Homosexuality and evolution


I made the mistake of reading some of the comments on those last youtube videos. There were some good ones, but they were also laced with the usual grunting assholes complaining about gays and “trannies” and quoting the Bible and making racist remarks about Africans. Let us pass over those contemptible arguments; there’s no dealing with them rationally. Spit and move on.

But there’s another flavor of argument that annoys me to no end: people who cite science and evolution to support their ignorant misconceptions about human nature. I want to address two, one anti-gay and the other pro-gay, both wrong.

First, there is the reductionist who knows a tiny bit about selection.

interesting point of view, but no. Evolution is all about competition. If you dont produce offspring, you take yourself out of the running. They may help the larger group, but that is more along the lines of the group exploiting a weakness. Their genes do not pass on. In the evolutionary crucible, thats a game over. It doesn’t matter what disease you cure, what philosophy you teach, biologically, you lose. Now, again, in modern society, things are more complex. There are more qualities to a life than how many mini-me’s you can make, but for the purposes of biology, it ends there.

If evolution is all about competition, how come reproduction in sexual species requires cooperation between two individuals to occur? Have you ever noticed that reproduction isn’t actually literally replication? You take your complement of 20,000 pairs of genes, and you throw half of them away, splice the remainder into different combinations, and then you merge those with the similarly mangled set of genes from another person, and you produce a unique individual. Not a clone of either of you — someone completely different.

That should tell you right away that you aren’t the focal point of evolution. You are a test platform for a battery of genes, genes that are shared with other members of your community. Evolution sees the propagation of a pool of genes that tends to produce successful individuals; look up inclusive fitness sometime. You share genes and combinations of genes with your siblings, your cousins, and more distant relatives — there’s more than one way for your population to propagate itself than for every individual to maximize the number of offspring they produce.

I also have to laugh every time some oblivious multicellular animal announces that evolution is all about competition, and that all that matters is how many progeny you produce. Do you realize that your existence is entirely a product of cooperation? Your parents were made up of trillions of cells, almost all of them dedicated to specialized, non-reproductive functions, all in support of a tiny minority of cells that can produce gametes. And of all those gametes, only two combined to make you — the great lumbering mass of agglomerated metazoan cells that were your parents then dedicated themselves to cooperatively nurturing the little zygote that was you (and which was not genetically identical to either) into a roughly similar lumbering mass.

Further, if that’s too abstract for you, consider this: you’d most likely be dead right now if scientists hadn’t collaborated to make vaccines against childhood diseases, if doctors and family hadn’t worked to keep you healthy and educated. Imagine all those carpenters who built your house and plumbers who put in the pipes and electricians who wired it up; imagine the vast combines that work to deliver fuel for heating and food for eating. Everything that you think is important about you was created by cooperation.

If you think otherwise, go masturbate into a mud puddle and hope that some of your offspring can make it without any assistance.

Here’s the pro-gay argument based on evolution. It’s just as annoying.

from a view strictly based in the ideas of natural evolution, i always assumed “homosexuality” was as old as the species… and that it was evolution’s way of both keeping the growth of the species in check (since humans are one of the few species that have sex for pleasure) and ensuring orphaned younglings have a chance at receiving care, guidence, and protection in their formative years. mind you this is just a personal theory based on the nature of nature…

Do not anthropomorphize evolution. Evolution is not an entity that plans and manages populations, it is not a nanny that cares about youngsters — if they are orphaned, one evolutionary outcome is for them to die, another is for survivors to support them, and all that matters is whether the population persists. In particular, evolution isn’t concerned with keeping populations in check — it’s simply a ratchet that permits populations to strive, and eventually and inevitably they hit physical and biological limitations, or pressure from some other growing population, and then physics happens.

Nothing personal. Evolution doesn’t play favorites. It can’t: it’s just the outcome of chance and physical laws interacting in particular environments.

Here’s my perspective on evolution and homosexuality.

Humans are complex organisms whose development is plastic and strongly dependent on environmental influences. There is selection pressure for the population reproduce, which we social beings accomplish with a significant subset of individuals providing sufficient progeny to replenish the population each generation, and with a similarly significant subset of the population working cooperatively to provide a supportive environment.

Evolution doesn’t care. All that matters is that the population thrives into the next generation, and that requires that individuals cooperate. Evolution is not a micromanager, either; we acquire random variations purely by chance, some work, some don’t, and in general, there are so many competing factors driving our survival that selection cannot possibly fine-tune emergent properties of behavior to such a degree that biology can specify exactly who you will bump genitals with. We are dealing with general tendencies expressed to varying degrees in individuals within a population.

If there is one biological imperative for humans, it is this: love one another. Build communities. Cooperate. Help each other in adversity. Successful populations will express these behaviors to a greater degree.

There are also biases towards favoring sexual interactions with members of a different sex, but that’s a secondary priority. Even if sexual preference were non-existent and totally random, women would pair up with men half the time, which would be more than sufficient to propagate our species, especially if the other half are working cooperatively to build safe homes and stable food supplies and provide loving educational environments.

From my biological perspective, the negative behavior that affects the survival of the species isn’t homosexuality, but anything that disrupts the cooperative bonds of community and foments hate — homophobia in humans is the destructive behavior that selection should work against. But keep in mind that if God has lousy aim, evolution is even worse…so we should also encourage behaviors that discourage attitudes that work against our survival.

Comments

  1. chigau (違う) says

    I’ve never understood why They™ think that homosexuality prevents reproduction.

  2. twas brillig (stevem) says

    “Homosexuality” is simply a variation of other aspects that humans exhibit. “Personhood” being the key [I think]. That is, part of our development was abstracting individuals into “persons”, where the sex of the person is incidental. Homosexuality is simply falling in love with a _person_, who just incidentally is the same sex as the other. [ … yes, this is a very simple abstraction of the h* issue, but this is how I deal with it, hope it helps others … ].
    – how often has it been said, “If we accept homos, then we’ll be extinct in N generations!!!”, and the opposite, “Homo is unnatural, evolution would not allow it!!!” The OP illustrates how incorrect these attitudes are.

