A short Book, advancing significant theory for human evolution.
Only 207 pages long, this book advances theory with significant implications for human evolution and paleo-anthropology.
Raw food is not good for humans, they lose body mass, men virility and women menstruation, suggesting man evolved to eat cooked food, from which energy is absorbed quickly and efficiently.
Speciation can follow rapidly a change in diet, usually consequential on ecological change. Wrangham suggests change, all in the direction of reduction in the size of the gut, necessary for other primates to digest a diet of raw vegetables, allowed an increase in brain capacity. This happened in four steps. The first was on the appearance of Australopithecines, which, in addition to the fruits and choice plant food eaten by their ancestors, ate starch filled roots, the second Homo habilis, which ate uncooked meat, made digestible by tenderising the meat or eating the soft innards, the third H erectus, which cooked food, and the last H heidelbergensis, which organised more efficient hunting leading to greater consumption of animal fat. Effectively energy no longer needed to digest food was switched to the larger hominin brain.
Cooking relies on control of fire. Critics say there is no archaeological evidence of hominins making fire as early as Wrangham is suggesting. He argues the physiological evidence that H erectus had a less flared rib cage and narrower pelvis than its predecessors, indicating a smaller gut, is the proof. Whilst the argument is circuitous, I find it persuasive. If H erectus was a tool maker, wasn’t it also a fire maker? One means of creating fire was with sparks produced when making stone tools.
Fire was not only used for cooking. It provided protection, so that hominins could sleep on the ground safe from predators rather than in the trees. They would have slept close to the embers, taking it in turns to remain awake. I have done exactly this in Alaska, when camping in an area where there were bears. Hunter gatherers sat around the fire at night telling stories, expanding their imagination. The fire provided warmth, allowing hominins to become the “naked ape”, able to walk and run without overheating.
Wrangham argues control of fire and cooking were key not only in human evolution, but in social organisation. Man is unique not only in sharing food, but in the way in which it is shared with a constant the sexual division of labour. Amongst hunter gatherers, men and women seek different foods, typically women gathering fruit,roots and tubers, men hunt. The food collected by the women is kept for her family, that hunted or prepared by men shared more widely. Even when men cook for the community, the women cook for their family. Wrangham explains this as originating in a protection racket. Smoke from a fire can be seen from afar, inviting theft. Having a husband meant a woman’s food will not be taken by others. Having a wife means he can expect an evening meal.
Anthropologists have suggested successive, and in part competing, theories, Man the Hunter, Scavenger, Social Animal and Tool Maker. Aiello and Wheeler put forward “The Expensive Tissue Hypothesis: the Brain and Digestive System in Human and Primate Evolution”. In “Catching Fire”, Wrangham developed it into the theory of Man the Cook, which is at least complementary to existing theories and potentially provides a general theory into which they can fit. Like the best theory it invites further testing.