tag:theconversation.com,2011:/uk/topics/caveman-10536/articlescaveman – The Conversation2023-05-24T21:21:01Ztag:theconversation.com,2011:article/2053672023-05-24T21:21:01Z2023-05-24T21:21:01ZIt’s time to leave the Paleo Diet in the past: Recent studies have failed to support its claims<figure><img src="https://images.theconversation.com/files/528111/original/file-20230524-44222-l4fgym.jpg?ixlib=rb-1.1.0&rect=369%2C485%2C6424%2C4082&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is this really what our Paleolithic ancestors ate? New data suggests prehistoric diets had a lot more overlap with our own than earlier studies estimated. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>The <a href="https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/paleo-diet/art-20111182">Paleo Diet</a> urges us to mimic our prehistoric ancestors’ food choices. In practice, this means eschewing dairy products, cereals, pulses and processed sugar, and consuming vegetables, fruit, nuts, pasture-raised meat and wild-caught seafood instead.</p>
<p>The Paleo Diet’s proponents contend that by eating this way, we will lose weight and reduce our risk of chronic diseases.</p>
<p>The roots of the Paleo Diet can be <a href="https://www.isbndb.com/book/9781684114399">traced to the 1950s</a>, but it owes its current popularity to a book by Loren Cordain called <a href="https://www.isbndb.com/book/9780471413905"><em>The Paleo Diet: Lose Weight and Get Healthy by Eating the Food You Were Designed to Eat</em></a>, the first edition of which was released in 2001.</p>
<p>In the 22 years since the publication of Cordain’s book, the Paleo Diet has been adopted by several million people and a <a href="https://www.researchandmarkets.com/reports/5030473/paleo-foods-global-strategic-business-report?utm_source=">multi-billion dollar industry</a> has developed in connection with it, including <a href="https://www.healthline.com/nutrition/best-paleo-brands-and-products#our-picks">premium-priced foods</a> and a certification scheme. </p>
<h2>The Paleo Diet’s health claims</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Collage of images of food products marketed as suitable for the Paleo Diet, and two restaurants that serve paleo food" src="https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527851/original/file-20230523-12079-6bjla5.jpeg?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>
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<span class="caption">A multi-billion-dollar industry has developed in connection with the Paleo Diet, including premium-priced foods and a certification scheme.</span>
<span class="attribution"><span class="source">(Amalea Ruffett)</span>, <span class="license">Author provided</span></span>
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<p>While the Paleo Diet has many adherents, clinical research has yet to substantiate its purported health benefits.</p>
<p>To begin with, it does not seem to outperform conventional recommended diets as a means of losing weight in the medium- to long-term. The only <a href="https://doi.org/10.1038/ejcn.2013.290">published multi-year study to have evaluated the Paleo Diet’s impact on weight loss</a> found that following the Paleo Diet was no more effective than following the <a href="https://doi.org/10.6027/Nord2014-002">Nordic countries’ official nutrition recommendations</a> after two years.</p>
<p>It is a similar story with the claims that have been made about the Paleo Diet’s impact on chronic diseases. For example, a <a href="https://doi.org/10.5694/mja16.00347">recent review</a> found that studies examining the Paleo Diet’s impact on Type 2 diabetes have been “inconclusive.”</p>
<p>Similarly, the authors of a <a href="https://doi.org/10.1007/s00394-019-02036-y">2020 study</a> reported that following the Paleo Diet resulted in a higher relative abundance of gut bacteria that produce a chemical associated with cardiovascular disease, which is at odds with the claim that the Paleo Diet will reduce the probability of experiencing chronic diseases.</p>
<p>Why have the health benefits claimed for the Paleo Diet not been supported by clinical research? As evolutionary anthropologists, we think the problem is that the Paleo Diet is based on a flawed premise and faulty data, and in what follows we’ll try to show why our research brought us to this conclusion.</p>
<h2>A flawed premise</h2>
<p>The idea underlying the Paleo Diet is that the <a href="https://www.discovermagazine.com/health/the-paleo-diet-should-modern-humans-eat-the-way-our-ancestors-did">ongoing surge in obesity and associated diseases in many countries is the result of a mismatch between the foods we eat and the foods our species evolved to consume</a>.</p>
<p>This mismatch, so the argument goes, is a consequence of there having been too little time since agriculture appeared, 12,000 years ago, for evolution to have adapted our species to deal with a high-carbohydrate, low-protein diet or to process domesticated food.</p>
<p>This argument seems reasonable because there is a perception that evolution is a very slow process. However, it is not in fact supported by research on diet-related genes.</p>
<figure class="align-right ">
<img alt="A pitcher and a glass of milk" src="https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1135&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1135&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528090/original/file-20230524-44339-4mfjil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1135&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Ancient DNA research indicates that lactase persistence — the continued ability to produce the enzyme lactase as an adult — is less than 5,000 years old in Europe.</span>
<span class="attribution"><span class="source">(Pixabay)</span></span>
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<p>Work on <a href="https://doi.org/10.1007/s00439-008-0593-6">lactase persistence</a> — the continued ability to produce the enzyme lactase as an adult — illustrates this. Lactase enables us to digest the milk sugar lactose, so lactase persistence is useful for a diet involving dairy products. Lactase persistence is found in just a few regions, one of which is Europe. <a href="https://doi.org/10.1146/annurev-genom-091416-035340">Ancient DNA research</a> indicates that lactase persistence is less than 5,000 years old in Europe.</p>
<p>Similarly, an <a href="https://doi.org/10.1093/molbev/msac183">analysis of genetic data from African populations published last year</a> found evidence of recent adaptation in a family of genes connected with metabolizing alcohol. In this case, natural selection operated within the last 2,000 years.</p>
