Whatever happens in 2007, we already have the most surreal headline of the year: "Sheep have right to be gay, says Martina Navratilova". But behind this headline and buried beneath the battery of baa-aad jokes it seems to beckon, there is a strange and serious story that will ripple out through the 21st century in ways we cannot predict.

For the past five years, a team of researchers at Orgeon State University has been investigating the sexuality of sheep. Early on, they proved what every sheep farmer knows: some 8 per cent of rams are gay. When it comes to sex, these woolly homosexuals shun ewes and engage exclusively in ram-on-ram action. They will swiftly pounce on any ram stuck in a fence - the sheep equivalent of the prison showers. The gay lovin' on Brokeback Mountain, it turns out, wasn't confined to Jake Gyllenhaal and Heath Ledger.