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Homo Mysterious: l

Evolutionary Puzzles of Human Nature

by David P Barash

(London Times)

In 1967, the zoologist Desmond Morris notoriously claimed that female breasts are really a pair of front-mounted pretend buttocks - or at least that their evolution helped persuade humans to abandon doggy-style mating and embrace emotionally bonded, face-to-face lovemaking instead. Morris's bestseller, The Naked Ape, gave popular audiences one if its first glimpses of the kind of sprightly, often counter-intuitive biological speculation that grew up to become an entire scientific discipline: evolutionary psychology. David Barash is a true disciple: professor of psychology and biology at the University of Washington, Seattle, and a prolific author of books of varying degrees of scientific whimsy. One past offering is Madame Bovary's Ovaries, being "A Darwinian Look at Literature".

In this similarly playful-yet-serious work, Barash surveys some of the more contentious 'evolutionary puzzles' of human biology and behaviour. Many surround women, and sex. Why do women not advertise their ­fertility, like most primate females, but conceal it? Why do they menstruate so much more copiously than any other species? Why do they - uniquely, apart from the short-finned pilot whale - undergo menopause? And what evolutionary need could possibly explain homosexuality? He also tackles three deeper mysteries: what environmental pressures, he wonders, could possibly have given rise to such strange and energy-draining phenomena as art, religion and indeed consciousness itself?

Barash's technique is to run through the answers offered by a generation of evolutionary scientists, acting as a clear-minded and good-humoured referee, and occasionally suggesting his own solutions. Take the female orgasm. This is puzzling because it isn't obviously linked to reproduction, and because it doesn't always happen. Barash wisely dismisses the amazingly common notion that it's a pale imitation of male orgasm, a "non-adaptive by-product" that exists for much the same reason that men have nipples (because the tissue has to be there in the human embryo). If this is true, it's strange that the clitoris has about twice the number of nerve endings as the penis. Strange, too, that female orgasm is much less reliable than the male version (or at least less reliable in heterosexual penetrative encounters).

Some biologists think there may be a point to this, beyond bungling. Did the pursuit of orgasm entice women to seek more sustained stimulation through multiple partners? Did it, conversely, prompt women to seek committed, caring partners? A man who generously focused on a woman's orgasmic needs might also be inclined to clean up the family cave and, a few tens of thousands of years later, mow the lawn and help put the kids through college.

As for breasts, Morris's explanation for them is apparently downright silly (flat-chested primates seem quite happy mating front-on, for a start). Yet evolutionary psychology doesn't seem to be able to agree on a more sensible alternative. Are women taking advantage of male obtuseness by promising an amply stocked, milk-soaked delicatessen (when in reality there is no correlation between breast size and milk production)? Or are breasts, like a peacock's tail, demonstrations of a superabundance of fitness, as if to say look at what I can lug about without compromising my survival? Do they exist to display bodily symmetry, which is a classic sign of genetic health, or are they advertising fertility? After all, only sexually mature but still youthful women have breasts that appear, to men, as neither too small nor too droopy, but just right.

Barash calls this last theory the Goldilocks hypothesis. Evolutionary psychologists like to give their pet theories cute names, and Barash, in particular, is fond of an avuncular joke. A fashionable explanation for menopause, similarly, is the grandmother hypothesis, which argues that looking after the grandchildren is a better way of ensuring the continuance of at least some of your genes than trying to carry on breeding when you're too old. (This is rather like the 'gay uncle' notion, which reckons that childless but caring homosexuals would have helped their siblings' children survive, and thus have passed on the family genes.) One of the best - and the best-named - of a host of hypotheses for why ovulation is concealed in women is the 'headache hypothesis'. This would have us believe that at least some of our ancestral grandmothers did know when they were fertile, and could choose to selectively fend off the advances of our would-be ancestral grandfathers. Those women who couldn't read their own cycles, by contrast, would have bred away merrily - and bred that ignorance of their own fertility into our genes.

