for National Geographic News
It's Valentine's Day, a day when the age-old questions naturally arise: "What do women really want?" "Who's in charge of the mating game?" and "Is beauty really only skin deep?"
A special two-hour presentation tonight on the National Geographic Channel (airing in the United States, see below for more details) might surprise you. When it comes to courtship and mating, it's all a matter of biology, the experts say.
Animal magnetism, it seems is fundamentally not that different across species. It's the male's job to persuade, and it's the female's job to make the best mate choice she can.
For many years, mate choice was seen as a male prerogative. The guy who could best defend his territory, or win the annual head-butting contests, or display the most gorgeous feathers, won the girlor girls as the case may be. The females were perceived as passive prizes.
That viewpoint has changed as the role of female choice has become more recognized: Quality of mate is far more important to the female than the male.
Motherhood is costly, and sperm is cheap, said John Maynard Smith, a biologist at the University of Sussex.
Take fruit flies, for instance.
"The males are not really concerned with who they mate with. After all, he can mate five times a day. The female is only going to mate once in her life, so she really cares."
The answer to the questionwhat do females really wantis symmetry, said Randy Thornhill, a biologist at the University of New Mexico. And that also cuts across species. Symmetry in nature is shorthand for quality, according to Thornhill. The more symmetrical a person's features are, the more likely he or she is to be perceived as attractive. The female scorpion fly is quite picky; she's looking for a mate with matched wingsa signal to the female that he's a good hunter.
There are two theories on how such a thing might dictate female choice. A beautiful tail on a peacock could mean that he's strong and healthy, because only a very fit male could afford to support such an extravagance. Alternatively, said Smith, a female could think that if other females like beautiful tails, she better mate with a male who has a beautiful tail so that her male offspring will be sexier and more successful at mating, which would extend her genes to future generations.
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