12 June 2009

The Importance of Protein in Evolution.

I was thinking about how human actions affected our evolution. Persons born with beneficial mutations or adaptations were more likely to survive and pass on those genes to successive generations. If it is in fact of genetic origin, a preference for the taste of cooked food seems to have protected certain humans from deadly microbes and hence led to the possession of those genes by a larger segment of the population.

Consequently, could a liking of the taste of meat have impacted human evolution irrevocably, whether positively or negatively? A little research seems to have borne out that eating meat has indeed had a dramatic effect on our evolution, although whether the taste itself contributed to it still eluded me. The increased amounts of protein had a beneficial effect on our brains, and our bodies also increased their ability to digest fats and cholesterol. This may seem like an endorsement of eating meat in modern times, but it is rather a recognition of the importance of diets that are high in protein and presumably low in sugar. While an omnivorous diet would meet those criteria, modern‐day vegetarians can consume large amounts of légumes, nuts and seeds as protein sources.

• Bernard Campbell, Human Evolution: An Introduction to Man’s Adaptations, 4th ed. (Piscataway: Aldine Transaction, 1998), 277. “Meat is a concentrated form of food comparable to seeds, which have been exploited by the rodents and are no doubt a contributory factor to their great success. Meat contains a high percentage of protein and, when digested, will release a whole range of amino acids necessary for the synthesis of body tissues. … Meat also contains vitamins (particularly in the liver) that are not readily available in a vegetable diet. There is little doubt that the final stage in human evolution was correlated with the exploitation of the large terrestrial mammals. … Our immensely successful evolutionary radiation must be associated, then,…with an important change in emphasis from a diet that was mainly vegetarian to one that was increasingly omnivorous.”

• Anna Gosline, “Taste for Meat Made Humans Early Weaners,” New Scientist, 29 January 2005. “[T]he nutritional benefit of eating meat at a younger age would have helped children’s brains to grow and develop more quickly. Human brains grow three times quicker than those of chimpanzees.” The article also states however that eating meat may have made human lives shorter: “[A] branch of hominids began to eat animal carcasses—a risky activity that would have brought them into contact with other predators and significantly raised mortality rates for the hunters. This would have created a selection pressure to wean infants earlier and earlier, since those no longer dependent on breast milk would have been more likely to survive their mother’s death….”

• Hillary Mayell, “‘Evolving to Eat Mush’: How Meat Changed Our Bodies,” National Geographic News, 18 February 2005, 2. “When humans switched to meat-eating, they triggered a genetic change that enabled better processing of fats…. [A]s a species we are relatively immune to the harmful effects of fat and cholesterol. Compared to the great apes, we can handle a diet that’s high in fat and cholesterol, and the great apes cannot.”

Photo credit: Matt Lewkowicz (Horsefeathered).

A version of this article is reproduced at webcitation.org/5kYw1atS3.

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