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Keywords:: Animal Sexual Orientation, Causes of Orientation, Science | ||||||||
Homosexual behavior in the animal kingdom, depending upon how the behavior is defined, has been documented and studied for many years and has been found in many non-human species. Here we will look at the controversies surrounding such research along with the causes of and ability to alter sexual orientation in other animals.
Contents:
- Introduction / Warning - The problems of researching sexual orientation in animals.
- Species - Where you can find detailed observations of gay animals in the wild.
- Causes and Alteration of Animal Orientation - The nature and human researchers making animals gay.
- Genetics - ATGC can spell gay.
- Hormones - Chemical alteration of orientation.
- Brain Surgery - Homosexuality by going under the knife.
- The Nose - Some creatures smell gay.
- Environment - The experiences that alter animal orientation.
- Consequences - What do homosexual animals mean to the politics of gay humans.
- Nature/Nurture - The effects on this long standing debate.
- Morality - The ethics of fruit flies.
- Science - Don't forget the big picture.
- A Poisonous Cure - Take two Straightegen and call me in the morning.
- References
As with all areas of science overlapping with politics, care must be taken in the study of homosexuality in other species. The research findings in this area are commonly diminished or over-extended to an unreasonably degree.
Not all apparently sexual activity between members of the same sex can be used to assume the practitioners hold what most would call a same-sex sexual orientation. Some of such behaviors may be explained by acts of dominance or a number of other alternate explanations. In human history, for example, homosexual rape has been used as humiliation on the battlefield, and when males are kept from females (e.g. prisons) otherwise heterosexually oriented men may resort to homosexual behavior. This does not mean these men are homosexuals and the same case can be made for other mammals and animals behaving homosexually.
Also, though we may be very similar in design, results on one species may not translate into results on another. While mammals are likely to have very similar properties and we see these similarities in the research on sexual orientation, homosexual behavior in creatures such as fruit flies and guppies should be extrapolated with care.
Nevertheless, it is possible to clarify an animal's orientation and it's relevance to human sexuality. For example, an animal's behavior when given options may be observed. Some rams may mount other rams in a show of dominance, but others will only mount rams, never females (estrous or otherwise) even when given the choice, and they will act to the point of ejaculation. Furthermore, there are instances of same-sex pair bonding in some species, even child rearing that may last a lifetime. Desires for such behaviors are the desires that describe what humans mean when they refer to people as heterosexual or homosexual, gay or straight. To attempt to deny such instances of animal same-sex activity have relevance to humans, who share the great majority of their genetic blueprint with many of these species, would only be reasonable if the aim was political instead of science. As we shall see, there have been found, in fact, many biological similarities in the causes of same-sex sexual orientation throughout many species, including the human species.
Species - We will not go through and list all of the species in which examples of homosexual behavior may be found. Dr. Bagemihl has put together a detailed book, Biologicla Exhuberance, compiling the research on many, from primates, to foul, to sea mammals, to insects and more (1). The same-sex behavior the author describes ranges from courting, to genital manipulation, to the rearing of young and such behaviors vary among species. Furthermore, a more conservative review, using a strict definition involving only sex acts, was published by Vasey (2), the online text of which may be found in its link in the isocrat library. Instead of detailing the observations of animals in the wild, we will look here at the research on the manipulation of the orientation of these animals in the lab, and what that may tell us about the origins of animal sexual orientation. Along the way, though, many of these same-sex oriented species will be introduced.
Causes and Alteration of Animal Orientation:
Many of the experimental routs to understanding sexual orientation are, of course and rightly, blocked by ethical limits on science. We cannot, for example, attempt to change straight men gay via brain surgery. Nevertheless, such experiments have been performed on animal models, and have revealed much about sexual orientation in general.
Genetics - There have been several successful attempts made to alter the sexual orientation of an animal by altering its genetic code. Essentially researchers have created creatures that are genetically programmed to be homosexual or bisexual at birth. The manipulation of several genes within the common fruit fly has been shown to alter their sexual orientation (3, 4, 5, 6, 7). Some ingenious forms of manipulation have even produced flies that will switch from male-male sexual interactions to male-female and back depending upon the ambient temperature (8), and the presence of chemical triggers (9). Similar research has been accomplished on nematodes (10). In mammals, manipulation of the mouse genome has been shown to alter sexual orientation as well (11, 12, 13). Among the finding on mice, it was revealed that the genetic code for the neural circuitry that dictates male-specific behavior is likely present in wild-type females as well, though normally repressed (14).
