Catching Fire: How Cooking Made Us Human
© 2009 Richard Wrangham
The genius of cooking is that it allows us to maximize the potential calorie intake of a given foodproduct. Raw food is tough; herbivorous animals in particular spend their entire day grazing and chewing. Their intestines must work throughout the day, and often into the night, breaking down ingested food into the fuel the body so desperately needs. But all that work takes energy itself. Meat eaters have an easier time of it, but muscle tissue is resilient; thick, tough, and tightly connected. At the outset, Wrangham establishes that the ease of digestion is fundamentally important, citing cases in which two sets of animals were given identical amounts of the same food; rats, for instance, given a set number of food pellets. Each group's calorie count was identical, but one group had "soft" pellets, or pellets in which air had been inserted. The group eating soft pellets put on muscle mass far more quickly than the group chewing on hard pellets; in fact, the soft-pellet group became obese. In processing and cooking food -- grinding seeds, tenderizing meat by pounding it with rocks, and then heating items -- we greatly reduce the amount of work our bodies must do to digest them. The more processed they are, the more efficiently we can take in the calories...and while easy calories have become a problem to us now, in the days prior to agriculture it was a godsend.
Cooking not only gave us a competitive edge, it altered our physiology. We no longer needed huge teeth for grinding raw muscle, nor expansive intestines for long-term digestion...and when those became smaller, we had more energy to invest in brains. Although Wrangham doesn't speculate on the result of increased intelligence and leisure time, one can assume the combination had a dramatic effect on human culture. Fundamentally, the author contends that the division of labor roles could have never transpired without cooking. Raw food requires so much time to chew and digest that men wouldn't have been able to spend their days hunting (or lounging around, as the case might be) if they could not have come back to the tribe camp with a cooked meal waiting for them. Since women, the gatherers, provided the economic foundation of the tribe -- supplying food if and when the men failed to deliver -- one might think this gave them the power. Instead, cooking became a liability. Women tending food at a fire needed to protect it, lest the food be stolen. Wrangham believes that pair bonds arose for this reason: women provided the food, and men protected it. Although this is more of a stretch than the biological claims, requiring more inference on our part, it offers a count to the usual sex-driven conception of pair bonds. Time and again Wrangham documents tribes that don't seem to care if married women sleep with other men...but woe betide them if they cook for other men.
Wrangham ends by chastising nutritionists for missing the point about food, and particularly for believing every food delivers a set amount of calories or nutrients, when that amount greatly varies depending on how the food has been processed and cooked. Given the obesity epidemic, the relationship between processing and calories is certainly one worth our consideration...and Wrangham's work is wide open to lay readers, so dig in.
ScienceFriday interview with Richard Wrangham regarding Catching Fire
Guns, Germs, and Steel, Jared Diamond