The Third Sex

There isn’t one. But you have to admit that it would be interesting if there were.

There are all kinds of different twists on basic biology that would make for a different kind of society, if they only existed in humans. Some of these have been talked about a lot, served as the framework of various science fiction novels, etc. Most have not, because not many people know the biology – including most biologists.

Bees, wasps, termites, aphids, ambrosia beetles, naked mole rats, and a few species of parasitic shrimp are eusocial. That is, they cooperate in taking care of the young, overlapping generations live within a colony, and there are reproductive and non-reproductive castes. Usually, there is a single shared living space which is protected by some of the non-reproductive castes – the Place That Must be Defended.

Are humans eusocial? They do cooperate, sometimes – but in truth they’re not at all like the social insects. E. O. Wilson thought so, but then he’s kind of dim. No castes, no reproductive division of labor, while most cooperation is with non-relatives. I’ve certainly seen SF stories with this theme – Big Sword, Rogue Queen

Some pinheads have suggested that male homosexuals are a kind of caste, one that pays its genetic way by helping their sibs raise more kids. As far as I can tell, this idea originated with a student of E.O. Wilson. Since homosexual men do not actually support their sibs noticeably more than straight men, this is silly. If you’re to invoke a behavior in support of some evolutionary hypothesis, the behavior has to actually exist. I shouldn’t have to say this. I could say that you expect mothers to work hard to take care of their offspring, because of kin selection, and because basic biology in mammals already requires that a female invest heavily in every offspring (not the case for males), etc, etc: but mother love ACTUALLY EXISTS.

One might as well talk about homosexual men as a natural soldier caste, born to die defending the nest. But they aren’t like that, don’t act like that, even counting the Sacred Band. And humans, especially in the old hunter-gatherer phase, didn’t usually have fortress-nests.

There are a lot of interesting twists in eusocial species that would make for even more interesting societies. There are harvester ants with two kinds of reproductives: females are AA or BB, males are A or B, but workers are all AB. It looks as if this is the residual of hybridization of two species. Apparently these ants have harnessed hybrid vigor, way before we invented mules.

There are cytoplasmically-transmitted thingies (microorganisms and rogue DNA) that distort sex ratios. Wolbachia infects many insects, and causes weird shit like male killing, parthenogenesis (curable by antibiotics), cytoplasmic incompatibility, and sometimes turning genetic males into functional females. Anything like this in humans? No, but it sure would be interesting if there were. Actually, cytoplasmic maternally-transmitted thingies might exist (they would probably be mutualistic), but if they do, they they don’t cause sex ratio distortion or parthenogenesis – we would have noticed.

Wood lemmings have two kinds of X chromosomes, X and X*. X* chromosomes ensure that the embryo is functionally female, whether the other chromosome is an X or a Y. So XX, X*X, and X*Y individuals are female, while only XY individuals are male – and are about 25% of the population. Sounds like a Beach Boys tune.

Some hybrid creatures, like our state lizard, are completely parthenogenetic. Again, that would make for a wildly different society. Virgin Planet, by Poul Anderson.

Many species have several different kinds of males (a few have different kinds of females as well). For example, a lizard species in California has three different kinds of males – aggressive orange-throated guys that successfully dominate blue males, sneaky yellow guys that get past orange males guarding a big territory, and blue mate-guarding males (that are also cooperative – possibly a green-beard gene) that successful guard females from sneaky yellows. The population frequencies oscillate: scissors, paper, rock.

Ruffs (birds) have three kind of males: territorial males, satellite males (literally ‘wingmen”, about 16% of males), and sneaker males ( ~1% ) that look very much like females. If we were like that, life would be complicated, but at least you’d know where you stand. I don’t think that anything similar exists in humans, though: right now there isn’t really any evidence that variation in human personality traits is adaptive, although it might be. Even if nonadaptive, it can be useful: you hire OCD guys for security and quality assurance, nymphomaniac receptionists, etc.

It’s not impossible that different Y-chromosomes have some effect on fitness in humans – they can influence behavior in mice – but again, no evidence for it right now. Never seen a story based on male morphs, but I haven’t read everything.

Green-beard-genes, originally suggested by Bill Hamilton, would modify appearance in a specific way and cause bearers to cooperate with others that bore the same allele. something like this occurs in fire ants: those with one version of a supergene have single-queen colonies that are hostile to each other, like Greek city-states, while those with the other version have multiple-queen colonies that extend indefinitely, rather like Los Angeles. In humans, a green-beard would probably rapidly lead to world conquest: perfect asabiya would be unstoppable. One more interesting application of CRISPR.

