University of Utah biologists genetically manipulated nematode worms so the animals were attracted to worms of the same sex part of a study that shows sexual orientation is wired in the creatures brains.
They look like girls, but act and think like boys, says Jamie White, a postdoctoral researcher and first author of the new study. The [same-sex attraction] behavior is part of the nervous system.
The study was published online Thursday, Oct. 25 in Current Biology, and will run in the journals Nov. 6 print edition.
"The conclusion is that sexual attraction is wired into brain circuits common to both sexes of worms, and is not caused solely by extra nerve cells added to the male or female brain, says laboratory leader and biology Professor Erik Jorgensen, scientific director of the Brain Institute at the University of Utah and an investigator with the Howard Hughes Medical Institute.
The reason males and females behave differently is that the same nerve cells have been rewired to alter sexual preference, he adds. Our conclusions are narrow in that they are about worms and how attraction behaviors are derived from the same brain circuit. But an evolutionary biologist will consider this to be a potentially common mechanism for sexual attraction.
We cannot say what this means for human sexual orientation, but it raises the possibility that sexual preference is wired in the brain, Jorgensen says. 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.
White and Jorgensen conducted the study with technician Jeff Gritton and three University of Utah biology undergraduates: Thomas Nicholas, Long Truong and Eliott Davidson. The study was funded primarily by the National Science Foundation.