Evolution and Food

Here’s a book review I wrote about “Catching Fire: How Cooking Made Us Human” by Richard Wrangham (the same fellow we saw chasing chimpanzees in Africa in the video, Why Sex?). The review first appeared on the blog Savage Minds. If you’re interested in the topic of how what we eat has affected how we evolved you might be interested to read it. After I finished the book I gave it to my dad and he loved it!

Throughout contemporary socio-cultural anthropology researchers are again turning to the biological, reexamining the relationship between the human body and the environment. Like some of the best recent anthropology this “new” vein of inquiry can be quite theoretically rigorous with language that appeals primarily to experienced professionals. Inverting this trend is a new book written at the popular level for an educated lay reader from primatologist Richard Wrangham, Catching Fire: How Cooking Made Us Human. Every living thing must eat but humans are unique in that the food we eat is processed and cooked. In the study of diet, anthropology may find a fruitful realm to explore the relationship among the human and animal worlds.

Catching Fire is a book of ideas. It makes a case for its thesis and rallies to its corner evidence from archaeology, human evolution, anatomy, and primatology. It also makes claims that are speculative and without direct evidence. Still the argument is compelling. At the crux of the book is Wrangham’s assertion that cooking kick-started the transition from Homo habilis to Homo erectus. In order for cooking to play the significant role that Wrangham says that it has, human ancestors must have controlled fire by 1.8 million years ago, almost twice as old as the current archaeological evidence. He bases this conclusion by claiming that the morphology of Homo erectus is one that is already largely adapted to the consumption of cooked foods, logically control of fire and thus cooking would have occurred prior to those physical transformations.

That our bodies are adapted to eating cooked food is obvious. The modern human body is so well suited for acquiring energy from cooked food that some seek to lose weight by going on a raw food diet! Compared to other apes humans have a drastically reduced gut size, only about 60% of what is expected for a primate our size, and without spending energy on all that expensive tissue we can afford to have an oversized brain. This idea that extra energy going to the brain is offset by reduced energy going to the gut is known as the “expensive tissue hypothesis” and in primates the tendency towards using energy saved for added brain tissue is strong. Presumably this is because primates tend to live in groups where social intelligence can reap big rewards.

Wrangham argues that the benefit of a smaller gut is not accessed simply by including meat in the diet, as has long been argued, but by switching to a diet that is based on cooked foods. Thus the addition of cooked vegetable matter is just as significant a dietary shift as the increasingly prominent role of meat, “We are cooks more than carnivores.” Nevertheless improving the quality of diet through the addition of meat is not a simple task for living apes because they do not have a carnivore’s dentition. As a result eating raw meat can be a very time consuming process simply due to the fact that it requires a great deal of chewing. The great advantage of cooking meat is that it becomes less costly to digest and the diner is freed from spending extended periods of time chewing it.

Cross-culturally there is a clear pattern as to who is called upon to invest time in cooking food: most commonly it is women. Wrangham believes that the ancient date of when cooking began, 1.8 million years ago, explains this division of labor by sex. I agree that behavioral ecology must play some role in the unique way that humans procure food. This has been observed among living hunter-gatherers. Women seek vegetable matter and men hunt then they both return from their daily foraging to a home camp and share. Usually the woman cooks and both sexes eat the foods the other acquired. No other animal behaves in this way. Why should the woman cook?

If food was raw, the sexual division of labor is unworkable. Nowadays a man who has spent most of the day hunting can satisfy his hunger easily when he returns to camp, because his evening meal is cooked. But if the food waiting for him in camp had all been raw, he would have had a major problem. The difficulty lies in the large amount of time it takes to eat raw food.

Before our ancestors cooked, then, they had much less free time. Their options for subsistence activities would therefore have been severely constrained… Males who did not cook would not have been able to rely on hunting to feed themselves. Like chimpanzees, they could hunt in opportunistic spurts. But if they devoted many hours to hunting, the risk of failure to obtain prey could not be compensated rapidly enough. Eating their daily required calories in the form of their staple plant foods would have taken too long.

For Wrangham it ultimately comes to this: the long hours of chewing a raw diet would have prevented males from specializing in hunting. Thus humans would not have benefited from the addition of substantial helpings of nutritious meat nor would they have been able to power their energy-needy big brains. There simply is not enough to time to hunt and chew raw food if one is not a carnivore. Only with cooking is the sexual division of labor possible.

But why should it be that women cook for men? Why is it not that men cook for each other in bachelor groups? Or women cook for other women, for that matter? Or why do men not cook for women on the days they do not hunt? The author’s answer is not entirely satisfying.

Cooking in the open is a very conspicuous activity. From quite a distance it produces attractive smells. Furthermore, among chimpanzees if a low-ranking individual manages to kill a small animal a higher-ranking individual will likely steal it. Female chimps get hardly any meat at all. If human behavior prior to the advent of cooking was at all similar then a cook needs a bodyguard otherwise the strong will take advantage of the weak. Since males are physically larger they make better fighters. Thus if a female wants to eat cooked food she cannot count on a male to provide it, she needs a male to protect her while she cooks it herself. The result is a mutually beneficial “household,” not organized around sexual relations but feeding behavior.

Wrangham concludes, “Cooking brought huge nutritional benefits. But for women, the adoption of cooking has also led to a major increase in their vulnerability to male authority. Men were the greater beneficiaries.”

Unaddressed by the author is the place of children in this household feeding economy. Females invest more time and energy into the care of young than males. That women care for their children as they forage for food is a primary reason why they are not hunters. It seems likely that female desire to feed their young is also a primary motivator in a sexual division of labor that also happens to result in females cooking for males. If the offspring are fed nutritious cooked food then they are more likely to reach reproductive maturity thereby increasing the parents’ fitness. That is the most parsimonious explanation. Wrangham focuses so intently on the relationship of women to men he completely overlooks the equally basic relationship of parents and children.

Catching Fire is an easy read that makes a compelling and original argument about human evolution. Like the works of Michael Pollan, which it will no doubt be compared to, its pages are larded with filler. Of the nine chapters, three could have been cut and the book’s main argument preserved. There is also the usage of eye-rollingly old-fashioned language. Anthropologists need to swear off the phrase “missing link” and any hint of associating evolution with “progress.” The general public is just too ill informed about what evolution is for anthropologists to have any excuse for deploying such literary devices.

Experts in the field of physical anthropology may prefer to read Wrangham’s scientific publications, but this book is easily within the grasp of undergraduates and lay readers. I happen to think that my General Anthropology undergrads will benefit more from the use of a textbook, but I would enthusiastically assign this work in a Food and Culture course or topics course in Evolution and Ecology. It will definitely inform my lectures in General Anthropology.

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About Matt Thompson

Matt Thompson is a project cataloger at The Mariners' Museum library. He has a Ph.D. in anthropology from the University of North Carolina - Chapel Hill and was formerly a professor at ODU. You can find him on Twitter @m4ttTh0mps0n.
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