<p>This evidence shows the mismatch rationale for adopting the Paleo Diet is not supported by genetic studies. Such studies demonstrate that evolution can produce diet-related adaptations in much less time than has elapsed since agriculture first appeared.</p>
<h2>Faulty data</h2>
<p>There is also an issue with the Paleo Diet’s recommendations regarding the contributions of the three macronutrients — protein, carbohydrate and fat — to a person’s diet.</p>
<p>According to the current version of the Paleo Diet, we should aim for a diet consisting of 19-35 per cent protein, 22-40 per cent carbohydrate and 28-58 per cent fat, by energy. This makes the Paleo Diet lower in carbohydrate and higher in protein than conventional recommended diets, such as those promoted by <a href="https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-macronutrients-dietary-reference-intakes-tables-2005.html">Health Canada</a> and the <a href="https://www.dietaryguidelines.gov">United States Department of Agriculture</a>.</p>
<p>The macronutrient ranges recommended by the Paleo Diet are based on a <a href="https://doi.org/10.1093/ajcn/71.3.682">study from 2000</a> that estimated macronutrient percentages for more than 200 hunter-gatherer groups. However, <a href="https://doi.org/10.1016/j.ajcnut.2022.12.003">recently we have found</a> there is a problem with this study.</p>
<p>The problem lies in the macronutrient values the researchers used for plant foods. While they employed several sets of macronutrient values for animal foods, they only used one set of macronutrient values for plant foods. They obtained the plant data from an analysis of foods traditionally eaten by Indigenous Australians.</p>
<p>In our study, we evaluated the effects of this decision with two plant macronutrient datasets, both of which consisted of values for plants consumed by hunter-gatherers from several continents.</p>
<p>Using multi-continent plant data produced significantly different macronutrient estimates. These in turn produced macronutrient ranges that are wider than the ones recommended by the Paleo Diet. The ranges we calculated are 14-35 per cent protein, 21-55 per cent carbohydrate and 12-58 per cent fat, by energy.</p>
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<img alt="A shopping bag with fruit, vegetables and other fresh groceries spilling out" src="https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528112/original/file-20230524-44222-7snxqd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">New research suggests that the diet of our prehistoric ancestors had more overlap with modern macronutrient recommendations than the Paleo Diet indicates.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<p>These ranges overlap those recommended by <a href="https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary-reference-intakes/tables/reference-values-macronutrients-dietary-reference-intakes-tables-2005.html">Health Canada</a> (10-35 per cent protein, 45-65 per cent carbohydrate and 20-35 per cent fat) and the <a href="https://www.dietaryguidelines.gov/">United States Department of Agriculture</a> (10-30 per cent protein, 45-65 per cent carbohydrate and 25-35 per cent fat).</p>
<p>That the macronutrient ranges of hunter-gatherer diets overlap government-approved macronutrient ranges casts doubt on the idea that the Paleo Diet is healthier than conventional recommended diets.</p>
<h2>It’s time to leave the Paleo Diet in the past</h2>
<p>Given that the rationale for adopting the Paleo Diet isn’t supported by the available scientific research, and its macronutrient recommendations aren’t scientifically robust, it is, we suggest, not surprising that the diet’s purported health benefits haven’t been supported by clinical studies.</p>
<p>The Paleo Diet has been a worthwhile experiment, but at this point it seems likely that people following it might just be wasting money. Conventional, government-recommended diets offer comparable outcomes <a href="https://doi.org/10.1016/j.nutres.2011.05.008">at a lower cost</a>. In our view, it’s time to leave the Paleo Diet in the past.</p><img src="https://counter.theconversation.com/content/205367/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Collard receives funding from the Canada Research Chairs Program, the Canada Foundation for Innovation, the British Columbia Knowledge Development Fund, and Simon Fraser University.</span></em></p><p class="fine-print"><em><span>Amalea Ruffett 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 Paleo Diet is popular, but research has yet to substantiate its purported health benefits. As evolutionary anthropologists, here’s why we think it’s time to leave the Paleo Diet in the past.Mark Collard, Canada Research Chair in Human Evolutionary Studies, and Professor of Archaeology, Simon Fraser UniversityAmalea Ruffett, PhD Student in Archaeology , Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1591592021-04-19T15:15:43Z2021-04-19T15:15:43ZPrehistoric cave painters might have been ‘high’ on oxygen deprivation – new study<figure><img src="https://images.theconversation.com/files/395701/original/file-20210419-13-etly5c.jpeg?ixlib=rb-1.1.0&rect=0%2C50%2C4135%2C2727&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Prehistoric hand paintings at the Cave of Hands in Argentina, thought to be over 10,000 years old
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/prehistoric-hand-paintings-cave-hands-spanish-1634481835">R.M. Nunes/Shutterstock</a></span></figcaption></figure><p>Long before the emergence of writing, palaeolithic cave paintings represent the very first examples of human visual culture. They provide a shadowy glimpse of a prehistoric world in which signs were beginning to be used to communicate meaning.</p>
<p>Archaeologists have long been fascinated over what exactly compelled “cave men” to produce these enigmatic paintings. Because they’re often located in caves – enchanting and atmospheric places in their own right – certain experts have argued that prehistoric painters may have produced their art under the influence of “altered states of consciousness”. The theory essentially claims the painters in some way got high.</p>
<p>In support of this theory, a <a href="https://www.tandfonline.com/doi/full/10.1080/1751696X.2021.1903177">new study</a> has found that low oxygen levels in poorly ventilated caves can induce hypoxia, which can inspire hallucinations. But while the theory is certainly plausible, here’s why I think it fails to explain the majority of cave art.</p>
<h2>Cave art</h2>
<p>Over <a href="https://www.nature.com/articles/s41559-018-0598-z">65,000 years ago</a>, the Neanderthals left finger dots and hand stencils on European cave walls. These basic markings were made using ochre, manganese and charcoal – common materials in Neanderthal life, likely also used to ornament the body.</p>