A species can have a weird genetic substructure, which may be hidden. Mice mate with mice that have dissimilar MHC alleles. Do people? Since it is a really fun idea, while the results of studies are mixed – probably not. Likely it’s all wishful thinking. It could be true though, or might be true in some populations.

White-throated sparrows fall into white and tan morphs with different behaviors. White males are highly promiscuous, while tan morph males are monogamous and contributed more to caring for offspring. The pattern is similar in females. In practice, practically all mating involves a male from one color morph and a female of the other color morph: effectively, this sparrow has four sexes. A similar pattern in humans would, I think, drive us all crazy.

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144 Responses to The Third Sex

  1. Among other SF stories with the themes you describe, there is Hellstrom’s Hive. It revolves around a German scientist who has created a colony of ant-like humans, which involves entirely infertile females which serve as a working caste, and which are implied to be haploid. Breeding is done with a different caste of females, so-called “breeding stumps”. Which are basically what they sound like.
    https://en.wikipedia.org/wiki/Hellstrom%27s_Hive

    Imagine the descriptions of the smells of a thousands-strong hive like this, operating on 20th century technology. Haunting stuff.

    I wonder what society would look like if there was some recognizable gene, or complex of genes – say, a green beard, a beak, a mode of speaking, style of surname, etc – which tended to have the bearers engage in nepotism and cryptic cooperation with one another, and against the surrounding society. Someone should write scifi about this wacky idea, and how an intelligent society might resolve such a difficult question.

    • Cpluskx says:

      ”which tended to have the bearers engage in nepotism and cryptic cooperation with one another, and against the surrounding society”

      Gulenists in Turkey were just like that.

    • melendwyr says:

      That’s an fairly inaccurate description of Herbert’s book.
      For example, the workers aren’t haploid females, they’re men and women who have been chemically neutered. The leader caste is derived from the workers by being fed special foods and hormones.
      Breeding stumps are explicitly both male and female, and they’re a secondary supplement to the Hive’s primary method, which is a straightforward breeding class. They’re made when a valued breeder becomes critically injured, or with captured outsider humans that are thought to have important traits but cannot be adapted to Hive life.
      I highly recommend the book as food for thought, but I think you should go reread it before recommending it yourself.

    • Eikos says:

      “Someone should write scifi about this wacky idea, and how an intelligent society might resolve such a difficult question.”

      Someone already did.

  2. A wacky idea indeed, given that just holding the wacky idea and encouraging that idea in others would be enough to engender nepotism and cryptic cooperation, so long as the idea is wacky enough, and makes big promises. Is Trooog your first name or your surname, and if so on you mother’s or your father’s side?

  3. Understood. I will send all your details to the Ecuadorian Embassy, London, who deal with such matters.

  4. Henk says:

    Homosexuality as a eusocial adaption would predict that homosexuals are about as healthy, intelligent, and productive as their straight brothers. However their productive output is used, it wouldn’t make sense to compromise it.

    Apart from modern consequences of the San Francisco lifestyle, this seems to be the case.

    Contrast with narcolepsy or schizophrenia.

    • ckp says:

      that’s a pretty big “apart from”

      • Henk says:

        The San Francisco gay lifestyle is a crash space.

        • albatross says:

          It’s important to remember that the effect of being gay or lesbian over most of history was probably not very close to what you see now in gay communities in modern Western cities. That’s as natural as women having sex with lots of men and never getting pregnant (also something you can find in modern Western cities, thanks to birth control).

          If being gay in a more traditional society means you get married and have kids, but don’t go out of your way to slip any bastards in on your neighbors, that’s probably still a fitness loss, but it’s a smaller one than the modern version. If it means you never really have an interest in girls at all, then it’s a big fitness cost. And you still see the pattern of guys who marry, have a few kids, and then come out as gay (having slept with men occasionally for many years) in their 40s. That’s worse for your genes than marrying and having occasionally slept with other women for many years, but it’s not a complete dead-end.

          I wonder if being a lesbian had much fitness impact, historically. A man who’s married and having a few kids with his wife can also add to his fitness substantially by slipping the odd bastard into his neighbor’s wife, or by raping the odd member of an enemy tribe when he goes off to war; even a gay man who marries for social-pressure reasons will have little interest in those extracurricular activities. (He’ll be sleeping with the male neighbors and raping the male enemies, with no offspring produced.)

