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.

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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.