The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [161]
Without this accumulated knowledge it would not have been possible for mankind to develop so rich and varied a diet, for the results of trial-and-error experiments would not have been cumulative, but would have had to be relearnt every generation. We would have been limited to fruit and antelope meat, not daring to try tubers, mushrooms and the like. The astonishing symbiotic relationship between the African honeyguide bird and people, in which the bird leads a man to a bees’ nest and then eats what remains of the honey when he leaves, depends on the fact that people know because they have been told that honeyguides lead them to honey. To accumulate and pass on this store of knowledge required a large memory and a large capacity for language. Hence the need for a large brain.
The argument is sound enough, but once more it applies with equal force to every omnivore on the African plains. Baboons must know where to forage at what time, and whether to eat centipedes and snakes. Chimpanzees actually seek out a special plant whose leaves can cure them of worm infections, and they have cultural traditions about how to crack nuts. Any animal whose generations overlap and which lives in groups can accumulate a store of knowledge of natural history that is passed on merely by imitation. The explanation fails the test of applying only to man.21
The Baby Ape
The humanist might be feeling a little frustrated by this line of argument. After all, we have big brains and we use them. The fact that lions and baboons have small ones and get by does not mean that we are not helped by our brains. We get by rather better than lions and baboons. We have built cities and they have not. We invented agriculture and they did not. We colonized ice-age Europe and they did not. We can live in the desert and the rain forest; they are stuck on the savannah. Yet the argument still has considerable force, because big brains do not come free. In human beings, eighteen per cent of the energy that we consume every day is spent in running the brain. That is a mightily costly ornament to stick on top of the body just in case it helps you invent agriculture, just as sex itself was a mightily costly habit to indulge in merely in case it led to innovation (see Chapter 2). The human brain is almost as costly an invention as sex, which implies that its advantage must be as immediate and as large as sex’s was.
For this reason it is easy to reject the so-called neutral theory of the evolution of intelligence, which has been popularized in recent years mainly by Stephen Jay Gould.22 The key to his argument is the concept of ‘neoteny’ – the retention of juvenile features into adult life. It is a commonplace of human evolution that the transition from Australopithecus to Homo and from Homo habilis to Homo erectus and thence to Homo sapiens involved prolonging, and slowing, the development of the body so that it still looked like a baby when it was already mature: the relatively large brain case and small jaw, the slender limbs, the hairless skin, the unrotated big toe, the thin bones, even the external female genitalia – we look like baby apes.23
The skull of a baby chimpanzee looks much more like the skull of an adult human being than either the skull of an adult chimpanzee or the skull of a baby human being. Turning an apeman into a man was a simple matter of changing the genes that affect the rate of development of adult characters, so that by the time we stop growing and start breeding we still look rather like a baby. ‘Man is born and remains more immature and for a longer period than any other animal,’ wrote Ashley Montagu in 1961.24