Harvard biological anthropologist and primatologist Richard Wrangham has explored eating, self-medication, dominance, and violence in chimpanzees. In his new book, Catching Fire: How Cooking Made Us Human, Wrangham lays out a problem about our own species that has bothered him for years: Why do humans cook? Though it’s all a chimp needs, raw food simply does not deliver the calories needed for a human to survive and reproduce, Wrangham writes. This led him to the fundamental fact that heating food increases its calories and that humans evolved eating cooked food—Catching Fire’s ultimate claim.
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Wrangham’s book takes the reader through a number of profound ruminations on the physiological effects of cooking (he says it explains our small mouths and guts and big brains) and then moves on to its thought-provoking cultural consequences (he says cooking led to marriage). Veronique Greenwood spoke to Wrangham about his “cooking hypothesis” and its potential implications for calorie counting and the human pair bond.
Seed: In your book, you articulate an energy theory of cooking: Cooked food yields dramatically more calories than raw. How does this work?
RW: When you cook, you increase the digestibility of the compounds in food, and you make it less costly for the body to digest: The more we cook it, the more its energy is available to us, and the less [our bodies] pay for it. What’s striking about that observation is that it is not reflected in the standard tables of nutritional composition of food. Those tables, on the USDA website or in books by institutes of food chemistry, report that the calorie value per gram is the same in food whether it’s cooked or whether it’s raw.
Seed: Why is the energy theory of cooking such a revolutionary idea?
RW: Well, it’s so amazing that nobody’s ever thought of it before. It’s astonishing that the energy theory of cooking is not something that’s part of standard science. It’s not that complicated!
Seed: Can you explain further why the current calorie count system is inaccurate?
RW: Under the current system, which was developed more than a hundred years ago, we work out how much of each of the types of organic compounds—carbohydrates fat, protein—there are in food, then estimate the food’s caloric content by multiplying the proportion of each of those compounds by their calories. How do you find their caloric content? You blow them up in a bomb calorimeter and see how much heat is released. The problem with this is that in our bodies we don’t blow food up. We have to use various chemical and physical processes to extract the energy from the food; as a result we get less energy from it than calorimetry predicts.
Seed: If the calorie counts on the sides of boxes are theoretical maximums, does that mean that we need fewer calories than we thought? Fewer than 2,000?
RW: This is a fascinating question, and I don’t know the answer. It certainly raises some pretty severe questions. When we developed the concept of how many calories you needed, the food people were eating was less processed than it is now. That means they were getting less out of their food at that point, which makes me suspect that the calculations of how many calories we need per day were overestimations.
There is a group of nutritional scientists who have been objecting for some years and saying we need to amend the convention to draw people’s attention to the fact that less processed food gives you fewer calories. Apparently, the debate has so far been resolved in favor of conventional wisdom, which says that it really doesn’t matter that much.
Seed: It’s ironic, then, that dieting supplements are some of the most processed foods out there—ground soy protein, shakes, etc.
RW: It’s exactly the opposite of what it should be! All those liquid protein diets…I mean, it’s hilarious. I’d be fascinated the find out the extent to which the proteins have been denatured and made even more calorie-rich by the addition of chemicals as well.
Seed: You move directly from the energy theory of cooking to the anthropology of cooking. Can you explain the relationship you see between male violence and cooking?
RW: The argument I present is that what cooking does is create a problem of ownership. When you cook, you have to leave your food exposed to view for a certain amount of time. And that means you can no longer do what a chimpanzee can do, which is pick a fruit from a tree and put it directly into your mouth. Among chimps, there would be fighting over it. But humans don’t fight at all. There are social rules against that. The rule is the woman is not allowed to feed any man other than her husband and is required to feed her husband. Those rules mean that her food is [protected from other males by her husband]. This makes sense if you see marriage, the pair bond, as a kind of protection racket in which the woman is required to feed a man because of the threat of having her food taken by other men.
Seed: Why would women be any more vulnerable to food thievery by males than would other physically weak groups like young adults?
RW: If there aren’t females, young males are forced to do the cooking. In polygynous societies [where men take on more than one wife, leaving some men with no wives], “boy slaves” are sometimes forced to do the cooking. But women are easier targets. I think about it from a female chimp’s perspective. A female chimp is totally vulnerable: If the males want something, they take it. The bigger ones are bullies.
Seed: Why wouldn’t everyone just cook for themselves?
RW: Well, everyone wants to reap the benefits of cooking. You could say that initially everyone cooks their own food. But perhaps someone comes home late and has had bad luck, they see someone else’s fire, they think great, there’s food there, and they can go and compete for the food. You need a system of social regulation to stop that.
Seed: At the end of the book, you arrive at the conclusion that the point of marriage is not sex or status, it’s food.
RW: Yes. There’s this huge distinction in most cultures between the status of men as bachelors or married men. It’s only when the man is married that he gains status and he gains it because he can do two things: He can go off during the day to do manly things—to hunt or raid the neighboring group or check on girlfriends in neighboring camps or sit around chatting and politicking—and still count on the evening meal. And the second thing: When another man invites him for a meal, he can reciprocate. And until he can reciprocate, he’s not part of the community of equals.
This is what the social anthropologists say, and to me it seems completely convincing. Cooking underlies this whole critical distinction because until the bachelor can rely on someone providing him cooked food, he must do the work himself, which means he can’t do the manly things properly.
Seed: This is a grim picture of pair bonding.
RW: Frankly, I don’t think there’s a real consensus about the anthropology of pair bonds. This is an area of the book that I’m sure that other people will think is speculative. My guess is that people will not agree with [some of these ideas], but on the other hand, I’ve thought about them for about 10 years, and I feel pretty comfortable with them.
Originally published June 9, 2009