Evolutionary history and nutrition – how personal does it get?

Eating healthy food is not as clear cut as you might think. When it comes to diet, what is ‘healthy’ and ‘unhealthy’ is highly dependent on the individual. The role of cultural adaptation can strongly influence genotype amongst individual groups of people on a micro-evolutionary scale. We need to consider how these changes affect the way individuals respond to certain kinds of food and the types of variation in responses amongst distinct populations.

The Weizmann Institute in Israel’s Personalised Nutrition Project investigated the variation in responses to a range of different food types from individual to individual. Each participant’s microbiome (the balance of micro-organisms or bacteria that live on and in your body) was analysed using stool samples to see what types of bacteria were present. The profiles and blood glucose responses of those studied varied wildly.

The preliminary results from the study involving 800 people revealed the there was incredibly high variability in how different people responded to the same foods. The study measured an individual’s blood glucose responses to both ‘healthy’ and ‘unhealthy’ foods. Surprisingly, while some people responded with spikes in blood glucose to supposedly high glycemic index foods, others did not produce any such spikes. The researchers then used an algorithm to produce tailored diets for individuals. Some conventionally unhealthy foods were fine for certain people to eat, and typically healthy foods were considered unsuitable for others.

The study did not take the participants’ ancestry into account. However, microbiome research is very much an emerging field within the spheres of archaeology and anthropology and has given some promising results with regards to variation between individual cultural groups. The University of Oklahoma’s Laboratories of Molecular Anthropology and Microbiome Research has produced some intriguing research working with ancient coprolite (excrement) samples and modern-hunter gatherer DNA.

Their research has revealed that the hunter-gatherer populations, whilst geographically isolated from each other, were much more similar in microbiome content than more agriculturalist populations adjacent to them. The microbe ‘Treponema sp.‘ which is associated with the digestion of fibrous plant materials is present in populations living a traditional lifestyle but absent in all of those living in industrialised societies. The microbe is also present in modern-day ape guts and in ancient coprolite samples. The lifestyle of modern humans has had a great impact on the way our microbiome is structured.

This invariably presents some massive implications for human health and disease. Autoimmune diseases such as multiple sclerosis, diabetes, and eczema are greatly influenced by our individual microbiomes. An understanding of what is beneficial and what is harmful to us through molecular anthropology and microbiota profiling would potentially solve some of the world’s biggest health problems. Running individual profiling as per the Weizmann Institute is likely to be too expensive for many people.

Therefore, the archaeological research discussed above is paramount in being able to provide widened accessed to understanding what might or might not be good for individual ethnic groups. This research could idealistically be used for production of guidelines for good and bad food groups for individual ethnic groups. The information could be distributed in a public health setting and stimulate a paradigm shift in the arena of the conventional recommended diet model.

References

Obregon-Tito, A., Tito, R., Metcalf, J., Sankaranarayanan, K., Clemente, J., Ursell, L., Zech Xu, Z., Van Treuren, W., Knight, R., Gaffney, P., Spicer, P., Lawson, P., Marin-Reyes, L., Trujillo-Villarroel, O., Foster, M., Guija-Poma, E., Troncoso-Corzo, L., Warinner, C., Ozga, A. and Lewis, C. (2015). Subsistence strategies in traditional societies distinguish gut microbiomes. Nature Communications, 6, p.6505.

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Is milk Paleo? For 35% of us, yes.

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Photo Credit: Kabsik Park

Is there is one single diet that the entire human species should follow? Probably not. Perhaps the picture is much more complex than what the Paleo diet postulates? Several archaeological studies have revealed that biological differences between human populations can arise as a result of repeated cultural activities. Cultural practices present as a type of ‘selection pressure’ on the human body and can result in physiological and morphological change within a population’s genotype. If we are to consider just how diverse the human species is culturally, the range in scope of human societal and behavioural adaptations (human niche construction) to environmental challenges is as variable as the planet’s geographies. This range in geographies and environments affects resource accessibility and, in turn, each culture’s resultant mechanism of coping with unique societal challenges. Consider the case of the lactase persistence gene in dairying versus non-dairying populations. Studies suggest that around 65% of the world’s population is unable to tolerate lactose into adulthood.

