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Earwigs' sexual antics give scientists the willies

Study finds that evolutionary biologists' research focuses predominantly on male reproductive organs

Evolutionary biologists appear to be strangely obsessed with male genitalia, a new study says.

Researchers found that nearly 49 per cent of 364 scientific papers on reproductive organs over the past 25 years dealt only with male parts, while less than 8 per cent looked at only females. About 44 per cent looked at both. The trend was particularly strong in relation to studies of mammals, with more than 60 per cent focusing on male genitalia only.

Malin Ah-King, co-author of a paper in the journal PLOS Biology, said the scientific bias towards the male role in reproduction dated back at least as far as Charles Darwin. In his 1871 book, The Descent of Man, he wrote: "Males of almost all animals have stronger passions than females. The female … with the rarest of exceptions, is less eager than the male … she is coy."

She said the study's findings showed that "even though the worst stereotypes have been abandoned by now, we still have a theoretical framework that is focusing more on the male side rather than the female".

She said there was also an "assumption" in the field that female genitalia "don't vary much", but added that it was hard to tell, given the lack of studies. However, the small amount of research that has been done suggests there could be significant differences among females.

Dr Ah-King, of the Centre for Gender Research at Uppsala University, Sweden, together with colleagues at Australia's Macquarie University, found that it made no difference to the focus of study whether a paper's lead author was female or male.

She said there were a number of examples which demonstrated that "when you look at both sides of the equation, you learn much more".

Dr Ah-King cited the earwig. Its penis, properly called its virga, has a fringe-like adaptation at the tip which is used to scoop out a rival's sperm from the female. "If you look at it, you'd think it must be very efficient to scoop out the sperm from previous males," she said. However, the virga is typically not long enough to reach all the sperm, so, the researchers concluded, the female retains control of the paternity of her offspring.