Breaking what is taboo for some, the Oslo Natural History Museum is showing an exhibition on homosexuality in the animal kingdom which organisers say is the first of its kind in the world.
"As homosexual people are often confronted with the argument that their way of living is against the principles of nature, we thought that ... as a scientific institution, we could at least show that this is not true," exhibition organiser Geir Soeli said.
"You can think whatever you want about homosexuals but you cannot use that argument because it is very natural, it's very common in animal kingdom," Soeli adds.
From beetles to swans and creatures considered to have a more macho image, such as lions and sperm whales, homosexual behaviour has been detected in 1,500 species.
The exhibition, entitled "Against Nature?" displays examples of this behaviour in pictures and models.
In one image two female adult bonobo chimpanzees are having sex, oblivious to a young male who is attempting to join in.
These peaceful primates, with whom humans shares 99 percent of his genetic makeup, use sex as a stress reliever regardless of age and gender barriers.
Be it a one-off, occasional or seasonal, homosexual and bisexual contact in the animal kingdom serves different purposes.
Big horn sheep "need to have sex with their own fellows just to be accepted. And by being accepted they are making up very important social relations which later give them better access to females," says Soeli.
Among swans and flamingos there have been cases of two females living together using sexual contact with males purely to reproduce.
"One of them might have a small affair with a male, have her eggs fertilized, and the two females bring up the young birds together just as a family," adds Soeli.
It has been reported that in certain bird species males double up allowing them to control a larger territory than a heterosexual couple which in turn serves to attract more females.
The first documented cases of supposed homosexuality in animals dates back to the Greek philosopher Aristotle who, more than three centuries before Christ, was intrigued by the promiscuity of male hyenas.
The subject was then ignored for many centuries, with incidents of male coupling described as part of fighting rituals.
"They did not describe it as homosexual activity, or as the result of lust," Soeli says.
"But animals have strong instincts ... maybe they're having sex just because it's good," Soeli adds.
The exhibition has sparked consternation in conservative Christians.
A Lutheran priest said he hoped the organisers would "burn in hell," and a Pentecostal priest lashed out at the exhibition saying tax payers' money used for it would have been better spent helping the animals correct "their perversions and deviances".