The human brain is not special, according to a Brazilian scientist who says that we have primate brains but cooking the food we eat has made all the difference, writes.
For many decades it was assumed that the human brain must be special, as superior to the brains of other mammals as our minds are. This specialness was never seriously questioned, and even basic facts, like asserting that the human brain contains 100 billion neurons, were arrived at with surprising casualness.
In an interesting 2013 TED talk, the articulate Brazilian neuroscientist Suzana Herculano-Houzel offers clarity for the first time on several of the basic issues. After devising a way to dissolve brain cell membranes so that only the nuclei remained, and isolating them to be counted, she determined that the human brain contains 86 billion neurons, the most of any primate. Even though the human brain is a small fraction of our total weight, it uses 25% of a person’s daily calorie consumption.
That may seem like an incidental fact, but Herculano-Houzel makes it the cornerstone of her argument, which declares that the human brain isn’t
We have primate brains, she says, that are in proportion to our primate relatives like chimpanzees and gorillas. But in an odd evolutionary twist, chimps and
gorillas cannot sustain the calorie load of an immense brain by eating raw food. Typically, a great ape feeds for eight hours a day to sustain its large body, and over time a choice was made to prefer a very large body with a smaller number of
In homo sapiens, the reverse occurred. We chose a small body and a huge brain, particularly the higher brain responsible for our superior mind. According to Herculano-Houzel’s explanation, this choice was made possible by the invention of cooking. Cooking raw food is like pre-digesting it outside the body; cooked food is easier to digest, contains more nutrients by weight than raw food, and takes many fewer hours to eat. You can get an entire day’s calorie load with a 15-minute visit to a fast-food chain.
So there you have it: cooking led to the enormous number of neurons we possess, and they in turn allowed our huge cognitive capacity to evolve in a growth spurt that took the early hominid brain on a skyrocketing curve for the last 1.5 million years since the discovery of fire.
But as intriguing as this hypothesis is, and as essential as fire was to human evolution, the whole thing doesn’t hold water. To begin with, if we started out in our hominid ancestry with unevolved primate brains, how were such brains smart enough to discover fire? No other higher primate did, and they already possessed big brains on the
(To be continued)
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