A recent article in the NY Times Tuesday Science section caught my attention and brought to mind one of the more interesting books I’ve read in past years: Catching Fire: How Cooking Made Us Human, by Richard Wrangham, 2009.

The argument in a nut-shell is that cooking meat and starches softens and changes the chemistry of food, and therefore the nutritional value to such a point that less energy is needed in the process of digestion, more energy is released from the foods and that the surplus over hundreds of thousands of years went into building the bigger brains that made us homo sapiens.

Wrangham does a very nice job of laying out the digestive chemistry and philology of the human body, along with archaeological and anthropological evidence for evidence of butchering, control of fire, changes in cooking methods — from meat on the flame to nuts and seeds buried in coals to hot stone heating of water to early ovens– and the growth in the size of the cranial capacity in the hominidae family — from 450 cubic centimeters in australopithecines to 1,400 cc in modern humans.

Along the way he takes a tour through raw-food devotees, analyzes chewing time and digestive time in our primate cousins and ourselves and looks at the world wide phenomenon of women being the principle meal preparers in some 97.8% of human societies.  In especially fascinating paragraphs he argues that the likely underpinning of the sexual division of labor and pair-bonding in humans was not sex or child-rearing, but cooking.  Cooked food, whether animal, hunted by men, or tubers, gathered by women, is softer and more easily digestible.  The higher nutrition at less digestive expense lead to greater health, mobility and physical prowess but at the expense of time spent in preparation (thus lost in gathering) and the risk of having food in quantity around the preparation area.  This created the need for protection from marauders and beggars, and so  an economic deal grew between a man (I’ll give you my meat (when I can get it,) and protect you and the food while you’re cooking) and a woman (I’ll give you cooked food, mine and yours, if you keep the others away.) Along with this came certain social conventions and even manners over time: only kin had a built-in claim to food; those wanting food learned — as wolves becoming dogs did– to be polite and wait.  The aggressive ones would be chased off and censured. Cooking necessarily created social time around the fire thus providing opportunity for the growth of semantic signalling and eventually language.  As one student of the matter observes, “cooking ends individual self-sufficiency.”  No more picking and eating, but picking, pulling, gathering, carrying, piling, sorting, cooking, and necessarily, sharing.

Sex, he argues, was an added benefit, not the prime mover.  For many, multiple couplings were quite common; child rearing by groups even more so.  The cooking cycle had to be more stable, and grew so as community ties grew to reflect that.

The reader may get a little uneasy at the amount of speculation or thought-experiments, the numbers of “could haves,” “would haves,” “maybes” and “perhapses.”  Given the lack of actual testable evidence for the proposed long chain of events it’s hard to know what else might be done.  The logic seems solid, the if-thens responsibly done.  That cooking made us human may not be as incontestable as evolution or plate tectonics, but it seems strongly on the right road.

Carl Zimmer’s recent article, “For Evolving Brains, A Paleo Diet of Carbs”, in the New York Times Science section, brings Wrangum up to date with a very readable description of the digestion process — how a potato gets turned into useful energy– and new information about DNA changes between our primate ancestors and ourselves:

“Chimpanzees, our closest living relatives, have two copies of the amylase gene in their DNA. But humans have many extra copies — some people have as many as 18. More copies of the amylase gene means we make more of the enzyme and are able to derive more nutrients from starches…”

His article, here, will give you a thumbnail of the argument.  Wrangham takes you deeper into details, speculations and and some of the objections.

If nothing else you’ll come away understanding that all food is brain food….