The ability to digest lactose sugar found in milk disappears in humans later in life as it is no longer a necessity past breastfeeding. However, following the advent of dairying and pastoralism, the ability to digest milk and lactose continued into adulthood with the expression of the Lactase Persistence (LP) gene. Genome biologist Ed Green discusses this in the video below.

The Lactase Persistence in the early Cultural History of Europe research project has investigated the prevalence of Lactase Persistence gene within European populations and the archaeological evidence surrounding the adoption of the genetic allele for its expression within these populations. Zooarchaeological and fat residue evidence from the Neolithic in Europe has provided supplementary evidence to support that the widespread presence of the gene within European populations has arisen as a result of the commonly adopted cultural practice of dairying that occurred on the continent historically.

Studies using modern populations have shown that in some areas of the world, such as southern Africa and eastern Asia, have populations where under 10% of adults are able to digest milk properly. Areas of the world with the highest number of people who can drink milk in adulthood are most of Northern Europe (around 90% in Swedish and Danish populations) and Southern Europe and the Middle East (approximately 50% in Spanish, French and pastoralist Arab populations).

This variability in lactase persistence is intrinsically linked to the cultural practices of individual ethnic and social groups, especially in the case of non-dairying versus dairying groups across Africa. So, are milk and dairy products Paleo or not? The evidence renders this debate redundant as the ability to digest such products is tightly linked to one’s own unique genetic ancestry and evolution as a result of cultural heritage.

References

Curry, A., 2013. Archaeology: The milk revolution. Nature.

Leonardi, M., Gerbault, P., Thomas, M.G., Burger, J. 2011. The evolution of lactase persistence in Europe. A synthesis of archaeological and genetic evidence. International Dairy Journal.

Ranciaro, A., Campbell, M.C., Hirbo, J.B., Ko, W.Y., Froment, A., Anagnostou, P., Kotze, M.J., Ibrahim, M., Nyambo, T., Omar, S.A., Tishkoff,

S.A. 2014. Genetic Origins of Lactase Persistence and the Spread of Pastoralism in Africa. American Journal of Human Genetics.

Tishkoff, S.A., Reed, F.A., Ranciaro, A., Voight, B.F., Babbitt, C.C., Silverman, J.S., Powell, K., Mortensen, H.M., Hirbo., J.B., Osman, M.,

Ibrahim, M., Omar, S.A., Lema, G., Nyambo, T.B., Ghori, J., Bumpstead, S., Pritchard, J.K., Wray, G., Deloukas, P. 2007. Convergent adaptation of human lactase persistence in Africa and Europe. Nature Genetics.

The Paleo Diet – is it academically sound?

Supporters of the Paleo diet believe that we should consume high amounts of our calories through animal fat and protein, restrict our diet to ‘natural’ foods such as nuts, and vegetables, and eschew ‘modern’ grains like wheat. However, archaeological evidence does not support this model.

Dr Christina Warinner‘s TEDxOU talk has gained over 1 million views on YouTube and provides an excellent comprehensive critique of the academic basis for the Paleo Diet. In summary, the diet has no archaeologically solid backing. The degree to which we are adapted to digesting meat is vastly overestimated in the modern version of the Paleo diet as our digestive tracts and dentition suggest a much more generalist set of adaptations, such as large molars that are not specifically tailored towards carnivorous diets. Furthermore, taphonomic bias (how materials survive or degrade in the archaeological record) adds to this the idea that we ate more meat as bones are much more likely to survive the test of time than any plant material.

The role of geographical and environmental variability is greatly simplified in the diet and pays little regard to the seasonality and availability of certain crops and meats. This would have invariably altered what each group of Paleolithic hunters throughout the world would have eaten. Warriner cites as an example a ‘Paleo breakfast’ from an online source that includes blueberries from New England, avocados from Mexico and eggs from China. How would a paleo hunter-gatherer ever accessed this set of produce?

The globalisation of food is a very recent trend that would not have been available to Paleolithic peoples. While this would no doubt be a nutritious and satiating meal, it would not have been one eaten that was eaten by the affectionately named ‘Grok’. Additionally, Warinner cites the variability of nitrogen stable isotope studies and how the results of these studies are not solid evidence of heavy meat consumption; it is likely that animals and humans simply ate what was available and easily accessible in their immediate environment. There is an extreme element of plasticity in the hominid diet that cannot be rigidly defined by a set of inert genetic rules to live by. The Paleo diet is academically unfounded and essentially erroneous, but that doesn’t necessarily mean it is unhealthy.

