tag:theconversation.com,2011:/id/topics/kalahari-23601/articlesKalahari – The Conversation2024-02-22T14:37:56Ztag:theconversation.com,2011:article/2197152024-02-22T14:37:56Z2024-02-22T14:37:56ZKalahari weaver birds lay bigger eggs when they have female helpers to feed nestlings<p><a href="https://tswalu.com/">Tswalu Kalahari Reserve</a> is a protected nature reserve at the southern edge of the Kalahari desert in South Africa’s Northern Cape province. It’s an arid area with high daytime temperatures and <a href="https://www.science.org/doi/10.1126/sciadv.abe8980">unpredictable rainfall</a>.</p>
<p>One of the species that lives in this harsh environment is the <a href="https://ebird.org/species/wbswea1?siteLanguage=en_ZA">white-browed sparrow-weaver</a> (<em>Plocepasser mahali</em>). They live here in social groups of up to 12 birds. Group members stay in the same group for many years at a time. </p>
<p>Within each social group, only one pair of birds breeds: the dominant male and female (which lays one to three eggs per breeding attempt). Other group members – usually offspring of the breeding pair – engage in a number of helping behaviours, from defending the territory to feeding the nestlings of the dominant pair.</p>
<p>This is not the only species in which the breeding pair has help raising the young. <a href="https://science.uct.ac.za/fitzpatrick/research-understanding-biodiversity-evolutionary-and-behavioural-ecology/pied-babblers-and-fork-tailed-drongos">Southern pied babblers</a> and <a href="https://theconversation.com/biggest-bird-nests-in-the-world-are-kept-together-by-family-ties-28932">sociable weavers</a> are other examples in the Kalahari. This type of behaviour, known as cooperative breeding, occurs globally and seems to be particularly associated with arid habitats. However, it’s still not clear what benefits it offers and how it aids species to adapt to the environment.</p>
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Read more:
<a href="https://theconversation.com/birds-evolve-different-body-temperatures-in-different-climates-new-study-of-53-african-species-189174">Birds evolve different body temperatures in different climates – new study of 53 African species</a>
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<p>In a long-term <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3002356#sec007">study</a> recently published in the journal PLOS Biology, covering 10 years of research (from 2007 to 2016) at the Tswalu Kalahari Reserve, my University of Exeter research colleagues and I added some evidence to help answer this question. Our study revealed that white-browed sparrow-weaver mothers lay larger eggs when they have help with nestling care. Egg size is an important trait which affects nestling survival. </p>
<p>This is the first formal evidence in birds that maternal investment in eggs changes with the availability of help. The results also counter the idea previously proposed that with more help, mothers would lay smaller eggs.</p>
<h2>Understanding correlations</h2>
<p><a href="https://peerj.com/articles/4028/">Previous studies</a> of cooperatively breeding birds have tended to find a correlation between having more helpers and laying smaller eggs. However, it was unclear whether this correlation arose from mothers changing their egg size according to the social conditions they experienced (known as “<a href="https://royalsocietypublishing.org/doi/10.1098/rstb.2009.0267">plasticity</a>”), or if other confounding factors could be explaining the results.</p>
<p>By using a number of statistical tools, we could investigate whether individual white-browed sparrow-weaver mothers laid larger or smaller eggs depending on their social conditions. The number of helpers during the post-natal phase is strongly correlated with the number of helpers when mothers laid eggs. So mothers should have reliable information to adjust egg size based on the availability of help with post-natal care. We found that mothers laid larger eggs in the presence of (female) helpers and they also reduced their feeding rates to the offspring.</p>
<p>In white-browed sparrow-weavers, <a href="https://www.science.org/doi/10.1126/sciadv.abe8980">female helpers provide significantly more post-natal care than male helpers</a>. The fact that the number of female helpers (and not male helpers) positively predicted egg size suggests the availability of cooperative care (and not simply the presence of helpers) as the causal mechanism of our results.</p>
<p>These findings indicate it is possible that having help allows mothers to invest more into pre-natal (egg) development of her offspring, to which helpers cannot contribute directly.</p>
<h2>Helpers and benefits to offspring</h2>
<p>It is possible that the lightening of maternal post-natal investment (feeding of nestlings) allows the mother bird to invest more resources into bigger eggs, which are then more likely to hatch into nestlings that survive into adulthood. </p>
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Read more:
<a href="https://theconversation.com/female-warblers-live-longer-when-they-have-help-raising-offspring-115332">Female warblers live longer when they have help raising offspring</a>
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<p>Through positive helper effects on pre-natal maternal investment, helper assistance with the post-natal care of breeders’ young in cooperative species (including our own) may thus have hitherto unknown benefits to offspring.</p><img src="https://counter.theconversation.com/content/219715/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pablo Capilla-Lasheras has received funding from the Biotechnology and Biological Sciences Research Council (UK) and currently works at the University of Glasgow.</span></em></p>The study shows that bird mothers can adjust egg size depending on their social conditions. This counters the idea that, with more help, mothers lay smaller eggs.Pablo Capilla-Lasheras, Research Associate in ecology, evolution and behaviour, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1924122022-11-13T05:29:42Z2022-11-13T05:29:42ZClimate change and wildlife: 3 studies that reveal the devastating toll on Africa’s animals<figure><img src="https://images.theconversation.com/files/494441/original/file-20221109-10877-26vl2o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The carcass of a Grévy's zebra, an endangered species which exists only in the northern part of Kenya, where drought is ongoing.</span> <span class="attribution"><span class="source">Photo by FREDRIK LERNERYD/AFP via Getty Images</span></span></figcaption></figure><p>Climate change has produced a number of threats to wildlife. Over time, changing rainfall patterns have transformed habitats and forced animals to move. Increasing <a href="https://theconversation.com/daytime-sightings-of-elusive-aardvarks-hint-at-troubled-times-in-the-kalahari-148120">temperatures</a> are causing mass die-off events during <a href="https://theconversation.com/vulnerable-lizard-species-gets-hot-and-bothered-in-rising-temperatures-171052">heat</a> waves and making it hard for animals to find food. </p>
<p>Drought is <a href="https://theconversation.com/saving-east-africas-wildlife-from-recurring-drought-183844">recurring</a> in parts of the continent. The increased frequency means there’s little or no time to recover before the next one occurs. The wildlife in some of these regions lives alongside people who are also struggling to survive and keep their livestock alive. This puts people and wildlife into conflict as they compete for diminishing sources of water and food. </p>
<p>Climate change can also strongly influence the physiology, behaviour and breeding success of animals. </p>
<p>Academics writing for The Conversation Africa have covered some of these issues. Their articles and research sound a warning bell on the effects of climate change on wildlife. Here we share three of these important reads. </p>
