"fire is needed to fuel the organ that makes possible all the other products of culture, language included: the human brain." Jerry Adler - Smithsonian Magazine
Once again I find I am way behind in catching up with a particular piece of knowledge, so maybe you will know everything I am about to share, but I'll try to summarise and point you to much better sources than I. Sources that claim (in a way) that what makes us uniquely human, and, moreover, supremely intelligent, is cooking.
We have been leant an old DVD dating back to 2011 - The Origins of Us - presented by the pinup lady of archaeology, Alice Roberts - now a professor who enjoys flaunting her dyed long red hair, but back then a mere doctor with blondish hair. I am being mean, as she is actually one of those star presenters of scientific stuff who is not boring and who explains clearly and entertainingly potentially difficult and/or boring archaeological stuff, in an endearingly weird northern/southern? accent that I can't place.
Anyway the other day we watched the second episode in this series called Guts in which the startling claim was made that our brains are as big as they are because we tamed fire and learnt to cook our food. Obviously I was captivated by this notion, so I have been looking into it a bit more today. If you want the more learned and detailed story go to an article by Jerry Adler in The Smithsonian Magazine called Why Fire Makes Us Human. And if you read that you probably don't need to read any further here. There are other articles from other well respected institutions, but of the limited options I looked at, this was by far the best. My leading picture for this article is taken from it.
Back to Alice. The most arresting thing to me, and something which really demonstrated this idea was a small demonstration she made of energy use and production. First of all she ate a bowl of raw carrots - there were quite a lot of carrots - it was a big bowl. She said it took her four hours. Then she ate the same number of cooked carrots - I cannot remember quite how long it took her but let's say 20 minutes - there were a lot of them. It was a clever demonstration of how eating raw food is time consuming and uses a lot of energy - both in the chewing part, and also in the body digesting it. Indeed it is so energy greedy that the overall gain in energy is pretty small. Animals, need it be said, only eat raw food, and as a result they have little time or energy to do anything other than eat and sleep. No time to think, talk, invent, create etc.
Back in 2011 - the year that The Origins of Us was made - Richard Wrangham, an anthropologist and primatologist, wrote a book called Catching Fire, in which he proposed that 1.8 million years ago Homo Erectus discovered how to tame fire, and thus how to cook. At around the same time, so the fossil record shows, teeth, and the digestive tract, became smaller and the size of the brain expanded hugely.
Why did the brain expand? The size of the teeth and digestive tract is perhaps more obviously linked to cooking, because cooked food does not require as much hard chewing and grinding, or as much digestion. But the brain?
"A human body at rest devotes roughly one-fifth of its energy to the brain, regardless of whether it is thinking anything useful, or even thinking at all. Thus, the unprecedented increase in brain size that hominids embarked on around 1.8 million years ago had to be paid for with added calories either taken in or diverted from some other function in the body." Jerry Adler - Smithsonian Magazine
It is unlikely that they suddenly found greater sources of food. What the calories were diverted from was digestion - the whole process of grinding up food and digesting it. Earlier hominids had also done a bit of food preparation - some was pounded with stones, or even cut up. but that required energy too - much more than throwing something onto a fire. Because we are not talking about complicated cooking processes here. Cooking 1.8 million years ago was not a refined process. Although that said, there was indeed an increasing use of processes such as grinding and cutting raw food.
There is actually still quite a bit of argument about when this whole process began. Many claim that taming fire did not happen until much later - some 4-600,000 years ago, but the proponents of the 1.8 million years (even 2 million in some cases) theory say that evidence of such fires would be difficult to find - they most likely would have been small fires in the open whose remains just blew away. But it has to be said that there is no definite evidence as yet of the link between the taming of fire and the expansion of the brain.
But with increased brain size came all manner of significant changes and developments that completely differentiated us from all other animals. They used to say it was the making of tools that made us human. Nowadays it's language, and creativity (perhaps) - and now cooking. Such a humble everyday thing but something no other animal does, even though they will eat cooked food - indeed like it. We still cook it for them though, although it might be possible I suppose to train chimpanzees to cook.
But fire, of course did more than provide a way to cook food.
"Fire, by keeping people warm at night, made fur unnecessary, and without fur hominids could run farther and faster after prey without overheating. Fire brought hominids out of the trees; by frightening away nocturnal predators, it enabled Homo erectus to sleep safely on the ground, which was part of the process by which bipedalism (and perhaps mind-expanding dreaming) evolved. By bringing people together at one place and time to eat, fire laid the groundwork for pair bonding and, indeed, for human society." Jerry Adler - Smithsonian Magazine
You are indeed what you eat.
These days, in some circles, eating raw food is considered to be the most healthy way of eating. But even more than other extreme diets you need to be very, very careful about it. You will lose weight - possibly a very good thing in some instances - but only up to a point. Being underweight is not a good thing, and for women there are even more dangers:
"Up to 50 percent of women who exclusively eat raw foods develop amenorrhea, or lack of menstruation, a sign the body does not have enough energy to support a pregnancy—a big problem from an evolutionary perspective." Alexandra Rosati - Scientific American
In another of Alice's programs - the one about Stonehenge, she said that often in a myth or a legend there is a tiny grain of truth, so it is interesting to consider the legend of Prometheus who stole fire from the gods and gave it to man, who was thus able to do all of those things mentioned in the Smithsonian article. For which, he was gruesomely punished by the gods for all eternity. A point which emphasises the huge importance of fire. So perhaps I am giving too much stardom to cooking and not enough to fire.
No I don't think so. Cooking is important in so many ways that far exceed keeping us alive. Go Alice.
Comments