Psychologists are free to use sexual selection theory just where it is most needed: to explain mental abilities that look too excessive and expensive to have evolved for survival. Generally, the larger the sex difference in body size, the more polygynous the species. Perhaps our big brains, evolved for technophilic survivalism, can be co-opted for the arts. A major theme of this book is that before language evolved, our ancestors could not easily perceive one another's thoughts, but once language had arrived, thought itself became subject to sexual selection. Maynard Smith set about studying the courtship dances of fruit flies.
For example, he showed that female birds that brood in open nests have usually evolved dull camouflage, whereas those that brood in enclosed nests tend to have colors as bright as the males of the species. In addition to its high impact on my world view, this book is written for a popular audience and has a nice, engaging, style. Yet they also raise the classic problem of runaway corruption in autarchies: who watches the watchmen? How could evolution favor the expansion of a costly organ like the brain, without any major survival benefits becoming apparent until long after the organ stopped expanding? O u r species has never been richer, better educated, more numerous, or more aware of our common historical origin and common planetary fate. It evolved because peahens preferred larger, m o r e colorful tails. T h e ability to exploit these new food sources, at a lower gut-cost, could have allowed our ancestors to afford larger bodies, larger brains, more milk production, or whatever other costly traits evolution might have favored.
The Descent of Man is mostly a report on sex differences in ornamentation in non-human animals. Ordinarily, natural selection favors camouflage on the outside, so animals often look dull and drab. This is easy to confuse. If we cannot fulfill this criterion, p e r h a p s we'll just have to live with the existential rootlessness that J e a n - P a u l Sartre viewed as an inevitable p a r t of the h u m a n condition. He left that as an exercise for the reader.
Psychologically, it fails to explain why it is so much harder for us to learn mathematics than music, surgery than sports, and rational science than religious myth. In many ways, it is a breath of fresh air as it gets the reader to think out of the box when it comes to evolutionary theory. This genetic correlation effect is subtle and counterintuitive, which is one reason why biologists took fifty years to prove that Fisher's idea could work. They lived outside on a sort of perpetual camping trip, and got a lot of exercise. Would migratory birds select for more convenient winds, lower gravity, and more intelligible constellations? In the 1 990s the new science of evolutionary psychology made valiant attempts. In scientific terms, sexual selection t h r o u g h m a t e choice seemed a neglected factor in h u m a n m e n t a l evolution.
Ladies, what are your honest thoughts on this? Usually we can appreciate the beauty of sexual ornaments in other species only because our senses happen to respond to some of the same stimuli as the senses of those other species. Skinner's manifesto Science and Human Behavior, in which people were portrayed as robots driven by conditioned associations. Why would they waste surplus energy in such displays? Certainly, runaway sexual selection was a theoretical possibility, but bizarre ornaments were not considered to be real adaptations. The idea that the human mind evolved as a sort of software peacock's tail has been mooted before, usually to be dismissed in favor of some alternative theory. Their intricate songs evolved for courtship.
We are a species that evolved to care about status, not truth. In this brilliantly ambitious and provocative book, evolutionary psychologist Geoffrey Miller shows the evolutionary power of sexual choice and the reasons why our ancestors became attracted not only to pretty faces and healthy bodies, but to minds that were witty, articulate, generous, and conscious. The first he explained as identification badges to help animals recognize which species others belonged to. T h e fact that there are no good theories of these adaptations is one of science's secrets. Miller does this, and he does it in an entertaining and sexy way. The result was that wits became quicker and spirits more generous. This sexual choice view also sounds rather circular as an explanation of human mental evolution.
However, this side-effect view is equally unsatisfying. I am perfectly aware that this is not the way professional biologists currently use these terms. Peacock tails do not need a sexual subconscious in order to be sexually attractive, a n d neither do our instincts for art, generosity, or creativity. The more classic statement that follows that line of reasoning is the claim that we evolved noses in order to wear glasses. Zahavi suggested that the high costs of many sexual ornaments are what keep the ornaments reliable as indicators of fitness.
The theory of sexual selection was an intellectual bolt from the blue, and sexual selection through female choice was especially shocking. Temperamentally, it reflects nothing more than a Wall Street trader's contempt for leisure. But in evolutionary psychology we have to deal with evolution, and that means paying attention to genetically heritable individual differences that give survival or reproductive advantages over other individuals. His reward was a mouthful of defensive beetle-acid, but his enthusiasm remained intact. Most provocatively, he combined sex with mind and the enigma of human evolution in his two-volume masterpiece The Descent of Man, and Selection in Relation to Sex.
This is easy to confuse. Also, geneticists will find out more about which genes we share with other apes. First off, I found this book very hard to read. Biologists recognize that sexual selection through mate choice is a fickle, unpredictable, diversifying process. No doubt an interesting fiction could be built up along these lines, but would anyone believe it, and, if he did, could he prove it? Runaway would never have started.