Hormones - Though the research is conflicting and limited by ethical constraints, evidence exists suggesting prenatal hormonal exposure in humans may affect their sex behaviors (15, 16). On the other hand, many times over and with several species injections of certain chemicals have been shown to alter an animal's sexual orientation.
Injections of sex steroids have been used to make female newts take on male-typical sexual behaviors... lesbian newts (17). Exposing female ferret fetuses to testosterone only during the last two weeks of their gestation was found to masculinize their sexual behavior, highlighting the importance and permanent effects of timing in regards to hormonal exposure (18). In rats, chemically halting the aromatization of testosterone to estradiol just after birth was found to make male rats more likely to behave sexually with an active male rather than with an estrous female (19), and exposure to testosterone was found to make female rats which behaved homosexually (20). Of course, the guinea pig has also been the guinea pig in such experiments (21) . Finally, in male-oriented rams, those that will only court or mount males, never females (about 8% of the range-bred population), it has been found that there are several significant differences in sex hormone levels and activities, when compared to female oriented rams (22, 23) .
Brain Surgery - A 1991 study by LeVay which revealed a statistical difference in the size of a certain cell group within the human hypothalamus between homosexual and heterosexual men (24). LeVay reported that a certain region of the hypothalamus was half the size in gay verses straight men.This work met with much publication and resistance. Far less widely known, though, are the confirming results found by surgically altering the hypothalamus in mammals.
As discussed above, it has long been known that prenatal exposure to testosterone or it's estrogenic metabolites may alter an animal's sexual orientation. In several mammalian species (including humans) one other effect of these hormones is to trigger, prenatally, the growth of certain nuclei within the male but not the female hypothalamus, leading some researchers to ask whether physically altering such areas of the brain would alter sexual orientation. In fact it does.
Paredes, et al. found that creating lesions in the preoptic area/anterior hypothalamus (mPOA/AH) of male ferrets, produced ferrets that, when compared to a control group (which received control lesions), preferred to approach and receive neck grip stimulus from males, rather than sexually approach females (25). These findings were repeated with a separate group of ferrets (26) as well as with rat subjects. In a 1998 study, male and female rats were given lesions in this area of the brain (27). It was found the females retained their heterosexual orientation but the males began behaving sexually as the opposite sex would.
Not only is orientation found to be an alterable consequence of brain anatomy, but of cellular function within the hypothalamus. Roselli, et al. found, again, that the size of the mPOA/AH in male-oriented rams was half that of female-oriented rams, the same size as the mPOA/AH of ewes. They also found that the mRNA levels encoding the P450 aromatase protein were lower in cells in that area of the brain of homosexual rams as well, comparable to ewes (28). Similarly, Alekseyenko et al. repeated the work of Paredes on ferrets described above, finding the same effects of surgically altering the hypothalamus on orientation, but they also found that, in response to the scent of soiled male bedding, the surgically altered male ferrets showed a female neurochemical response (29).
Some similar research has focused on female mammals as well. Roberts and Baum examined the effects of creating lesions in a separate area of the hypothalamus on female ferrets. This area is the ventromedial hypothalamic nucleus (VMH) and had been shown to produce a strong neurochemical reaction to the scent of males in female ferrets only. Females with lesions in the VMH were found to show significantly less intimacy with and more aggression towards male ferrets than the control groups with shame lesions or lesions in their mPOH/AH (30). They essentially surgically turned down the female's attraction to males.
In less complicated organisms, similar experiments have been conducted. For example, White, et al. found they could make nematode worms homosexual by eliminating, via laser surgery, certain sensory neurons (10).
Unfortunately for those homosexuals hoping to change their orientation, it's much easier to remove a structure and remove the programming that makes mammals orientated towards their opposite sex, rather than grow a new structures in areas such as the mPOA/AH to make homosexual mammals straight. Furthermore, such research should put to rest the claim that the differences in size of hypothalamus nuclei in gay verses straight mammals result from behavior altering brain structure; in this case, it's clearly the brain structure guiding behavior. Regardless, such experiments on humans will not likely be forthcoming due to the ethical ramifications.
The Nose - MRI Experiments on humans have already shown scent plays a significant role in orientation for both heterosexual and homosexual men and women alike (related isocrat.org article coming) (26, 31, 32). Furthermore olfactory stimulation may be seen activating the hypothalamus, an important player in determining a mammal's orientation as described in the previous section. With animal test subjects, less humane experiments have been conducted. For example, when the nasal passages of ferrets are blocked off with dental impression material, both sexes essentially stop differentiating between male and female partners, though they seem to remain able to differentiate between male and female individuals (33).
