tag:theconversation.com,2011:/fr/topics/hadza-36333/articlesHadza – The Conversation2023-12-20T19:19:54Ztag:theconversation.com,2011:article/2163282023-12-20T19:19:54Z2023-12-20T19:19:54ZDreaming may have evolved as a strategy for co-operative survival<figure><img src="https://images.theconversation.com/files/566059/original/file-20231215-21-wi7j11.jpg?ixlib=rb-1.1.0&rect=0%2C83%2C7000%2C3908&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A comparison of dreams shows they play out much differently across various socio-cultural environments.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/dreaming-may-have-evolved-as-a-strategy-for-co-operative-survival" width="100%" height="400"></iframe>
<p>Have you ever woken from a dream, emotionally laden with anxiety, fear or a sense of unpreparedness? Typically, <a href="https://vividmaps.com/googled-dreams/">these kinds of dreams</a> are associated with content like losing one’s voice, teeth falling out or being chased by a threatening being. </p>
<p>But one question I’ve always been interested in is whether or not these kinds of dreams are experienced globally across many cultures. And if some features of dreaming are universal, could they have enhanced the likelihood of our ancestors surviving the evolutionary game of life? </p>
<p>My research focuses on <a href="https://davidrsamson.com/">the distinctive characteristics that make humans the most successful species on Earth</a>. I’ve explored the question of human uniqueness by comparing <em>Homo sapiens</em> with various animals, including chimpanzees, gorillas, orangutans, lemurs, wolves and dogs. Recently, I’ve been part of a team of collaborators that has focused our energies on working with small-scale societies known as hunter-gatherers.</p>
<p>We wanted to explore how the content and emotional function of dreams might vary across different cultural contexts. By comparing dreams from forager communities in Africa to those from western societies, we wanted to understand how cultural and environmental factors shape the way people dream.</p>
<h2>Comparative dream research</h2>
<p>As part of this research, published in <a href="https://doi.org/10.1038/s41598-023-43319-z"><em>Nature Scientific Reports</em></a>, my colleagues and I worked closely for several months with the BaYaka in the Democratic Republic of Congo and the Hadza in Tanzania to record their dreams. For western dreamers, we recorded dream journals and detailed dream accounts, collected between 2014 and 2022, from people living in Switzerland, Belgium and Canada. </p>
<p>The Hadza of Tanzania and the BaYaka of Congo fill a crucial, underexplored gap for dream research due to their distinct lifestyle. Their egalitarian culture, <a href="https://doi.org/10.1111/etho.12284">emphasizing equality and co-operation</a>, is vital for survival, social cohesion and well-being. These forager communities rely heavily on supportive relationships and communal sharing of resources.</p>
<p>Higher mortality rates due to disease, intergroup conflict, and challenging physical environments in these communities (without the kind of social safety nets common to post-industrial societies in the West) means they rely on face-to-face relationships for survival in a way that is a distinct feature of forager life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a black and white photo of a group of men sitting" src="https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566061/original/file-20231215-19-5h9arg.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>
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<span class="caption">The Hadza are an Indigenous community in Tanzania, and one of the last hunter-gatherer societies remaining.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<h2>Dreaming across cultures</h2>
<p>While studying these dreams, we began to notice a common theme. We’ve discovered that dreams play out much differently across different socio-cultural environments. We used a new software tool to map dream content that connects important psychosocial constructs and theories with words, phrases, and other linguistic constructions. That gave us an understanding about the kinds of dreams people were having. And we could model these statistically, to test scientific hypotheses as to the nature of dreams. </p>
<p>The dreams of the BaYaka and Hadza were rich in community-oriented content, reflecting the strong social bonds inherent in their societies. This was in stark contrast to the themes prevalent in dreams from western societies, where negative emotions and anxiety were more common. </p>
<p>Interestingly, while dreams from these forager communities often began with threats reflecting the real dangers they face daily, they frequently concluded with resolutions involving social support. This pattern suggests that dreams might play a crucial role in emotional regulation, transforming threats into manageable situations and reducing anxiety.</p>
<p>Here is an example of a Hadza dream laden with emotionally threatening content:</p>
