Should adults drink milk

Should adults avoid drinking milk, if other animals don’t drink it?

Pawel Malczewski
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Short Summary

The effects of milk on human health have no logical association with the fact that other adult animals don’t drink milk. Other species of mammals don’t drink milk mainly because of their incapacity of extracting it, due to the lack of physical and mental capacity and different evolutionary paths. For a quick answer click here.

Explanation

This is a popular argument among some Paleo diet enthusiasts and vegans. They state that if other animals do not drink milk from other species, therefore, it must be unnatural and humans past infancy shouldn’t drink milk either.

There are two factors which make humans different from animals when it comes to milk consumption: our ability to extract milk from animals and the genetic changes that have occurred in some populations over thousands of years, as a result of that ability to extract milk.

Ability to extract milk from other mammals

Humans have a superior intelligence and the physical ability to extract milk from milkable domesticated animals. That’s a great advantage compared to other mammals. It started about 80,000-10,000 years ago, when our ancestors learned how to domesticate animals and then to extract milk without harming them. (1)Ingram CJ, Mulcare CA, Itan Y, Thomas MG, Swallow DM. Lactose digestion and the evolutionary genetics of lactase persistence. Hum Genet. 2009 Jan;124(6):579-91. Available here. (2)Itan Y, Powell A, Beaumont MA, Burger J, Thomas MG. The Origins of Lactase Persistence in Europe. PLOS. Computational Biology. Aug 2009. Available here. (3)Curry A. Archaeology: The milk revolution. Nature. International weekly journal of science. Available here.

It is technically difficult and impractical for other adult animals to feed on milk from either their mother or animals of other species.

Genetic changes in humans but not in other mammals

After farming replaced hunting and gathering and the domestication of animals became widespread in some areas of the world, farmers started to extract and use milk. Initially they produced tolerable, low in lactose fermented dairy products such as yogurt or cheese.

People, who still were not able to produce the lactase enzyme, adapted slowly to this new source of nutrients. This change in the diet created a need for the breakdown of lactose, triggering a genetic mutation which spread over thousands of years to the surrounding areas. (4)Ingram CJ, Mulcare CA, Itan Y, Thomas MG, Swallow DM. Lactose digestion and the evolutionary genetics of lactase persistence. Hum Genet. 2009 Jan;124(6):579-91. Available here. (5)Itan Y, Powell A, Beaumont MA, Burger J, Thomas MG. The Origins of Lactase Persistence in Europe. PLOS. Computational Biology. Aug 2009. Available here.

The spread of these genetic mutations could only occur after many generations of consistent consumption of milk and milk products. Lactase persistence is currently found in approximately 32% of adults worldwide.

Please note, however, that outside those centers lactose intolerance is prevalent. (6)Itan Y, Powell A, Beaumont MA, Burger J, Thomas MG. The Origins of Lactase Persistence in Europe. PLOS. Computational Biology. Aug 2009. Available here. (7)Colledge S, Conolly J, Dobney K, Manning K, Shennan S. Origins and Spread of Domestic Animals in Southwest Asia and Europe (Univ Col London Inst Arch Pub) (UCL Institute of Archaeology Publications). Left Coast Press (July 15, 2013). Available here. (8)Leonardi M, Gerbault P, Thomas MG, Burger J. The evolution of lactase persistence in Europe. A synthesis of archaeological and genetic evidence. Volume 22, Issue 2, February 2012, Pages 88–97. Available here.

In contrast, other mammals did not go through the same evolutionary path and so could not experience similar genetic mutations. The ability of mammals to produce lactase reduces during the weaning period, making them gradually lactose intolerant.

Logical aspect of the myth

It is also simply not logical to draw such a conclusion as in the myth question. Even if all the other mammals are unable to drink milk for any reason, we cannot assume that humans can’t. Moreover, there are many things that humans can do and eat that other mammals just can’t.

Conclusion

Back to top

There are various reasons why drinking cows or other animal’s milk should be avoided. This argument, however, is a not valid reason and is unscientific.

References   [ + ]

1. Ingram CJ, Mulcare CA, Itan Y, Thomas MG, Swallow DM. Lactose digestion and the evolutionary genetics of lactase persistence. Hum Genet. 2009 Jan;124(6):579-91. Available here.
2. Itan Y, Powell A, Beaumont MA, Burger J, Thomas MG. The Origins of Lactase Persistence in Europe. PLOS. Computational Biology. Aug 2009. Available here.
3. Curry A. Archaeology: The milk revolution. Nature. International weekly journal of science. Available here.
4. Ingram CJ, Mulcare CA, Itan Y, Thomas MG, Swallow DM. Lactose digestion and the evolutionary genetics of lactase persistence. Hum Genet. 2009 Jan;124(6):579-91. Available here.
5. Itan Y, Powell A, Beaumont MA, Burger J, Thomas MG. The Origins of Lactase Persistence in Europe. PLOS. Computational Biology. Aug 2009. Available here.
6. Itan Y, Powell A, Beaumont MA, Burger J, Thomas MG. The Origins of Lactase Persistence in Europe. PLOS. Computational Biology. Aug 2009. Available here.
7. Colledge S, Conolly J, Dobney K, Manning K, Shennan S. Origins and Spread of Domestic Animals in Southwest Asia and Europe (Univ Col London Inst Arch Pub) (UCL Institute of Archaeology Publications). Left Coast Press (July 15, 2013). Available here.
8. Leonardi M, Gerbault P, Thomas MG, Burger J. The evolution of lactase persistence in Europe. A synthesis of archaeological and genetic evidence. Volume 22, Issue 2, February 2012, Pages 88–97. Available here.

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