          By contrast, a woman’s fertility is limited by her resources and the need to bear and nurse her own kids. A woman inclined to lesbianism who also marries under social pressure, and who reluctantly has sex with her husband often enough to have a full brood of kids, has the same fitness as a woman who has sex with her husband, the neighbor, the milkman, etc., with more enthusiasm. She still can only process so many kids through her uterus, can only nurse so many kids, etc. I wouldn’t be shocked to see a genetic basis for lesbianism, though I’ve never heard of any evidence for that.

          • gcochran9 says:

            The idea that being uninterested in women wouldn’t have had much impact on fitness in the good old days is widespread. It is also stupid. Is there some common source, some book or essay that says this silly thing?

            • R. says:

              I’ve heard some heartbreaking stories about how a woman marries some dude, they have kids, and then he founds out he’s gay and it all ends badly.

              This in a place where no one’s setting gay people aflame or confiscating their property so social consequences are not that severe.

              Is it hard to imagine that gays would just shut up about their feelings, dutifully try to get a few more kids to help out with farming and so on, in a society which punished homosexual behavior?

              • gcochran9 says:

                I don’t know everything.

                But I know that lots of people in the past, for example in Europe in 1600, never married, had almost no kids. I think that being uninterested in women would have greatly increased your probability of ending up in the unmarried fraction.

                Studies of Y-chromosomes suggest that this was generally true of the human race: significantly fewer men than women reproduced.

                Other guys are willing to fight over women, not just Helen. If you’re not interested, why bother?

                In other words, your picture of the past seems completely wrong. One might just as well talk about all the people that maintained a normal weight while never getting hungry.

                Of course, as far as I can tell, college does its level best to instill a completely wrong view of history and human nature in every graduate. A typical Harvard man might agree with me that it’s a bad thing to have a safe fall on your head, but I’m not even confident of that.

              • Sandgroper says:

                When I was a kid, when homosexual practices were illegal and when a man getting caught screwing another guy in a public toilet would lose him his job and probably also put him in prison for a while, there were guys that people referred to as ‘confirmed bachelors’, i.e. men that chose never to get married. They were quite common. Not hugely, but everyone knew a few such people, and might even have had one of them in their family.

                I know one ‘confirmed bachelor’ now, but he isn’t gay – he has had a progression of live-in girlfriends who have each lasted for a fair length of time, before they got fed up with him not marrying them and decided to move on. He could have married any one of them, but didn’t. No idea why, and not my business to ask him. I have never seen the slightest evidence that he swings both ways, and would bet money against it. OK, sample of one, but it means that the number of hetero-normative males who consciously elect never to marry and reproduce is not zero.

                But I fancy that when I was a kid, quite a few of the ‘confirmed bachelors’ were actually gay. It was hard to tell in those days, because the smart gays would have kept it very, very quiet. Even so, two of the teachers at my secondary school lost their jobs for being caught out engaging in homosexual activity. You would think they would have had enough brains to avoid detection, but no.

              • R. says:

                I think that being uninterested in women would have greatly increased your probability of ending up in the unmarried fraction.

                Here, in the past, people married someone their family chose for them, not out of love. In what passes for my nation’s past literature, there is a good deal of angsty moaning about this. Very boring, especially the ones written by women.

                Note that I didn’t and I don’t disagree with your theory that homosexuality is not genetic, but caused by something else.

                However, what if the instinctual desire to have children is not inextricably entwined with sexuality? Is there such an instinct in men, or is it all simpler? Are lesbians overwhelmingly stony faced when shown some some babies?

                Of course, as far as I can tell, college does its level best to instill a completely wrong view of history and human nature in every graduate. A typical Harvard man might agree with me that it’s a bad thing to have a safe fall on your head, but I’m not even confident of that.

                Closest I’ve been to Harvard was, I believe, almost getting killed near it because of a pothole. I didn’t expect Boston roads to be as atrocious as Bratislava’s. I don’t think I’ve ever personally listened to a humanities academic, neither in university nor among family or acquaintances.