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Read more:
<a href="https://theconversation.com/how-we-discovered-that-neanderthals-could-make-art-92127">How we discovered that Neanderthals could make art</a>
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<p>Eurasian figurative art – featuring representations of people and animals – appeared some 40,000 years ago in <a href="https://www.nature.com/articles/nature13422">Indonesia</a> and 37,000 years ago in <a href="https://www.nature.com/articles/nature07995">Europe</a>. This appears to have been exclusive to the successors of Neanderthals: <em>Homo sapiens</em>. </p>
<p>These people’s images of herbivorous prey animals were carved, engraved and painted on bone, stone and mammoth ivory – and on the walls of caves. The overwhelming dominance of prey such as horse, bison, deer and mammoth reflects the critical importance of these species to survival in the <a href="https://global.oup.com/academic/product/images-of-the-ice-age-9780199686001?cc=ro&lang=en&">harsh environments</a> of the Pleistocene north.</p>
<figure class="align-center ">
<img alt="What appear to be bison painted on a cave wall" src="https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=347&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=347&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=347&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=436&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=436&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395702/original/file-20210419-15-mulbw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=436&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The Lascaux Cave in south-western France, thought to have been painted around 20,000 years ago.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/vezere-valley-france-april-22-2017-659932633">thipjang/Shutterstock</a></span>
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<p>But why figurative “cave art” emerged and how it functioned has baffled archaeologists since its rediscovery and authentication in the late 19th century. Whether they’re simple stencils of hands or complex drawings of prey, cave paintings are a window into the minds of the very first artists. Scholars believe that knowing what inspired them could teach us something about the very human compulsion to express ourselves creatively.</p>
<h2>Why paint?</h2>
<p><a href="https://global.oup.com/academic/product/images-of-the-ice-age-9780199686001?cc=ro&lang=en&">Successive theories</a> have purported to explain the origins of ancient art – a rich and varied collection that we know was added to over at least 50,000 years of prehistory. Yet these theories inevitably say more about their proponents than about the motives of Pleistocene man. </p>
<p>To the Victorians, those motives boiled down to pure aesthetics. In the 20th century, scholars began to believe the paintings had a magical function, and theories of hunting and fertility magic arose to explain drawings of animals and sculptures of “venuses”.</p>
<p>As we entered the information age, the images came to be seen as repositories of ecological information – recording details about things like prey animals and their behaviour. And by the 1980s, the worst excesses of new age thinking promoted the idea that cave art was the product of altered states of consciousness and the <a href="https://www.amazon.co.uk/Mind-Cave-Consciousness-Origins-Art/dp/0500284652">visions that can</a> go hand in hand. Since then, the notion has never gone away.</p>
<h2>Altered states</h2>
<p>But what could have caused ancient altered states? Psychoactive substances other than fly agaric (the red and white topped mushroom) were not present in <a href="https://www.cambridge.org/core/journals/cambridge-archaeological-journal/article/abs/waking-the-trancefixed/EAECEF9095A87C13979B1D37306669EC">Pleistocene Eurasia</a>. Ingesting ochre or manganese would give you a poor stomach, not hallucinations. </p>
<p><a href="https://www.tandfonline.com/doi/full/10.1080/1751696X.2021.1903177">The new study</a> has proposed altered states instead caused by low oxygen levels, produced by small hearths and simple animal-fat lamps that would have been burning in confined caves. The authors claim this could have induced hypoxia (oxygen deprivation), leading to hallucinations which, in turn, stimulated creativity in the form of cave art. </p>
<p>Typically, around 21% of air is oxygen. Any reduction below 18% produces a mild hypoxia, and below 13% produces severe hypoxia. The study uses computer simulations to demonstrate the plausibility of this new theory, while drawing on ethnography – notably the ubiquity of “shamanic” belief systems among hunter-gatherers, and the idea that caves form a link between this world and others.</p>
<h2>Reviewing the theory</h2>
<p>It’s plausible that altered states stimulated some cave art. But it’s just as plausible that hypoxia in caves produced far more <a href="https://www.britannica.com/science/hypoxia">common symptoms</a> of weakness, headaches, drowsiness, nausea and breathlessness, which don’t sound inspiring to me. </p>
<p>In any case, cave chambers vary considerably in size and are often decently ventilated. <a href="https://www.cambridge.org/core/journals/antiquity/article/abs/div-classtitlelorblanchet-michel-la-naissance-de-landaposart-genese-de-landaposart-prehistorique-304-pages-bandampw-and-colour-figures-1999-paris-errance-2-87772-165-5-hardback-ff290div/A8A4C3BE8E4DDA5CF60CDB6F59EDF7E3">Niaux’s Salon Noir</a> in southwestern France is positively cathedral-like, and features many cave paintings. Many examples of cave art are also complex and highly skilled compositions that took hours to produce – they’re unlikely to be the product of hallucinations.</p>
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<figcaption><span class="caption">France is home to many of the world’s most impressive prehistoric cave paintings.</span></figcaption>
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<p>It’s difficult to falsify the new hypothesis scientifically – but even if it’s true, what would it really tell us? At best, altered states could provide a mechanism but not an explanation for some Palaeolithic art. If they did cause some individuals to create, they would not explain the content, themes, style or wider function of the art. </p>
<p>To discuss altered states is therefore as meaningless as making the observation that the tomb builders of Egypt’s Valley of the Kings <a href="https://openlibrary.org/books/OL7653843M/The_Egyptians">drank beer</a>: we know that, but we can be sure that it wasn’t drunkenness that stimulated them to create the art on the walls of the tombs they built. </p>