  3. says

    We’re dealing with a crowd that seems to think human beings should emulate non-social insects. Males mate, then they fly away to find another female and/or die young.

  4. Beatrice, an amateur cynic looking for a happy thought says

    Haters will find an excuse to hate. Whether that’s religion or some faulty knowledge about evolution.

  5. says

    I think they mean corals.
    You known, when you sit around all your life and then just release millions of eggs or sperm into the sea together with millions of others and then literally don’t give a fuck about what happens afterwards.

  6. says

    Indeed, chigau . People do all sorts of things they don’t like because it results in something they want. Until 1979 the only way to have a child if you weren’t straight was to have sex with a straight person, whether you liked it or not. Not that there aren’t lots of straight people who dislike straight sex either. I would guess a large percentage of people ever born were conceived by people who wished there was some other way to produce a baby than having a penis in a vagina.

  7. Beatrice, an amateur cynic looking for a happy thought says

    Bronze Dog,
    Not to mention that “dying young” can include the female eating them.

  8. chigau (違う) says

    timgueguen

    Until 1979 the only way to have a child if you weren’t straight was to have sex with a straight person, whether you liked it or not.

    I’m pretty sure that both parties could be not-straight.
    ;-)

  9. says

    It seems like some people think evolution has a moral or ethical component, kind of like the way libertarians think about the “free market”. The reality is all creatures are equally evolved and I don’t think evolution rewards moral creatures. And I can almost guarantee the free market doesn’t reward people with ethics

  10. says

    timgueguen:

    Until 1979 the only way to have a child if you weren’t straight was to have sex with a straight person, whether you liked it or not.

    Um, ingenious devices like turkey basters were known about well before ’79, allowing for cooperation sans unwanted intercourse.

  11. The Mellow Monkey: Singular They says

    from a view strictly based in the ideas of natural evolution, i always assumed “homosexuality” was as old as the species… and that it was evolution’s way of both keeping the growth of the species in check (since humans are one of the few species that have sex for pleasure) and ensuring orphaned younglings have a chance at receiving care, guidence, and protection in their formative years. mind you this is just a personal theory based on the nature of nature…

    I’ve gotten many variations of this little “yay gay!” speech from people…usually while telling me how utterly selfish and awful it is for people in partnerships who cannot sexually reproduce on their own to not adopt See, my partner and I can’t sexually reproduce not because we both produce eggs, but because evolution made us partner up so we could take care of the offspring resulting from all those reproductive “sex for pleasure” partnerships. We’re the nanny class for cisheteronormative society, ordained by God evolution.

    Yep. Absolutely nothing bigoted there.

  12. says

    twas brillig:

    Homosexuality is simply falling in love with a _person_, who just incidentally is the same sex as the other. [ … yes, this is a very simple abstraction of the h* issue, but this is how I deal with it, hope it helps others … ].

    If I may…
    I understand this helps you, but I’ve found a shorthand that I feel might work better: Homosexuality is an expression of physical, psychological, and/or emotional attachment felt by members of the same sex.

  13. says

    MM:

    I’ve gotten many variations of this little “yay gay!” speech from people…usually while telling me how utterly selfish and awful it is for people in partnerships who cannot sexually reproduce on their own to not adopt

    You get this when you’re childfree, too, with extra vituperativeness if you’re in a mixed sex relationship, ’cause you’re obviously able, just unwilling.

  14. chrislawson says

    PZ, you can add to your list the co-operation of the billions of cells in our bodies that are programmed to self-destruct during embryonic development. Without those cells dying we’d have no fingers and no gut lumen. Co-operation FTW.

  15. The Mellow Monkey: Singular They says

    You get this when you’re childfree, too, with extra vituperativeness if you’re in a mixed sex relationship, ’cause you’re obviously able, just unwilling.

    Inaji @ 15, yeah, I think I’ve seen a Childfree Bingo card with that as one of the squares. It’s a really obnoxious mindset. No, we’re not here as some kind of clean-up crew.

    The goal should be to provide adequate support to people who want to raise their children, contraceptives to those who don’t want to get pregnant, abortion services to those who don’t want to be pregnant, to make efforts to reunite the families who’ve been torn apart by foster care based on racial and cultural biases, to crack down on the predatory adoption agencies, etc, etc, etc.

    Not just guilt-tripping people who aren’t reproducing and praising Jebus evolution.

  16. says

    There’s also this nonsense: “since humans are one of the few species that have sex for pleasure.”

    Does he think every wren, duck, and hawk, every gecko and turtle, every mammal from dog and pig and giraffe to chimpanzee, when having sex is thinking, “well, this is no fun, but how else will the species survive?” I don’t know what it is like to be a bat. I realize one has to be cautious in talking about other animals having pleasure. But there are a lot of animals that sure seem to enjoy sex.

  17. evilinky says

    I’m not a biologist, but it’s my understanding that a “gay gene” could be selected for if it conferred some sort of advantage when expressed in offspring of the opposite sex. For example, a gene that increased the chances of female offspring successfully reproducing by x%, but decreased the chances of male offspring successfully reproducing (by increasing the chance the male offspring was homosexual) by y%, would be “worth it” in evolutionary terms if x > y.

    (This is in no way a moral judgement on homosexuality.)

  18. stevebowen says

    From a strictly evolutionary point of view if homosexuality is genetically determined those genes must have some survival value ( or at least be neutral) in some context, for example conferring extra fertility when present in members of the opposite sex or increased survival and success of offspring even if they are less likely to have any. I’m not wholly convinced by group selection theories…yet.
    But who cares? even if same sex attraction is just one one of those things that happens with some people or is just a “lifestyle choice” it makes no difference to the moral point that people should be allowed to be self fulfilled in whatever way they want barring harming others.

  19. says

    Steve Bowen: Not necessarily. Homosexuality could be a phenotype that sometimes arises because a developmental program goes awry, but either the fix has other, greater costs, or the mutation to fix it doesn’t happen to occur, or the environmental factors that are associated with it come and go so the selection pressure is not sustained, and there are other explanations that don’t require it to be adaptive. E.g., we have lots of obese people and so on, it’s because of the way the organism develops in a particular environment, not because obesity is adaptive; whereas the mechanisms that produce it in our environment are adaptive in others, but they don’t produce obesity.

