http://www.arts.telegraph.co.uk/connected/main.jhtml?xml=/connected/2003/02/21/ecnaa19.xml&sSheet=/c onnected/2003/02/21/ixconn.html
Lesbian Japanese monkeys challenge Darwin's assumptions By David Derbyshire, Science Correspondent, in Denver (Filed: 19/02/2003)
The promiscuous sex life of lesbian Japanese monkeys is challenging one of the central tenets of Charles Darwin. He argued that females are coy, mate rarely and choose mates to ensure the best genetic inheritance for their offspring, while males are promiscuous and fight among themselves for female partners.
But after studying Japanese macaques in the wild, Dr Paul Vasey, of the University of Lethbridge, Canada, begs to differ. He found that bisexuality is common in females and that they often compete with males for sexual partners.
"In some populations, female Japanese macaques sometimes prefer same-sex partners," he told the American Association for the Advancement of Science in Denver. "That occurs even when they are presented with sexually motivated, opposite-sex alternatives."
Males are often prompted into sexual intercourse only if they are first mounted by females. Dr Vasey said: "Female-male mounting in Japanese macaques is an adaptation that sexually motivated females employ to prompt sluggish or uninterested males to copulate with them."
He observed that the females gain pleasure from mounting males, often rubbing themselves against a male's back or stimulating themselves with their tails.
Dr Vasey said that once they evolved the capacity to mount males, they could gain the same sexual gratification from mounting females. "I see females competing for males all the time," he said. "I see males ignoring females that are desperate to copulate with them."
Dr Joan Roughgarden, a biologist at Stanford University, said the macaque was just one of many species that did not fit Darwin's theory of sex selection.
Female langur monkeys promiscuously mated with many males, for instance. Homosexuality in animals - at least 300 invertebrates practise it - was also unexplained by Darwin.
Dr Roughgarden said that a more comprehensive theory of sex selection should take into account social as well as sexual selection. Mating could function to build and manage relationships as well as to reproduce. "Female choice, I am pretty sure, has much more to do with managing male power than it does with trying to obtain good genes."