              • jasonbayz says:

                My hypothesis is that they, the individuals who if time transported into the modern era would be gay, wouldn’t be “uninterested in women.” Sexual interest, like hunger, is a pretty strong force, so strong that if you throw a group of heterosexuals in prison, a type of “homosexuality” will develop. In the environment faced by your typical European peasant, his world was much smaller than ours is today, he’d rarely leave his home village, he’d be illiterate, and he may have never heard of the idea of homosexuality, certainly he’d have a hard time practicing it.* I think the large majority would turn out “heterosexual.” Their sexual desire would be less than the general population, but is that necessarily a bad thing? With hunger, a motivation to go get food will always be good. But a too-strong desire for sex might get you killed, as it did to Paris, the guy who abducted Helen. Imagine a tribe where a few older hunters monopolize the women. Brother A has a strong desire for sex, so strong that he tries to cuckold one of the hunters and ends up thrown off a cliff. Brother B simply waits for the day when the hunter comes home with an arrow through his chest. A healthy medium is the ideal configuration, with a strong enough sex drive to do what’s necessary to get sex but with the ability to be patient and “wait your turn.”

                *You can say “family environment has no effect on homosexuality,” but that particular family environment hasn’t been tested. A boy growing up in a religious Christian family today knows how to read, has heard of homosexuality and is told by his school that “it’s okay to be gay.”

          • Gabriel M says:

            If only there was some institution that men uninterested in women could have joined that would have freed them from the social pressure to have children and allowed them myriad opportunities for furtive homosexual coitus.

            https://en.wikipedia.org/wiki/Clerical_celibacy#Other_religions

            Oh.

          • John Saunders says:

            I ran across an fMRI study of sexual arousal a decade+ back. It was conducted back when the standard in alternative sexualities was still LGB, not LGBTQWhatever. Males and females of various declared sexualities were exposed to sexual imagery, and their brains were monitored to see how the sexual arousal areas lit up.

            Results – male brains showed only activation for pure-heterosexual imagery or pure-homosexual imagery. Men who declared as bisexual lit up to one preference or the other, but not both; bisexuality was essentially a social/learned phenomena. This lines up with the observation that there are essentially two kinds of gays historically – bisexuals and pure-homosexuals. On the bisexual side you have Ancient Greeks and modern prison behavior; get the wife pregnant but also get it on with the boys in the baths due to social pressure or a lack of available females as options. On the pure-homosexual side you have men like Fredrick the Great – men so gay they are unable to lie back and think of Prussia to father an heir for the realm. The bisexuals are men wired pure-hetero or pure-homo who have learned to enjoy playing in the middle.

            Female brains showed a different activation pattern under fMRI. Females lit up as either pure-heterosexuals, or bisexuals. Women who declared as pure homosexuals had brains that lit up to one of the two observed arousal patterns. Pure homosexual brain activation was not observed in females, which makes sense as such women would be reproductive neuters. Its a pattern easily formed into a compelling just-so evolutionary tale, much like the student of E.O. Wilson asserting that male homosexuals are additional free producers for the family. Bisexual females would have additional pathways to resources to provide for their young. Whether that just-so story has any reality is another question.

            And human society does appear to have an analogue to yellow-throated lizards. Female-esque males that sneak past the protector males to get it on with the females. They were called dandies 120 years ago, and are called metrosexuals today. Whether this behavior is all social or has a genetic component in the human case is an open question.

    • misdreavus says:

      Were it not for antibiotics and anti-retrovirals, the average homosexual in the United States would have a life expectancy in the thirties.

      • Maciano says:

        Average or median?

      • Tom Bri says:

        If that. High school classmate of mine died in his very early twenties of AIDS, way back when the disease was new to the US.
        On the other hand, given current rates of venereal disease, without antibiotics, there would be a lot more sterility among straight folks too.

      • Yudi says:

        We’ve all missed you. What are the chances of your posting more often?

      • Mark F. says:

        I don’t know about that. Using condoms and/or avoiding anal sex can bring your risk down a lot. I’ve had about 300 sex partners with little health impact. Never have needed to take antibiotics or antivirals.

        • Tom Bri says:

          Never had one break? And in my much younger and much stupider days, got caught twice with chlamydia.
          OT, odd thing about Obama-care, all sorts of female contraceptives are covered, up to and including sterilization, but not condoms. The only method other than abstinence that prevents (most) VD. Interesting priorities, those Dems.

        • Misdreavus says:

          “Using condoms and/or avoiding anal sex can”

          Can

          1) Condoms have a significantly higher rate of failure during anal intercourse — especially if the insertive partner is “too small” or “too large” (which happens not infrequently), if the wrong kind of lubricant is used, if you are careless about opening the wrapper, etc. Compound the risk over hundreds of partners during a lifetime, with diminishing costs of intercontinental travel. It poses a public health disaster just waiting to happen.

