Just over two and a half million years ago, our brains swelled. Less than a million years later, they swelled again, our posture and our gait changed, our jaws shrank, and we grew taller. These two evolutionary changes define our species, distinguishing us from our fellow primates.
Richard Wrangham has new ideas about why these changes occurred. He has no argument with the generally accepted wisdom that our first transformation – from nimble tree-climbing australopithecines to sociable, tool-wielding habilines – was the consequence of a meat diet. But the character of the second change – from Homo habilis to the protohuman Homo erectus – has never been adequately explained, and Wrangham believes he has the answer: 1.8 million years ago, we learned to cook. Cooking improves the caloric value of food, and widens the range of what is edible. It literally powered our evolution.
Good, big ideas about evolution are rare. Often they’re merely 'just so’ stories, stringing specious skeins of cause and effect over a much more complicated intellectual landscape. At first glance, Wrangham’s argument seems to have been fished from that dodgy pot. Nobody can know for sure when cooking got going because the chances are minute that anyone will ever stumble upon an ancient half-eaten spit-roast and recognise it for what it is. (That archeologists have found earth ovens more than 250,000 years old is startling enough.)
Wrangham’s task, then, is to come up with compelling evidence that the invention of cooking is the only possible explanation for the transformation that stood us on our feet, shrank our guts, gave us silly teeth and receding jawlines, and swelled our brains to their current, horrendously fuel-inefficient size. The big news – I think it is big news – is that he succeeds. Catching Fire is that rare thing, an exhilarating science book. And one that, for all its foodie topicality, means to stand the test of time.
Homo erectus’s novel dentition, skull shape and gut capacity sit at the heart of Wrangham’s account. This is a hominid that chewed less and thought more. The circumstantial evidence Wrangham gathers is, if anything, even more compelling. His review of the anthropological literature, for instance, shows that no one, ancient or modern, settled or nomadic, has ever survived for more than a couple of seasons on an exclusively raw diet. Humans, Wrangham says, are as adapted to cooked food as cows are to grass.
These adaptations are both physical and psychological. Why do women still end up doing more housework than men? Why are so many instances of domestic violence triggered by apparent or perceived failures in the preparation and ready provision of food? Wrangham believes that human monogamy evolved as a protection racket, in which males ensure that their vulnerable stove-tending spouses don’t get their food stolen.
Wrangham’s slippage into the territory of evolutionary psychology naturally sets alarm bells ringing. But, once again, the alarm proves false. Wrangham’s life has been spent studying the behavioural ecology of apes. He grasps the economics of cooking and understands how it may have influenced primate social behaviour. His arguments are compelling and he does not claim too much for his insights into our species’ less-than-blissful domesticity.
For all our primate inheritance, we are still what we thought we were: an adaptable ape. Our past skews our present behaviour in ways we should try to understand. Ultimately, though, immediate economic circumstance dominates the way we cook and eat and behave around food. As domestic obesity rates continue to climb, this is both a liberation, and a worry.