Warinner is not alone in her views, The Paleodiet Meets Paloepathology conference held in Santiago de Compostela, Spain in October 2015 gathered researchers from 27 universities and 17 countries to discuss the current research using skeletal biogeochemistry to understand links between mobility, ancient health, and diet. Of the papers presented, Aurora Grandal d’Anglad’s research on dietary study using stable isotopes and DNA supported the idea that fluctuations in climate and variability in an animal’s diet throughout their lifetime is a result of selecting foods that are opportunistically available and down to geographical availability. Consequently, there are serious implications for human paleodietary analysis. The role of the individual and cultural selection of foods played a large role in what people were eating.

In future posts I will consider the impact of individual and social selection of foods and behavioural adaptations throughout human history and how this has shaped our own ability to digest and respond to different types of diet in view of our genetic heritage.

Was early man pushing cars or running marathons?

There is no denying that physical activity is vital to good health, but just what did our Paleo ancestors do for exercise? It may have been strenuous, but how can this activity be compared to our modern lives?

In BBC Two’s ‘Eat to Live Forever‘ Giles Coren attended ‘Primal Con’ run by Mark Sisson of Mark’s Daily Apple mentioned in an earlier post on this blog.

Eat to Live Forever with Giles Coren by Catadecal

During the convention, Coren joins in on paleo style exercise which involved pushing a car and ‘the sledgehammer workout‘. Where did a creative interpretation of Paleolithic activities arise from? Other online self-proclaimed fitness gurus have developed numerous ‘systems’of exercise that our bodies were ‘designed’ or ‘programmed’ to do. These include MovNat by Erwan Le Corre, Primal Fitness by Greg Hetherington, and the Primal Blueprint by Mark Sisson to name a few.

All of these programmes differ from each other to a certain degree but are unified in promoting largely bodyweight only exercise, sprinting, interval training, and some form of lifting which, supposedly, is akin to the types of activities early man would have performed. Interval training is promoted as part of a ‘paleo’ lifestyle, similar to our ancestors having to run intensely for short periods of time to escape from predators and to hunt effectively.

Physiological studies into the effectiveness of interval training compared with traditional long distance endurance cardio training have produced some very impressive results including increased resting metabolic rate for at least 24 hours post training and increased insulin sensitivity of up to 28% in males. The degree to which participants benefitted from HIIT however, was affected by their individual genetic makeup and therefore, we must consider the role of genetic variability in our approach to exercise, and possibly, within the wider spectrum of diet. However, whether or not high-intensity interval training style activity actually occurred during the Paleolithic is debatable, and it is perhaps misleading to use an evolutionary basis for promoting a certain type of exercise.

Paleoanthropological perspectives on running

As mentioned in an earlier post, Harvard University paleoanthropologist Daniel Lieberman argues that humans were evolved to run long distances. According to Lieberman, humans ran long distances in the Savannah to scare large animals (ungulates) into sprinting. While these ungulates were good at running quickly for a short period of time, they would eventually overheat and experience exhaustion. Hunter-gatherers were, subsequently, able to successfully hunt and access meat by practicing this technique. This would contradict the view that humans alternated between short and long rest and activity periods during hunting. He argues that evidence for this is present in our own anatomy as we are biomechanically optimised to run barefoot through our shorter and easy to stabilise toes, the size of our glute muscles, and our achillies tendons that allow us to access energy at the appropriate time when we run. Our ancestors may have lead very active physical lives but that doesn’t mean we should all participate in intense physical activities. Pushing a car or running for miles is not for everyone. We need to consider what would be sensible and safe for our modern lifestyles and individual levels of fitness.

References

Bramble, D.M., Lieberman, D.E. 2004. Endurance running and the evolution of Homo. Nature.

King, J.W. 2001. A Comparison of the Effects of Interval Training vs. Continuous Training on Weight Loss and Body Composition in Obese Pre-Menopausal Women. Unpublished PhD Thesis. East Tennessee State University.

