There are not a lot of things that separate us from other species. Nightingales sing. Chimps use tools. Ants domesticate animals (aphids). Bower birds do home decorating. But only humans cook their food.
Harvard University primatologist Richard Wrangham thinks cooking may be the reason for our big brains. No kidding. Brains use a lot of energy. A human brain uses 25 percent of an adult's energy supply, whereas a chimp's brain sucks up only 8 percent of available energy. Where did humans get the extra energy to support their large brains?
By cooking their food, says Wrangham (see Science, June 15, 2007). Cooking is a kind of predigestion. Less energy to the gut, more to that knot of nerves on the top of the spine. We are Homo sapiens because first we were Homo juliachild.
Not everyone agrees. There is a problem of timing. The brains of our hominid ancestors started ballooning about 1.9 million years ago. The first solid archeological evidence for the controlled use of fire comes much later, about 250,000 years ago. Wrangham is not dissuaded. The evidence for fire is elusive. He sticks with the image of hairy ancestors sitting around a campfire gnawing on a roast leg of wildebeest, perhaps with a side of steamy manioc. And all those soft, yummy calories puffing up the brain.
Well, maybe so, maybe not. But I was thinking about this the other evening when our house guests -- my nephew and his girlfriend -- were cooking dinner. And quite the cooks they are. Lots of fresh ingredients direct from the market. The flash of stainless steel as the knife went chippetty-chop. Pepper and salt mills whirling. A pinch of this, a pinch of that. Hands kneading dough whipped up from pure white flour. In such young people, it was a joy to behold.
A fire in the fireplace. Some Motown on the stereo. An open bottle of good wine. And those two talented youngsters at the stove, whipping up a meal that looked as good as it tasted. Whether cooking made the brain bigger, or whether our bigger brains make cooking such an intellectual delight, I will leave to the archeologists. I offer a picture here of proof that we live in the age of Homo delicious.