    On the other hand, it seems to me a reasonable question whether the presence of the occasional dispositional homosexual in a typical small, largely genetically closely related human group might have conferred some advantages. Positive kin selection is possible, but that’s speculative, it doesn’t follow from the mere existence of homosexuality. Of course, homosexuals can and do reproduce. It didn’t stop Oscar Wilde.

  20. unclefrogy says

    I do not see how anyone can say very much definitively about human evolution and sexuality really. The expression of our genes in behavior is so heavily influenced cultural practice that I do not see how they could be teased apart.
    That a percent of the population enjoys sexual activity with members of the same sex is universal in all humans populations that percent in a given culture may very in expression but exists none the less and has over time. It certainly has not hindered population growth much nor does it seem to be diminishing either.

    the haters and reactionaries are correct in a sense but it is not a threat to the human population but it is a threat to their own personal cultural practices and attitudes. It is their own culture and their place within it that is under threat and is being forced to change into something else.
    uncle frogy

  21. Crip Dyke, Right Reverend Feminist FuckToy of Death & Her Handmaiden says

    @evilinky & stevebowen, #s 19 & 20:
    First:

    opposite sex

    Yeah, okay, now that we’re done with that…

    the easiest way to understand it doesn’t even involve the necessity of of sex-different outcomes in overall reproductive success.

    Say that in each others’ presence, GayGene1 & GayGene2 produce SUPERGAY and reproductive success% drops by, say (just to be obvious) 100% to 0.

    When not expressed in the same person, GayGene1 & GayGene2 each produce a reproductive benefit of 10% increased chance of success.

    So long as GayGene1 & GayGene2 are expressed 11 times more often separately than together, you get a net success benefit. So you have lots of GayGene1 & GayGene2 carriers humpin & birthin & parentin before croakin. You have very few GayGene1 + GayGene2 carriers humpin & prancin & interior decoratin & feminist theorizin before croakin. Yay! The gene spreads!

    It’s even easier to understand if GayGene1 emerges in a Han population & GayGene2 first emerges in a Hmong population, so you don’t get any feminist theorizin until GayGene1 & GayGene2 spread far enough to come in contact with one another. By that time, they may be widely enough established that genetic drift is unlikely to overcome the survival benefit, even if you get Golden Horde sweepin through increasin the croakin without regard to the functions of GayGene1 & GayGene2, and, by the by, humpin and birthin and parentin a wave of kids that are inheriting lots of genes from a population with neither GayGene1 nor GayGene2.

    Does that help? My expertise in population genetics sometimes causes me to speak in impenetrable jargon, I know.

  22. unclefrogy says

    correction- The expression of our genes in behavior has been so heavily influenced cultural practice that I do not see how they could be teased apart.

    I hope that is clearer
    uncle frogy

  23. unclefrogy says

    I need more something I do not know what!
    correction of the correction

    The expression of our genes in behavior has been so heavily influenced by cultural practice that I do not see how they could be teased apart.

  24. robnyny says

    The anti-gay versions seems to be based on the idea that it is evolutionarily good for every member of a species to mate.

    However, in a lot of species with harem-like social structures, very few of the males ever mate. One rooster, lots of hens; one lion, lots of lionesses. And there’s the bee colony model: lots of drones, lots of workers, but the vast majority of them never mate.

  25. Monsanto says

    “If you don’t produce offspring, you take yourself out of the running.”

    Bingo. Since (as everyone knows) there is only one homosexuality gene and it is dominant, homosexuality will die out after a generation. Unless… They must be recruiting! As we all know, once you’ve had a taste of the homosexual lifestyle, you’re hooked, and there’s no way to return to being hetero. We’re doomed!

  26. says

    From a strictly evolutionary point of view if homosexuality is genetically determined those genes must have some survival value ( or at least be neutral) in some context

    No.

    Just no.

    Wrong.

  27. says

    it’s my understanding that a “gay gene” could be selected for if it conferred some sort of advantage when expressed in offspring of the opposite sex.

    Yes. But “could be” does not mean “was”.

  28. Anton Mates says

    The greater part of human sexual behavior doesn’t and can’t result in babies. Masturbation, anal & oral, even opposite-sex PiV intercourse f the woman is too young or too old or not about to ovulate in the next couple of days. Clearly, non-procreative sex must often be beneficial or at least not particularly costly, so why would homosexual behavior be a massive conundrum?

    The only thing that might be hard to explain is the existence of “obligate” homosexuals who never (or almost never) sleep with the opposite sex. But a) this isn’t any stranger than the existence of asexuals and voluntarily celibate heterosexuals, and b) for all we know, most ancient humans who survived to adulthood felt obliged to spawn a couple of kids even if they had little innate interest in hetero sex.

    The evolution of human sexuality is an interesting topic of course, but the particular question of “Why the gay???” is ill-formed.

  29. oh222 says

    On the first argument you make all these wonderful points about cooperation and such, but if nobody reproduces in the end it doesn’t matter, does it?

    On the first argument you say evolution does not plan, but the poster didn’t even say that.

  30. Becca Stareyes says

    Add in that there’s plenty of examples in non-human animals were sexually mature individuals stay with their kin and help raise relatives before striking it out on their own. Impossible to explain if you assume ‘successful evolution’ = ‘pumping out as many offspring as your body can stand’.

  31. knowknot says

    @32 oh222
    Hwat?
    Hhhhhwat?
    All I could figure is the wonderful was almost certainly used in its non-sarcastic, Sunday in the park sense.
    As for the rest, hwat?

  32. anbheal says

    @29 PZ — YAY!! I wish we could get it into people’s heads (particularly evo-psych fetishists) that lots and lots of things about us do not necessarily have any survival or reproductive value at all, they just arose and they just are. A big Mediterranean nose may have nothing to do with the ability to support more offspring from sniffing out more truffles to feed them.

