Harvard scientist says we are what we eat -- and wh...( CAMBRIDGE Mass. June 1 2009 -- You ...)

CAMBRIDGE, Mass., June 1, 2009 -- "You are what you eat." Can these pithy words explain the evolution of the human species?

Yes, says Richard Wrangham of Harvard University, who argues in a new book that the invention of cooking -- even more than agriculture, the eating of meat, or the advent of tools -- is what led to the rise of humanity.

Wrangham's book, "Catching Fire: How Cooking Made Us Human," is published today (June 1) by Basic Books. In it, he makes the case that the ability to harness fire and cook food allowed the brain to grow and the digestive tract to shrink, giving rise to our ancestor Homo erectus some 1.8 million years ago.

"Cooking is the signature feature of the human diet, and indeed, of human life -- but we have no idea why," says Wrangham, the Ruth Moore Professor of Biological Anthropology in Harvard's Faculty of Arts and Sciences. "It's the development that underpins many other changes that have made humans so distinct from other species."

Drawing on a wide body of research, Wrangham makes the case that cooking makes eating faster and easier, and wrings more caloric benefit from food. Moreover, he writes, cooking is vitally important to supporting the outsize human brain, which consumes a quarter of the body's energy.

By freeing humans from having to spend half the day chewing tough raw food -- as most of our primate relatives do -- cooking allowed early humans to devote themselves to more productive activities, ultimately allowing the development of tools, agriculture, and social networks. Cooked food is also softer, meaning the body uses less energy merely digesting what it takes in.

Since physical remnants of fire tend to degrade rapidly, archaeological evidence of fire and cooking dates back only about 800,000 years. Wrangham looked to biological evidence, which shows that around 1.8 million years ago, Homo erectus arose with larger brains and bodies and smaller guts, jaws, and
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