From MSNBC News:
A first-ever museum display, “Against Nature?,” which opened last month at the University of Oslo’s Natural History Museum in Norway, presents 51 species of animals exhibiting homosexuality. Homosexuality has been observed in more than 1,500 species, and the phenomenon has been well described for 500 of them,” said Petter Bockman, project coordinator of the exhibition. “I think to some extent people don’t think it’s important because we went through all this time period in sociobiology where everything had to be tied to reproduction and reproductive success,” said Linda Wolfe, who heads the Department of Anthropology at East Carolina University. “If it doesn’t have [something to do] with reproduction it’s not important.”
However, species continuation may not always be the ultimate goal, as many animals, including humans, engage in sexual activities more than is necessary for reproduction. “You can make up all kinds of stories: Oh it’s for dominance, it’s for this, it’s for that, but when it comes down to the bottom I think it’s just for sexual pleasure,” Wolfe told LiveScience. Conversely, some argue that homosexual sex could have a bigger natural cause than just pure pleasure: namely evolutionary benefits.
More here.