<p>I have spent enough time underground, observing cave art in its context, to understand how making simple links between hallucinations, shamanism and cave art fails to do justice to the remarkably complex works created by early artists in these mysterious places.</p>
<h2>A seductive theory</h2>
<p>But why are altered states perennially popular explanations for Palaeolithic cave art? It’s probably because caves are mysterious, suggestive places, triggering responses in our brains such as pareidolia – our <a href="https://www.cambridge.org/core/journals/cambridge-archaeological-journal/article/abs/origins-of-iconic-depictions-a-falsifiable-model-derived-from-the-visual-science-of-palaeolithic-cave-art-and-world-rock-art/CC686395FE47390DE88F67ADDF85A838">evolutionary propensity</a> to give meaning to natural things, like finding faces in clouds. </p>
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Read more:
<a href="https://theconversation.com/warning-signs-how-early-humans-first-began-to-paint-animals-95597">Warning signs: how early humans first began to paint animals</a>
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<p>In our everyday lives, we constantly toggle between mild altered states of consciousness. They make our imaginary lives immensely rich, and may go some way to explaining how early art took the form it did. Ultimately, imagination is far richer than trance – and we do a disservice to our prehistoric ancestors when we argue their art was the product of a “high” rather than creative expression.</p><img src="https://counter.theconversation.com/content/159159/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Pettitt 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>It’s possible that low oxygen levels in caves produced hallucinations – but that doesn’t explain the majority of prehistoric art.Paul Pettitt, Professor in the Department of Archaeology, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/828782017-11-02T02:54:41Z2017-11-02T02:54:41ZWhat the history of iconoclasm tells us about the Confederate statue controversy<figure><img src="https://images.theconversation.com/files/188062/original/file-20170928-2939-1sqtnls.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Confederate statue lies on a pallet in a warehouse in Durham, North Carolina after protesters toppled and defaced it.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Confederate-Monument-Protest-Statue-Toppled/15d7476fae6e4d1d887d525278683db8/4/0">AP Photo/Allen Breed</a></span></figcaption></figure><p>Over the last few months, a new American civil war seems to have broken out. It isn’t being fought with weapons. Instead, it’s being fought with statues and symbols, and at the heart of the dispute is the question of whether statues of Confederate heroes should be allowed to stand.</p>
<p>After a violent “Unite the Right” rally ostensibly intended to protest the removal of a statue of Robert E. Lee, an enthusiastic mob <a href="http://time.com/4900779/durham-north-carolina-confederate-statue-pulled-down-protesters/">pulled down a bronze figure in North Carolina</a>, massive Confederate statues in Baltimore <a href="http://www.huffingtonpost.com/entry/baltimore-confederate-statues_us_5994274fe4b009141641806b">were surreptitiously removed at night</a> and New York City <a href="https://hyperallergic.com/397022/confederate-symbols-removed-nyc/">is formally reviewing</a> which of its public statues should be allowed to remain in place. </p>
<p>The President <a href="http://thehill.com/homenews/administration/346929-trump-revives-defense-of-confederate-monuments">has weighed in</a>, along with his chief of staff, John Kelly, <a href="https://www.washingtonpost.com/politics/trump-chief-of-staff-kelly-decries-removal-of-monuments/2017/10/31/f46b2702-be24-11e7-9294-705f80164f6e_story.html?utm_term=.36fbbc09e2b3">who said</a> their removal would set a “very, very dangerous” precedent. It’s even become <a href="https://www.cbsnews.com/news/confederate-monuments-become-hot-button-issue-in-va-governors-race/">an issue</a> in the Virginia governor’s race.</p>
<p>How did a bunch of statues (most of which are conventional in their appearance) become a canvas for passion, vitriol and violence? Are the defenders of the Confederate statues correct when they say their destruction or their removal sets a dangerous precedent?</p>
<p>To answer these questions, it’s helpful to look at the issue through the lens of history – to when the destruction of statues became a political act. </p>
<h2>‘I will hack up the flesh’</h2>
<p>The art of the cavemen tended to use animals as its subject; the representation of humans – aside from female fertility statues – is rare. The images of people that do exist mostly show them in animal guise or animal costume, presumably shamans. Art was religious but apparently not very political.</p>
<p>This changed with the advent of agriculture and the emergence of Middle Eastern city-states – empires ruled by kings who claimed support from gods and who maintained strict forms of social hierarchy. These rulers asserted their power with statues of themselves and their gods. And it was during this period in human history that <a href="http://csmt.uchicago.edu/glossary2004/iconoclasm.htm">iconoclasm</a> – the destruction of images for political and religious reasons – first emerged.</p>
<p>If these kingdoms were overthrown, it was standard practice to subject their rulers and military leaders to horrible forms of public torture and execution: flaying them alive, cutting off of eyes, noses and other body parts and then displaying them. </p>
<p>“I will hack up the flesh and then carry it with me, to show off in other countries,” <a href="http://www.jmhinternational.com/news/news/selectednews/files/2009/05/20090519_SpiegelOnline_TheWorstWaysToDie_TorturePracticesOfTheAncientWorld.pdf">proclaimed Ashurbanipal</a>, an Assyrian king who ruled from 668 to 627 B.C. (<a href="http://www.britishmuseum.org/research/collection_online/collection_object_details/collection_image_gallery.aspx?partid=1&assetid=32865001&objectid=366859">A well-known relief</a> in the British Museum shows Ashurbanipal consuming a sumptuous meal, while the severed head of Teuman, King of Elam, hangs from a nearby tree as a marker of his power.)</p>