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<h2>Drought takes a toll on East Africa’s wildlife</h2>
<p>Over the past two decades, the Horn of Africa – specifically Ethiopia, Somalia and Kenya – has experienced more intense and frequent droughts. Drought adds to the pressure on resources like water and pasture. This makes livestock and wildlife more susceptible to malnutrition, disease, mass mortalities and competition with each other over resources. </p>
<p>Kenyan scientist and conservationist Abdullahi Ali has worked for over 15 years along the volatile Kenya-Somalia border region. He’s seen at first hand the devastating effect that these droughts have on wildlife and habitat. For instance, based on monitoring herds, he’s recorded the deaths of 30 endangered hirola (about 6% of the global population) as a direct consequence of drought over the past year. </p>
<p>Ali <a href="https://theconversation.com/saving-east-africas-wildlife-from-recurring-drought-183844">is concerned that</a> droughts are recurring. Their increased frequency means there’s little or no time to recover before the next drought. </p>
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<a href="https://theconversation.com/saving-east-africas-wildlife-from-recurring-drought-183844">Saving East Africa's wildlife from recurring drought</a>
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<h2>Warmer temperatures, fruit trees and forest elephants</h2>
<p>Gabon is home to some of the highest densities of forest elephants. Many of them live in Lopé National Park, a 5,000km² protected area. </p>
<p>Ecological experts Katharine Abernethy, Emma Bush and Robin Whytock have <a href="https://theconversation.com/fruit-famine-is-causing-elephants-to-go-hungry-in-gabon-152757">observed</a> a significant drop in the physical condition of these elephants – an 11% decline since 2008.</p>
<p>This corresponds with a massive collapse in tree fruiting events. Elephants are much less likely than before to find ripe fruit. On average, elephants would have found ripe fruit on one in every 10 trees in the 1980s, but need to search more than 50 trees today. </p>
<p>The collapse in tree fruiting events is attributed to warmer temperatures. Lopé tree species depend on a critical drop in night-time temperatures during the long dry season to trigger flowering. In years when temperatures in the dry season did not dip below 19ºC these species produced no fruit. </p>
<p>So, even where forest elephants and other large animals are relatively well protected from threats such as hunting, global human pressures – such as the climate crisis – could affect their survival. </p>
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Read more:
<a href="https://theconversation.com/fruit-famine-is-causing-elephants-to-go-hungry-in-gabon-152757">Fruit famine is causing elephants to go hungry in Gabon</a>
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<h2>The loss of the Kalahari’s hornbills</h2>
<p>For birds in arid zones, rising temperatures pose a significant problem. They usually breed in response to rainfall, which often occurs during the hottest time of the year. And birds are mostly active during the day, when they are exposed to the sun’s heat. This is when their vital processes for reproduction take place – such as territorial defence, courtship, finding food for their young and attending the nest.</p>
<p>Ornithology expert Nicholas Pattinson <a href="https://theconversation.com/hotter-kalahari-desert-may-stop-hornbills-breeding-by-2027-183937">assessed</a> the effects of air temperature and drought on the breeding output of southern yellow-billed hornbills in southern Africa’s Kalahari Desert over a decade, from 2008 to 2019.</p>
<p>His study found that breeding output fell when air temperatures rose in the breeding season. Breeding attempts all failed when average daily maximum air temperatures exceeded 35.7°C. </p>
<p>In the Kalahari, air temperatures have already risen more than 2°C in a few decades. At this rate, by 2027, these birds will not breed at all at this site. They will quickly become locally extinct.</p>
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<a href="https://theconversation.com/hotter-kalahari-desert-may-stop-hornbills-breeding-by-2027-183937">Hotter Kalahari desert may stop hornbills breeding by 2027</a>
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<img src="https://counter.theconversation.com/content/192412/count.gif" alt="The Conversation" width="1" height="1" />
Changing habitat ranges, competition for food and water, and biological effects of climate change all pose threats to wildlife.Moina Spooner, Assistant EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1839372022-05-31T13:34:56Z2022-05-31T13:34:56ZHotter Kalahari desert may stop hornbills breeding by 2027<figure><img src="https://images.theconversation.com/files/465669/original/file-20220527-19-3z5c87.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Southern Yellow-billed Hornbills struggled to breed at high temperatures.</span> <span class="attribution"><span class="source">Nicholas B. Pattinson</span></span></figcaption></figure><p>Rapid climate change has the potential to strongly influence the physiology, behaviour and breeding <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/fee.2324">success of animals</a>. Research is showing that increasing temperatures, for instance, are having negative effects <a href="https://www.pnas.org/doi/10.1073/pnas.1908791116">on animals</a>. These range from mass die-off events during heat waves to less obvious problems like <a href="https://www.pnas.org/doi/abs/10.1073/pnas.1821312116">difficulty finding food</a>.</p>
<p>For birds in arid zones, rising temperatures pose a significant problem. Birds in these dry zones usually breed in response to rainfall, which often occurs during the hottest time of the year. And birds are mostly active during the day, when they are exposed to the sun’s heat. This is when their vital processes for reproduction take place – such as territorial defence, courtship, finding food for their young and attending the nest. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0003347216300653">Research</a> suggests that high temperatures over a few days or weeks can have negative effects on foraging and body mass. At the scale of one or two breeding seasons, these <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0074613">effects</a> have a negative impact on breeding performance. This can be through reducing the condition of offspring or the probability that young birds will survive to adulthood and breed. </p>
<p>The longer-term effects of responses to high temperatures – over decades – are less well-known.</p>
<p>Our recent <a href="https://www.frontiersin.org/articles/10.3389/fevo.2022.842264/full#h5">research</a> aimed to help bridge this gap in knowledge. We assessed the effects of air temperature and drought on the breeding output of southern yellow-billed hornbills (<em>Tockus leucomelas</em>) in southern Africa’s Kalahari Desert over a decade period, from 2008 to 2019.</p>
<p>We found that the breeding output of our study population collapsed during the monitoring period and was strongly correlated with temperature and rainfall. In the Kalahari, air temperatures have already risen more than 2°C in a few decades. At this rate, by 2027, these birds will not breed at all at this site.</p>
<h2>Desert temperatures and breeding birds</h2>
<p>First we examined air temperature and rainfall data from the <a href="https://www.weathersa.co.za/">South African Weather Service</a> for the Kalahari region between 1960 and 2020. The frequency and severity of drought have not changed but spring and summer average daily maximum air temperatures have been increasing. They have risen from about 34°C to well over 36°C from the mid 1990s to <a href="https://www.frontiersin.org/articles/10.3389/fevo.2022.842264/full#h5">the present day</a>. This equates to a warming rate of about 1°C per decade, a rate five times faster than the worldwide average of about <a href="https://www.pnas.org/doi/10.1073/pnas.0606291103">0.2°C per decade.</a> </p>
