About 2 million years ago, the human brain rapidly increased its mass until it was double the size of other primate brains.
For a long time, we were pretty dumb. Humans did little but make “the same very boring stone tools for almost 2 million years,” he said. Then, only about 150,000 years ago, a different type of spurt happened — our big brains suddenly got smart. We started innovating. We tried different materials, such as bone, and invented many new tools, including needles for beadwork. Responding to, presumably, our first abstract thoughts, we started creating art and maybe even religion.
In most animals, the gut needs a lot of energy to grind out nourishment from food sources. But cooking, by breaking down fibers and making nutrients more readily available, is a way of processing food outside the body. Eating (mostly) cooked meals would have lessened the energy needs of our digestion systems, Khaitovich explained, thereby freeing up calories for our brains.
Instead of growing even larger (which would have made birth even more problematic), the human brain most likely used the additional calories to grease the wheels of its internal functioning.
They point out in the article that other vertebrates use as little as 2% of their energy to run their brains, in contrast to our 20-25% (or more?).
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Also on LiveScience.com, Stéphan Reebs, of Natural History Magazine, says in “Chimps Prefer Cooked Food” (22 September 2008 11:09 am ET):
Victoria Wobber and her graduate advisor at Harvard University, Richard Wrangham, along with a third colleague, gave a choice between cooked and raw food to a number of captive apes.
Chimpanzees clearly preferred cooked carrots, sweet potatoes, and beef over the raw alternatives. They did not express any preference in the case of white potatoes and apples — perhaps, the scientists say, because both remain relatively unchanged by cooking. …
The findings concur with research showing that cats favor cooked meat and rats opt for cooked starch.