<p>Statues and memorials of rulers were subjected to similar forms of mutilation. For example, a copper statue of an Akkadian ruler from Nineveh <a href="https://www.learner.org/courses/globalart/work/266/index.html">was famously defaced</a>, very likely when the Medes sacked Nineveh in 612 B.C. The head was severed from the body, the ears were cut off, the eyes were gouged out and the lower part of the beard was trimmed, as if an actual captive were being tortured and humiliated. (Today, its “remains” live in the National Museum of Iraq.)</p>
<p>In many ways, the destruction of a statue mimicked attacks on real people, and this aspect of iconoclasm surely remains central to the practice today.</p>
<p><a href="https://www.youtube.com/watch?v=H-uAZa4H1vk">In videos</a> of the Durham, North Carolina statue of a Confederate soldier being roped around the neck and pulled from his pedestal, what’s striking is the glee of the crowd in mutilating it. Aggressive instincts were clearly at work, not unlike those present in a lynching, or that led to the dismemberment of the Akkadian effigy.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/H-uAZa4H1vk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Protesters topple a Confederate statue in Durham, North Carolina.</span></figcaption>
</figure>
<h2>Religious iconoclasm</h2>
<p>While such vandalism has most often been directed at images of warriors and rulers, it’s been directed toward religious images as well. </p>
<p>In Egypt, the Pharaoh <a href="http://www.encyclopedia.com/people/literature-and-arts/english-literature-1499-biographies/akhenaten">Akhenaten</a> created a monotheistic religion that worshiped the sun god, Aten. He ordered the destruction of all images of other gods, a practice rescinded after his death. (Most likely the edicts reflected a political struggle of some sort between Akhenaten and powerful priests.)</p>
<p>But perhaps <a href="http://www.cambridge.org/us/academic/subjects/history/european-history-450-1000/byzantium-iconoclast-era-c-680850-history?format=PB">the most famous instance of iconoclasm</a> still isn’t very well-understood, since we have accounts only from the victors, written years after the fact. </p>
<p>During the early Christian period, the Byzantine Emperor Leo III ordered the destruction of all Christian images, on the grounds that they represented idolatry and were heretical. The policy deeply divided the empire and caused the pope in Rome to anathematize and excommunicate the emperor’s iconoclast followers. The dispute finally ended about 842 with the compromise that henceforth icons would be venerated but not worshiped in the Byzantine Empire. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/188061/original/file-20170928-1488-ja3sun.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The destruction of a church during the Byzantine era.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:48-manasses-chronicle.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>What’s fascinating is that a theological debate – how to treat religious icons – also served as a focal point for political and cultural rivalries within the empire. We see echoes of this today in the Confederate statue debate, with various political and cultural factions picking sides.</p>
<h2>Monuments to…losers?</h2>
<p>Confederate monuments are unusual in that they celebrate not the victors of a war, but the losers. </p>
<p>When Confederate General Robert E. Lee surrendered in 1865, <a href="http://www.colorado.edu/ibs/es/alston/econ4524/readings/South%20After%20the%20Civil%20War-%20Atack%20and%20Passell.pdf">the South was in shambles</a>. Beyond the defeat of its military, courts, law enforcement capabilities and local economies had collapsed. </p>
<p>In order to gloss over the extent of this disaster, <a href="http://www.thedailybeast.com/its-time-for-the-lost-cause-of-the-south-to-get-lost">the region devised a series of fictions</a>, among them the notion that the leaders of the defeated Confederate Army were unblemished heroes, or perhaps hadn’t even been defeated in the first place. It was a way to impose some sort of order on a society that risked descending into pure anarchy – and also a sham front to all sorts of dysfunctional things (above all a nasty, codified racial hierarchy).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/188060/original/file-20170928-2939-435ari.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">A frieze from a Confederate monument in Virginia depicts a Confederate soldier kissing a black baby.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/5/5a/Confederate_Monument_-_NE_frieze_mammy_-_Arlington_National_Cemetery_-_2011.JPG">Tim1965</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Confederate statues, which were erected into the mid-20th century, were an outgrowth of this attitude. What’s surprising is how many of them there are: While there doesn’t seem to be an exact count, they number <a href="https://www.splcenter.org/20160421/whose-heritage-public-symbols-confederacy#findings">well over 1,000</a>. For more than a century they stood mute, unquestioned and largely unnoticed in thousands of public squares. </p>
<p>Rather abruptly, that’s changed.</p>
<h2>A symbolic hollowness</h2>
<p>A matter that’s intriguing to me, given the vehemence of the outcry, is that most Confederate monuments aren’t particularly interesting. As purely visual statements, they’re not very expressive. With a few exceptions, they take one of two forms – that of a standing foot soldier, or that of a colonel or general riding a horse. </p>
<p>For the most part, they’re indistinguishable from monuments celebrating Union soldiers; absent historical context, it would be hard to deduce that they celebrate racism – or anything, for that matter. </p>
<p>Their distinguishing characteristic is a sort of symbolic hollowness.</p>
<p>As “works of art” they’re strangely similar to Marcel Duchamp’s <a href="https://www.sfmoma.org/artwork/98.291">famous urinal</a>, a store-bought object which became an artistic masterpiece not because an artist made it but because an artist – the eponymous R. Mutt – signed his name to it, and thereby transformed an ordinary object into a work of art. Similarly, the message attached to these Confederate statues has little to do with their visual appearance. It’s almost entirely arbitrary. The central factor in determining their meaning is the name we assign to them: Bragg, Branton and Bratley (Confederate heroes), or Banks, Burnside and Butler (who fought for the Union). </p>
<p>But iconoclasm tends to almost entirely ignore visual and artistic considerations. Instead, the monuments and statues are seen as assertions of political power. Mutilating a statue becomes equivalent to killing or mutilating an enemy. Both major and minor works of art are destroyed impartially. </p>