          Last time I checked, there are still no prophylactics that are approved for anal intercourse by the FDA. There exist a few on the market, but from what I hear, they provide all the sensitivity of mylar gift wrap on your member. They also cost extra. Nobody ever wants to use them.

          2) By consensus, sex doesn’t feel anywhere near as good with a condom, and it most likely never will. Gay men are not famous for their ability to defer gratification, are they? Condom usage rates among MSMs in the US have gone UP since the early 1990s, not DOWN. Nobody cares what the CDC has to say — back in the 1980s/early ’90s, gay activists organized protests and sent death threats when the Feds tried to shut down the bathhouses. Yes, during the middle of a DEADLY EPIDEMIC. LGBTs weren’t even a protected class back then. So who, in the year 2016, is really going to care what bunch of breeder epidemiologists have got to say about anything? In my current social circle, you can hardly allude to these facts without facing social opprobrium.

          3) The gay pornographic industry has discovered that their profits are healthier when their actors do not use condoms. Nearly every single major studio now prefers to shoot “bareback” scenes — sometimes exclusively, when a decade ago, this was the exclusive province of weirdo fetish studios with “last resort” models.

          Currently, all the cool people are saying “condoms are so last century”. Kids don’t really listen to nagging dorks in lab coats.

          4) There are now smartphone apps that can show you how many registered (gay) users exist within a 50 mile radius, whether or not you may be interested in ****ing them, and whether or not the attraction is mutual. This is a hundred times worse than a bathhouse in every way.

          I really didn’t want to see the advent of super-super-AIDS in my lifetime, but now, the odds seem more likely than not. Looks like our civilization will have to learn the facts of life the hard way.

          “I’ve had about 300 sex partners with little health impact.”

          You don’t really know that, do you?

          How indeed do you know? It’s the ones who don’t know that harm the most people.

  5. Anonymous says:

    Beach Boys? All I hear is Jan and Dean.

    • Cpluskx says:

      You can’t smell from a Tinder picture but people find attractive peoples scent more attractive so if you like the pic you’ll probably like the scent too.

    • gcochran9 says:

      I don’t have any confidence at all in the “t-shirt smell” studies.

      If this happened there would be deviations from Hardy-Weinberg equilibrium. They don’t seem to actually exist.

      • albatross says:

        More to the point, this is exactly the kind of result that seems to get clobbered by replication studies, and that is afflicted by what Andrew Gellman refers to as the garden of forking paths. (Where you look at the data, and then decide what comparisons to make and what statistical tests to run, thus helping yourself to a huge amount of possibly-unintentional p-value fishing.)

      • Why would that deviate from H-W. Isn’t it just assortative mating? (e.g. its not as if everyone prefers the same smells). We get this in other critters (e.g. mice–although I have no idea how they get them to wear the T-shirts)
        Roberts, S. C., & Gosling, L. M. (2003). Genetic similarity and quality interact in mate choice decisions by female mice. Nature genetics, 35(1), 103-106.

        • gcochran9 says:

          “Assortative mating can be contrasted with disassortative mating (also known as negative assortative mating or heterogamy) in which individuals with dissimilar genotypes and/or phenotypes mate with one another more frequently than would be expected under random mating. Disassortative mating reduces the genetic similarities within the family. Positive assortative mating occurs more frequently than negative assortative mating. In both cases, due to the nonrandom mating pattern, there is a deviation from the Hardy–Weinberg principle. “

  6. st says:

    There had been a century long custom in Roma population to buy children from the given host population and rear them as their own – to use them as beggars later in life, within the host population. The reason is, these children were getting more tips for the locals and thus were more profitable than the genetic roma children. Call it racism or call it a green beard effect. If there is difference. In both cases, Roma at least believed that the effect was real and had been trying to benefit from that for many centuries.

    • j says:

      You can see that everyday in the media. The pictures of Yazidi women enslaved are blondes, to excite your compassion. The pic of Ethiopian (African) children used to solicit donations look like cute Europeans.

  7. Cpluskx says:

    Hybrid vigor superhuman is really the best and most likely superhero scenario.

