By Jill Neimark
Ask any biologist — sex seems like a waste. It’s costly: Think of the enormous energy that goes into producing a peacock’s spectacular fan-shaped tail, apparently meant to entice a female to mate with him. And it seems inefficient: Sex allows us to pass on only half of our genes, and fully half the species (males) can’t bear children. Evolution is unsentimental, so those costs must bring benefits. The usual answer is that, by reshuffling genes with every generation, sex creates new genetic combinations, detaches beneficial mutations from harmful ones and gives a species a degree of evolutionary flexibility. It keeps genes in the pool that might not be of use today, but might save a creature’s descendants from plagues, pestilence, and parasites.
All that is probably true, but the thesis has one flaw. While the benefits of sexual reproduction tend to be subtle and become evident only over many generations, its costs are heavy and immediate. To understand sex completely, we need an explanation that goes back to the primordial soup of very early complex organisms and the immediate survival pressures they were under. Damian Dowling, an Australian evolutionary biologist, set forth a surprising idea last year with…
