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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