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<span class="caption">In the Kalahari, average spring and summer air temperatures have already risen more than 2°C since temperatures began rising.</span>
<span class="attribution"><span class="source">Nicholas B. Pattinson</span></span>
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<p>We then assessed the effects of air temperature and drought on the breeding output of a population of southern yellow-billed hornbills in the Kalahari over the decade 2008 to 2019. <a href="https://animals.mom.com/habitat-yellowbilled-hornbill-4620.html">These birds</a> are still common across much of central and eastern southern Africa. </p>
<p>The study population comprised about 25 pairs each breeding season. These hornbills nest in cavities and at our study site pairs usually made one breeding attempt per season. Their breeding strategy is unusual: the female seals herself inside the nest cavity and moults all her flight feathers. This leaves the male parent as the sole provisioner to the nest for the female parent and the chicks. A successful breeding attempt usually takes about two months, with a pair raising between one and four chicks.</p>
<p>Although the number of pairs at the site remained constant over the study decade, more pairs skipped breeding each year. And those which did breed did so less and less successfully, producing fewer offspring or none at all. </p>
<p>Comparing the first three seasons (2008-2011) of monitoring to the last three (2016-2019), the mean percentage of nest boxes occupied declined from 52% to 12%. Nest success – a breeding attempt successfully raising at least one chick – fell from 58% to 17%. Fledglings produced per breeding attempt declined from 1.1 to 0.4. </p>
<p>Without successful breeding, the population will not be able to persist, and will quickly become locally extinct.</p>
<p>We found that breeding output was negatively correlated with increasing air temperatures and the occurrence of drought within the breeding season. Breeding attempts all failed when average daily maximum air temperatures exceeded 35.7°C. And the effects of high air temperatures were present even in non-drought years. </p>
<p>Considering the strong negative correlation between high air temperature and breeding output, we argue that global warming has likely been the primary driver of the recent, rapid collapse in breeding success in our study population. The consequences of high air temperatures (regardless of high rainfall) and drought on the parents affect the probability of successfully fledging offspring or even attempting to breed at all. </p>
<p>Based on current warming trends, the 35.7°C threshold for successful breeding attempts will be exceeded for the entire hornbill breeding season by approximately 2027 at our study site. </p>
<p>Overall, while our study is specific to southern yellow-billed hornbills, we suggest that our findings are likely applicable to a range of species. Even for species that are unlikely to die in large numbers because of heat, climate change can drive rapid declines and potentially local extinctions.</p>
<h2>What we can do about it</h2>
<p>Luckily, a few mitigation strategies are still available to help prevent local and global extinctions. </p>
<p>In the short term, there are options such as providing water and insulated nest boxes. </p>
<p>Long-term, it would be necessary to preserve habitats which warm less rapidly or which can buffer the effects of climate change on biodiversity. </p>
<p>Even preservation of habitat won’t be enough, however, if the <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature#:%7E:text=April%2020%2C%202022-,Highlights,land%20areas%20were%20record%20warm.">current rate</a> of climate change is sustained. <a href="https://academic.oup.com/conphys/article/8/1/coaa048/5851118?login=true">Recent models</a> based on current <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2020.1140">rates of warming</a> and <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/aec.13025">what’s known</a> about how birds handle heat are suggesting that rare and endangered species will be lost over the next century. But so will species which are currently common, such as the southern yellow-billed hornbill.</p><img src="https://counter.theconversation.com/content/183937/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicholas B. Pattinson receives funding from DST-NRF Centre of Excellence at the FitzPatrick Institute.</span></em></p>Without successful breeding, the hornbill population will not survive, and will quickly become locally extinct.Nicholas B. Pattinson, Doctoral student FitzPatrick Institute of African Ornithology, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1550472021-03-31T15:20:23Z2021-03-31T15:20:23ZAncient southern Kalahari was more important to human evolution than previously thought<figure><img src="https://images.theconversation.com/files/383946/original/file-20210212-13-vbm8va.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ga-Mohana Hill in South Africa's Northern Cape province.</span> <span class="attribution"><span class="source">Benjamin Schoville</span></span></figcaption></figure><p>The Kalahari is a <a href="https://www.britannica.com/place/Kalahari-Desert">huge expanse of desert</a> in southern Africa, stretching across Botswana and into the northernmost part of South Africa’s Northern Cape province. </p>
<p>It’s in the Northern Cape that we studied and described a new archaeological site, Ga-Mohana Hill, for research <a href="https://www.nature.com/articles/s41586-021-03419-0">just published in Nature</a>.</p>
<p>Our international team, made up of researchers from South Africa, Canada, the UK, Australia and Austria, has <a href="https://theconversation.com/ancient-eggshells-and-a-hoard-of-crystals-reveal-early-human-innovation-and-ritual-in-the-kalahari-154191">found evidence</a> for complex symbolic behaviours 105,000 years ago. </p>
<p>Humans use symbols as a shortcut to communicate important ideas. Identifying the ancient roots of symbolism is limited to what preserves over time. Large calcite crystals from several kilometres away were found in the cave alongside stone tools. Why the crystals were brought there is unknown; they are not modified and do not seem to have a functional purpose. They may have been collected for their aesthetic properties, or included in ritual activities. </p>
<p>Crystals are collected by many people around the world to this day for ritual purposes. Early humans bringing crystals into Ga-Mohana suggests innovation in how people interacted with each other and their environment.</p>
<p>But such ancient innovation didn’t occur in a bubble: there is context to when and where innovation occurs. What brought people there in the first place, at that time, to begin using those tools and collecting those crystals?</p>
<p>Reconstructing past environments allows us to understand this context. And so, a major part of our research centred on working out what the area’s climate was like 105,000 years ago. To do so, we looked at Ga-Mohana’s rocks.</p>
<p>The southern Kalahari is often considered too arid to be important for human evolution. Our work contradicts the idea of an arid and empty interior. At some points, Ga-Mohana was much wetter than today, with pools of standing water and waterfalls tumbling down the hillside. The fact that the climate was very different then opens up possibilities about why this previously under-appreciated region must have played an important role in our species’ evolutionary history. </p>
