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| The Evolution of Bisexuality (in Women) and Homosexuality (in Men) (765504) | |
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The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by JayMan on Sat Apr 16 16:15:36 2011 Who doesn't love bisexual women? I know I sure do!But, bisexuality, or for that matter lesbianism or homosexuality in men don't seem to make sense evolutionarily. In terms of strict homosexuality, one would expect that since both gay men and women would have procreated less, that the trait would have been removed from the gene pool over time. As well, one might imagine that attraction to both sexes confers no additional benefit, and would not have been selected for. But recent info indicates that female bisexuality is incredibly common, as now as much as 15-20% of women identify as being non-heterosexual, the vast majority of those being bisexual. Since non-heterosexuality is still somewhat frowned upon (depending on who's doing the frowning—or smiling), the true number may be even higher. Of course, despite the greater incidence of girls identifying as bisexual, the trait cannot be more prevalent now than it was just a generation ago, because sexual orientation (like all behavioral traits) has been found to be highly heritable, and evolution does not occur that quickly. Since female bisexuality is so common, it must serve some function. As most straight guys will tell you (the ones that don't lie, anyway), girl-on-girl sex is a massive turn on. For anyone who doubts this (who?), the enormous girl-girl market industry speaks to that. Despite what our friend says in the above link, the increased incidence of female bisexuality is not because women are feeling increasingly driven to other women because of a dearth of good men, because female bisexuality has been found to be a true sexual orientation, stable throughout life and highly heritable. So what's the reason? Perhaps the fact that men like (love) it is a clue. One hypothesis contends that female bisexuality evolved in response to polygyny, which was the norm for human societies up until fairly recently. In a polygynous society, a few men (the alphas) dominate most of the females. This is obviously beneficial to the alphas, but not at all beneficial to the loser males. More importantly, it is not ideal for the women, because this reduces the genetic variability of their offspring (dangerous if calamity calls for traits different than the alpha's), so women in polygynous relationships have an incentive to cheat with the loser men with the hope of cuckolding the alpha. Naturally, of course, the alpha has an incentive to avoid this, so mating with lesbian women—who show no interest in men—was an excellent way to ensure that he was the only man inseminating her. But these lesbian women are again in the same place their straight counterparts were in terms of genetic variation. But what if a woman could fool the alpha into thinking that she was lesbian? Bisexuality just does that; it takes advantage of men's attraction to lesbianism but gives the women the advantage of attraction to other men (other than the alpha). This would predict that bisexuality is common, that bisexual women have higher sex drives than straight women and a greater desire for multiple men, that bisexual women ultimately are more interested in men, and that bisexual women would have more girl children (since the trait is obviously more useful for girls) and there is some evidence for all but the last of these (so far). Research has shown there is strong positive correlation between a woman's sex drive and her chances of being bisexual. Bisexual women are also more orgasmic, fantasize more about sex, and are open to more sexual experimentation even with men (anecdotally from my personal experience I can confirm all of these to be correct). As well, bisexual women have had a greater number of male partners than straight women, (something that anecdotally I can confirm also). I have yet to find evidence that bisexual women have more girl children, however. So it appears that the hypothesis that female bisexuality is a strategy for attracting men and possibly cuckolding them has some merit. So what about male homosexuality? It has been equally mysterious, and the reasons for the trait, evolutionarily, have not been clear. (As for male bisexuality, there is some evidence that suggests that it, strictly speaking, does not exist. A study that looked at the arousal patterns of men found that men who identified as being bisexual are either actually gay or straight (usually gay). Whether or not this is true or will be confirmed by larger studies remains to be seen.) But I am going to contend that female bisexuality and male homosexuality may be related, and that the latter is probably a consequence of the former, and may not just be a side effect but possibly even specifically selected for. Compared to female bisexuality, male homosexuality is less common but still quite prevalent, with 5% of men identifying as gay. As well, it had eluded explanation evolutionarily, because the genes for the trait should have been selected out. Since that is clearly not the case, those genes must do something beneficial, if not for gays themselves, then possibly their relatives. One has been the "gay uncle" hypothesis—that gays serve as caretakers for their siblings' and cousins' children—which thus far has found fairly limited support by the evidence. However, it is possible that the genes for the trait benefit the relatives of gays, and it turns out that that is the case. Recent evidence indicates that female relatives of gay men have more children, but this is only true of those on the maternal side. On top of this, male homosexuality seems to be only inherited along the maternal line. This would be case if genes responsible for homosexuality were found on the X-chromosome. But what I found interesting is that the reason that female relatives of gay men have more children because they have higher sex drives than average; in fact, although as far not explicitly demonstrated by studies thus far, this sounds like the behavior of bisexual women. It's not hard to see how genes that influence bisexuality in women might also lead to homosexuality in men. Some have speculated this effect in tandem with the "gay uncle" hypothesis; that in this fecund line of women, an occasional gay offspring pops out to help ensure that there are enough caretakers for all the children born (which would be difficult if women in every