>
<h2>Strategy</h2>
<p>While the best strategy in mating is probably “be as attractive as you can be”, there will always be variation in male traits (e.g. differences in strength or colour) that mean not everyone can be the “best”.</p>
<p>In which case, males may need to employ different strategies that allow them to do the make the most of what they have. But how can they decide what this strategy will be?</p>
<p>For the answer, we need only to think of a typical night out at a bar. If every male plays the same “strategy”, then they might all approach the same girl with the exact same pick-up line (admittedly, this may not be too far from the truth in some cases!). </p>
<p>At best one man might successfully get the woman’s number, while the rest would fail in their attempt. </p>
<p>It’s not the case that the strategy the other men used was inherently bad – only that in competition with identical strategies it failed miserably. </p>
<h2>Game theory</h2>
<p>If this all sounds like a meat-market, it pretty well is. That’s because a lot of reproductive behaviour follows the economic principles of <a href="http://academicearth.org/courses/game-theory">game theory</a>.</p>
<p>Developed by John Nash, this theory shows us that the success of any one strategy can only be measured in relation to the competing strategies, and that the best solutions for the whole group come about when every “player” does what’s best for them. </p>
<h2>Courtship</h2>
<p><a href="http://www.alexjordan.org/research">My research</a> examines whether animals in nature follow the principles of game theory in their reproductive behaviour to determine what constitutes a “good” strategy for male reproductive success. </p>
<p>Using tropical fish species on the reefs and in African lakes, I study how male courtship behaviour is influenced by social and competitive environments. In doing so, I’ve found the following:</p>
<p>1) Factors such as the availability of potential mates and the strategies used by competing males can make males modify their tactics. </p>
<p>2) The success of males seeking to avoid competition, or to only court the most attractive females, is highly dependent on what other males are doing.</p>
<p>Males also take into account their recent experiences with females. </p>
<p>When males have recently mated with one female, they show extremely high reproductive effort in subsequent encounters – effectively chatting up every girl in the bar. </p>
<p>Males that have recently mated with many females are far more discerning about their reproductive strategy, reducing their overall effort and preferring to court only the most attractive females. </p>
<p>All of the above can also depend on the reactions of the females, which have been shown to change according to their social experiences. </p>
<h2>The final score</h2>
<p>It seems there’s not a single “best” strategy for males, but rather multiple strategies that are “best” only in relation to the wider social context. </p>
<p>So if you’ve read this far to find out the answer to the question “how do I get the girl”?, well, I’m sorry to say, that all depends …</p><img src="https://counter.theconversation.com/content/527/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Long before men asked themselves “What’s the meaning of life?”, they were scratching their heads and wondering “How do I get the girl?” And it’s not just humans who have been consumed with this question…Alex Jordan, JSPS Research Fellow, Evolutionary Biology, Osaka City UniversityCarla Avolio, Science Communicator, University of SydneyLicensed as Creative Commons – attribution, no derivatives.