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Cornell Researcher May Have Found Evidence for Sexual Mate Preference

By Donald G. Mcneil Jr.

The New York Times -- It is the “hey there, big boy” version of the nature-nurture debate: Are some gentlewomen born preferring blonds, or do their tastes develop as they age?

Idle though the question may sound, it has now been addressed scientifically, though not at the evolutionary level of ladies and gentlemen.

Rather, Dr. Eileen A. Hebets of Cornell University chose wolf spiders, and she is not shy about drawing parallels between the instincts of female spiders and female humans.

Her dry-sounding hypothesis was that exposure to a certain morphological phenotype before adulthood influenced mating preference.

But in practice, her lab work sounds as if it were being conducted in Studio 54 or Andy Warhol’s Factory: she painted the tibias of male wolf spiders with nail polish and tricked them into dancing suggestively for leggy nymphets not even old enough to appear in an arachnid version of Barely Legal.

The results were published on Oct. 28 in The Proceedings of the National Academy of Sciences.

The courtship dance of adult male wolf spiders, Schizocosa uetzi, involves waving their quarter-inch forelegs, which range in color from light brown to dark black.

Hebets enhanced those endowments with nail polish so all the boys were either firmly “browns” or “blacks.” (Or, technically, because she used Cover Girl, “bronze ices” or “midnight metals.”)

Then they were exposed to young females in plastic boxes known, for reasons that will become clear, as “arenas.”

Better-behaved than male humans, male wolf spiders will not go into courtship displays in front of subadult females, but they were tricked. Hebets used boxes in which adult females had stayed, leaving their pheromone-laden webs behind.

Drunk on the Shalimar of absent femmes fatales, the male spiders danced, and the girls, who still had one molt to go before they could physically do anything about it, watched in fascination.

Then the couples were separated while the females waited for their last molt, 11 to 21 days later, at which point they re-entered the arenas for a bit of mix-and-match speed dating. By that time, as with many spiders, the ladies substantially outweighed the gentlemen.

About 50 percent of the time, females who had been exposed to glossy black forelegs copulated with males with the same.

But when they were introduced to a male showing a brown leg, he got a rude surprise.

He had only a 13 percent chance of mating. And he had a 27 percent chance of being eaten.

Females who had been exposed early to brown forelegs showed much the same appetites.

And for females who had not been conditioned, it was chaos: cannibalize, copulate, whatever.