For years, homosexuality in the animal kingdom has baffled many scientists around the world because the behaviour does not have any benefit from an evolutionary perspective. However, according to a study from the Department of Ecology and Genetics at Uppsala University, many animals engage in same-sex sexual behaviour because the genes that cause the behaviour has benefits like making the gay animal’s siblings more fertile.

The findings have been published in the journal BMC Evolutionary Biology. This involved observing small male and female seed beetles with low levels of same-sex sexual behaviour.

The research team created genetic strains that increased same-sex sexual behaviour among beetle offsprings through artificially breeding the offsprings’ parent. The siblings of those who were bred for increased tendency of the homosexual behaviour also experienced an increase in reproductive performance.

same-sex

This is a group of male seed beetles. Two of the males are mounting and trying to mate with two other males, which happens frequently when males are kept in single sex groups. Credit: Ivain Martinossi-Allibert

‘For example, we noted that males that had been bred for increased same-sex mounting behaviour were less discriminating when given a choice between courting a male or a female in later tests,” adds research team member David Berger, an assistant professor at the Department of Ecology and Genetics at Uppsala University. “While their sisters laid more eggs and produced more offspring than before.”

same-sex

These are two male seed beetles. The male to the left is trying to insert his genitalia into the other male after having mounted him. This usually results in the mounted male kicking with his hind legs in an attempt to escape. Credit: Ivain Martinossi-Allibert

Another study published in Psychological Science says that one possible evolutionary role of homosexuality is to enhance the survival prospects of close relatives. The researchers call this kin selection hypothesis.

Recently, Perth-based researcher Cyril Grueter observed same-sex sexual behaviour among wild female gorillas for the first time in the mountains of Rwanda. The associate professor and primate expert from the University of Western Australia says that the behaviour between the two female gorillas was motivated by sexual arousal after the male gorillas did not show interest in them.

A Belgian photographer and lawyer also photographed two lions in a seemingly “Brokeback Mountain” moment. However, other experts believe that the male lions’ behaviour toward each other was just a bromance.