To impregnate female ducks as quickly as possible, a certain species of male ducks has evolved corkscrew-shaped penises that shoot out of the ducks' bodies in less than half a second, Yale researchers have found. To thwart the males, female duck vaginas have evolved to spiral the other way — an adaptation the researchers say is one of the most dramatic examples of the conflict between the sexes to control fertilization.
The finding was officially announced today by Yale researcher Patricia Brennan, who worked with fellow Yale researchers Christopher Clark and Richard Prum on the study. They published their results in the Dec. 23 issue of the journal Proceedings of the Royal Society, Series B.
--Cross Campus, Yale Daily News, on the battle between the sexes