<blockquote>
<p>“I dreamt I fell into a well that is near the Hukumako area by the Dtoga people. I was with two others and one of my friends helped me get out of the well.”</p>
</blockquote>
<p>Notice that the resolution to the dream challenges incorporated a social solution as an answer to the problem. Now contrast this to the nightmare disorder-diagnosed dreamers from Europe. They had scarier, open-ended narratives with less positive dream resolutions. Specifically, we found they had higher levels of dream content with negative emotions compared to the “normal” controls. Conversely, the Hadza exhibited significantly fewer negative emotions in their dreams. These are the kind of nightmares reported:</p>
<blockquote>
<p>“My mom would call me on my phone and ask me to put it on speakerphone so my sister and cousin could hear. Crying she announced to us that my little brother was dead. I was screaming in sadness and crying in pain.”</p>
<p>“I was with my boyfriend, our relationship was perfect and I felt completely fulfilled. Then he decided to abandon me, which awoke in me a deep feeling of despair and anguish.”</p>
</blockquote>
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<a href="https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a man sleeping with his mouth open" src="https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/566062/original/file-20231215-31-9eh6xs.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">The dreams of people living in the West tended to reflect more anxiety.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<h2>The functional role of dreams</h2>
<p>Dreams are wonderfully varied. But what if one of the keys to humanity’s success as a species rests in our dreams? What if something was happening in our dreams that improved the survival and reproductive efforts of our Paleolithic ancestors? </p>
<p>A curious note from my comparative work, of all the primates alive, <a href="https://doi.org/10.1002/ajpa.23427">humans sleep the least, but we have the most REM</a>. Why was REM — the state most often associated with dreams — so protected while evolution was whittling away our sleep? Perhaps something embedded in dreaming itself was prophylactic for our species?</p>
<p>Our research supports previous notions that dreams are not just random firings of a sleeping brain but <a href="https://doi.org/10.2307/27784372">may play a functional role in our emotional well-being and social cognition</a>. They reflect the challenges and values of our waking life, offering insights into how we process emotions and threats. In forager societies, dreams often conclude with resolutions involving social support, suggesting that dreams might serve as a psychological mechanism for reinforcing social bonds and community values. </p>
<h2>Why dream?</h2>
<p>The ultimate purpose of dreaming is still a subject of ongoing research and debate. Yet these themes seem to harbour within them universals that hint at some crucial survival function. </p>
<p>Some theories suggest that dreaming <a href="http://doi.org/10.25358/openscience-79">acts like a kind of virtual reality</a> that serves to simulate threatening or social situations, helping individuals prepare for real-life challenges. </p>
<p>If this is indeed the case, then it’s possible that the dreams of our ancestors, who roamed the world in the distant Paleolithic era, played a crucial role in enhancing the co-operation that contributed to their survival.</p><img src="https://counter.theconversation.com/content/216328/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Samson 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>Dreaming differs across cultures, and these differences may hold the clue to how and why dreaming evolved for humans and other species.David Samson, Associate Professor, Anthropology, University of TorontoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1098402019-01-31T00:21:47Z2019-01-31T00:21:47ZSkipping breakfast may help you lose weight - what hunter-gatherers can teach us<figure><img src="https://images.theconversation.com/files/254358/original/file-20190117-32810-tin6ck.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Give it a miss.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/577772020?src=R7NVI1rsVES9-UXs_UN38A-1-0&size=medium_jpg">Elena Veselova/Shutterstock</a></span></figcaption></figure><p>Breakfast, we are told, is the most important meal of the day. Over the last 50 years, we have been bombarded with messages extolling the health benefits of processed cereals and porridge oats. We are told breakfast helps us reduce weight by speeding up our metabolism – this helps us avoid hunger pangs and overeating later in the day. </p>
<p>These are not just marketing messages, they are core to nutritional guidelines in developed countries, such as in the US, UK and Australia, prepared by expert scientific panels. These messages are mirrored in the media and websites worldwide. But what if the benefits of breakfast are just another diet myth?</p>
