Researchers are studying gay sheep to try to figure out if homosexuality has a biological origin. They've discovered that certain groups of cells are different in a part of the sheep's brain that controls sexual behavior. Charles E. Roselli says, "This particular study, along with others, strongly suggests that sexual preference is biologically determined in animals, and possibly in humans.
"The hope is that the study of these brain differences will provide clues to the processes involved in the development and regulation of heterosexual, as well as homosexual, behavior," Roselli says. "Same-sex attraction is widespread across many different species."
Kay Larkin says that by studying sheep's brains, scientists can tell if they prefer having sex with rams or ewes. "There's a difference in the brain that is correlated with partner preference rather than gender of the animal you're looking at," she says. About 8% of rams prefer other males as their sexual partners.
"They're one of the few species that have been systematically studied, so we're able to do very careful and controlled experiments on sheep," Roselli says. "We used rams that had consistently shown exclusive sexual preference for other rams when they were given a choice between rams and ewes."
The researchers discovered an irregularly shaped, densely packed cluster of nerve cells in the hypothalamus of the sheep brain, which they call the ovine sexually dimorphic nucleus, or oSDN. The hypothalamus is the part of the brain that controls metabolic activities and reproductive functions, and it?s a different size in rams and in ewes. The oSDN in rams that preferred females was "significantly" larger and contained more neurons than in male-oriented rams and ewes. In addition, the oSDN of the female-oriented rams had higher levels of a substance that converts testosterone into a hormone that controls male sexual behaviors.
Next, they'll try to find out if a sheep's sexuality can be changed by manipulating its hormones while it's still in the womb. Homosexuality has always been baffling for biologists because, unlike so much else that governs our behavior, it can't be carried on the genes. If it was, it would have died out due to homosexuals' low level of reproduction, so there must be some other mechanism that produces it.
The world is full of wonderful discoveries, if we can be open to exploring them. And now, many of them are on sale!
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