Fire and the Evolution of the Brain

in Uncategorized
November 15th, 2012

Behold – our recent ancestor, the gorilla, and ourselves, the human:

There are many characteristics that separate us from our monkey fathers. Most notably, factors that mark the evolution are the use of fire, use of tools, and a bigger brain. A recent study suggests that it is actually the onset of the use of fire that explains the ability to begin to grow a larger brain. According to a timeline of human history, the earliest Homo Sapiens appeared shortly after beginning to use fire to cook food:

What is it about cooking that allowed us to grow bigger brains? As the brain grows bigger, more energy is required to sustain the increased number of neurons. Gorillas could spend up to ten hours a day obtaining the food necessary to sustain both their brain and large body mass. Why is it that humans can spend significantly less than 10 hours per day to consume our required energy intake, but gorillas must be constantly eating? The tradeoff is in how we prepare our food. Gorillas live off of a raw food diet, whereas humans cook food. Cooking can be thought of as “pre-digesting.” Because we’ve already broken down much of the food by cooking, the calorie absorption process becomes more efficient than if the food had been raw, and requires that we put in a significant amount of energy to just digest. On just a raw-food diet of the gorilla, evolution could not have been possible, because the gorilla could never consume enough energy via raw food in a day to support a larger brain. The use of fire to prepare food paved the way for the evolution of organisms that could support significantly larger brains.

I’m no expert on nutrition, but as a general public service announcement after seeing this study, I would caution going on a raw food diet for a long period of time. Sure, as a vegetarian my canine teeth aren’t being put to use like they’re supposed to be. But I can still consume enough energy to be healthy by cooking my veggies. For those of you who want to try a raw food diet… well, I’m seeing some pretty solid evidence that the whole reason we’re here is because of cooking. And you can’t really argue with evolution.

For more information on the topic, see the transcript of a recent Live Chat hosted by Science.

Sources:

Raw Food Not Enough to Feed Big Brains – Science

Metabolic constraint imposes tradeoff between body size and number of brain neurons in human evolution – PNAS

Food for Thought – Science