Scientists have created ‘lesbian worms’ in a new development that some are suggesting could shed light on the nature vs nurture debate over sexuality, according to a number of licentious news sources (Sidney Morning Herald for example). University of Utah researchers tweaked nematode worms to make them attracted to worms of the same sex and appear to have demonstrated that sexual orientation is hard wired, at least in nematodes (abstract, pdf). “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 biologist Erik Jorgensen (press release).

The ‘lesbian worms’ line is a bit of red herring. There aren’t true females in the C. elegans nematodes used, only hermaphrodites and (rare) true males. “A hermaphrodite makes both eggs and sperm,” says Jorgensen. “… Most of the time, the hermaphrodites do not mate. But if they mate, instead of having 200 progeny, they can have 1,200 progeny.”

As attraction in the worms is based on smell Jorgensen and co monkeyed around with male worms to find out whether their attraction to hermaphrodites was influenced by core nerve cells, accessory nerve cells, or a combination of the two. The answer was both. They also took hermaphrodite worms and turned on the genes that determine maleness, these then became the famous ‘lesbian worms’, chasing after other hermaphrodites. (The Daily Utah Chronicle notes that Jorgensen calls hermaphrodites “females” because they reproduce independently.)

The Salt Lake Tribune is one of those taking on whether this means human sexuality is hard wired. Basically the answer is only “maybe”, but it adds some credence to the idea.

Image: hermaphrodite (top) and male (bottom) pair of worms / Jamie White