SALT LAKE CITY — A new study on sexual orientation in worms suggests human sexual orientation might be controlled by mechanisms in the brain.

By manipulating circuits in a worm’s brain that control behavior, University of Utah biologists were able to alter the sexual preferences of male and female worms to mirror the opposite gender. The females became attracted to their own sex. However, male worms that took on female characteristics were not attracted to other males, because the female worms in the species are not drawn to males either.

If a worm’s sexual preference can be altered by adjusting circuits in the brain, is human sexual preference controlled solely by the brain as well?

U biology professor Erik Jorgensen led the study investigating worm sexual orientation. "When we started this, we thought there were specific cells in males only that were responsible for male behavior — it’s simply not true," he said.

The study found that cells existing in both male and female worms can be rewired to activate certain modes of behavior.

"You can take a female and activate the male genetic program — if you do it in the entire female, it will even begin to look like a male," said Jamie White, a postdoctoral researcher in Jorgensen’s lab. …