Environment - In some species less complex than mammals, social environment has been shown to play a role. For example, Field and Waite found that by raising guppies in all male groups they could produce males that behaved homosexually more often than guppies raised in mixed sex groups (34). Interestingly, this social alteration of orientation was found to be permanent for some individuals even after the introduction of females into the group, once again highlighting that the nurture/nature debate is likely not as clear as it is portrayed by activists on either side of human politics (related isocrat.org article).
In mammals, it has been shown an environment causing prenatal stress in a pregnant mouse increases the likelihood that her male offspring will exhibit homosexual behavior (35). In humans, the results have been inconclusive while relying on natural stressors (We cannot, of course, lock mothers up and expose them to stressful heat, noise and sound). It seems males of mothers who experience more stress during pregnancy are more effeminate though show no difference in sexual orientation (36).
Nature/Nurture - Problematically, many anti-gay activists and conversion therapy groups depend upon the source of homosexuality being found in some pseudo-freudian parent issue or socialization failure with peers, a case that's difficult to make with flies and sheep. The case is even made more difficult for them by the fact that hormone injections, genes, and surgeries may alter a mammal's sexual orientation. Even if a person's orientation is homosexual by biology, it is important, sometimes even religiously important to tell that person it is a psychological problem with a solution. For that reason some will make understandable and valiant attempts to deny the existence or relevance of homosexuality in such animal models and the research on them altogether (37).
Nevertheless, there is good objective reason to see homosexual behavior and pair-bonding in animals as applicable to the nature/nurture argument in humans, just as there is in the use of model animals in more mundane areas of medical research. While homosexuality in humans may be caused through a more complex web of nature and even, at times, nurture, and the causes for each individual gay human may be different, this research does further push the lion's share of determinism into nature's camp. The data is there and, as it piles up, there will be more and more pressure to admit what should be obvious: that human motivations,such as hunger, thirst and sexual orientation, must have a cause in our circuitry and roots in our nature, else they'd never take hold (Related isocrat.org article).
Morality - Typically, the first issue to come up in the area of animal sexuality is the issue of the ethical relevance. Natural, though, should not imply good, and the animal kingdom is ripe with behaviors humanity would rightly call wrong. As such, this research is, largely, irrelevant to the morality of homosexuality.
However, such research may be relevant to a gay-rights opponent's argument if they do make the mistake of equating natural with moral. Some will argue that homosexuals are "unnatural" and gay couples do not meet the definition of the "natural family" for their moral opposition to gay rights. As this research indicates, though, gay men and women are behaving naturally and their innate drives, just like the drives of heterosexuals, often include the drive to create a family as naturally as any other. Homosexuals, in effect, are a subtler version of biologically intersexed humans, with a fraction of their biology, that which directs pair-bonding drives and emotions, resembling the biology of the average member of their opposite sex. The unnatural choice for gay individuals, if there can be an unnatural event, would best be found in the coercion used to essentially couple two people of the opposite anatomical sex who, between the ears, share the same aim in their sexual orientation.
Science - This fact often gets lost in research conducted in realms claimed by politics, but there is interesting and important science being conducted here, all gay issues aside. There are some important questions to be answered by probing the origins of our deepest human drives, including our sexuality, and research on our distant genetic relatives is helping our understanding immensely. This sort of research also informs the heterosexual as to what made them who they are, even if who they are is not a heated political debate. Simply, understanding ourselves and our world better is the consequence of the ingenuous work of these researchers that will endure long past the day gay men and women are treated with equity.
A Poisonous Cure - Lastly, gay men and women should be aware that such research may reveal a way to alter the sexuality of gay humans. To date, the research on animals has not shown such a method. An animal's altered homosexuality relies, typically, on events that are irreversible (currently): altering their genetics before birth; exposing animals to certain hormones at a particular time during gestation (In mammals, these chemicals seem to have little effect once the animal is grown); and surgically altering the brain in a way that removes the heterosexual drive, rather than the homosexual drive. Nevertheless, for some forms of homosexuality, there may be a cure or poison, depending on your politics, on the horizon. It may result from the research described above. If, by that time, this mind-altering option hasn't become unconscionable in the developed world, the gay community will have to learn to deal with the new politics. However, the other side of the political coin will likely gain new respect for this research.
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isocrat > science > animal > hs_in_nature
Created: 2008-09-15; Last Edited: 2008-09-15; (ID443)