  8. st says:

    But hey, that instant-conquest-of-the-world thing by the green beards; would not that go against game theory conclusions? Evolution would instantly favor a mutant, who has that green beard but not the associated with it with fitness costly asabiya and his offsprings will quickly become majority in the once victorious green beard gang, making a revolt or otherwise rising to power in the green gang, which no longer would be that victorious so the honorable green beard would become more of a burden than a sign of a membership in an uncrushable asabiya circle. I guess in the case, instead of invading the world, the green beards would start secretly shaving themselves to the last green hair.

  9. marcel proust says:

    Can you give a (not too technical) reference for the harvester ants you mention? Also, the wood lemmings. I’d like to read more. Thx

  10. teageegeepea says:

    Does the green beard effect really need to be based on appearance? My understanding is that most animal species rely less on sight than humans do.

  11. biz says:

    “Sounds like a Beach Boys tune.” -> I think you mean a Jan and Dean Tune, if you are referring to Two Girls for Every Boy

  12. The Z Blog says:

    Wait. If there is no third sex, then why am I required to choose from 58 gender options on Facebook? As a two-spirited, cisgendered male, I’m offended by this.

    As far as the possibilities, I think the way to come up with some interesting sci-fi possibilities is to break free of the male-female model. Imagine a species that requires three sexes to reproduce. DNA is a triple helix with the third strand functioning as a random modifier to increase variation. Then you could have a corresponding social structure based on biological function.

  13. please start a podcast 🙂

  14. spottedtoad says:

    I wonder if there are any species where two different types of hybrids regularly occur, depending on whether it was the male or the female with the A versus B genotype. Like Ligers versus Tigons but within the same species.

  15. albatross says:

    Niven’s Known Space series has Protectors, which have three sexes (two biological sexes from the same species, and then a host that’s a different species, into which the other two lay their eggs or whatever). And in Banks’ Player of Games, there is a three-sex species, with male, female, and apex sexes. (The apices receive genetic material from both males and females, and are also socially dominant in the rather nasty society in which they live.)

    IIRC, a lot of species of fungus have rather complicated sexual reproduction schemes, with many different sexes and a fairly complicated set of rules for who reproduces with whom. This link talks about some of this stuff.

    • albatross says:

      Arggh! Not protectors, puppeteers. Protectors are a different idea–super intelligent, super strong, sterile, and completely dedicated to protecting their offspring.

  16. Greying Wanderer says:

    soldier ants

    “One might as well talk about homosexual men as a natural soldier caste, born to die defending the nest. But they aren’t like that, don’t act like that, even counting the Sacred Band.”

    In humans i’d say soldier ants would be the end result of a process rather than in at the beginning i.e. if violence genes are a big thing among HGs and in settled socieities those genes gradually get culled over time those genes will most likely surive if they are paired with genes that provide restraint so you selection for the soldier ant type as an end product of civilization.

    Hence (imo) cop face

    or with the balance shifted slightly more to the violence soldier face

    personally i think it could easily be proved by doing a GWAS(?) study with three groups: cops, criminals and accountants

    you will find (imo) a collection of genes that cops share with criminals but not accountants and a second collection cops share with accountants but not criminals

  17. Greying Wanderer says:

    green beard gene

    “Green-beard-genes, originally suggested by Bill Hamilton, would modify appearance in a specific way and cause bearers to cooperate with others that bore the same allele…. (snip) … In humans, a green-beard would probably rapidly lead to world conquest: perfect asabiya would be unstoppable.”

    A lot of my relatives have dark hair and red beards – i don’t know but guess the result of only one copy of M1CR?

    So if there was a red “green-beard” gene and if it had the effect you suggest except after each conquest they married local so the effect diluted with distance from the source.

  18. RCB says:

    Impressive rundown.

    Even wackier: I think in Slaughterhouse Five, Vonnegut talks about alien species with something like 4 sexes. The really creative part is that all 4 sexes are required for reproduction, which must be a lot of fun. I’ve never heard of anything like that in the real world. One could imagine that any system that required a large number of sexes would be unstable: you couldn’t reproduce until you found one of each type. Any time there is a rarity of one time, population fertility drops rapidly.

    Alternatively one could imagine a system with multiple types of males, Y1 and Y2. I think the most likely outcome is that one of them will either drift to extinction… or get selected away. This isn’t unlike having males of two races competing for the females of one, I suppose.

    • gcochran9 says:

      William Tenn (Philip Klass) wrote “The Seven Sexes”, about a Hollywood producer trying to film a love story on Venus.