Metcalfe, R.S., Babraj, J.A. Fawkner, S.G., Vollaard, N.B.J. 2011. Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. European Journal of Applied Physiology.

Raw Veganism and the Hominid Diet – is there a case for cooked food?

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Image by: voyagevixen2

There are any number of modern commercial diets, each promoting very particular approach to the way we should eat. But which diet makes sense?

Consider the merits of a diet that prefers raw fruit over cooked food. Would archaeological evidence support such a diet?

Some wellness experts argue that humans were evolved to live almost entirely on raw fruits and vegetables. One controversial health blogger (with over half a million subscribers) in favour of this diet is Leanne Ratcliffe – otherwise known as Freelee the Banana Girl.

Speaking to the Daily Mail, Ratcliffe claims that consuming a high carbohydrate, low-fat vegan diet consisting of ‘mono meals’ is in keeping with how humans were evolved to eat. According to Ratcliffe, such a diet is supposedly optimised for our digestive system:

Most of the body’s energy goes towards digesting food so when we eat meals that contain several different foods the body has to work harder not only to process the complicated combination but to extract the nutrition it needs.

…Just one type of digestive enzyme is needed to process the meal. If you look to nature you will see that animals in the wild always eat mono meals and do not suffer the same digestive problems or weighty issues as we humans commonly do.

…Imagine our ‘tribe’ came to an abundant mango tree in nature, we would have happily filled our bellies with only mangoes and then moved on to the next location. This is what I largely replicate on the raw till four lifestyle.

Take a look at the ‘Raw Till 4’ Food Pyramid:

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Photo Credit: Freelee the Banana Girl via the Daily Mail Online

The food pyramid that doesn’t add up

The problem with this food pyramid is that it emphasises the consumption of raw fruit while cooked vegetables make up the smallest meal of the day. The consumption of raw fruits and vegetables in nature is often seen in animals with smaller brain sizes and larger digestive systems, such as cows and gorillas. The importance of cooked vegetables is underestimated in human evolution; indeed, cooked vegetables circumvent the need for complex digestive systems and free up more energy to grow larger brains. This is archaeologically reflected in hominid fossil teeth and jaw shape. The more primitive species of humans possess more robust features, such as large canines and chewing apparatus. Archaeological evidence for cooking and hearth use is indicated as early as the Acheulian period 790,000 years ago at the site of Gesher Benot Ya’aqov in Israel where the charred remains of several edible plant species were found including olive, wild barley, and wild grape.

Furthermore, physical anthropologist Katherine Milton argues that meat was eaten by hominids as a means of providing essential amino acids and nutrients. This left more stomach space for the selection of higher quality and more easily digested plant foods. Studies on primate metabolism have indicated that there is an upper limit to how much raw food can be eaten over a day and a trade-off between access to calories and ability to digest such foods.

While raw veganism might superficially appear to be a ‘natural’ diet for humans insofar that it is rooted in fruits and vegetables, it is not reflective of the actual hominid diet that allowed our brains to reach the cranial sizes we see today.

References:

Conroy, G.C., 2005. The Debate Over “Man the Hunter”. In: Reconstructing Human Origins: A Modern Synthesis. New York: W.W. Norton

Evolved to exercise – but how?

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Image by Andy Wright

Obesity is now a global problem

According to the World Health Organisation, the global obesity rate has more than doubled since 1980 and 1.9 billion adults were overweight in 2014 while over 600 million of these were obese. Sedentary modern lifestyles present a unique problem for the human metabolism. We have evolved to be attracted to high-energy foods and sugars. During the Paleolithic period, sugars and fats were beneficial when we needed to run and hunt; calories were naturally burnt off throughout the day. However, switch the Savannah for the office and the scenario changes.

Our brains are hardwired to crave foods that will provide us with high energy but, it is energy we no longer need for the types of activities we do. Furthermore, our bodies are evolved to move, and bearing body weight is essential for the retention of bone density. In fact, after 36 weeks of bedrest, we lose between 24-40% bone density in the heel (Bortz, 1984).

