Scientists look at worms' sexuality

Last Modified: 27 Oct 2007
Source: PA News

Lesbian laboratory worms have offered scientists evidence that sexual orientation is "wired" into the brain.

Researchers altered circuits in the worms' brains so that they were attracted to members of their own sex.

"They look like girls, but act and think like boys," said Dr Jamie White, from the University of Utah in Salt Lake City, US, who led the study.

The findings suggest that sexual attraction is imprinted into the same brain circuits in males and females. However, the circuits are wired a different way in each case, causing differences in behaviour.

Although the scientists were studying millimetre-long worms, the creatures possess many genes thought to be conserved in higher animals, including humans.

Co-author Professor Erik Jorgensen, scientific director of the Brain Institute at the University of Utah, said: "We cannot say what this means for human sexual orientation, but it raises the possibility that sexual preference is wired in the brain. Humans are subject to evolutionary forces just like worms. It seems possible that if sexual orientation is genetically wired in worms, it would be in people too. Humans have free will, so the picture is more complicated in people."

The nematode worm, Caenorhabditis elegans, lacks eyes so relies on its sense of smell for attraction.

Most of the worms are hermaphrodites, having both male and female sex organs, and only one in 500 is male. The scientists loosely refer to the hermaphrodite worms as "females" because they produce offspring. Experiments showed that rewiring in the worms' brains takes place during their equivalent of puberty. As a result, male worms become attracted to hermaphrodites.

The scientists activated genes in the hermaphrodite brain that determined maleness. They found that hermaphrodites with masculinised brains were attracted to other hermaphrodites.

The findings, published in the online journal Current Biology, showed that eight different worm neurons involved in smell and taste played a part in sexual attraction. "Why would an organism that has only 383 nerve cells use eight of them for sexual attraction?" asked Dr White. "It must be that the behaviour is very important."

These news feeds are provided by an independent third party and Channel 4 is not responsible or liable to you for the same.