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<span class="caption">Survey team from University of Cape Town and University of Queensland.</span>
<span class="attribution"><span class="source">Jayne Wilkins</span></span>
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<p>Archaeological and geological fieldwork allowed us to piece together this story. </p>
<h2>The rocks</h2>
<p>Some kinds of rocks preserve traces of the past environment. The Ga-Mohana hillside is draped in deposits called <a href="https://www.howitworksdaily.com/how-are-tufa-towers-formed/">tufa</a>; these form from water leaking out of cracks in the bedrock. This occurs when underground aquifers are recharged with rain water and begin to overflow. Over time, these waters precipitate calcium carbonate and form tufa. </p>
<p>The tufa system is no longer active, apart from small drips during the rainy season. But the fossil tufas represent periods in the past when there was more water available. Similar structures are growing today at places like <a href="https://youtu.be/IowL8FebJ5I">Sitting Bull Falls, New Mexico in the US</a>. Knowing when the tufas formed at Ga-Mohana tells us when it was wetter there.</p>
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<figcaption><span class="caption">Fossil tufas occur in several parts of the world.</span></figcaption>
</figure>
<p>To find out how old the tufas are and when these wet periods occurred, we used a method called <a href="https://www.futurelearn.com/info/courses/human-fossils/0/steps/49021">uranium-thorium dating</a>. Uranium is radioactive, meaning that it decays at a constant rate over time and produces ‘daughter’ elements; thorium is one of them. When tufa forms, uranium is ‘locked’ into the crystal structure and begins to decay to produce thorium. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/384945/original/file-20210218-26-1aue7zc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Jess von der Meden standing next to large tufa flow at Ga-Mohana.</span>
<span class="attribution"><span class="source">Robyn Pickering</span></span>
</figcaption>
</figure>
<p>The uranium-thorium system acts like a clock that starts when the tufa is formed. By precisely measuring how much uranium and thorium is in the tufa today, we use the known decay rate to calculate when the ‘clock’ started. This method is <a href="https://theconversation.com/how-we-calculated-the-age-of-caves-in-the-cradle-of-humankind-and-why-it-matters-104856">routinely applied</a> to cave deposits like stalagmites and flowstones but has not been used very much on tufa. </p>
<p>This is because dating tufas is not straightforward. Unlike protected caves, tufa forms in the open where sunlight, dust, and debris can contaminate the ages. It took several years of dedicated work to get around these problems: we chose the tufa samples in the field with care and used a sensitive laser to make images of the layers with the most uranium present. We could then target these layers for dating. This provided a real breakthrough.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-we-calculated-the-age-of-caves-in-the-cradle-of-humankind-and-why-it-matters-104856">How we calculated the age of caves in the Cradle of Humankind -- and why it matters</a>
</strong>
</em>
</p>
<hr>
<p>In the end, we dated two layers from an ancient tufa waterfall to between 110,000 and 100,000 years old. This means that fresh water was flowing down the hillside at exactly the same time that people were living at the shelter. Such wet conditions at this time were unexpected, so we wanted to know what caused such a large increase in water to begin with.</p>
<p>To understand the reasons for the region being much wetter 105,000 years ago than it is today, we looked at how climate processes influence modern rainfall there. </p>
<p>We did this by comparing historical rainfall records to current major climate drivers. We then looked back into the past and used data from an ocean core (deep sea sediments drilled out of the ocean floor which record changes in the earth’s ocean and climate). These data show that parts of the Indian Ocean were warmer around 105,000 years ago. Climate systems are complex, but basically this would have increased the amount of rain in the southern Kalahari, filling the aquifer, and causing the build up of the tufa during this time period. </p>
<h2>An important role</h2>
<p>People were drawn to Ga-Mohana for many reasons. Surface water would have been one. The many ostrich eggshell fragments we also found were probably used as water carriers 105,000 years ago. Perhaps these were being filled with water as it flowed down the hillside. One possibility is that water carriers allowed our ancestors to travel further distances. </p>
<p>There is still more to be learned from Ga-Mohana, its artefacts and its rocks. This will allow scientists to understand the role this space played in human evolutionary history better.</p><img src="https://counter.theconversation.com/content/155047/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Benjamin Schoville receives funding from the University of Queensland, National Geographic, the Tswalu Foundation, and the Centre for Excellence in Palaeoscience. </span></em></p><p class="fine-print"><em><span>Jessica von der Meden receives funding from the National Research Foundation of South Africa and the NRF Centre of Excellence in Palaeosciences.</span></em></p><p class="fine-print"><em><span>Robyn Pickering receives funding from The University of Cape Town, the National Research Foundation and the NRF Centre of Excellence in Palaeosciences.</span></em></p><p class="fine-print"><em><span>Wendy Khumalo receives funding from the University of Cape Town, the NRF Centre of Excellence in Palaeosciences, and the South. African National Antarctic Programme.</span></em></p>People were drawn to Ga-Mohana for many reasons. Surface water was likely among them.Benjamin Schoville, Senior Lecturer in Archaeology, The University of QueenslandJessica von der Meden, PhD candidate, University of Cape TownRobyn Pickering, Senior lecturer, University of Cape TownWendy Khumalo, Student, Department of Geological Sciences, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1541912021-03-31T15:18:36Z2021-03-31T15:18:36ZAncient eggshells and a hoard of crystals reveal early human innovation and ritual in the Kalahari<figure><img src="https://images.theconversation.com/files/381438/original/file-20210129-20464-1tiype6.jpg?ixlib=rb-1.1.0&rect=43%2C16%2C1554%2C1173&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>A rockshelter in South Africa’s Kalahari documents the innovative behaviours of early humans who lived there 105,000 years ago. We report the new evidence today in <a href="https://dx.doi.org/10.1038/s41586-021-03419-0">Nature</a>. </p>
<p>The rockshelter site is at Ga-Mohana Hill — a striking feature that stands proudly above an expansive savanna landscape.</p>
<p>Many residents of nearby towns consider Ga-Mohana a spiritual place, linked to stories of a great water snake. Some community members use the area for prayer and ritual. The hill is associated with mystery, fear and secrecy. </p>
<p>Now, our findings reveal how important this place was even 105,000 years ago, documenting a long history of its spiritual significance. Our research also challenges a dominant narrative that the Kalahari region is peripheral in debates on the origins of humans. </p>
<p>We know our species, <em>Homo sapiens</em>, first emerged in Africa. Evidence for the complex behaviours that define us has mostly been found at coastal sites in South Africa, supporting the idea that our origins were linked to coastal resources. </p>