<h2>No word for breakfast</h2>
<p>It’s popular these days to follow the nutritional regimes of our ancient ancestors, but no one seems to be studying whether or not they ate breakfast. The Hadza people in Tanzania are the last true hunter-gatherers in East Africa who we believe live much like our ancestors. Living with them, we noticed a definite lack of a breakfast routine. They also have no regular word to describe “breakfast”. </p>
<p>After waking up, the men usually leave on a hunting or honey-gathering trip without eating, maybe grabbing some berries a few hours later, en route. If they stay in camp in the morning or even all day, a handful of honey late morning – or even consumed as late as early afternoon – may be all they eat until a larger, evening meal. That said, there is no routine and eating patterns are highly variable, depending on the camp size and season. </p>
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Read more:
<a href="https://theconversation.com/i-spent-three-days-as-a-hunter-gatherer-to-see-if-it-would-improve-my-gut-health-78773">I spent three days as a hunter-gatherer to see if it would improve my gut health</a>
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<p>The women stay close to the camp and on some days make simple food, like baobab porridge, or they eat some stored honey, but rarely before 9-10am, giving them a fasting time since their evening meal of over 15 hours. Lacking a regular breakfast routine has not made them fat or unhealthy and they lack most Western diseases. Perhaps we should take a leaf from their book. At least, that’s what the latest scientific evidence suggests.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254357/original/file-20190117-32828-11ziyuw.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">
<figcaption>
<span class="caption">A bit of honey for breakfast.</span>
<span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>An honest mistake</h2>
<p>The health benefit of breakfast has now been completely debunked by a new <a href="http://www.bmj.com/content/364/bmj.l42">systematic review and meta-analysis</a> of 11 randomised trials that investigated the impact of skipping breakfast on weight and metabolic rate. </p>
<p>The studies vary widely in duration and quality, and seven looked at changes in weight as well as changes in energy usage. Their conclusion is the same as in <a href="https://www.ncbi.nlm.nih.gov/pubmed/27292940">recent reviews</a> that have been largely ignored, namely, there is no evidence to support the claim that skipping meals makes you put on weight or adversely reduces your resting metabolic rate. </p>
<p>There is now considerable evidence from these studies that skipping breakfast can be an effective way to reduce weight for some people. So why has the field got it so wrong in the past? </p>
<p>One reason is the belief in “grazing” rather than “gorging” to avoid “stress” on the body from having to digest large meals, especially later in the day when glucose and insulin peaks are higher and metabolic rate lower. The flawed rationale was based on lab rodents and a few <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=Jenkins+DJ+NEJM+1989">short-term human studies</a>. While the concept of over-compensation later in the day was correct – breakfast skippers do eat more lunch and slightly reduce their activity – it is not nearly enough to make up the energy deficit in a real-world setting outside a lab. </p>
<p>Scientists were honestly misled in the past by many observational studies showing that obese people skipped meals more often than thin people. This mindset became ingrained in nutritional dogma. But these observational studies were seriously biased. Breakfast skippers were more likely, on average, to be poorer, less educated, less healthy and have a poorer diet. Overweight people were more likely to diet and, after a binge, more likely to feel guilty and skip a meal. </p>
<p>Despite these flaws in the science and the steady increase in opposing evidence from randomised controlled trials, the idea that skipping meals is unhealthy has prevailed for decades. It’s still part of current NHS recommendations by Public Health England and one of its eight key <a href="https://www.nhs.uk/live-well/eat-well/eight-tips-for-healthy-eating/">healthy diet messages</a>, part of <a href="https://www.cnpp.usda.gov/2015-2020-dietary-guidelines-americans">USDA Dietary Guidelines for Americans</a>, as well as the <a href="https://nhmrc.gov.au/about-us/publications/australian-dietary-guidelines">Australian Guidelines for Nutrition</a>.</p>
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Read more:
<a href="https://theconversation.com/exaggerated-portions-alongside-real-nutrition-claims-on-cereal-boxes-may-mislead-consumers-new-study-101269">Exaggerated portions alongside real nutrition claims on cereal boxes may mislead consumers – new study</a>