When he sticks to biology, Barash is on relatively safe ground: there is at least some evidence for him to stand on. When he turns to art and religion, however, he is floundering in the shallows. Part of the problem is that he, like so many evolutionary biologists, has a condescending attitude to both, paired with an astonishingly unsophisticated understanding of them. 'Art' - whatever that is - supposedly shows off our cleverness and fitness to potential sexual partners. Or it teaches us better to understand the minds of others and predict their actions. Or helps us hone a more flexible, imaginative brain, the better able to survive strange environments.

The explanations for religion seem no less airily speculative. Did it help tribes bond more tightly, making them more cohesive and more trusting - and more successful in battle? Or did it evolve because we ourselves evolved to see causes and patterns in everything around us? It's safer to hear a rustle in the African savannah and jump up, wrongly assuming it's a snake, than to dismiss the rustle and get bitten one time in a thousand. And just as we assume there's a snake in the grass, we imagine there's a god in the clouds. As cognitive scientists have put it, we are HADDs (hyperactive agent detection devices). Or, as David Hume put it, a long time before cognitive scientists, "we find human faces in the moon, armies in the clouds".

You might well say something similar about evolutionary psychology. It hyperactively seeks evolutionary agency - adaptations, to use the jargon - in everything. But as long as its explanations are so varied, so contradictory and so simplistic, and as long as its underlying evidence base is so thin, it will continue to build nothing more substantial than armies in the clouds, and castles in the air. Like this enjoyable but ultimately unsatisfying book, it will play with puzzles, but never really solve them.

(New Scientist)

Why did we evolve to have religion and female orgasms? Evolutionary psychologist David Barash tackles these and other puzzles in Homo Mysterious.

THERE are some thorny mysteries in the evolution of female sexuality. Is there a purpose to the female orgasm? What about menopause, menstruation and prominent breasts? Evolutionary psychologist David Barash jumps bravely into exploring these and other conundrums of human evolution in his new book, Homo Mysterious.

In searching for the "why" behind these unexplained oddities, Barash provides a wide-ranging survey of the territory, and he is at his most entertaining when describing his own ideas.

His handicap theory of female breasts is rather clever. He suggests that, like the peacock's tail, a permanently voluptuous bosom might be a woman's way of signalling her fitness by showing that she can thrive despite depositing so much valuable fat into cumbersome and mostly decorative appendages of a sort found nowhere else in nature.

Equally appealing is his favoured explanation for concealed ovulation - the fact that women's increased fertility is not broadcast. Barash suggests that once females became intelligent enough to link sex with babies - and babies with hard work - they could have tried to limit their birth rates. Those whose cycle was least discernible to themselves would have been least successful at avoiding pregnancy, so women with concealed ovulation gradually became more common.

But why are evolutionary mysteries of female sexuality far more numerous and prominent than their male counterparts? Barash remains disappointingly silent on this, although he does scrutinise some manly mysteries, such as why men are the more dowdy sex when sexual selection usually produces showy males, and why they tend not to live as long as women. There is also a very cogent chapter on homosexuality - although while Barash notes recent evidence pointing to its having different genetic underpinnings in men and women, he fails to consider that homosexuality might therefore have separate adaptive rationales in the two sexes.

Barash also takes on the weighty topics of religion, art and human intelligence. There is plenty here to inform and entertain, but he doesn't always marshal his eclectic material effectively. The chapters on religion make particularly frustrating reading, often just noodling around the subject instead of asking why this particular primate and no other evolved strong tendencies to spiritual thinking. No distinction is drawn between traditional, small-scale religions and today's predominant world religions. And Barash leaves a rather grudging explanation of evolutionary group selection until last, so that readers are not provided with a sufficient theoretical framework in which to assess some frankly iffy ideas from Freud and the like.

No mysteries were solved in the writing of this book. Instead, Barash argues that wisdom comes from learning about what we don't know. I agree, but I am not convinced, as he is, that these evolutionary puzzles are ultimately solvable.

We can use new insights from genetics, psychology, palaeoanthropology and archaeology to hone our ideas, but when it comes to human evolution there will always be an element of mystery.

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