  33. david says

    well, obviously, the gay genes confer a group survival advantage, by bringing us fabulous fashions, musicals, and interior decoration. d’oh.

  34. Krasnaya Koshka says

    Inaji @ 11 covered what I wanted to say (as per usual):

    I babysat three turkey baster kids in 1978. All boys, raised by only women. And they all grew up to be straight. Fancy that.

    / end useless anecdote

  35. says

    oh222:

    On the first argument you make all these wonderful points about cooperation and such, but if nobody reproduces in the end it doesn’t matter, does it?

    And as we all know, us humans aren’t into reproducing at all. Nope. There are hardly any humans on the planet!

  36. says

    Krasnaya Koshka @ 37:

    Inaji @ 11 covered what I wanted to say (as per usual):

    I babysat three turkey baster kids in 1978.

    Well, I never babysat three turkey baster kids! Oh, the marvelous, multi-use turkey baster. (Which was not, of course, the only possible delivery system.)

  37. says

    oh222 #32

    On the first argument you make all these wonderful points about cooperation and such, but if nobody reproduces in the end it doesn’t matter, does it?

    This makes no more sense than saying that same-sex marriage is detrimental to heterosexual marriage.

    Some people having non-reproductive sex ≠ nobody having reproductive sex.

  38. The Mellow Monkey: Singular They says

    Anton Mates @ 31

    The greater part of human sexual behavior doesn’t and can’t result in babies. Masturbation, anal & oral, even opposite-sex PiV intercourse f the woman is too young

    Er. You mean a prepubescent child?

  39. Anton Mates says

    Mellow Monkey,

    Er. You mean a prepubescent child?

    Well, that too–there’s been an awful lot of sexual contact between adults and prepubescent children in history, abusive though that is. But I was more thinking about teenage girls, who would not have been fertile for most of prehistory. (The median age of menarche in a lot of hunter-gatherer societies is 18 or so. Our girls start menstruating much earlier, AFAIK mostly because we have higher-calorie diets.)

  40. says

    Note that bonobos continually engage in sexual behavior pretty much indiscriminately, with no reproductive function. It’s social bonding, kind of like conversation is for us. There is an element of that in human sexuality as well, whether or not the sexual play results in orgasm. Just something to consider when you think about evolution of sexuality. It’s not only about reproduction, after all.

  41. says

    Anton Mates:

    The median age of menarche in a lot of hunter-gatherer societies is 18 or so.

    You sure about that? Because that doesn’t sound even half way right to me.

  42. Esteleth is Groot says

    It is possible that a Kinsey score > 0 confers some fitness on the organism or the organism’s relatives – there is, for example, some evidence that the sisters of gay men have more children than women whose brothers are all straight.

    Or maybe not.

    It is possible that something “makes” someone be gay – there is, for example, some evidence that the probability that a man will have a Kinsey score > 0 rises the more older brothers he has (to be precise, the more male fetuses a woman gestates, the higher the probability that a subsequent male fetus will grow up to be attracted to men).

    Or maybe not.

    Incidentally, isn’t it interesting that most of the just-so stories about “how is gay babby formed” seem to feature men? If lesbianism – or hell, bisexuality – is mentioned at all, it’s as a sort of afterthought.

    It could easily be that sexual orientation just kind of happened, and is one of those things that isn’t deleterious or advantageous either way, or that the cost of fixing the gene(s) is higher than the cost of leaving them be.

    Also, well, “is gay” and “is childless” are not necessarily totally overlapping – in many times and places a person might marry and/or have children because that is socially expected of them, so it could easily be that being gay confers some fitness on an individual that is then passed to their own offspring.

  43. Anton Mates says

    I might be off by a year or two, sorry. I know it’s 17 in the Agta of the Philippines, and 16-17 in the Hadza of Tanzania. Could have sworn I saw 18 in a review paper somewhere, but I’m getting on a plane now so I can’t google scholar for it. Feel free to correct me!

  44. brucegee1962 says

    OK, but there’s more than just biological evolution. There’s also cultural and societal evolution — back in the past, there were thousands of different human cultures all competing over resources, each equipped with a slightly different set of memes that they passed on to their successive generations with variations, or copied from their neighbors, or impressed upon other cultures after they had subjugated them. Some of those memes made them fitter than others.

    And yes, overall, I completely agree with PZ that societies that had more memes for cooperation (whether in the form of “Love one another” or “Do as I say or Yahweh will smite you”) would have had an enormous competitive advantage over societies where it was every man for himself. Before I realized this, I thought the best argument for a deity was the universality of certain moral values — but the meme hypothesis explains the development of morality nicely.

    HOWEVER, I also can’t help but think that most of the emphasis worldwide on cultures policing who is allowed to bump uglies with whom, goes back to the days when the difference between your culture’s possessing a 5% birthrate or a 7% birthrate could mean the difference between whether your great-grandchildren were conquerors or slaves or dead.

    Of course, realizing that also should make you realize how utterly useless these customs and mores are in our own society.

  45. Krasnaya Koshka says

    Chigau @ 38: Thank you. I am doing well. Living mostly in the Russian countryside these days.

    Inaji @ 40: Haha, yep. My first thought, though, was “turkey baster! Ahh, Inaji beat me to it.” In the past three years, six of my lesbian couple friends have had babies. And without PIV and without In Vitro.

    Generally conversations about why I’m gay are not interesting. I just am. Deal with it.

  46. chigau (違う) says

    Krasnaya Koshka
    I’m happy to hear you are well.
    Given the shit going on in Russia these days.

  47. Krasnaya Koshka says

    Esteleth @ 47: As usual, you’re right on.

    Why do we over think the gay aspect? Is it because there may be sex involved?

    For me, the most apt metaphor has been a redhead. They’re roughly the same percentage of humans. If there were an outrage against redheads, they could cover it up by dyeing their hair. But when it came to sex, it wouldn’t be so easy to cover up.

    What good can come from being a redhead in evolution? That’s how I think of homosexuality. It just is. It’s there. It’s a trait. Hello. And move on.

  48. says

    Krasnaya Koshka:

    What good can come from being a redhead in evolution?

