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Cooking Gave Humans Edge Over Apes?

Christine Dell'Amore in Chicago
National Geographic News
February 13, 2009
 
The simple, everyday act of cooking could have given humans an evolutionary edge over apes, researchers proposed at a scientific meeting this week.

Preparing meals is a "signature feature" of the human diet that likely originated in the extinct species Homo erectus 1.8 million years ago.

"The hallmark of dietary evolution is our flexibility and plasticity. What made humans humans is the ability to find or make a meal in the environment," said William Leonard, an anthropologist at Northwestern University who was not involved in the new research.

H. erectus had a large brain and body size, and many believe that the species' hunter-gatherer lifestyle—associated with more cooked meat—fueled its growth.

But scientists aren't sure why these first chefs initially put food to fire.

Yesterday Richard Wrangham, a biological anthropologist at Harvard University, served up new evidence for his hypothesis: Cooking decreases the energy cost of eating.

For primates, including humans, "energy is absolutely critical, and [it's] what natural selection is constantly trying to maximize," Wrangham said during a preview of his work at the American Association for the Advancement of Science's annual meeting in Chicago.

Cooking makes starchy things gelatinous, breaks up proteins, and softens rock-hard edibles, Wrangham said. Such textural and chemical changes make foods easier to eat and digest.

Designed for Cooking

The shift to cooking is reflected in modern human anatomy. For one, our jaws are considerably smaller—and thus less able to bite into hard foods—than those of our earliest ancestors.

Also, our gut is not set up for processing raw items as effectively as cooked food.

What set us apart from apes, Northwestern's Leonard said, was a need for a high-quality, high-calorie diet, combined with a drive to be active over a large area.

Humans' "remarkable ability" to find and process many types of food is what probably led to the tremendous diversity of healthy diets across the globe, Leonard said.

The flip side is that many people today have shifted to a more sedentary lifestyle than that of our hunter-gatherer ancestors.

We continue to consume many calories, but we don't get nearly as much exercise as early humans.

"We're a victim of our evolutionary successes," Leonard said.

Diet and Exercise

Some studies suggest that a return to ancient lifestyles could clear up "diseases of civilization," Leonard said.

One paper, for example, shows that putting diabetic Australian Aborigines on the diets of their ancestors reverses their diabetes in just seven weeks.

Likewise, researchers have put pedometers on members of hunter-gatherer groups that have maintained the same ranges for thousands of years. Those studies found that these people all walk roughly the same amount a day: about 8 miles (13 kilometers).

That's "remarkably close" to many government initiatives that recommend a daily walking allowance of about 6 miles (9.6 kilometers), Leonard said—lending credence to the idea that an ancient lifestyle could be the healthiest.

That's not to say that popular manifestations of the idea, such as movements touting "paleodiets," are going to be weight-loss miracles.

"Many of the popular books written on the topic are foolish … and others are potentially dangerous," Leonard warned.
 

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