Food for thought in one volume

IN 1773, James Boswell declared that ‘man is the cooking animal’; no other creature, he observed, treats food the way we do.

Every community, ancient and modern, lights fires and cooking is common to all cultures. But was the roasting of food in campfires long ago any more significant than the drying of fish or the pounding of meat? Could it have had more profound implications? Harvard zoologist Richard Wrangham thinks so. In Catching Fire, How Cooking Made Us Human, he argues that the invention of cooking led to changes in our ancestors’ bodies that made us a unique species. Even social and family structures, he thinks, owe their origins to it.

Despite what ideological vegetarians claim, a person can’t survive indefinitely on a diet of raw food, or so Wrangham claims. Eating and digesting require more energy when the food is raw than when it is cooked. Apes and monkeys spend much of the day chewing. A snake’s digestive system uses 43% of the creature’s resources. Modern humans are much more efficient; only 5% to 10% of the energy from our food goes to eating and digesting it. Cooking softens and breaks up fibres, rendering digestion and absorption easier. Humans need to keep food in the stomach for only two hours before sending it on to the small intestine. Dogs and cats, whose diets in many ways resemble ours, retain food for twice as long and plant-eating creatures take longer still.

Cooking shortened the time our ancestors spent eating and digesting. By breaking down the more unpalatable ingredients, it increased the amount of energy to be derived from the food. The range of items which could be eaten expanded enormously; no creature on Earth today eats as many foods as we do. The time and energy saved through cooking, Wrangham thinks, went into developing our ancestors’ brains, already large thanks to the meat-based diet of earlier forebears. A fifth of the energy we derive from our food goes to power our brains.

Early humans encountered fires caused by lightning strikes and learned to harness them. Campfires brought security, warmth and bonding. Our ancestors slept on the ground at the mercy of predatory animals. Fire kept such creatures at bay. Food items may have fallen accidentally into the flames and, when retrieved, were found to be more palatable. Even chimpanzees prefer food which has been burned in wildfires.

Modern people have smaller teeth and jaws than the early hominids and our guts are shorter. These changes reflect a change in diet which, Wrangham argues, was brought about by cooking. But who were the first cooks? Some researchers think that the practice began less than 25,000 years ago but this does not allow enough time for the changes to our digestive systems to have taken place. Archaeological evidence suggests fires have been lit for at least 250,000 years and these must surely have been used to cook. Others think cooking had little impact on our ancestors’ biology.

Wrangham, however, dismisses all of these suggestions. He thinks the first cooks were the Homo erectus people who appeared around 1.8 million years ago. Their ancestor is thought to have been Homo habilis who had a smaller brain and bigger teeth than Homo erectus. But Wrangham goes further, arguing that eating cooked food was the crucial factor in the evolution from habilis to erectus. The reduced tooth and jaw size of erectus were adaptations to eating cooked food. Monogamy, the extended family and even civilisation itself, derive ultimately from the campfire and the cooking of meals.

The problem for Wrangham is that the earliest reliable archaeological evidence of fire use dates to only 500,000 years ago. Asked on RTE’s Mooney Show to explain the discrepancy between the arrival of Homo erectus and the earliest date for the lighting of fires, Wrangham replied fires seldom leave long-term traces of their presence.

Catching Fire: How Cooking Made Us Human by Richard Wrangham, (Profile Books) €18.