An exhibition in Bern, Switzerland, is highlighting same-sex relationships found outside the human species.
"Many people think that homosexuality and being queer are marginal and perverse phenomena. They say they are unnatural," Christian Kropf, a biologist at the Institute of Ecology and Evolution at the University of Bern, told Swissinfo.ch. "But this is nonsense!"
He explained that what is unnatural is homophobia. "I don't know of a single case of homosexual individuals being marginalized or disadvantaged in the animal world," said the biologist.
Kropf studies invertebrates and is employed at Bern's Natural History Museum as a specialist. He is also the curator of the exhibition titled "Queer - Diversity Is in Our Nature." The show highlights the diversity of gender and sexuality in humans and other animals, and it features discussions on homosexuality and its biological aspects.
The exhibition shows plenty of examples of same-sex behavior found in nature. Dolphins, for example, can form same-sex couples. Male European rams are known to mate with other males about 6 percent of the time, according to the museum.
"Although they have the choice, they aren't interested in females. Male sheep have intense contact, lick their genitals and have anal intercourse," Kropf told the outlet.
Same-sex behavior has been observed in about 1,500 species and is probably present in all social vertebrates. "The reasons for homosexual relationships are not always clear, but we do know that they strengthen social bonds and can contribute to group unity," he explained.
Research from Murdoch University in Australia and cited by Swissinfo.ch found that interactions among animals of the same sex can help create bonds and produce hierarchies, which could aid in hunting.
"I don't know if [the exhibition] contributed to the acceptance of the new marriage law in Switzerland," Kopf said. "But it certainly had an impact on my father. He is 87 years old and has never spoken well of homosexual people. But since he came here, he has changed. He realized that same-sex behavior is absolutely normal."
Earlier this year, Switzerland became one of the last European Union countries to legalize same-sex marriage.