<p>This view now requires revision. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=117&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=117&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=117&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=147&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=147&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381291/original/file-20210129-13-179wgn5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=147&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Ga-Mohana Hill North Rockshelter is located near the town of Kuruman in the Northern Cape province of South Africa.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>A crystal-clear finding</h2>
<p>We found 22 white and well-formed calcite crystals brought to the site 105,000 years ago. We determined this using a method called “optically stimulated luminescence”, which dates sediments the crystals were excavated from.</p>
<p>Our analysis indicates the crystals were not introduced into the deposits via natural processes, but rather represent a small cache of deliberately collected objects. </p>
<p>Crystals found across the planet and from several time periods have previously been linked to humans’ spiritual belief and ritual. This includes in southern Africa.</p>
<p>People at coastal sites similarity started to collect non-food seashells around the same time (but not earlier) — perhaps for similar reasons.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381292/original/file-20210129-15-drjo0d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One of 22 calcite crystals excavated from 105,000-year-old deposits.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>Egg-citing technology</h2>
<p>Ostrich eggshells can make excellent water storage containers and were used as such in southern Africa during the Pleistocene and Holocene. At coastal sites, the earliest evidence for this technology dates back about 105,000 years. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/got-your-bag-the-critical-place-of-mobile-containers-in-human-evolution-142712">Got your bag? The critical place of mobile containers in human evolution</a>
</strong>
</em>
</p>
<hr>
<p>At Ga-Mohana Hill, we found ostrich eggshell fragments that show all the signs of being human-collected, based on their strong association with artefacts (including animal bones that are cut-marked from being butchered), and evidence of having been burned. These fragments may be the remains of early containers. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=335&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=335&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381293/original/file-20210129-23-5yndli.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=335&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">105,000-year-old ostrich eggshell fragments (left). Modern day example of ostrich eggshell canteen (right).</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<p>This suggests early humans in the Kalahari were no less innovative than those living on the coast.</p>
<h2>A global effort</h2>
<p>International and interdisciplinary collaboration makes for the best research and our paper’s authorship includes researchers from eight institutions across Australia, South Africa, Canada, Austria and the UK.</p>
<p>Local South African collaborators had an especially crucial role. For example, Robyn Pickering, Jessica von der Meden and Wendy Khumalo at the University of Cape Town provided <a href="https://theconversation.com/ancient-southern-kalahari-was-more-important-to-human-evolution-than-previously-thought-155047">important palaeoenvironmental context</a> for the archaeology. </p>
<p>By dating tufa deposits around Ga-Mohana Hill, they showed water was more abundant 105,000 years ago when early humans were using the rockshelter.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381294/original/file-20210129-17-kjsnub.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">
<figcaption>
<span class="caption">The excavation team in Ga-Mohana Hill North Rockshelter during our 2017 excavation season.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>Noga ya metsi</h2>
<p>Many who visit Ga-Mohana Hill today for ritual practice see it as part of a network of places linked to the Great Water Snake (Noga ya metsi), a capricious and shape-shifting being. Many of these spiritual places are also associated with water.</p>
<p>Places such as Ga-Mohana Hill and their associated stories remain some of the most enduring intangible cultural artefacts from the past, linking modern indigenous South Africans to earlier communities. </p>
<p>These enduring beliefs establish an important sense of orientation in a country that has been spatially disorientated by colonial disruption.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381295/original/file-20210129-17-4xr0cs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An illustrative representation of the Great Water Snake by Sechaba Maape, Lecturer at the University of the Witwatersrand.</span>
<span class="attribution"><span class="source">Sechaba Maape</span></span>
</figcaption>
</figure>
<h2>Respectful research benefits all</h2>
<p>Those who visit the site today for ritual purposes rely on its association with fear to launch them into their desired ritual states. The site’s remoteness greatly contributes to this. </p>
<p>Recognising this significance, we’ve been adjusting our project methods to not undermine the practices held there. For example, following each excavation season, the areas we work from are completely back-filled and covered with sediment.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-southern-kalahari-was-more-important-to-human-evolution-than-previously-thought-155047">Ancient southern Kalahari was more important to human evolution than previously thought</a>
</strong>
</em>
</p>
<hr>
<p>In this way, we can carefully recover our sections later, but leave almost no visible trace of our work. We haven’t erected any signage or structures, or otherwise left any significant permanent modifications.</p>
<p>Community engagement continues as we consider ways to integrate the cultural and archaeological values of Ga-Mohana Hill. We are working to further develop an approach that has a positive impact on local communities, while also reflecting on what these communities teach us — particularly regarding respect and ritual. </p>
<p>From an archaeological perspective, we believe this approach will help ensure Ga-Mohana Hill can continue to offer new and valuable insights into the evolution of <em>Homo sapiens</em> in the Kalahari.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RKYo1XiyVWU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Jayne Wilkins, ARC DECRA Research Fellow at Griffith University, summarising the significance of the finds at Ga-Mohana Hill North Rockshelter.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/154191/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Jayne Wilkins is a recipient an Australian Research Council Discovery Early Career Research Award (DE 190100160), a National Research Foundation (South Africa) Centre of Excellence (COE) in Palaeosciences Operational Grant, and a National Research Foundation (South Africa) Research Development Grant for Y-rated Researchers. </span></em></p><p class="fine-print"><em><span>Dr Sechaba Maape works for the University of the Witwatersrand, Johannesburg South Africa. He is Also a member of the South African Council for the Architectural Professional as a Candidate architect CANT46409427. </span></em></p>Researchers unearthed the 105,000-year-old artefacts from a spiritual site in southern Africa. Although far from the coast, the area is associated with stories of a great water snake.Jayne Wilkins, ARC DECRA Research Fellow, Griffith UniversitySechaba Maape, Senior Lecturer, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1481202020-11-26T15:10:15Z2020-11-26T15:10:15ZDaytime sightings of elusive aardvarks hint at troubled times in the Kalahari<figure><img src="https://images.theconversation.com/files/371495/original/file-20201126-13-fwhhpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Disappearance of aardvarks from dry ecosystems could have devastating consequences for the many other animals that rely on their burrows. </span> <span class="attribution"><span class="source">Kelsey Green</span></span></figcaption></figure><p>Aardvarks are notoriously elusive, nocturnal mammals. They generally hide in their underground burrows during the day and emerge at night to feed exclusively on ants and termites. Aardvarks are widespread throughout most habitats of Africa south of the Sahara, except deserts. But their actual numbers are not known because they’re so elusive. </p>
