Homosexuality is widespread in several species, ranging from worms to insects, birds to dolphins, sheep to reptiles. What is more, it serves a purpose:-
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Biologist Nathan Bailey’s recent scientific conclusions may be a shocker for the religious leaders or self-professed moral guardians who are indignant at the recent Delhi High Court ruling decriminalising sexual intimacy between same sex individuals in India.
While some argue that homosexual behaviour is “deviant” or “unnatural”, Bailey, a professor of evolutionary biology at the University of California, Riverside, has amassed scientific evidence that it might be as ubiquitous as life itself.
Bailey and colleague Marlene Zuk, who co-authored the study, collected several past research studies that reveal same sex behaviour — males having sex with males, females with females — in diverse species, from worms to insects, birds to dolphins, sheep to reptiles. While some of them are mere flings, others lead to lifelong relationships. Their study shows that it serves a purpose.
The study, which recently appeared in the journal Trends in Ecology and Evolution, has listed as many as 14 animal species that exhibit homosexual tendencies. “It is by no means an exhaustive list, but it provides a starting point for those interested in obtaining further information and examples,” they say.
The variety and ubiquity of same sex sexual behaviour in animals is impressive. They found thousands of instances of same sex courtship, pair bonding and copulation in a wide range of species.
Domestic sheep exhibit it. Birds like the laysan albatross and zebra finch indulge in it. So do bonobo monkeys, chinstrap penguins, bottlenose dolphins and garter snakes. Behavioural biologists have recorded male-male pairing among insects like the flour beetle and African bat bug too.
In the past, researchers, investigating whether gay sex is genetically encoded, found that tweaking certain genes can turn fruit flies and roundworms into homosexuals.
The attempts to find a genetic link to homosexuality have a strong Indian connection. The first-ever such gene manipulation study was conducted by an Indian scientist Kulbir Singh Gill who was a visiting researcher at Yale University in the 1960s. Gill, while studying the genetic causes of female sterility, almost serendipitously found in 1963 that male flies lacking a gene — later named fruitless gene — court other males. Gill’s pioneering work opened the floodgates and many other scientists subsequently discovered several other genes whose manipulation yields varying types and degrees of male-male courtship in fruit flies.
“Same sex sexual behaviour has long been viewed as a fascinating puzzle from the evolutionary perspective. The most obvious mystery is why animals would engage in sexual behaviour that does not directly result in reproduction,” says Bailey who, along with Zuk, seeks to understand the significance of such acts in the evolution of species.
Interestingly, a closer examination by them led to several significant conclusions. Some species use same sex pairings as a social glue for bonding (bottlenose dolphins), while for others (the bonobos, dung flies) it is a tool to resolve intra-sexual conflicts. In certain other species like fruit flies, immature individuals use them as an opportunity for practice, but for flour beetles it is a ploy for indirect insemination. More often than not, male members among the beetles use same sex copulation to deposit sperm in other males, which then transfer it to females during subsequent opposite sex mating.
“The secret of the peaceful bonobo society appears to rest with their sexual behaviour; in their society sex is used to solve conflicts,” writes Morten Kringelbach, psychiatrist at the University of Oxford, in his recent book The Pleasure Center.
The authors of the new study think that there may be many more animal species indulging in homosexual behaviour. It is difficult to know their sexual orientation, as there are no means of knowing what their ‘desire’ is. “We can only observe what they do,” they say.
Qazi Rahman of Queen Mary, University of London, who has been studying homosexuality in humans, says genes responsible for such behaviour have a significant role in evolution. One reason nature keeps these genes intact — although they have no role in reproduction — is that they confer certain other traits. A certain dosage of gay genes is found to be beneficial even in heterosexual people because they might express traits that are more attractive to the opposite sex — like kindness, parental skills and co-operative traits. But a higher dosage of these genes leads to homosexuality, he adds.
“Evolution keeps genes for homosexuality intact because they benefit heterosexual carriers of those same genes,” Rahman, a scientist of Pakistani descent, told KnowHow. For instance, a study by Rahman and others, which appeared in the Journal of Sexual Archives last year, showed that gay men may tend to come from larger families with more fertile females. In other words, the females in gay men’s families “outreproduce” those in heterosexual men’s families.
Kringelbach says homosexual behaviour is a natural phenomenon in all human societies. Quoting American sex researcher Alfred C Kinsey, who studied in the 1940s and 1950s sexual habits, he says 37 per cent of all men have homosexual experiences, 10 per cent have homosexual relationships lasting longer than three years, and 4 per cent are exclusively homosexual throughout life. “The exact numbers have been disputed but it remains a fact that all serious sex studies have found that homosexuality is naturally occurring among both men and women,” Kringelbach told KnowHow.
Bailey hopes that scientific contributions from animal studies will shed more light than heat on the topic of same sex sexual behaviour.
Source: The Telegraph (Kolkata, India)