    Considering how redheads have been treated throughout history, it could not be seen as any sort of advantage.

  49. Krasnaya Koshka says

    Chigau, the thing is it’s always been this way (from what I take from my gay friends here). Law, no law, nothing’s changed. “It was worse in Soviet times” is the general refrain. “Eh, I’d like to see the cops enforce it.” Granted, I live in Saint Petersburg, and the kids here are really liberal.

    The only thing worrying me is the U.S. sanctions because they’ve been deporting Americans over it. But that’s totally OT.

  50. The Mellow Monkey: Singular They says

    Anton Mates @ 43

    Well, that too–there’s been an awful lot of sexual contact between adults and prepubescent children in history, abusive though that is. But I was more thinking about teenage girls, who would not have been fertile for most of prehistory. (The median age of menarche in a lot of hunter-gatherer societies is 18 or so. Our girls start menstruating much earlier, AFAIK mostly because we have higher-calorie diets.)

    The Gluckman and Hanson paper is behind a paywall, but:

    The age at menarche, the best documented sign of reproductive maturation, in Paleolithic times was probably around the ages of seven to 13 (Gluckman and Hanson 2006); full reproductive competence would have been achieved in concert with the psychosocial maturation required for function as an adult within society. The subsequent occurrence of agriculture and settlement, and the attendant negative outcomes of childhood disease and postnatal undernutrition, resulted in the delay of puberty onset, but again this would have been matched to the increased complexity of society. However, the age at menarche has fallen in Europe from a mean of 17 years around 1800 to about 12 years now (Gluckman and Hanson 2006).

    Agriculture is associated with a higher age at menarche, not a lower one. The lives of modern hunter-gatherer peoples cannot be divorced from the fact that they are part of the modern world and subject to marginalization and colonialism in various ways. They are, first and foremost, modern people and not an infallible window into history.

    The age at menarche of 17 at the start of the 19th century is a particular high-mark, not indicative of all human history. As many laws were based around adulthood beginning at puberty, it’s clear that in many places and at many times the age fell back to closer to that paleolithic norm. (And even then, people weren’t typically marrying twelve-year-olds.)

  51. Lofty says

    If a thousand people engage in a million sex acts that result in 1001 fertile kids, on average the population will increase. Plenty of scope for variation in sex acts.

  52. chigau (違う) says

    The Mellow Monkey

    The lives of modern hunter-gatherer peoples cannot be divorced from the fact that they are part of the modern world and subject to marginalization and colonialism in various ways. They are, first and foremost, modern people and not an infallible window into history.

    Quoted For Truth.
    With bells and a neon sign.

  53. hyrax says

    Ugh. I can’t believe that everyone who makes these arguments– and the “why should I pay for your birth control you whores” and “well if you didn’t want a baby you shouldn’t have had sex” arguments– haven’t noticed that the primary reason humans have sex is not for reproduction! I mean, unless they’re all like the Protestant couple in The Meaning of Life (“Well we’ve got two children, and we’ve had sexual intercourse twice!”), you’d think they would have picked up on the fact that most of the time when even the most fertile of hetero couples has sex, it doesn’t result in babby. I mean, the whole idea of consummating a marriage is predicated on the assumption that sex helps cement some sort of bond between people. We really need to get the idea that sex is all about passing on genes out of the dominant cultural understanding. It’s obviously not, and this misconception is proving to be the basis of some pretty harmful ideas.

  54. L David Recker says

    I have come to wonder that if there is a evolutionary basis for (male) homosexuality that it is more epigenetic than genetic. Perhaps related to an unmethylated X-chromosome which may be tied to higher fertility rates in women.

  55. chimera says

    What is all this nonsense up-thread about making babies before 1979 requiring penis in vagina sex? All you need is a turkey baster.

  56. says

    Since homosexual behavior is common in many other species besides homo sapiens, it strikes me that it must have some sort of evolutionary advantage to the species, if not the individual, or it would have likely been selected against long since. This seems to be true of both social and non-social species.

    That it is seen in many other classes, beside just mammalia, suggests that the advantage is broadly applied. We may not have figured out WHY it exists, but that it does, suggests at minimum that there is no evolutionary disadvantage, and that it exists across as many classes of animals, suggests that there is an advantage that we just haven’t figured out yet.

  57. says

    Chigau:

    I read timgueguen way up at #6 as meaning a time much longer ago than 1979.

    Yeah, so did I, but it’s still bleedin’ wrong. Serious wrong.

  58. What a Maroon, oblivious says

    That’s how I think of homosexuality. It just is. It’s there. It’s a trait. Hello. And move on.

    This.

    Steve Goodman said just about all there is to say about people’s sexuality (can’t find a version of him singing it, this is the best cover).

  59. says

    Course, you could always freak everyone out by suggesting that preference is at least partly cultural, that hard line heterosexual, or homosexuals are, to some extent, on the “edges”, while there is really a huge overlap. The fact that this overlap appears in women more.. well, Just read the book “Bonk”, and one of the odd things that is pointed out is that women “tend” to have a disconnect between physical arousal, and emotion. This means they may have a physical reaction, but not an emotional one, and tend to be more worried about the latter, than a former. Men.. connect very strongly their emotion with their physical arousal. So, to have either, in a context they have learned to see is fundamentally wrong, it seems to me leads to a lot of negative, sometimes even violent denials. So, what of the connection was looser for guys, and stronger for women, between their physical and emotional states? What if the guy could derive attractive emotionally, without needing the physical so much, or women had a clearer idea what their own bodies where doing, in reaction to stimulus? What would the picture look like then?

    My suspicion, just purely from the amount of “experimentation” that has been done in some cultures, even high level, uppity up ones, in some cases, between the same sex, of both sexes, when the opposite sex wasn’t available, that the result is probably closer to a double hump, just like with other attributes. Their may be a natural drift in attraction, that make heterosexual, but without the societal skewing that happens, from early on, it would contain a lot of wiggle room.

