Lesbian albatrosses and bisexual bonobos have last laugh on Darwin

Charles Darwin argued that sexual preferences can shape the progress of evolution, creating displays, such as the peacock’s tail, that are inexplicable by natural selection alone.

It’s safe to say, however, that he did not anticipate the lesbian albatrosses of Hawaii. Nor bisexual bonobos. Let alone sadomasochistic bat bugs or the gay penguins of New York.

Homosexuality is so widespread among some animal species that it can reshape their social dynamics and even change their DNA, according to the first peer-reviewed survey of research on the subject.

From mammals to snails, and even nematode worms, homosexual behaviour is almost universal across the animal kingdom, and Californian scientists argue that it should be considered a selective force in its own right.

“The variety and ubiquity of same-sex sexual behaviour in animals is impressive — many thousands of instances of same-sex courtship, pair bonding and copulation have been observed in a wide range of species, including mammals, birds, reptiles, amphibians, insects, molluscs and nematodes,” write Nathan Bailey and Marlene Zuk of the University of California, Riverside.

Animals engage in same-sex activity for a variety of reasons, ranging from the need for an alternative child-rearing strategy to mistaken identity. “Male fruit flies may court other males because they are lacking a gene that enables them to discriminate between the sexes,” Dr Bailey said.

“But that is different from male bottlenose dolphins, who engage in same-sex interactions to facilitate group bonding, or female Laysan albatrosses that can remain pair-bonded for life and co-operatively rear young.”

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