Run versus sprint: suggestions from archaeology that might save us

Prominent Paleoanthropologist Daniel Lieberman argues that humans were evolved to run extremely long distances. His studies on the biomechanics of the human foot indicate that we are morphologically adapted to long distance running. In contrast, Mark Sisson of Mark’s Daily Apple argues for high-intensity interval training through his Primal Blueprint Workout Planwhich supposedly can ‘hack’ our evolutionary biology to attain the best physical fitness possible. His suggestions stipulate ‘running really fast once in a while’ on the basis that our ancestors existed in a world of infinite danger that required us to sprint after and away from predators. He argues that this constant environmental pressure resulted in a gene expression within fast twitch muscle that meant we were evolved to sprint faster. In the most basic of terms: survival of the fittest.

However, these arguments rely heavily on theoretical knowledge. We cannot go back in time and watch our hominid ancestors carry out their day to day activities, but we do know that the paleo-environment was unforgiving and it would have required enormous effort just to survive and reproduce successfully. We can look to modern day hunter-gatherer groups and their activity patterns as a means of ethnographic analogy.

References

Bortz, W.M., 1984. The disuse syndrome. Western Journal of Medicine.

Health – What’s Paleo got to do with it?

Paleo Diet FlowchartPhoto by: NextTwentyEight

The application of evolutionary frameworks onto modern world issues has proved popular in a range of spheres with particular mention given to evolutionary medicine, psychology and even social policy. To avoid improper interpretation by non-specialists in this field, archaeologists and anthropologists should encourage knowledge and awareness to avoid stereotypical assumptions and sometimes dangerous conclusions.

Misinformation is particularly a problem in the case of the health and fitness industry. The popularity of the Stone Age Diet and ‘ancestral eating’ plans such as Neanderthin has soared over the past ten years. Eating ‘primally’ has gathered celebrity backing from actresses such as Cameron Diaz who purports in The Body Book that our bodies are still that of ‘hunter-gatherers’ and struggle to align with modern ways of eating.

The idea of attempting to eat like our ancestors did was pioneered by medical doctor Walter Voegtlin in the 1970s. The degree to which the recommendations of the diet are backed up by archaeological and ethnographic evidence, however, is debatable.

The basic principles of the diet as stipulated by Voegtlin are as follows:

  • Any type of meat
  • Any type of fish
  • Only canned or cooked vegetables allowed
  • No vegetable or fruit juice
  • Only black coffee allowed

This is all very theoretical, is there any archaeological evidence to support this?

Paleolithic diet reconstruction comes in the form of environmental reconstruction, coprolite, and isotopic analysis. The remains of some large animals that were likely hunted, such as Mammoth and big game, can also give us some clues as to the types of meat our hominid ancestors were eating. However, the pattern in which they were consuming these animals likely differed considerably to modern interpretation.

If we were consuming pure meat from muscle alone, we would quickly become malnourished, as it does not provide all the required essential nutrients. Fats and other essential nutrients are gathered through the accessing of bone marrow and the consumption of the partially digested stomach contents of the hunted animal. This is a significant shortcut to biomass that our ancestors used as a means of bypassing the need to digest difficult-to-process plant foods. In turn, humans were able to invest more energy into growing larger brains (a process known as encephalisation) and evolve a simpler digestive system that consumes significantly less energy.

This corresponds with the expensive tissue hypothesis (Aeillo and Wheeler 1995). Animals of larger size that are herbivores, such as cows, have two stomachs that are able to digest difficult-to-process resources such as grasses. Digesting plant material takes significant amounts of energy that could be directed towards brain development.

It makes sense to assert that our ancestors ate meat as it was efficient source of energy; however, the degree to which meat featured prominently within their diet is debatable. High consumption of meat is associated with a range of health conditions including heart disease and obesity. Bacon, a component of the Paleo diet which is heavily publicised, has recently been named a carcinogen and processed meat by the WHO.

References

Aiello, L.C., Wheeler, P., 1995. The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution. Current Anthropology.

Diaz, C. 2013. Hunter, Gatherer, Drive-Thru-er. In: The Body Book: The Law of Hunger, The Science of Strength, and Other Ways to Love Your Amazing Body. New York: Harper Collins.

Voegtlin, W.L., 1975. The stone age diet: Based on in-depth studies of human ecology and the diet of man. New York: Vantage Press.