The British anthropologist Richard Wrangham argues that the discovery of fire, about
1.8 million years ago, caused a major evolutionary change:
humans started cooking, the first and (so far) only animal to do so,
which resulted in the ability to extract more calories to support big brains.
This fueled the evolution of both the body (that could do survive with smaller jaws, teeth and guts)
and the brain (that could grow virtually at will). The importance of cooking had an impact on the evolution of society.
Cooking is not only a product of human evolution, but the enabling factor of it.
Any book that praises the value of meat for the evolution of the human brain claims to have studied "hundreds of hunter-gatherer culture". Somehow they all missed south India, that has always contained about 10% of the world's population. If they have always been vegetarian, any theory of the critical importance of meat is false. But that's not the focus of this book: it is about cooking, not necessarily meat eating.
Wrangham is more credible when he omits meat from the picture: cooking certainly allowed to eat "more" and to digest it "better". In other words, the human body was able to absorb more energy with less effort than it would have without cooking.
Wrangham's claim is actually even stronger: he thinks that humans have physically evolved and adapted to cooking. To prove his point, he analyzes what happens to "raw foodists". Citing no more than two or three cases, he concludes that a raw diet makes you consistently hungry (it doesn't give you enough energy) and even sexually impotent. Women become "psychologically unable to have babies". In the wild, they would even become physically unable to have babies because, in his opinion, a raw diet entails much more work than cooking it: it is not easy to find enough food in the wild to fill you up. Unfortunately, i am occasionally a "raw foodist" and i have never experienced the symptoms that he describes. Of course, it all depends on what kind of raw foods are admitted. I eat a lot a bread and a lot of nuts. I guarantee that it doesn't take many nuts to fill you up. And bread gives me more energy when i hike than any of the popular "energy food" bars. Bread is cooked, but one can eat the same carbs from the raw seeds, as i have sometimes done. Cereals still constitute more than 50% of the diet in the world, and they presumably accounted for even more in the past. A close second would be cheese: Wrangham does not mention if cheese is allowed in his "raw diet".
Wrangham also fails to analyze the other major oddity of the human race: humans spread all over the planet, even to hostile places like the Arctic. Why would they be so stupid to risk their lives for remote, unknown and difficult places? There is no evidence that the world was overpopulated in ancient times: quite the opposite. Wrangham indirectly and involuntarily provides a possible explanation. He shows how difficult it is for raw foodists to survive without moving around: a raw foodist (before the invention of supermarkets!) had to cope with seasonal fruit and vegetables, hybernating animals (if s/he was eating raw meat), etc. This would have certainly been a motivation to scout larger and larger areas of the world. Other animals with smaller brains could live with what they found locally: humans had to venture further away, and some didn't come back.
Wrangham mentions Roman Devivo's and Antje Spors' "Genefit Nutrition" (2003) but entirely omits their DNA-based arguments. They argue that the human DNA is a repository of eating wisdom, and that cooking (or, better, processed food) misleads your senses of taste and smell into desiring food that you would otherwise instintively avoid. Wrangham also ignores the simple fact that the modern diet is almost entirely "modern": the (highly processed) foods that the average Western person eats today never existed before. It is hard to believe that our bodies adapted so quickly to the ingredients listed in the back of a food package (that one cannot even pronounce without a degree in chemistry). Wrangham provides a little bit of explanation for why he thinks that cooking heated food provides more energy: the density of calories remain the same but the food is easier to digest. However, that's hardly a scientific proof. He focuses on starchy food and animal proteins. He does not deal with fruit and nuts. The side-effects of cooking are so many that it would take a much bigger study. He only mentions in passing that cooking food causes a loss of vitamins: a loss of vitamins accounts for catastrophic effects on health in poor countries. It is hard to believe that a fat mother who eats cooked food and lacks vital vitamins would provide better-fit offspring. Today we live in the age of hyper-prepared food and no dietist thinks that overcooking is good for your health: if Wrangham is right, there is just about an ideal point of cooking until which nutritional value increases and beyond which the loss of nutritional value increases. It would seem more natural to assume that it is a straight line: the more you cook, the more you lose. He points to our preference for softened food as evidence that cooking is a good idea. Saying that our body prefers softened foods is like saying that our body prefers to sit on a couch and watch television: true... and it is not good at all for your body. He writes that "better-fed mothers have more and healthier children". This statement is obviously not true: Western mothers are having a lot less children than mothers in developing countries, and the percentages of children with all sorts of problems (from allergies to structural weakness) seems to be much higher in rich countries than in poor countries. In any case, he still has to prove what diet constitutes a "better-fed" person. The amount of energy intake per se does not seem to make one "better-fed" otherwise the winners would be the customers of fast-food joints. My guts tell me that cooked food contributed to a massive increase in heart attacks, cancer and probably weak immune systems: in prehistoric times this would have caused the extinction of the human race.
The small mouths, weak jaws, small teeth, small stomachs and small colons of the modern human have often been attributed to the transition to meat eating (that happened before the invention of cooking), but Wrangham argues that they are more elegantly explained as an adaptation to cooking. However, the argument about previous non-cooking hominids evolving into modern cooking humans is weak to say the least (then again the argument that meat caused those transitions is even weaker).
The reason he thinks that all of this happened 1.8 million years ago is that Homo Erectus appears to be the first major departure of hominids from the other apes. Homo Erectus was also the first hominid to leave Africa and spread to other continents. To be precise, Wrangham posits two major expansions in brain size: Home Abilis learned to use tools and to eat meat; Homo Erectus learned to cook. Each of these inventions fostered the growth of the human brain. He doesn't stop there: as humans discovered more efficient ways to cook their food, and therefore to digest it, more energy was available for brain growth. Homo Sapiens is the beneficiary of this process of ongoing diet improvement.
Wrangham points out a side effect of cooking: we don't need to spend the day chewing, like most apes do. Cooking enabled our bodies to absorb food quickly, therefore freeing the day for other chores. Men and women had more time to spend doing other things than chewing food.
The argument in the book is weak to say the least. Focusing only on energy intake, Wrangham might be committing slow suicide. However, i'm sure that there is a difference between writing a book and living your own life, and he probably supplements his cooked food with plenty of raw fruit, nuts and vegetables. And i suspect he stays away from the biggest sources of energy: fast food.
TM, ®, Copyright © 2009 Piero Scaruffi