<p>The impulse toward destruction often seems to override normal inhibitions. Byzantine and Protestant iconoclasts, for example, destroyed images of the mother and child; in most social situations, mothers and children are people we’re urged to safeguard and protect. Symbolic meaning overrode normal social instincts.</p>
<p>It’s a bit scary to witness the primitive instincts – at times the raw violence – that these monuments set in motion on both sides of the issue. Clearly, they touch on social wounds that have been festering for centuries, and they’ve eliciting a divergent range of responses among historians, politicians and the public.</p>
<p>One would hope that the controversy can be one that will lead not just to destruction or to erasure of history, but to thoughtful reexamination and acknowledgment of the injustices and sores of the past.</p><img src="https://counter.theconversation.com/content/82878/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Henry Adams 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>Over the course of human history, symbols and monuments have invoked violent impulses and destruction.Henry Adams, Ruth Coulter Heede Professor of Art History, Case Western Reserve UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/346052014-11-27T19:25:30Z2014-11-27T19:25:30ZThe palaeolithic diet and the unprovable links to our past<figure><img src="https://images.theconversation.com/files/65416/original/image-20141125-8672-1hdgku2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Harking back to the diet of the caveman.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/daniandgeorge/8699416930">Flickr/George </a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>We still hear and <a href="http://www.theaustralian.com.au/news/world/paleo-diet-worked-for-me/story-fnb64oi6-1227132311448">read a lot</a> about how a diet based on what our Stone Age ancestors ate may be a cure-all for modern ills. But can we really run the clock backwards and find the optimal way to eat? It’s a largely impossible dream based on a set of fallacies about our ancestors.</p>
<p>There are a lot of <a href="http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=palaeolithic+diet">guides and books</a> on the palaeolithic diet, the origins of which have <a href="https://theconversation.com/caveman-cravings-rating-the-paleo-diet-14995">already been questioned</a>. </p>
<p>It’s all based on an idea that’s been around for decades in anthropology and nutritional science; namely that we might ascribe many of the problems faced by modern society to the shift by our hunter-gatherer ancestors to farming roughly 10,000 years ago.</p>
<p>Many <a href="http://robbwolf.com/what-is-the-paleo-diet/">advocates of the palaeolithic diet</a> even claim it’s the only diet compatible with human genetics and contains all the nutrients our bodies apparently evolved to thrive on.</p>
<p>While it has a real appeal, when we dig a little deeper into the science behind it we find the prescription for a palaeolithic diet is little more than a fad and might be dangerous to our health.</p>
<h2>Mismatched to the modern world</h2>
<p>The basic argument goes something like this: over millions of years natural selection designed humans to live as hunter-gatherers, so we are genetically “mismatched” for the modern urbanised lifestyle, which is very different to how our pre-agricultural ancestors lived.</p>
<p>The idea that our genome isn’t suited to our modern way of life began with a highly influential <a href="http://www.nejm.org/doi/full/10.1056/NEJM198501313120505">article</a> by Eaton and Konner published in the New England Journal of Medicine in 1985. </p>
<p>Advocates of the palaeolithic diet, traceable back to Eaton and Konner’s work, have uncritically assumed a gene-culture mismatch has led to an epidemic in “diseases of civilisation”.</p>
<p>Humans are, it’s argued, genetically hunter-gatherers and evolution has been unable to keep pace with the rapid cultural change experienced over the last 10,000 years. </p>
<p>These assumptions are <a href="http://www.nature.com/ijo/journal/v31/n9/full/0803610a.html">difficult to test</a> or even outright wrong.</p>
<h2>What did our Stone Age ancestors eat?</h2>
<p>Proponents of the palaeolithic diet mostly claim that science has a good understanding of what our hunter-gatherer ancestors ate.</p>
<p>Let me disavow you of this myth straight away – we don’t – and the further back in time we go <a href="http://ajcn.nutrition.org/content/71/3/665.full">the less we know</a>.</p>
<p>What we <em>think</em> we know is based on a mixture of <a href="http://eclectic.ss.uci.edu/%7Edrwhite/worldcul/atlas.htm">ethnographic studies</a> of recent (historical) foraging groups, reconstructions based on the archaeological and fossil records and more recently, genetic investigations.</p>
<p>We need to be careful because in many cases these historical foragers lived in “marginal” environments that were not of interest to farmers. Some represent people who were farmers but returned to a hunter-gatherer economy while others had a “mixed” economy based on wild-caught foods supplemented by bought (even manufactured) foods.</p>
<p>The archaeological and fossil records are strongly biased towards things that will preserve or fossilise and in places where they will remain buried and undisturbed for thousands of years.</p>
<p>What this all means is <a href="http://www.anth.ucsb.edu/faculty/gurven/ember1978.pdf">we know little</a> about the plant foods and only a little bit more about some of the animals eaten by our Stone Age ancestors.</p>
<h2>Many variations in Stone Age lifestyle</h2>
<p>Life was tough in the Stone Age, with high infant and maternal mortality and short lifespans. Seasonal shortages in food would have meant that starvation was common and may have been an annual event.</p>
<p>People were very much at the mercy of the natural environment. During the Ice Age, massive climate changes would have resulted in regular dislocations of people and the extinction of whole tribes periodically. </p>
<p>Strict cultural rules would have made very clear the role played by individuals in society, and each group was different according to traditions and their natural environment.</p>
<p>This included gender-specific roles and even rules about what foods you could and couldn’t eat, regardless of their nutritional content or availability.</p>
<p>For advocates of the palaeolithic lifestyle, life at this time is portrayed as a kind of biological paradise, with people living as evolution had designed them to: as genetically predetermined hunter-gatherers fit for their environment. </p>
<p>But when ethnographic records and archaeological sites are studied we find a great deal of variation in the diet and behaviour, including activity levels, of recent foragers.</p>
