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Freud would have loved it: a tale of sexual cannibalism brought on by girls' youthful experience of older men. The only twist is that it is in spiders.

Eileen Hebets, of Cornell University in New York state, studies wolf spiders. Like the females of many other species of arachnid, female wolf spiders are as prone to eat a passing male as to mate with him. Indeed, in some species, the former generally follows the latter unless the male makes a speedy getaway. In wolf spiders, though, the girls make their preferences known before coitus, with extreme prejudice to any suitor to whom they take a dislike. What Dr Hebets wondered was exactly how they make their choice.

search on wolf spiders is published in the Proceedings of the National Academy of Sciences. See also an earlier article on the spiders.

She reasoned that it might have something to do with looks—those, after all, are a criterion common to many species. Male wolf spiders do vary in appearance, particularly in the colour of their forelegs. Since the forelegs are used in the elaborate display by which a wolf spider indicates that he is a potential mate rather than (he hopes) a potential meal, Dr Hebets hypothesised that if any variation in appearance was likely to be important, it would be in the colour of a well-turned leg.

However, she carried the thought one stage further, wondering if a preference for a black versus a brown leg, assuming it existed, might be instilled in a young and impressionable female by reference to the sort of males she had met before she was, shall we say, truly interested in such matters herself. To test this idea, Dr Hebets turned to her make-up bag and brought out two shades of nail varnish (NailSlicks, midnight metal and bronze ice, as her paper in the Proceedings of the National Academy of Sciences quite properly describes in its materials and methods section, in case any other researcher wishes to replicate the experiment). She used these to alter the fashion sense of a clutch of male spiders.

In total, 81 young female spiders were exposed either to a number of males whose legs had been painted black, or to a number whose legs had been painted brown. When these females had matured, they were put, one at a time, into a box with a painted male, who may or may not have matched the sort of male they were used to.

The result was clear-cut. Being of a familiar type did not guarantee a male success and survival, but it brought pretty good odds with it. By contrast, being of an unfamiliar type resulted, in almost all cases, in a male becoming lunch.

As a control, Dr Hebets kept another batch of females away from contact with males until they were mature. These females did not seem to care about the colour of their suitors' legs. In spiders as in people, it seems, mating preferences are decided before sexual maturity.

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