generation were reproducing out of control). But it is possible that the occasional gay male is only a side effect of an otherwise beneficial trait for females, and survives only because of its positive effect on reproduction for these women. So what's left? Well, to confirm if this link between female bisexuality and male homosexuality is true, research is needed to see if these fecund female relatives of gay men are in fact more likely to be bisexual. Since this is a trait that primarily affects women, research is needed to see if bisexuals/female relatives of gay men do indeed have more girls, as I would expect. I admit, despite the apparent thoroughness of my post, I was somewhat lazy and I didn't completely comb the literature to see if such evidence exists. As far as a racial/IQ slant, since homosexuality is found in blacks and in Africa, the trait is obviously very ancient and predates the evolution of Eurasians. As well, gay men have been shown to have higher IQ's on average, but this is probably due to the association with decreased masculinity and IQ; these genes might also play a role in increasing the prevalence of male homosexuality as you go up the IQ ladder. So discussion gentlemen. Anecdotes are welcome! (You're free to offer religious/non-scientific |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by vfrt on Sat Apr 16 16:47:16 2011, in response to The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by JayMan on Sat Apr 16 16:15:36 2011. But why do gay men like show tunes? |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by SelkirkTMO on Sat Apr 16 16:50:09 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by vfrt on Sat Apr 16 16:47:16 2011. To avoid having Gaga's snizz in their faces. :) |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by Spider-Pig on Sat Apr 16 17:35:34 2011, in response to The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by JayMan on Sat Apr 16 16:15:36 2011. Re: having more girlsHow would any trait increase the probability of more girls? Is there some gene that is more likely to spontaneously abort male babies? |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by JayMan on Sat Apr 16 18:05:17 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by Spider-Pig on Sat Apr 16 17:35:34 2011. Evolutionary theory would predict that any trait that benefits one sex more than the other would tilt the number of offspring parents have in that direction. Attractive women have more girls (since attractiveness is more useful to girls) and aggressive men (as measured by incidence of domestic violence) have more boys as (aggressiveness is more useful to boys). It is obvious how it would work with fathers since a man could produce more X- or Y-sperm. In mothers, it could be that the uterine environment favors more X- or Y- sperm; or perhaps even the egg cells themselves are more receptive to one type of sperm than the other. |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by SUBWAYSURF on Wed May 18 10:20:25 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by SelkirkTMO on Sat Apr 16 16:50:09 2011. yup, that's it |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by SMAZ on Wed May 18 13:28:29 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by JayMan on Sat Apr 16 18:05:17 2011. Attractive women have more girls (since attractiveness is more useful to girls) and aggressive men (as measured by incidence of domestic violence) have more boys as (aggressiveness is more useful to boys).I find that conclusion faulty and here's why: In the past people had lots of kids which meant that on balance a family would be more even matched between boys and girls if they've got 6-8 kids. With people just having a couple of kids nowadays, if what you say is true, it means that such traits would only be valid for the first and second-borns. Six of the last nine POTUSs (and last three in a row) have only had girls. Explain. |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by Mitch45 on Wed May 18 14:31:55 2011, in response to The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by JayMan on Sat Apr 16 16:15:36 2011. I don't come to OT Chat for anthropology lessons. Sorry. |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by SMAZ on Wed May 18 14:33:19 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by Mitch45 on Wed May 18 14:31:55 2011. I don't come to OT Chat for anthropology lessons. Sorry. OTChatters ARE an anthropology lesson. |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by FYBklyn1959 on Wed May 18 15:42:18 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by SMAZ on Wed May 18 13:28:29 2011. You're right about the last 3 POTUS--but six of last 9?Reviewing (POTUS with only girls in bold) LBJ (Lynda, Luci) Nixon (Julie, Tricia) Ford Carter Reagan Bush 41 Clinton (Chelsea) Bush 43 (Jenna, Barbara) Obama (Malia, Sasha) Unless I'm in error, 5 out of 9 |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by JayMan on Wed May 18 15:55:01 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by SMAZ on Wed May 18 13:28:29 2011. In the past people had lots of kids which meant that on balance a family would be more even matched between boys and girls if they've got 6-8 kids.With people just having a couple of kids nowadays, if what you say is true, it means that such traits would only be valid for the first and second-borns. Kanazawa controlled for sibship size in his studies. Attractive women still have more girls. Even still, if you're saying higher sibships would produce more boys, then your hypothesis is that there is a tilt for girls in earlier borns but boys in later borns in attractive women. That's slightly harder to explain, and perhaps unnecessarily complicated. Six of the last nine POTUSs (and last three in a row) have only had girls. 1. Nine couples isn't a significant sample. 2. Clinton only had one child, not enough to be meaningful. 3. Many of the First Ladies were fairly attractive women in their prime. |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by JayMan on Wed May 18 15:55:20 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by SMAZ on Wed May 18 14:33:19 2011. Well said! |
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Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men) |
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Posted by SMAZ on Wed May 18 23:29:11 2011, in response to Re: The Evolution of Bisexuality (in Women) and Homosexuality (in Men), posted by FYBklyn1959 on Wed May 18 15:42:18 2011. Carter (Amy) |
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