    Now, that hypothesis would actually, imho, make damn sense. All the, “Nature is driven by competition, so homosexuals are unnatural”, vs., “Homosexuals keep species growth in check.”, are both batty. They ignore the actual data, period. They ignore how people’s very reaction to failing to conform skews the results, and always had, or, otherwise their wouldn’t be so many “coming out of the closet”, including people married, with kids, because that is what they where “supposed to be”, not what they are. It ignores the fact that it doesn’t keep jack all of anything in check, and that it couldn’t happen, at all, if there was some hard wired on/off switch, for attraction. It makes far more sense if there is a wide overlap, where hetero is maybe “more likely”, or may only, Zod forbid, only “appear to be”, without the cultural drives in place to skew the results, and that far more would fall “between” the extremes, if such behavior wasn’t, ironically, even more disdained than full on homosexuality (there are, after all, according to dang near everyone with an axe to grind on the subject, and no real clue, no ‘bi’ men. Though, they grudgingly admit there might be some women that way, as long as it means they might get to sleep with some of them…)

  60. azhael says

    Why do people who know nothing about biology and its diversity always use it to justify their narrow prejudices?

    I really think it’s extremely silly that even though we observe variation in almost every trait, even in single locus, relatively simple ones, there are people who totally expect a trait about brain physiology that is dependent on a large number of genes and affected by complex hormonal influences, to have only one phenotype distributed among billions of individuals and millions of species, with no variation whatsoever…everybody a 100% straight , as if that was even remotely a realistic possibility.
    Plus, if our friends the bonobos have taught us anything is that bisexuality is adaptive. :P

  61. azhael says

    Pffffff, where the fuck is my head…that should be “single gene” not “single locus” and thousands of species rather than millions…..
    Ok that’s it, i need coffee….

  62. Anton Mates says

    Mellow Monkey @56,

    The Gluckman and Hanson paper is behind a paywall, but:

    Gluckman and Hanson’s hypothetical paleolithic norm for the age at menarche (7-13) is actually based on developmental data from chimpanzees, tweaked by a rather arbitrary factor that’s based on differences in tooth eruption timing between chimpanzees and humans. They also argue that paleolithic humans would not need more than 13 years to become socially functional adults, because their societies were “simpler” than modern ones. Additional evidence is needed for both hypotheses, to put it mildly.

    The trend of decreased age at menarche with increased urbanization is worldwide–documented in Brazil, Cameroon, South Korea, Japan–and I don’t see much reason to think that it only happened to begin right around the time we started gathering decent demographic data. Gluckman & Hanson’s idea that menarche peaked in the 19th century doesn’t seem to have been widely accepted by anthropologists, so far as I can tell–but I’m not an expert. Maybe I just haven’t found the right papers.

    The lives of modern hunter-gatherer peoples cannot be divorced from the fact that they are part of the modern world and subject to marginalization and colonialism in various ways. They are, first and foremost, modern people and not an infallible window into history.

    Oh, absolutely. The question is whether a better window exists by which to examine this particular question. There’s no accepted osteological marker of menarche, AFAIK. So for societies before the 1800s, we have to rely on statistically iffy estimates by contemporary medical and legal authorities–and of course even those sources are unavailable for preliterate cultures. In light of that, modern hunter-gathers may provide the best data we’ve got.

    Also, marginalization does not necessarily have a unidirectional impact on the rate of maturity. The !Kung are by most standards more marginalized and more threatened by disease and malnutrition than the Hadza, but they actually have a lower age at menarche. (If I recall my behavioral ecology correctly, you expect more rapid maturity in populations where adult mortality is high relative to child mortality.

    As many laws were based around adulthood beginning at puberty, it’s clear that in many places and at many times the age fell back to closer to that paleolithic norm.

    Those laws tended to be crafted for the benefit of the upper classes, though, and should be treated as indicating a lower bound on the age of menarche, since their purpose was to get women safely married away before they were likely to start producing illegitimate children. Case in point: Roman law defined adulthood for girls at age twelve, but Roman doctors (who were themselves examining an exceptionally healthy section of the population) reported a typical age at menarche of fourteen, with very few girls reaching it earlier. Ancient writers actually commented on the mismatch between the age of marriageability and the actual age of reproductive competence.

    (And even then, people weren’t typically marrying twelve-year-olds.)

    Nope, but marriage is a poor proxy for the beginning of sexual activity–particularly in egalitarian foraging societies, which (again, in modern samples) tend to feature a lot of sex play between older children and premarital sex among adolescents. Such societies have relatively flat distributions of wealth and there’s not much material stuff to inherit, so they’re a lot less obsessed about virginity and premarital abstinence.

    Not that most twelve-year-olds have actual intercourse in any society that I’m aware of! But adolescent hunter-gatherers do start engaging in sexual activity years before they’re likely to actually conceive.

  63. The Mellow Monkey: Singular They says

    Anton Mates @ 71

    The question is whether a better window exists by which to examine this particular question. There’s no accepted osteological marker of menarche, AFAIK.

    The calcification of the iliac crest occurs at roughly the same time as the onset of menstruation. The hand phalangeal epiphyses fuse at around the same time as well. Skeletal age depends on sex steroid levels and physical development rather than chronological age. It’s nailing down chronological age that’s more difficult, not menarche.

    Mary Lewis, Janet Montgomery, and Fiona Shapland have been doing some fantastic research into identifying pubertal stages in skeletal remains. They have a sample size of 2422 individuals aged 10-25 from 1125-1598 AD in England, which is the largest group of adolescent skeletons ever studied on record. It’s fascinating and might give better insight into the study of adolescent remains in general.

    Those laws tended to be crafted for the benefit of the upper classes, though, and should be treated as indicating a lower bound on the age of menarche, since their purpose was to get women safely married away before they were likely to start producing illegitimate children. Case in point: Roman law defined adulthood for girls at age twelve, but Roman doctors (who were themselves examining an exceptionally healthy section of the population) reported a typical age at menarche of fourteen, with very few girls reaching it earlier. Ancient writers actually commented on the mismatch between the age of marriageability and the actual age of reproductive competence.