<p>Our ancestors – and even more recent <a href="http://www.nt.gov.au/health/healthdev/health_promotion/bushbook/volume2/chap3/index.html">hunter-gatherers in Australia</a> – exploited foods as they became available each week and every season. They ate a vast range of foods throughout the year. </p>
<p>They were seasonably mobile to take advantage of this: recent foraging groups moved camps on average 16 times a year, but within a wide range of two to 60 times a year.</p>
<p>There seems to have been one universal, though: all people ate animal foods. How much depended on where on the planet you lived: rainforests provided few mammal resources, while the arctic region provided very little else.</p>
<p><a href="http://www.jstor.org/stable/3629672">Studies show</a> on average about 40% of their diet comprised hunted foods, excluding foods gathered or fished. If we add fishing, it rises to 60%.</p>
<p>Even among arctic people such the as Inuit whose diet was entirely animal foods at certain times, geneticists have failed to find any mutations enhancing people’s capacity to survive on such an extreme diet. </p>
<p>Research from anthropology, nutritional science, genetics and even psychology now also shows that our food preferences are partly determined <em>in utero</em> and are mostly established during childhood from cultural preferences within our environment.</p>
<p>The picture is rapidly emerging that genetics play a pretty minor role in determining the specifics of our diet. Our physical and cultural environment mostly determines what we eat.</p>
<h2>Evolution didn’t end at the Stone Age</h2>
<p>One of the central themes in any palaeolithic diet is to draw on the arguments that our bodies have not evolved much over the past <a href="http://dx.doi.org/10.4065/79.1.101">10,000 years</a> to adapt to agriculture-based foods sources. This is nonsense.</p>
<p>There is now abundant evidence for <a href="http://www.nature.com/news/past-5-000-years-prolific-for-changes-to-human-genome-1.11912">widespread genetic change</a> that occurred during the Neolithic or with the beginnings of agriculture.</p>
<p>Large-scale genomic studies have found that more than 70% of protein coding gene variants and around 90% of disease causing variants in living people whose ancestors were agriculturalists arose in the past 5,000 years or so. </p>
<p>Textbook examples include genes associated with lactose tolerance, starch digestion, alcohol metabolism, detoxification of plant food compounds and the metabolism of protein and carbohydrates: all mutations associated with a change in diet.</p>
<p>The regular handling of domesticated animals, and crowded living conditions that eventually exposed people to disease-bearing insects and rodents, led to an assault on our immune system.</p>
<p>It has even been suggested that the light hair, eye and skin colour seen in Europeans may have resulted from a diet poor in vitamin D among early farmers, and the need to produce more of it through increased UV light exposure and absorption. </p>
<p>So again, extensive evidence has emerged that humans have evolved significantly since the Stone Age and <a href="http://www.theguardian.com/commentisfree/2013/sep/10/david-attenborough-humans-still-evolving">continue to do so</a>, despite some uninformed commentators still <a href="http://bigthink.com/videos/mankind-has-stopped-evolving-2">questioning</a> whether evolution in humans has stalled.</p>
<h2>A difficult choice</h2>
<p>In the end, the choices we make about what to eat should be based on good science, not some fantasy about a lost Stone Age paradise.</p>
<p>In other words, like other areas of preventative medicine, our diet and lifestyle choices should be based on scientific evidence not the latest, and perhaps even harmful, commercial fad.</p>
<p>If there is one clear message from ethnographic studies of recent hunter-gatherers it’s that variation – in lifestyle and diet – was the norm.</p>
<p>There is no single lifestyle or diet that fits all people today or in the past, let alone the genome of our whole species.</p><img src="https://counter.theconversation.com/content/34605/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Darren Curnoe receives funding from the Australian Research Council.</span></em></p>We still hear and read a lot about how a diet based on what our Stone Age ancestors ate may be a cure-all for modern ills. But can we really run the clock backwards and find the optimal way to eat? It’s…Darren Curnoe, Human evolution specialist, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/269452014-05-20T14:32:40Z2014-05-20T14:32:40ZCaveman instincts may explain our belief in gods and ghosts<figure><img src="https://images.theconversation.com/files/49000/original/x3xkm622-1400582645.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Does mankind's religious instinct date back to prehistoric times?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-110802431/stock-photo-ancient-people-against-the-evening-landscape.html?src=aD1Iiqd1l6yCdOdYkSD9gA-1-70">iurri</a></span></figcaption></figure><p>Notions of gods arise in all human societies, from all powerful and all-knowing deities to simple forest spirits. <a href="http://books.google.co.uk/books/about/The_Naturalness_of_Religious_Ideas.html?id=5jkhjMvYpa4C&redir_esc=y">A recent method</a> of examining religious thought and behaviour links their ubiquity and the similarity of our beliefs to the ways in which human mental processes were adapted for survival in prehistoric times. </p>
<p>It rests on a <a href="http://ruccs.rutgers.edu/%7Ealeslie/images/publications/Leslie%201994b.pdf">couple of observations about human psychology</a>. First, when an event happens, we tend to assume that a living thing caused it. In other words, we assume agency behind that event. If you think of the sorts of events that might have happened in prehistoric times, it’s easy to see why a bias towards agency would be useful. A rustling of a bush or the snapping of a twig could be due to wind. But far better to assume it’s a lion and run away. </p>
<p>The survivors who had this tendency to more readily ascribe agency to an event passed their genes down the generations, increasingly hard-wiring this way of making snap decisions into the brain. This is not something that people need to learn. It occurs quickly and automatically. </p>
<h2>Empathic tendencies</h2>