<p>Aardvarks top the bucket list of many wildlife enthusiasts, but few have been fortunate enough to see them – until recently. Daytime sightings of aardvarks are becoming more common in the drier parts of southern Africa. But seeing them in the daytime does not bode well because <a href="https://www.frontiersin.org/articles/10.3389/fphys.2020.00637/full">it indicates</a> they might not be finding enough food.</p>
<p>To understand how aardvarks cope with hot and dry conditions, we <a href="https://www.frontiersin.org/articles/10.3389/fphys.2020.00637/full">studied</a> them in the Kalahari, one of the hottest and driest savannah regions in southern Africa in which aardvarks occur. Our study took place at Tswalu, a private reserve in South Africa that supports research through the <a href="https://tswalu.com/tswalu-foundation/">Tswalu Foundation</a>. We equipped wild, free-living aardvarks with biologgers (minicomputers) that remotely and continuously recorded their body temperature (an indicator of well-being in large mammals), and their activity. Each aardvark also received a radio-tracking device, allowing us to locate them regularly. Tracking the aardvarks provided clues on how they changed their behaviour in relation to environmental stressors in the different seasons and years of our three-year study.</p>
<p>Our study found that in drought periods, aardvarks struggled to find food. It was difficult for them to maintain their energy balance and stay warm during the cool night, so they shifted their active time to the day. Some died from starvation. Given the aardvark’s importance to ecosystems, these findings are a concern.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Comparison of Aardvarks at night and day" src="https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=255&fit=crop&dpr=1 600w, https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=255&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=255&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=321&fit=crop&dpr=1 754w, https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=321&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/363385/original/file-20201014-15-164qwo7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=321&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aardvarks usually emerge from their burrows at night (left), but during drought periods, they are increasingly seen during daytime (right).</span>
<span class="attribution"><span class="source">N. Weyer</span></span>
</figcaption>
</figure>
<h2>Aardvarks are important ecosystem engineers</h2>
<p>No other mammal in Africa digs as many large burrows as the aardvark. <a href="https://www.tandfonline.com/doi/abs/10.1080/15627020.2011.11407509">Dozens of mammals, birds and reptiles</a> use aardvark burrows as shelter from extreme heat and cold, protection from predators, or a place to raise their young. In many of <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/joc.4377">South Africa’s conservation areas</a>, temperatures have already risen by 2°C over the past 50 years. Further warming <a href="https://iopscience.iop.org/article/10.1088/1748-9326/10/8/085004/meta">by 4-6°C</a> by the end of the century has been projected. </p>
<p>With <a href="https://www.ipcc.ch/srccl/chapter/chapter-3/">deserts and drylands expanding</a> across much of Africa, climate change might threaten the aardvark itself as well as the many animals reliant on aardvark burrows as a cool shelter from rising temperatures. </p>
<p>During typical years, aardvarks were active at night and were able to regulate their body temperature between 35-37°C. </p>
<figure class="align-center ">
<img alt="Aardvark active at night during non-drought times" src="https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/370533/original/file-20201120-21-177nnda.jpg?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">
<figcaption>
<span class="caption">Aardvark active at night during non-drought times.</span>
<span class="attribution"><span class="source">adapted from Weyer et al., 2020, Frontiers in Physiology, https://doi.org/10.3389/fphys.2020.00637</span></span>
</figcaption>
</figure>
<p>However, this pattern changed during two severe summer droughts that occurred in the Kalahari during our study. During the droughts, aardvarks shifted their activity to the daytime and their body temperature plummeted below 30°C. </p>
<p>Using remotely-sensed vegetation data recorded by <a href="https://giovanni.gsfc.nasa.gov/giovanni/">NASA satellites</a> and our own camera trap footage and logger data, we showed that these dramatic changes in body temperature and activity of aardvarks were related to the availability of grass, on which their ant and termite prey rely. When grass was scarce during droughts, the ant and termite prey became inaccessible to aardvarks, preventing them from meeting their daily energy requirements. As their body reserves declined, aardvarks were unable to sustain the energy costs of maintaining warm and stable body temperatures and shifted their activity to the warmer daytime.</p>
<figure class="align-center ">
<img alt="Aardvark active in the daytime during drought" src="https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/370534/original/file-20201120-21-7isbok.jpg?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">
<figcaption>
<span class="caption">Aardvark active in the daytime during drought.</span>
<span class="attribution"><span class="source">adapted from Weyer et al., 2020, Frontiers in Physiology, https://doi.org/10.3389/fphys.2020.00637</span></span>
</figcaption>
</figure>
<p>Shifting activity to the warmer daytime while food is scarce can <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ele.13404">save energy</a> that would otherwise be spent on staying warm during cold nights. But, for our aardvarks, even these energy savings were insufficient during drought, when the ground was bare and the ant and termite prey inaccessible. As a result, seven of our twelve study aardvarks and many others died, presumably from starvation.</p>
<h2>A bleak future for aardvarks in a hotter and drier world</h2>
<p>On the Red List of Species of the International Union for Conservation of Nature, aardvarks are currently categorised as a species of “<a href="https://www.iucnredlist.org/species/41504/21286437">Least Concern</a>”. However, we consider aardvarks to be threatened in the drier parts of their distribution in Africa, such as the Kalahari, where <a href="https://journals.ametsoc.org/jcli/article/22/13/3819/31467/Projected-Changes-in-Mean-and-Extreme">climate change brings about droughts</a>. Disappearance of aardvarks from these ecosystems could have devastating consequences for the many other animals that rely on the aardvarks’ burrows. </p>
<p>We hope that our findings will raise further awareness about the consequences of climate change and inform future wildlife conservation and management decisions. Such steps might include assessments of the actual population status of aardvarks across Africa, or mitigation measures to preserve species that depend on burrows for refuge in regions where aardvarks might go locally extinct. More extensive measures, like water-wise reserve management, increasing sizes and connectivity of nature reserves in semi-arid regions, and reducing emissions to mitigate climate change, are just as urgent. </p>