    Is it really fair to describe that as marriage without qualification, though? That word will imply things that weren’t true of those arrangements in general. Their “marriagability” was more akin to being available for betrothal or promise, with the actual consummation not occuring until the bride was determined to be physically mature enough to handle pregnancy. This same pattern was occasionally repeated in western Europe in later centuries, with the nobility wanting to get their daughters secured in marriage without getting them killed during their first pregnancy and making the political benefits of the match moot. And losing the dowry! They had financial and political incentives to ensure their daughters weren’t getting pregnant too young, if not emotional ones.

    Nope, but marriage is a poor proxy for the beginning of sexual activity–particularly in egalitarian foraging societies, which (again, in modern samples) tend to feature a lot of sex play between older children and premarital sex among adolescents.

    And, as you say, this is a modern sample. These complex, modern people aren’t living fossils and not an ideal of historical human sexuality. Considering that the vagina grows in length, begins to lubricate, thickens its walls, and becomes more elastic in the presence of mature levels of hormones, it’s simply not physically prepared for intercourse prior to maturity.

    But adolescent hunter-gatherers do start engaging in sexual activity years before they’re likely to actually conceive.

    And is sexual activity synonymous with PIV intercourse? Reading about the Hadza courtship customs–since you mentioned them specifically–I rather doubt it.

    The Hadza: Hunter-gatherers of Tanzania by Frank Marlowe

    Hadza girls and boys begin “playing house” literally, building little grass huts, around the age of 7 or 8. There is some sex play when they enter the huts. Sometimes sex play among children occurs in full view of everyone; sometimes it is between children of the same sex.

    After girls reach menarche and when boys are 17 or 18 years old, they begin to have sex.

    I cut out the descriptions of the kinds of sex play the children were engaging in (in this case, they were two girls), but it’s pretty clear that “sex play” is not synonymous with PIV intercourse here and that, in fact, PIV intercourse is delayed until after menarche. Some form of sexual contact between childhood peers isn’t unusual, but that’s not the same as the statement you made that I took issue with.

  64. throwaway, never proofreads, every post a gamble says

    I thought it was pretty cool to think that we’re a finely structured colony on the micro scale. Something like a Mgalekgolo. It gives me a strange mix of existential crisis and the numinous to think of this in conjunction with the scale of our universe. Everything is just fucking weird to me now. There is no wrapping my head around the strangeness of being. I wish more people were preoccupied with such, that way they’d have less time to moralize about the meaningless sexual activities of people they do not know.

  65. Esteleth is Groot says

    The writings of Medieval and Renaissance nobility/royalty on the topic of their weddings is somewhat revealing. These are girls who would have been amongst the best nourished (it is known that malnourishment delays puberty) and would have gotten the best medical care.
    Many were, indeed, married at ages that seem gross today – ten, twelve. But few of them became mothers that young. A girl might be married and delivered to her husband, but her husband was expected to wait until she was “old enough” (and this was understood to be dependent on her physical maturation and not simply an arbitrary age) before the marriage was consummated. Between the time of the engagement – which could feature either or both parties being in their cradles – and the consummation (which was itself definitely seen as a separate event from the wedding) there were often a flurry of letters going from the parents discussing in frank terms the physical development of the young couple and thus when the consummation could be reasonably expected and planned for.
    Here’s a handful of examples, all from the same extended family:
    In November of 1455, twelve-year-old Margaret Beaufort married Edmund Tudor, who was ten years her elder. He was dead a year later, and Margaret was pregnant. This was seen as scandalous in their own time, as Margaret’s small stature and relatively undeveloped body was well-known. That she almost died in childbirth had no more children by her subsequent husbands was directly ascribed by her contemporaries to Tudor getting her pregnant before her body could handle it, thus risking her life and damaging her body so badly that she couldn’t have future children.
    Margaret had two granddaughters who survived childhood: the sisters Margaret and Mary Tudor. Both were engaged as very young girls, but were actually delivered to their respective husbands (James IV of Scotland and Louis XII of France) at fourteen and eighteen, respectively. Their grandmother’s influence is specifically cited as holding up Margaret’s wedding until such time that the girl was judged to be sufficiently developed. For what it’s worth, Margaret Tudor’s first child was born when she was seventeen, meaning that either she and James tried unsuccessfully for three years, or that they waited.
    Margaret Beaufort’s grandson, Arthur Prince of Wales, married a Spanish princess, Catherine, in 1501, when he was fifteen and she sixteen. He died within six months of the wedding, at which point it became very important to determine if Catherine was still a virgin or not.

    So within the span of 50 years, in a single family, we have a twelve-year-old getting married and impregnated, with accompanying tongue-clucking over how she was too young; a fourteen-year-old getting married (and the wedding being delayed until she was that age by concerns over her physical maturity) but not having a child until she was seventeen; and a sixteen-year-old marrying and there being open questions as to whether or not she and her husband had slept together or not. All of which is to say that people in pre-modern societies that practiced child or adolescent marriage did not necessarily see “is of marriageable age”/”is past menarche” and “is ready for sex and parenthood” as synonymous.

  66. David Marjanović says

    and all that matters is whether the population persists

    It doesn’t “matter”. If the population persists, it persists; if it doesn’t persist, it doesn’t persist; that’s life, shit happens, yadda yadda.

    Whether the population has persisted matters in hindsight, because it’s one factor in shaping the present state.

    “Homosexuality” is simply a variation of other aspects that humans

    Stop right there. :-) Trying to explain homosexuality by looking only at humans is like trying to explain why “the dinosaurs” went extinct by looking only at dinosaurs! Every vertebrate species that has been observed for long enough has exhibited homosexual behavior – last time I came across a number, it was 400 species, and I’m sure it’s growing.

    Homosexuality is simply falling in love with

    Romantic and sexual orientation line up for most people, but not for all.

    Does that help? My expertise in population genetics sometimes causes me to speak in impenetrable jargon, I know.


    That is all.

    Considering how redheads have been treated throughout history, it could not be seen as any sort of advantage.

    That’s a very small part of history, small in both time and space.

    women “tend” to have a disconnect between physical arousal, and emotion. This means they may have a physical reaction, but not an emotional one, and tend to be more worried about the latter, than a former. Men.. connect very strongly their emotion with their physical arousal.