<p>The second trait is about how we view others. While living together in a tribe would have had many advantages for survival in prehistoric times, getting along with everyone would not always have been easy. Comprehending others’ behaviour requires you to understand their thoughts and beliefs, especially where these may be incorrect due to someone not knowing the full facts of a situation. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/49005/original/r8hnk29y-1400583091.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&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">The prehistoric posse.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-152290322/stock-photo-illustrated-silhouettes-of-cavemen-hunters-on-patrol.html?src=aD1Iiqd1l6yCdOdYkSD9gA-1-75">Robert Adrian Hillman</a></span>
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<p>This is known as “theory of mind”. This idea says that we automatically assume that there are reasons behind others’ behaviour which we try to work out in order to better understand why they behave the way they do. Not having this ability <a href="http://autismtruths.org/pdf/3.%20Does%20the%20autistic%20child%20have%20a%20theory%20of%20mind_SBC.pdf">has been proposed</a> to underlie developmental disorders such as autism.</p>
<p>You may be wondering what these two hard-wired processes have to do with belief in gods. Imagine a pebble falling in the back of a cave. Our agency device tells us that someone caused that to happen. With nothing in evidence, could it be an invisible creature or a spirit? If so, why would it be sneaking around? To find out secrets about us or to discover if we are good or bad people? </p>
<p>Another example might be a volcanic eruption. In the absence of geological knowledge, our tribal ancestors’ agency system would have ascribed this event to a person – but one that surely has superhuman ability. And why would they want to cause such destruction? Perhaps the eruption signified a punishment, perhaps because the tribe had not acted in accordance with the being’s wishes. </p>
<h2>Of ghosts and gods</h2>
<p>These two very simplistic examples should help illustrate how these hard-wired mechanisms could lead to the beginnings of a belief in gods, as well as ghosts and other supernatural creatures. Our ancestors would have drawn conclusions about supernatural occurrences by fitting together these instincts towards agency and the theory of mind. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/48925/original/2knn873v-1400518465.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/48925/original/2knn873v-1400518465.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">Are ghosts just part of human survival function?</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jeffkrause/5772943082/in/photolist-9N8QRq-9BV8JD-4z7WBo-aj81YJ-79UZDg-dZzHu8-8kSEQJ-aCJXQH-reFFA-6deavc-mZSgY5-jqbXHS-6MmBWr-jCD33M-itJbUY-8MzECa-fy3c8J-7gZAG9-igBJMm-334iz8-hRg7nc-4zM8QH-d34hh3-zistE-59MMoQ-adRyKt-7vBhDe-33i3-6hATVa-agKkxD-bqvkAA-7o9w7j-8mQqhr-gTjSMV-jA1oKs-2bY1Vj-fhCPdC-mKEQte-dyzpKp-wUgAp-nzJhAR-8PpEAR-2kxD3w-56LfTG-m5fw-5Fwq5S-d34Dc7-LuNtx-7AfiNW-3hHnhM">Jeff Krause</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>This even applies to the Abrahamic, all-knowing, all powerful god. He may seem very inhuman at first glance, but <a href="http://www.wjh.harvard.edu/%7Elds/readinggroup/barrett1996.pdf">it has been shown</a> that we reason about Him in a very human way. For example we depict Him helping one person before moving to the other side of the world to help someone else. Hard-wired reasoning processes helps explain how religious ideas are so durable, spreading across continents and down through generations. </p>
<p>Both these and other ancient instincts appear to be in evidence from observations of children. Very young children seem to show very accurate understanding of physical laws. For example they know that two solid objects cannot merge into one or that horses do not have metal gears inside them. <a href="http://fitelson.org/woodward/baillargeon.pdf">Developmental psychologists have suggested</a> that children are intuitive biologists, physicists and – using theory of mind – psychologists.</p>
<h2>Sumus rosaceae!</h2>
<p>Concepts which violate these intuitive understandings <a href="http://strathprints.strath.ac.uk/25716/">seem to be</a> more memorable than others. A rose that whispers in Latin violates an intuitive understanding that plants do not have minds or mouths and therefore cannot whisper in an ancient language – or any language for that matter.</p>
<p>It may be that violating an intuitive concept draws special attention and interest and therefore helps embed the idea in memory. Many religious stories contain concepts that seem to violate this special kind of intuition, such as a man walking on water or a burning bush that talks. These tales take advantage of this feature of memory to successfully propagate themselves and resist being forgotten.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=772&fit=crop&dpr=1 600w, https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=772&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=772&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=971&fit=crop&dpr=1 754w, https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=971&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/48924/original/tpwhp45f-1400518190.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=971&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Got a cup of water?</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Bourdon,_Sébastien_-_Burning_bush.jpg">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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</figure>
<p>Putting these ideas together is one way of explaining religious thought and behaviour. You could go further and suggest that, if these ideas are correct, religion is merely a by-product of mental processes operating in error. </p>
<p>But this assumes that religious/supernatural experiences are not true. If the human mind was to truly experience a god, then the theories of agency and mind and our memory for the counterintuitive would help us make sense of it. If that were to happen, the conclusions would not be in error at all. </p>
<p><em>Dr Kelly will be elaborating on these ideas at a</em> <em><a href="http://www.strath.ac.uk/events/campuscalendar/event_title_798613_en.html">lecture in Glasgow</a></em> <em>on the evening of Thursday May 22.</em></p><img src="https://counter.theconversation.com/content/26945/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steve Kelly 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>Notions of gods arise in all human societies, from all powerful and all-knowing deities to simple forest spirits. A recent method of examining religious thought and behaviour links their ubiquity and the…Steve Kelly, Senior Lecturer, University of Strathclyde Licensed as Creative Commons – attribution, no derivatives.