Why gay rams are caught on the horns of a dilemma

The ram, symbol of male virility, has been outed by scientists who have shown that it has a gay side to its nature.

Studies of sexual preferences in sheep found that between 6 and 10 per cent of rams were attracted to other males rather than to ewes, according to researchers at Oregon Health and Sciences University in Portland.

The scientists analysed the brains of 27 sheep – nine "gay" rams, eight "straight" rams and 11 ewes – and found that these sexual preferences could be predicted by structural differences in the tissues of the central nervous system when analysed after death.

A part of the brain known to be involved in sexual preferences, called the preoptic hypothalamus, has a "sexually dimorphic nucleus" that is normally considerably bigger in males than in females. The scientists found similar differences in the size of the nucleus when they compared straight rams with gay ones, said Dr Kay Larkin, a researcher.

The study, presented yesterday to the American Society for Neuroscience meeting in Oregon, Florida, suggested a specialised centre in the brain could influence sexual preferences in mammals, including possibly humans, said Professor Charles Roselli.