The Human Advantage: A New Understanding of How Our Brain Became Remarkable

“People need to drop the idea that the human brain is exceptional,” said Vanderbilt University neuroscientist Suzana Herculano-Houzel. “Our brain is basically a primate brain. Because it is the largest primate brain, it does have one distinctive feature: It has the highest number of cortical neurons of any primate. Humans have 16 billion compared with 9 billion in gorillas and orangutans and six-to-seven billion in chimpanzees. It is remarkable, but it is not exceptional.”

In her popular science book The Human Advantage: A New Understanding of How Our Brain Became Remarkable (MIT Press: March 2016), Herculano-Houzel explains how human brains grew so large, even larger than the brains of gorillas and orangutans, whose bodies are larger than ours. Her answer is surprisingly simple. It is the invention of cooking.

“Our big brains are very costly. They use 25 percent of all the energy the body needs each day,” Herculano-Houzel said. “Cooking allowed us to overcome an energetic barrier that restricts the size of the brains of other primates.”

Take the case of the gorilla. It must spend at least eight hours per day foraging and eating to support its body and brain. The human brain is three times larger than that of the gorilla. If a gorilla had a brain the size of a human, it would have to spend an additional one and a half hours a day finding food. So there simply aren’t enough hours in the day for the gorilla to support a bigger brain. Likewise, if humans ate like any other primate, we would have to spend nine and a half hours per day eating – every single day.

That’s where cooking comes in. “By cooking, I mean cutting, dicing, smashing –all types of food preparation,” Herculano-Houzel said.
“Take a single carrot. If you eat it raw, it will take 10 to 15 minutes of vigorous chewing and your digestive system will only capture about one third of the calories. But, if you cut the carrot up and cook it for a few minutes, it takes only a few minutes to consume and your body gets 100 percent of the calories.”

The origin of cooking, as Herculano-Houzel defines it, dates back about 2.5 million years ago with the development of the first stone tools. Among other things, these stone tools were man’s first food processors, allowing our ancestors to slice and dice and mash their food. Evidence for the controlled use of fire appears about 400,000 years ago.

“Those early tool makers had brains about the same size as gorillas. But, beginning about 1.8 million years ago, the brains of our ancestors began growing steadily, tripling in size over the next 1.5 million years,” said Herculano-Houzel.

“It’s amazing that something we now take for granted, cooking, was such a transformational technology which gave us the big brains that have made us the only species to study ourselves and to generate knowledge that transcends what was observed firsthand; to tamper with itself, fixing imperfections with the likes of glasses, implants and surgery and thus changing the odds of natural selection; and to modify its environment so extensively (for better and for worse), extending its habitat to improbable locations.”

Follow Vanderbilt on Twitter:   / vanderbiltu  , on Instagram:   / vanderbiltu   and on Facebook:   / vanderbilt  .

See all Vanderbilt social media at http://social.vanderbilt.edu.