Canadian researchers believe they have found evidence that homosexuality may be an example of ‘kin selection’ whereby individuals within a species pass on genes by helping their relatives survive, rather than reproducing themselves.
The most dramatic examples of kin selection are the sterile worker ants that protect the reproductive queen and drones in an ant colony.
Evolutionary psychologists Paul Vasey and Doug Vanderlaan of the University of Lethbridge travelled to Samoa to study fa’afafine-identifying individuals, comparing them to women and heterosexual men.
Fa’afafine is the name given to effeminate same-sex attracted men in Samoan culture. They are well integrated into Samoan society and family life despite the spread of Christianity and homosexuality remaining technically illegal.
Fa’afafine traditionally dress as women and are recognised as a third gender. Men who sleep with them are not considered homosexual in Samoan culture.
Past research showed that fa’afafine were more inclined to support their nieces and nephews compared to women and heterosexual men in the same living situation.
Fa’afafine supported nieces and nephews by babysitting and tutoring, helping out financially with school fees and medical bills, and giving gifts.
Vasey and Vanderlaan wanted to rule out the possibility that fa’afafine were more likely to help out children in general.
After over two years of study, the researchers said they found that a willingness to support nieces and nephews among fa’afafine was significantly less likely to translate into generosity to unrelated children. Heterosexuals who showed generosity to nieces and nephews were more likely to share that generosity with children in general.
“If kin selection is the sole mechanism by which genes for male same-sex sexual attraction are maintained over time, the fa’afafine must be ‘super uncles’ to earn their evolutionary keep,” Vasey said.
He said that fa’afafine enthusiasm for being uncles “probably contributes to the evolutionary survival of genes for male same-sex sexual attraction, but is unlikely to entirely offset the costs of not reproducing”.
He estimated a fa’afafine would have to aid the survival of two extra of his siblings’ children compared to families without fa’afafine for this to be an effective way of passing on genes.
The researchers suggested that while Samoan gay life was very different from life for gay men in Westernised nations, because Samoa was a tight-knit society based on extended families and relatives were less geographically dispersed, conditions more like early traditional societies where such kin selection mechanisms would have evolved.