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<p>Another common pro-breakfast argument is that, as well as reducing obesity, it is essential for the mental well-being and attention span of children, even if well nourished. Again the evidence of over 20 trials, <a href="https://www.ncbi.nlm.nih.gov/pubmed/27184287">when reviewed independently</a>, is at best weak and inconsistent, and probably biased in the same way as for adults.</p>
<p>Evidence is also accumulating that restricted eating times and increasing fasting intervals can help some people <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6004924/">lose weight</a>. Some of these recent developments that seem counterintuitive to traditional thinking, make sense when we consider the importance of the gut microbiome on our health and metabolism. The community of 100 trillion gut microbes have a circadian rhythm and vary in composition and function in fasting and fed states. Data suggests microbial communities could benefit from <a href="https://www.sciencedirect.com/science/article/pii/S1550413114005051">short periods of fasting</a>. They, like us, may need to rest and recuperate.</p>
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Read more:
<a href="https://theconversation.com/intermittent-fasting-could-help-tackle-diabetes-heres-the-science-82281">Intermittent fasting could help tackle diabetes – here's the science</a>
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<p>Some of us are programmed to prefer eating food earlier in the day and others later, which may suit our unique personal metabolism. Around a third of people in developed countries regularly skip breakfast while many others enjoy it. This does not mean that everyone overweight would benefit from skipping breakfast. There is no one size fits all, and prescriptive diet guidelines filled with erroneous information look increasingly counterproductive and detract from important health messages. </p>
<p>Different populations have their own varied breakfast habits, but before you next go hunting, why not try your own personal breakfast skipping experiments - it may suit you.</p><img src="https://counter.theconversation.com/content/109840/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tim Spector Receives royalties from book “The Diet Myth: the science behind what we eat”. Orion 2016,
He is a scientific founder of Zoe Global Ltd (a personalised nutrition company) and has received research grants from Danone. He receives grants from the MRC, EU, NIH and NIHR amongst others.
TS is a regular breakfast eater.</span></em></p><p class="fine-print"><em><span>Jeff Leach is the Founder of the Human Food Project, co-Founder of American Gut Project and on the advisory board of Zoe Global Ltd (a personalised nutrition company). He receives funding from A Team Foundation and Emch Foundation. He is the author of the book REWILD.</span></em></p>‘Eat breakfast like a king’ is flawed advice, new study finds.Tim Spector, Professor of Genetic Epidemiology, King's College LondonJeff Leach, Visiting Research Fellow, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/787732017-06-30T09:34:20Z2017-06-30T09:34:20ZI spent three days as a hunter-gatherer to see if it would improve my gut health<figure><img src="https://images.theconversation.com/files/176267/original/file-20170629-29069-1yxvqga.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Mounting evidence suggests that the richer and more diverse the community of microbes in your gut the lower your risk of disease. Diet is key to maintaining diversity and was strikingly demonstrated when an undergrad student went on a <a href="https://theconversation.com/your-gut-bacteria-dont-like-junk-food-even-if-you-do-41564">McDonald’s diet for ten days</a> and after just four days experienced a significant drop in the number of beneficial microbes. </p>
<p>Similar results have been <a href="https://bmcmicrobiol.biomedcentral.com/articles/10.1186/s12866-016-0883-4">demonstrated</a> in a number of larger human and animal studies. </p>
<p>Your gut microbiome is a vast community of trillions of bacteria that has a major <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3983973/">influence</a> on your metabolism, immune system and mood. These bacteria and fungi inhabit every nook and cranny of your gastrointestinal tract, with most of this 1kg to 2kg “microbe organ” sited in your colon (the main bit of your large intestine). </p>
<p>We tend to see the biggest diet-related shifts in microbes in people who are unhealthy with a low-diversity unstable microbiome. What we didn’t know is whether a healthy stable gut microbiome could be improved in just a few days. The chance to test this in an unusual way came when my colleague <a href="http://humanfoodproject.com/about/founder-jeff-leach/">Jeff Leach</a> invited me on a field trip to Tanzania, where he has been living and working among the Hadza, one of the last remaining hunter-gatherer groups in all of Africa.</p>
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<img alt="" src="https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/176263/original/file-20170629-16069-1985iz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hadza hunters.</span>
