In a Central American rain forest, male hummingbirds flit through the shrubs, stopping to mate with a female one moment, then with a male in the next. Over in the Arctic, a whale glides through the ocean and surges toward the surface, splashing water in a playful frenzy, her fins and tail caressing another female.
Biologist Bruce Bagemihl, author of Biological Exuberance: Animal Homosexuality and Natural Diversity, writes that homosexual behaviour occurs in more than 450 different kinds of animals worldwide. Male African elephants, for example, kiss each other by intertwining their trunks and touching mouths and noses. Some species, such as squirrel monkeys and the common chimpanzees, even engage in full mouth-to-mouth contact. Bagemihl shows a photo of two young male bonobo monkeys in an open-mouthed embrace.
“Kissing among primates bears a startling resemblance to kissing among humans,” writes Bagemihl.
There is also homosexual pair-bonding. Found primarily in birds, such pair-bonding is as strong as that of heterosexual couples. Partners engage in courtship and sexual behaviours, sometimes even becoming parents. A pair of female Canada geese, for example, would raise their young together after having copulated with a male goose. The male is in effect the sperm donor.
“One thing is certain: the animal kingdom is most definitely not just heterosexual.”
Bagemihl writes that animals on every continent have probably been seeking same-sex partners for millions of years. But if “survive and reproduce” is the general rule, how do evolutionary biologists view the various non-reproductive forms of sexual orientation? And how do scientists reconcile the nature/nurture debate surrounding the origin of homosexuality?
In his book Sexual Landscapes: Why We Are What We Are, Why We Love Whom We Love, psychobiologist James Weinrich raises the concept of kin-selection: you have to take into account not only your own reproduction, but also the reproduction of your relatives. Throughout most of our history, child and adult mortality were very common. Fortunately, because we used to live closely with our extended family, aunts and uncles often stepped in to rear their orphaned nieces and nephews. The lesbian “maiden aunt” and the gay “bachelor uncle” would pass on their genes through the successful rearing of these children.
In addition, Weinrich writes that homosexual and heterosexual men don’t differ much in abilities more commonly found in men than in women, such as visual-spatial skills, but they do tend to differ in occupational interests. Gay men tend to be aesthetically inclined and like designing things, whereas straight men tend to have what he calls stereotypically masculine interests like “building, hammering, and sawing.” As we moved from hunting and gathering to agriculture and subsequent societal developments, the number of different jobs would increase and it was important to have enough people interested in different occupations. If it was beneficial for society to have men with interests more typically found in women, then natural selection would have kept these individuals in the gene pool.
Dr. Ray Blanchard, Head of Clinical Sexology Services at the Centre for Addiction and Mental Health (CAMH) in Toronto, conducts birth order research on male homosexuality. His findings suggest that the fetal environment may play a role in shaping sexual orientation for some gay men. After having studied homosexual and heterosexual men from England, the Netherlands, Canada and the United States, he and his colleagues have found a link between male sexual orientation and the number of older brothers in the family. The more older brothers a man has, the higher the likelihood that he may be gay.
And he proposes a possible biological explanation for why this may be the case. There is a group of substances called H-Y antigens on the cell surfaces of male, but not female, fetuses. Sometimes, these H-Y antigens get into the mother’s circulation, and her immune system reacts by producing antibodies, which accumulate in her system with each succeeding male offspring.
The more of these antibodies the male fetus is exposed to, the more likely that his brain will develop in a pattern that is not typical of heterosexual males. This is why later born males with several older brothers are more likely to be gay than, say, males who are the oldest in their family.
What about women? What do scientists say about female sexuality?
“Some argue that sexual orientation in women is a bit more fluid and flexible than it is in men,” says Dr. Kenneth Zucker, Psychologist-in-Chief at CAMH, and head of its Child and Adolescent Gender Identity Clinic. If you show gay and straight men nude pictures of men and women, gay men would be aroused by nude males and straight men by nude females. For women, however, the picture is not as clear-cut. Some researchers argue that female sexual arousal is more affected by context and interpersonal relationships, and therefore more subject to social factors.
Indeed, women’s sexual patterns have been found to be malleable. Dr. Lisa M. Diamond, Assistant Professor of Psychology and Gender Studies at the University of Utah, recently published a 5-year study of 80 women. Her results: just because a woman identifies herself as homosexual or bisexual, it doesn’t necessarily mean that she will stay that way for life. Over this 5-year period, some women abandoned their lesbian or bisexual identity and pursued heterosexual relationships. One notable example cited by Diamond is actress Anne Heche, who became engaged to a man after her relationship with comedian Ellen Degeneres dissolved.
“But basically,” says Zucker, “where research is at right now with regards to factors that determine sexual arousal in women has gone back to Freud: nobody has any idea. Everybody is confused.”
Why is all this important? Why do we need to find any explanation for any form of sexual orientation? Wouldn’t the LGBT minority regard such research with disdain?
“At a pure intellectual level, there are gay people who have some curiosity as to why they are gay or lesbian and not heterosexual,” Blanchard explains. “It’s not by any means the case that all gay people are utterly intellectually indifferent to this question, or opposed to somebody asking it.”
He also points out that no one to date knows how any erotic preference is formed, from ordinary heterosexuality to those of social concern such as pedophilia and dangerous sadism. “You have to start somewhere,” he says. “The easiest way is to start with something that departs in some way from the standard. You need some entry point.”
Zucker believes that homosexuality and heterosexuality are two sides of the same coin. “The more you learn about one, the more you learn about the other. Why people become heterosexual is as interesting as why people become homosexual.”
In the early 1990s, molecular biologist Dr. Dean H. Hamer, currently Chief of the Section on Gene Structure and Regulation at the National Cancer Institute in the U.S., set out his search for the “gay gene.” He and his colleagues provided the first piece of evidence that a certain gene in the X chromosome may be involved in male sexual orientation: A significant portion of the gay men in his study shared the same version of the gene. However, Hamer reported that this gene was not involved in the sexual orientation of all men, and according to Zucker, no other researchers have published any findings that support the results. “The verdict is still out,” he says.
Some, however, argue that being homosexual can simply be a matter of personal preference. In an interview published by the National Association for Research and Therapy of Homosexuality (NARTH) in the U.S., Dr. Stanton L. Jones, Professor of Psychology at Wheaton College in Illinois, and Dr. Mark A. Yarhouse, Associate Professor of Psychology at Regent University in Virginia, claim that in addition to genetics and hormones, “early childhood environment and experiences, along with adult choice, can all be participants in the mix of factors.”
According to Bagemihl, arguments about the origin of homosexuality-or the origin of any form of sexual orientation, for that matter-often invokes opposite categories: genetics versus environment, nature versus nurture. What most research shows, he emphasizes, is that both environment and biology are relevant in contributing to sexual orientation in people, and probably also in animals. “Some individuals may have an innate predisposition for homosexuality,” he writes, “but the right combination of environmental (including social) factors is required for this to be realized.”
At this very moment, two male monkeys are probably drifting off to sleep, lying in each other’s arms, in the depths of a jungle in Asia.