    …Do I need to read the book to find the evidence? It’s clear to me that few people are 0 or 6 on the Kinsey scale (among those who fit on it at all), but I’m sure there’s a less convoluted, more parsimonious explanation…

  67. Esteleth is Groot says

    women “tend” to have a disconnect between physical arousal, and emotion

    Let me assume for the sake of argument that I accept this factoid as true.

    For women, becoming physically aroused (specifically, increasing vaginal secretions) can be a defense mechanism that protects her body against harm if she is being raped (lubrication!). This does not mean that she wants to have sex at that exact moment, or with that person.

    So, that could be less a “just so” story that rationalizes some consensual sexual practice or another and more a “here’s a way that women have developed methods to protect themselves from harm.”

  68. The Mellow Monkey: Singular They says

    Esteleth @ 74

    In November of 1455, twelve-year-old Margaret Beaufort married Edmund Tudor, who was ten years her elder. He was dead a year later, and Margaret was pregnant.

    While I was familiar with the other figures you mentioned, I didn’t know about Margaret Beaufort being so young. I’m surprised, considering my interest in this topic. I clearly need to brush up on my Tudor history more!

  69. Esteleth is Groot says

    When I learned it, I was also surprised, Mellow Monkey: and an examination of the dates just further emphasizes it:
    Margaret Beaufort was born May 31, 1443. The wedding was November 1, 1455. Tudor died in November of 1456.
    Their son, Henry VII of England, was born on January 28, 1457 – meaning that the conception happened in April or May of 1456.
    Which means that Edmund wasn’t exactly waiting for anything.

  70. The Mellow Monkey: Singular They says

    Esteleth, yeah, it’s very striking. Little wonder she never had another child and it’s a surprise she and Henry VII both survived. Ew, Edmund. Ew.

  71. Esteleth is Groot says

    Yeah, I read something about the marriages of Margaret and Mary Tudor that commented that despite Margaret being promised to James around 1497 or so (she was born in 1489, so she was a whopping eight years old), the wedding contract wasn’t signed until 1502, and she was actually sent to Scotland in 1503. Her grandmother was known to be heavily involved in the negotiations and planning, and specifically was recorded as worrying that “the king of Scots would not wait, but would injure her.”
    My reaction to the elder Margaret being thus “worried” kinda, uh, makes sense when seen in the light of her personal history.
    Her sister Mary was initially engaged at a similarly young age, with plans for her “delivery” when she was fifteen or so. But that marriage fell through (read: her father got in a diplomatic pissing match and the wedding got cancelled) and she was eventually married at eighteen to Louis in 1514. This was at the time regarded as a bit of a joke, as Louis was in poor health and publicly assumed to be impotent. He died three months after the wedding, and the contemporaneous joke was that the stress of trying to consummate his marriage killed him. As he had no sons, the Orléans branch of the House of Valois died with him and his distant cousin François of Angoulême inherited the throne. Mary came back to England, married the man of her choice (to great scandal, as he was of common birth) and proceeded to be generally badass until she died.

    In general, the Tudor men seem to be a not-so-nice grasping assholes. The Tudor women seem to be stubborn, fiendishly smart, and badass. Fascinating family, in a generally soap-operaish manner.

    Um, this has rather drifted off-topic. Sorry about that.

  72. says

    Let me assume for the sake of argument that I accept this factoid as true.

    For women, becoming physically aroused (specifically, increasing vaginal secretions) can be a defense mechanism that protects her body against harm if she is being raped (lubrication!). This does not mean that she wants to have sex at that exact moment, or with that person.

    Uh.. Wait, what? Is this like the a mirror universe version of, “you won’t get pregnant unless you enjoy it.”? First off, this isn’t some “factoid”. The whole book is about “current” research into human sexuality that is on going, and everything from methods used to treat problems, to new MRI research into what actually goes on during it. The reason they know there is a fundamental disconnect is, and I quote, “Women, while thought to be non-visual, start producing lubrication, increasing blood flow to the genitals, and all the rest, even when watching videos of other animals making out, not just humans. And yet, they **report** no arousal to such images.” Are we to presume that, in the ancient past, they needed to become “lubricated”, on the chance that they might be raped by animals? Heh, maybe men get hard when physically stimulated, regardless of their desire or attraction, “in case” their partner intends to rape them too?

    I already pointed out that women, despite what their bodies are doing, “Do not necessary want to have sex, even though their bodies are doing things that imply they might want to.” My argument is **purely** that men are more aware of these physiological effects, and rightly or wrongly, tend to connect their mental state with their physical state more directly, such that they may, perhaps, convince themselves of having desire, where there isn’t? But, the other possibility is, there may be some “limited” desire anyway, which women are less aware of. But, the key word there is **limited**. It means that awareness of the physical reaction could increase the odds of developing a mental desire, as reaction to it, in some cases. It would mean that, for women, visual would be just as important as it is for guys. This isn’t the same things as wanting to immediately jump someone, just because you get the female equivalent of a hard on, any more than guys want to jump everyone when they have one (well, not most anyway).

    But, seriously. We don’t do evo-psych just so explanations here, and your, “Its a defense mechanism”, given the conditions under which its been witnessed (i.e., with even videos of animals doing it), is just.. disturbing, if it made any sense at all. The point here is that men and women have nearly the same physiological responses. Men, ironically, despite seeming to be more “visual”, do not *generally* react to non-human videos of sex. Women do, which is down right strange. The explanation has to come from some place, and the prevailing theory, supported by evidence that this is in fact the case, is that men as very aware when they become physically aroused, while women are not, and this, ironically, means that men react to just about any nude photo, of people, you can give them, and are completely aware of the fact that they are, while women, have no clue they are, even when reacting to stuff that it makes no sense, at all, they should become aroused by.

    None of which constitute “factoids”, but research results. Very strange, odd, results, but born out by repeated studies. Unlike your odd assertion that watching a wildebeest bang its mate would “prepare” a women against being the next one it comes after, or what ever your hypothesis actual is.