<span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span>
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<p>My microbiome is pretty healthy nowadays and, among the first hundred samples we tested as part of the <a href="http://mapmygut.com">MapMyGut</a> project, I had the best gut diversity – our best overall measure of gut health, reflecting the number and richness of different species. High diversity is associated with a low risk of obesity and many diseases. The Hadza have a diversity that is <a href="https://www.ncbi.nlm.nih.gov/pubmed/24736369">one of the richest on the planet</a>.</p>
<p>The research plan was devised by Jeff who suggested I should have an intensive three days of eating like a hunter gatherer during my stay at his research camp. I would measure my gut microbes before heading to Tanzania, during my stay with the Hadza, and after my return to the UK. I was also not allowed to wash or use alcohol swabs and I was expected to hunt and forage with the Hadza as much as possible – including coming in contact with the odd Hadza baby and baboon poo lying about. </p>
<p>To help us record the trip I was accompanied by Dan Saladino, the intrepid presenter and producer of <a href="http://www.bbc.co.uk/programmes/b006qnx3">BBC Radio 4’s The Food Programme</a>, who was preparing a Hadza microbe special. </p>
<p>After a long tiring flight to Mount Kilimanjaro Airport in Tanzania, we stayed overnight in Arusha, a city in the north of the country. Before setting off the next morning, I produced my baseline poo sample. </p>
<p>After an eight-hour journey in a Land Rover over bumpy tracks, we arrived. Jeff beckoned us to the top of a huge rock to witness the most amazing sunset over Lake Eyasi. Here, within a stones throw of the famous fossil site of Olduvai Gorge and with the stunning plains of the Serengeti in the distance, Jeff explained that we were never going to be closer to home as a member of the genus <em>Homo</em>, than where we were standing at that moment. </p>
<h2>The million-year-old diet</h2>
<p>The Hadza seek out the same animals and plants that humans have hunted and gathered for millions of years. Importantly, the human-microbe tango that played out here for aeons probably shaped aspects of our immune system and made us who we are today. The significance of being in Hadza-land was not lost on me.</p>
<p>Unlike the Hadza, who sleep around the fire or in grass huts, I was given a tent and told to zip it up tight as there were scorpions and snakes about. I had to be careful where I stepped if I needed a nocturnal pee. After an interesting but restless night’s sleep, a large pile of baobab pods had been collected for my breakfast. </p>
<p>The baobab fruit is the staple of the Hadza diet, packed with vitamins, fat in the seeds, and, of course, significant amounts of fibre. We were surrounded by baobab trees stretching in the distance as far as I could see. Baobab fruit have a hard coconut-like shell that cracks easily to reveal a chalky flesh around a large, fat-rich seed. The high levels of vitamin C provided an unexpected citrus tang. </p>
<p>The Hadza mixed the chalky bits with water and whisked it vigorously for two to three minutes with a stick until it was a thick, milky porridge that was filtered – somewhat – into a mug for my breakfast. It was surprisingly pleasant and refreshing. As I wasn’t sure what else I would be eating on my first day, I drank two mugs and suddenly felt very full. </p>
<p>My next snacks were the wild berries on many of the trees surrounding the camp – the commonest were small Kongorobi berries. These refreshing and slightly sweet berries have 20 times the fibre and polyphenols compared with cultivated berries – powerful fuel for my gut microbiome. I had a late lunch of a few high-fibre tubers dug up with a sharp stick by the female foragers and tossed on the fire. These were more effort to eat - like tough, earthy celery. I didn’t go for seconds or feel hungry, probably because of my high-fibre breakfast. No one seemed concerned about dinner.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/176261/original/file-20170629-16083-1601lfh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hadza women lightly roasting starch and fibre-rich //ekwa tubers.</span>
<span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A few hours later we were asked to join a hunting party to track down porcupine – a rare delicacy. Even Jeff hadn’t tasted this creature in his four years of field work. </p>
<p>Two 20kg nocturnal porcupines had been tracked to their tunnel system in a termite mound. After several hours of digging and tunnelling – carefully avoiding the razor-sharp spines – two porcupines were eventually speared and thrown to the surface. A fire was lit. The spines, skin and valuable organs were expertly dissected and the heart, lung and liver cooked and eaten straight away. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175824/original/file-20170627-24782-ay9hcr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hadza hunter walking back to camp with a dispatched porcupine flung over his shoulder.</span>
