Duck Sex Is Even More Screwed Up Than Human Sex

Female ducks can thank evolution for avoiding becoming impregnated by undesirable but aggressive males endowed with large corkscrew-shaped penises: vaginas with clockwise spirals that thwart oppositely spiraled males.  That's right, males are literally screwed. The research on this evolutionary 'battle of the sexes'  at the genitalia level were described in the December 23 issue of the journal Proceedings of the Royal Society B. read more

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