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.

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.