<span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The rest of the fatty carcass was taken back to camp for communal eating. It tasted much like suckling pig. We had a similar menu the next two days, with the main dishes including hyrax – a strange furry guinea-pig-like hoofed animal, weighing about 4kg – a relative of the elephant, of all creatures. </p>
<p>Harvested high from a baobab tree, our dessert was the best golden orange honey I could ever imagine – with the bonus of honeycomb full of fat and protein from the larvae. The combination of fat and sugars made our dessert the most energy-dense food found anywhere in nature and may have competed with fire in terms of its evolutionary importance.</p>
<p>In Hadza-land nothing is wasted or killed unnecessarily, but they eat an amazing variety of plant and animal species (around 600, most of which are birds) compared with us in the West. My other lasting impression was how little time they spent getting food. It appeared as though it took just a few hours a day – as simple as going round a large supermarket. Any direction you walked there was food – above, on and below ground. </p>
<h2>Massive increase in microbiome diversity</h2>
<p>Twenty-four hours later Dan and I were back in London, him with his precious audio tapes and me with my cherished poo samples. After producing a few more, I sent them to the lab for testing. </p>
<p>The results showed clear differences between my starting sample and after three days of my forager diet. The good news was my gut microbal diversity increased a stunning 20%, including some totally novel African microbes, such as those of the phylum Synergistetes.</p>
<p>The bad news was, after a few days, my gut microbes had virtually returned to where they were before the trip. But we had learnt something important. However good your diet and gut health, it is not nearly as good as our ancestors’. Everyone should make the effort to improve their gut health by <a href="https://theconversation.com/east-african-hunter-gatherer-research-suggests-the-human-microbiome-is-an-ecological-disaster-zone-73668">re-wilding</a> their diet and lifestyle. Being more adventurous in your normal cuisine plus reconnecting with nature and its associated microbial life, may be what we all need.</p><img src="https://counter.theconversation.com/content/78773/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tim Spector is a co-founder of Map My Gut Ltd a microbiome testing company and also receives grants from the MRC, NIHR, CDRF, ARUK and is author of 'The Diet Myth: the science behind what we eat' Orion 2016 </span></em></p><p class="fine-print"><em><span>Jeff Leach is the Founder of the Human Food Project and Co-Founder of Map My Gut Ltd and the author of ReWild.</span></em></p>Here’s what happened to a professor of genetic epidemiology’s ‘microbiome’ when he lived with the Hadza.Tim Spector, Professor of Genetic Epidemiology, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/736682017-02-28T14:12:49Z2017-02-28T14:12:49ZEast African hunter-gatherer research suggests the human microbiome is an ecological disaster zone<figure><img src="https://images.theconversation.com/files/158432/original/image-20170226-23000-1xf95qa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hadza man with zebra head.</span> <span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The world we occupy today is very different from the one occupied by our not-so-distant ancestors. As we enter a new geological epoch – the Anthropocene, in which the human footprint has left its mark – there is much concern about global deforestation, melting ice sheets and general biosphere degradation. But another, often overlooked, casualty of this new epoch is the diversity of microorganisms (including bacteria, viruses and fungi) that live on and in us. If our microbiome – the genetic diversity of these organisms – is a canary in the microbial coal mine, then my work with East African hunter-gatherers suggests that it is hanging upside down on its perch. </p>
<p>In the field I have watched a Hadza hunter skillfully butcher a baboon and share meat with others around a fire. Nothing goes to waste. Organs, including the brain, are consumed along with raw colon and stomach. By sterile Western standards, it is a gruesome sight for an evening meal. No matter how many times I watch Hadza carve up animals dispatched with a bow and arrow, I am always taken aback by the extraordinary exchange of microbes between this group and their environment. A microbial tango that probably characterised the entirety of human evolution. </p>
<p>Why is this important? <a href="http://www.cell.com/cell-host-microbe/abstract/S1931-3128(15)00021-9">Recent research</a> has shown that disease is often associated with a fall in microbial diversity. What we don’t know is which way cause and effect runs. Does disease cause a drop in microbial diversity or does a drop in diversity cause – or precede – disease?</p>