<p>Finally, any solution to the plight of climate change on free-living animals requires a better understanding of their capacities to cope with drought. Therefore, many more long-term comprehensive studies are needed on the physiology and behaviour of the vulnerable animals living in hot, arid regions of the world.</p>
<p><em>Nora Marie Weyer’s disclosure statement has been updated.</em></p><img src="https://counter.theconversation.com/content/148120/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robyn Hetem receives funding from South Africa’s National Research Foundation. </span></em></p><p class="fine-print"><em><span>Nora Marie Weyer is affiliated with the Aardvark section of the IUCN/SSC - Afrotheria Specialist Group.</span></em></p>Aardvarks are nocturnal animals but climate change is altering that and it’s a problem.Robyn Hetem, Senior Lecturer, University of the WitwatersrandNora Marie Weyer, PhD - Wildlife Conservation Physiology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/642562016-10-24T15:10:44Z2016-10-24T15:10:44ZThe story of how livestock made its way to southern Africa<figure><img src="https://images.theconversation.com/files/142638/original/image-20161021-1748-1t7xjxj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Livestock ultimately came to South Africa from the north in a migratory event.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Much of South Africa has good grazing for livestock. And sheep, goats and cattle have played an important role in the history of the region’s diverse cultures. But how did these animals get here?</p>
<p>For a long time scholars were convinced that the first livestock in southern Africa had to have come along with a significant migration of people from north as <a href="https://archive.org/stream/cu31924029888587/cu31924029888587_djvu.txt">far as Egypt</a>. This view became prevalent after the first European settlement was established in 1652 where Cape Town stands today. The settler community was largely concerned with obtaining livestock from the local <a href="http://www.sahistory.org.za/article/khoikhoi">Khoekhoen herders</a>, the antecedents of the Nama people who still speak that language. </p>
<p>Nineteenth century scholars thought Khoekhoen and their herds had originally come from far to the north. Later, the source of the Khoekhoen was thought to have been further south, perhaps in East Africa <a href="https://books.google.co.za/books?id=U55eucC8XzMC&pg=PA144&lpg=PA144&dq=Elphick,+R.+1985.+Khoikhoi+and+the+Founding+of+White+South+Africa%20%20.+Johannesburg:+Ravan+Press&source=bl&ots=lOrOGA7wG7&sig=vxuWKUf0dIB93YcPkugIiv1Eg7o&hl=en&sa=X&ved=0ahUKEwiTpeb_2J3PAhWIB8AKHZLKDRcQ6AEIHDAA#v=onepage&q=Elphick%2C%20R.%201985.%20Khoikhoi%20and%20the%20Founding%20of%20White%20South%20Africa.%20Johannesburg%3A%20Ravan%20Press&f=false">or the Zambezi Basin</a>. Another theory was that livestock was brought southwards along the Atlantic seaboard through Angola and Namibia to the Cape of Good Hope and beyond. Lately however this theory had fallen out of favour.</p>
<p>In all cases, however, scholars were convinced that the first livestock in southern Africa had to have come along with a significant migration of people from the north. This was typical colonial thinking, attributing all economic innovations – like livestock herding – to northerners since the locals were not considered innovative enough. Even today the conventional view still holds that a migratory event in the north resulted in livestock coming to South Africa.</p>
<p>But can such thinking still be supported in the 21st century?</p>
<h2>New research, new thoughts</h2>
<p>There is no doubt – and never has been – that livestock must have come from the North, ultimately the Near East. At issue is who brought them and what was the mechanism: a migration of a large number of livestock herders? Or small scale infiltration of herders, perhaps only young males? Perhaps a sort of down-the-line relay with one group of herders passing livestock to their neighbours and so on.</p>
<p><a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134215">New research</a> based on a detailed reexamination of stone tools and ancient ceramic vessel shards it seems that it was the northern San people who introduced the first sheep to South Africa. They are the non-Khoe speaking indigenous hunter-gatherers of the northern parts of southern Africa who are close relatives of the ethnographically famous Kalahari “Bushmen”. Where and how they obtained the livestock remains unclear, principally because for the past few decades there has been little relevant archaeological research in Zambia and Tanzania.</p>
<p>Complicating the story, recent reports indicate that the first sheep may have arrived in South Africa several centuries earlier than previously thought. Bones identified as domesticated sheep, which were <a href="http://www.sahumanities.org/ojs/index.php/SAH/article/view/370">excavated</a> from the Blydefontein shelter in the upper Karoo, have been dated to 2700 years ago. But the analysis of ancient DNA from these <a href="https://www.researchgate.net/publication/283582974_Molecular_identification_of_sheep_at_Blydefontein_Rock_Shelter_South_Africa">bones suggests</a> that they may be of wild bovids. </p>
<h2>Where livestock hailed from</h2>
<p>The colonial view relied on the fact that livestock are not native to southern Africa. The wild ancestors of African sheep, goats and cattle were all first domesticated in southwestern Asia and cattle perhaps also in <a href="http://archaeology.about.com/od/shthroughsiterms/qt/Sheep-History.htm">northeastern Africa</a>. </p>
<p>The origins of the language of the seventeenth century Cape Khoekhoen, proto-Khoe, is also convincingly traced to East Africa by <a href="http://www.sahumanities.org/ojs/index.php/SAH/article/viewFile/231/190">historical linguists</a>. Since the language of the Cape Khoekhoen and the livestock must have originally come from the lands to the north of the River Zambezi, the assumption was made that they probably came together in one <a href="http://www.sarada.co.za/traditions/african_pastoralists_and_herders_/khoekhoen_rock_art/">migratory event</a>. </p>
<p>The parsimonious, or most economical, explanation is that these events were related: Khoe-speakers brought the earliest livestock. This is the researcher’s equivalent of killing two birds with one stone. Since the mid-1970s the view has held that proto-Khoe-speaking people in a region between the Zambezi River and East Africa first acquired livestock and the necessary herding skills from other populations to their north around 2,000 years ago. The putative other populations were thought to have been Bantu-speakers who spread out of their homeland in west-central Africa, beginning some <a href="https://www.researchgate.net/publication/304248461_Admixture_into_and_within_sub-Saharan_Africa">5 000 or 6 000 years ago</a>. </p>
<p>This view is now challenged by a sizeable collection of sheep bones dated using a complex chemical technique known as radiocarbon dating. The oldest southern African livestock bones are several centuries older than the first villages of the Bantu-speaking farmers and metallurgists in the Zambezi basin. The oldest livestock bones also invariably occur in typical Later Stone Age sites, usually rock shelters, known to have been occupied by the indigenous San hunter-gatherers of southern Africa. </p>
<h2>Early sheep</h2>
