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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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 linksĀ 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.