<p>It’s still early days and a lot of work lies ahead. However, the idea that the microbes, and the diversity of microbes, that we carry may help us better understand and head off disease has spawned a level of optimism in medical research not seen since the introduction of antibiotics over 50 years ago. </p>
<p>Which brings me back to the Hadza.</p>
<p>Living and working among the Hadza makes me think of the intimate relationship humans have probably evolved with diverse groups of microbes. With each animal killed, microbes are given the opportunity to move from one species to the next. With each berry that is plucked from a bush or tuber dug from beneath the microbial-rich ground, each and every act of foraging keeps the Hadza connected to an extensive <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev-ecolsys-120213-091759">regional (microbial) species pool</a>. </p>
<p>It is their persistent exposure to this rich pool of microorganisms that has endowed the Hadza with an extraordinary diversity of microbes; much greater than we see among people in the so-called developed world. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/158561/original/image-20170227-20702-16u5jdd.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hadza hunter cleaning blood from his hands with the microbial-rich stomach contents of the same animal.</span>
<span class="attribution"><span class="source">Jeff Leach</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Ecology with gut feeling</h2>
<p>Viewed through the lens of ecology, the less diverse gut microbiome in the West can potentially be seen as either a result of a degraded regional species pool (all species available to colonise a local site) or an increase of environmental filters (things that thwart or limit the movement of microbes in the environment, or alter their composition). A combination of both is probably at play. </p>
<p>Much attention has been focused on environmental filters, such as diet, as the primary culprit for decreasing microbial diversity in the Western gut. Another environmental filter is the overuse of antibiotics. Each course of antibiotics can <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831151/">reduce the diversity of microbes in the host</a>. Other filters may include <a href="http://msystems.asm.org/content/1/2/e00033-16">too much time spent indoors</a>, an <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5308924/">increase in caesarean births and a decrease in breastfeeding rates</a>, <a href="http://www.livescience.com/51635-antibiotic-resistant-bacteria-deadly.html">antimicrobial products</a> such as handgels, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939477/">small doses of antibiotics</a> in the meat we eat, and <a href="https://www.ncbi.nlm.nih.gov/pubmed/28207081">modern hygiene</a>. </p>
<p>But the contribution of the regional species pool gets little attention in microbial research. I suspect it has something to do with the difficulties in such large-scale sampling and, of course, cost and priorities. Given that regional species pools - though focused on macroorganisms (organisms large enough to see with the naked eye) - is a central theme in ecology, it would be beneficial if it was incorporated into more human-microbe research.</p>
<p>Considering our classic environmental filtering example of antibiotics, one wonders if someone who took an antibiotic and experienced a reduction in microbial diversity would not recover more quickly - to their pre-antibiotic state of microbial diversity - if he or she had exposure to a robust and diverse regional species pool, once the course of antibiotics was completed.</p>
<p>Surely more attention and better management of environmental filters would pay dividends in improving microbial diversity in humans. However, having a better understanding of how ecological degradation may be hitting a little closer to home (our own gut) than most of us previously imagined may provide the much-needed impetus that this generation needs to finally put the health of ecosystems, large and small, into perspective. </p>
<p>Importantly, all the buzz around the microbiome may be an opportune moment to mobilise a much-needed group of micro-environmentalists to better teach how to appreciate the importance of what’s happening to our shared biosphere.</p>
<p><em>In a previous version of this article, the following sentence contained an error: “…an increase in caesarean births and breastfeeding rates” should have read: “…an increase in caesarean births and a decrease in breastfeeding rates”.</em></p><img src="https://counter.theconversation.com/content/73668/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeff Leach receives funding from the Peter Emch Family Foundation, The A Team Foundation and the Forrest Lattner Foundation. </span></em></p>We need micro-environmentalists to fight for the cause.Jeff Leach, Visiting Research Fellow, King's College LondonLicensed as Creative Commons – attribution, no derivatives.