When Norway's museums authority called for ideas for an exhibition that engaged with contemporary societal debates, Geir Söli, head of exhibitions at Oslo's Natural History Museum, had just the theme. He had been listening to a priest arguing on the radio that homosexuality is a sin and contrary to nature.

Credit: S. WONG/MARINETHEMES.COM A. VAN ZANDBERGEN/LPI

People can only make up their minds about whether such behaviour is 'unnatural' if they know the current state of research on homosexuality in nature, he reasoned.

No sooner had the authority approved his proposal than church groups began to protest against this use of public money. But Against Nature? An Exhibition on Animal Homosexuality opened peacefully at the Natural History Museum on 12 October to wide acclaim. It will run until next August.

Söli focused the exhibition around 50 species, out of the 500 or so in which homosexual behaviour has been well documented. The exhibition comprises photographs, stuffed animals, models and other objects, along with explanatory text in Norwegian and English.

Two male giraffes are shown here indulging in roadside sex. Such encounters have been recorded in the literature as involving anal penetration and ejaculation. The inset shows two male whales (Eubalaena australis) engaged in sexual games.