Tuesday, July 23, 2002


All aboard the sperm train
Most animals exhibit cooperative behaviour, yet the wood mouse takes this to extremes. A new study has revealed that its sperm organise themselves into long 'trains' in order to travel faster and so beat the competition
By Tim Birkhead
22 July 2002

...Female chimpanzees are promiscuous, and if human testicles were the same relative size as the chimps', they would be as big as grapefruits. The male chimp's titanic testicles allow him to copulate frequently and transfer a huge number of sperm each time. Their cousin, the gorilla, lives in a world almost bereft of sperm competition because male aggression keeps sexual competitors at bay. He has tiny testicles. If men's testicles were the same size, they would be the size of broad beans....