<p>And now a <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134215">re-analysis of stone tools</a> from many previously excavated sites all across southern Africa seems to have located the first herders. The sub-continental distribution of a particular stone toolkit matches the distribution of northern San genes and languages, and it is precisely that stone toolkit which is found in the South African rock shelter sites with the oldest sheep bones. This indicates the high probability that the earliest sheep reached southernmost Africa by one or more sporadic infiltrations by small groups of northern San hunter-gatherers.</p>
<p>The earliest sheep seem to have arrived in such an infiltration event in the last few centuries BC along the <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040340">Atlantic seaboard</a>. That is at least two or three centuries before the earliest farming villages appeared in the Zambezi basin and on the <a href="http://stpxml.sourceforge.net/Sites/Stilbaai/KRK/pdf/front.pdf">east coast of southern Africa</a>. The earliest arrival of livestock seems to have had few consequences or implications for the continuation of a basically southern African Later Stone Age hunting and gathering <a href="http://link.springer.com/article/10.1007/s10437-016-9229-8">way of life</a>. Hunting and gathering remained the main subsistence activity despite the availability of livestock. </p>
<p>For now, indications are that the Khoe-speakers may not have arrived with the first livestock, but a little later, perhaps around the same time as the first bantu-speaking farmers of the so-called Iron Age.</p>
<p>The moral of the story seems to be that the most parsimonious answer is not always the correct one.</p><img src="https://counter.theconversation.com/content/64256/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karim Sadr receives funding from the University of the Witwatersrand and the South African National Research Foundation. He works for the University of the Witwatersrand. </span></em></p>There are many theories on how livestock made its way to South Africa. The answer is quite complex and not as simple as one would think.Karim Sadr, Associate Professor Geography, Archaeology and Environmental Studies, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/518772016-01-06T04:19:39Z2016-01-06T04:19:39ZIt’s true: what a sheep eats affects the taste of your lamb roast<figure><img src="https://images.theconversation.com/files/105399/original/image-20151211-8291-ejbz51.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You are what you eat – and so's your festive lamb, in terms of flavour.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>For those who enjoy a meaty spread during the festive season, it’s worth knowing that not all lamb tastes the same. It depends on where it comes from, and what it has been eating.</p>
<p>South African folklore has long suggested that sheep meat in the country has a distinct – often herbal or even medicinal – flavour and aroma. But more recently, <a href="http://www.karoomeatoforigin.com/downloads/ARC%20Report%20on%20sensory%20analysis%2027%20sept%2007.PDF">studies</a> have confirmed that there is a detectable sensory difference in sheep meat produced in different regions of southern Africa.</p>
<p>The flavour of meat develops through cooking. Flavour can also be added to meat through brining or marinating. But the inherent flavour in meat is largely dependent on what the animal feeds on.</p>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/2286578">Traditionally</a> it has been believed that high-energy, grain-based diets produce more intense flavours in red meats than forage or grass diets. But the fact that the pungent flavour and aroma of local lamb and mutton comes from sheep reared on natural pastures and open fields goes against this. </p>
<p>Lamb and mutton from certain grazing regions such as the <a href="http://www.southafrica.net/za/en/articles/entry/article-southafrica.net-the-magical-great-karoo">Karoo</a> or <a href="http://freestatetourism.org/?page_id=1367">Free State</a> have their own unique flavours. These meats are often sought after by South African consumers who prefer a certain taste and are prepared to <a href="http://repository.up.ac.za/bitstream/handle/2263/19889/Weissnar_Consumer(2012).pdf?sequence=1">pay a premium</a> for it. </p>
<h2>Establishing an unique taste</h2>
<p>Sheep are produced in most corners of South Africa. Special breeds do well in arid areas. They can withstand harsh temperatures, arid soils and sparse vegetation in areas where there is limited rainfall. The Karoo in South Africa’s Northern Cape province is one such area. </p>
<p>The <a href="http://www.karoomeatoforigin.com/">Karoo Development Foundation</a> was established in 2009 to certify meat from the region. The certification scheme would mean lamb and mutton products from the area could be traded using the Karoo Meat of Origin <a href="http://www.karoomeatoforigin.com">certification</a>. </p>
<p>A <a href="http://www.karoomeatoforigin.com/downloads/ARC%20Report%20on%20sensory%20analysis%2027%20sept%2007.PDF">study</a> was done to evaluate the aroma, texture and flavour attributes of sheep meat from different regions in South Africa. The aim was to determine whether, statistically, there was a significant difference in the taste of meat from sheep reared in different parts of South Africa, stretching into Namibia.</p>
<p>During the <a href="http://www.karoomeatoforigin.com/downloads/ARC%20Report%20on%20sensory%20analysis%2027%20sept%2007.PDF">study</a>, mutton carcasses from two major breeds of sheep – <a href="http://www.dorpersa.co.za/info/characteristics">Dorper</a> and <a href="http://merinosa.co.za">Merino</a> – were procured from eight farms in various regions. These include the Free State, Kalahari, Northern Cape (specifically De Aar and Carnarvon), and Namibia. </p>
<p>The study found that mutton from the Karoo region – in the Northern Cape and Kalahari – had definite flavour characteristics. These could be attributed to the grazing plants the sheep fed on.</p>
<p>Lamb and sheep from Karoo graze on indigenous plants found exclusively in this region. These plants can endure heat, cold, wind and hail, providing feed for the animals all year round. Karoo plants have developed in different ways to survive the harsh conditions of the region.</p>
<p>Sheep reared in the Free State have a different diet. This is a summer-rainfall region that gets very cold during the winter months, especially towards the eastern mountainous regions. <a href="http://www.southafrica.info/about/geography/free-state.htm#.VmFW8nYrLIU">The landscape</a> features spacious grass-covered prairie land. These grasslands contribute to the associations of mild grass-like flavour attributes in meat produced in this region.</p>
<h2>The flavour is in the fat</h2>
<p>There are two other factors that play a role in the flavour of the meat: the fat and the age of the animal. </p>
<p>Fat is an energy source stored in animal muscles, which also contributes to the flavour of meat. Although water is the most prevalent component of meat, most of the aroma molecules which carry flavour are repelled by water but dissolve in fat.</p>
<p>Each animal has a unique fat content. This varies from cut to cut. Muscles that are used most by the animal contain the least amounts of fat. More tender cuts of meat which contain muscles that are less used by the animal will contain more fat and, as a result, more intense flavours.</p>
<p>Age also plays an important role in flavour development. The older the animal gets, the more time it has had to build up fat. As a result of age, more flavour is deposited within the meat.</p><img src="https://counter.theconversation.com/content/51877/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nicolette Hall consults to the South African Red Meat Industry and Lamb and Mutton South Africa. She has received funding from RMRDSA. </span></em></p>Lamb and mutton meat from parts of South Africa have a unique taste, which, according to science, depends on what the animal eats.Nicolette Hall, Researcher in Human Nutrition, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.