    • ohwilleke says:

      The virtue of needing all four sexes at the same time for reproduction would be similar to the benefits of the quirk present in hyena reproduction. When hyenas reproduce, both the male and the female must have the equivalent of an erection at the same time. This means that is it all but impossible to get a female hyena pregnant without her full consent, while in the wild, pregnancies of almost all other female mammals routinely occurs through rape or at least with lack of full consent from a male’s pressuring. It would be very hard to negotiate a reproductive session with four sexes at the same time without the prior consent and deliberation of all involved, and that would enhance the efficacy of conscious sexual selection by virtually eliminating the down sides of unplanned pregnancies from less than optimal partners. In a simultaneous four partner reproduction system, you are much less likely to go to a bar one night and get knocked up.

      There is also no good reason that four sex reproduction would have to be ineffective at producing a sufficient number of children, if stable plural marriages with one member of each of the four sexes were the norm. While it is true that “you couldn’t reproduce until you found one of each type”, there is no reason to think that an extended period of courtship leading to almost everybody ending up in a meta-stable reproductive group couldn’t happen almost as easily as our current system of courtship followed by meta-stable mating pairs. Despite the fact that it is possible to get pregnant from a one night stand, overwhelmingly not just now but for most of human history, most pregnancies arise during reasonably long term cohabiting relationships rather than from flings. As a thought experiment, I doubt that human fertility rates would take much of a hit if you could only get pregnant after you’d been exposed to your partner’s pheromones for six continuous months.

      Giving female hyenas great control over their reproduction, allows them to be choosier about potential mates and to select more carefully for traits that female hyenas find to be desirable in addition to the male selection for traits that males find desirable in a female. The result has been that hyenas have intelligence and social skills without a rival among African megafauna and are one of the only wild megafauna species in the world that is thriving rather than being threatened or endangered.

      • RCB says:

        Imagine that there’s a probability p that an individual of one sex is willing to enter a relationship with one of another. Then the probability that a selected pair will work is p^2: both have to agree (barring coercion, of course).

        For a group of 4, it’s p^12 (each of the 4 have to approve of the other 3). That’s a factor of p^10. If each such group produces a whole bunch of offspring, then maybe that’s not a problem for population survival (except that you will have a relatively small effective population size – i.e. lower than expected genetic diversity). Or, if p is near 1, no problem. But in that case, since very little choosiness is being applied, then the effect of mate selection for good traits that you mention is weak – most people are willing to accept anyone into the mating group just so that they can have kids.

        Actually, it seems to me that gang rape would be encouraged in this species. All you need is a group of 3 to agree (probability p^6), and they can probably easily coerce the 4th one – 3 on 1.

      • Bert says:

        “Consent” doesn’t necessarily mean intellectual consent after performing due diligence. It could easily mean arousal. A four-sex species might be promiscuous and sex-crazed (like the British “dogging” phenomenon gone mainstream) with low parental investment.

        • melendwyr says:

          I suspect that an alien species that required four sexes to reproduce would have some equivalent of ‘pon farr’ to bypass all that pesky cognitive activity and go straight to instinct.

  19. ohwilleke says:

    As albatross notes, some fungi, such as Basidiomycota fungi, have perhaps the most complex mix of sexual and asexual reproduction of any species on the planet. They can have tetrapolar sexual reproduction with other fungi of the same species and also “sexually” reproduce with themselves. Historically there were also tripolar fungi although it isn’t clear that this kind of fungi still exist.

    There are also patchwork viruses that don’t “come to life” and have an effect until four of five independent components are present in a host.

    It is also worth mentioning that sex ratios (at least as expressed) are not infrequently governed by environmental conditions at birth or during a developmental phase such as temperature and pH, and that there are some species which have more than one gender despite not having gender specific chromosomes.

    There are anomalies in sex chromosomes and in gender expression in humans, but there is really no reason to think that this is due to anything but errors in the reproductive process that have no evolutionary or adaptive value. The proper way to pose the question is not so much, “how do anomalies in sex chromosomes and gender expression add to selective fitness?”, as “how does completely anomaly free sex chromosome and gender expression add to selective fitness relative to the less than perfect mechanism we have?”

    Indeed, even asking the question that way suggests an answer. While sex chromosome anomalies and gender expression anomalies, in particular, may not add to selective fitness; in general, sexual reproduction and gene expression in a manner that is not 100% faithful to parental chromosomal DNA probably does have selective fitness at some low level because it can foster phenotypic and genetic diversity which can be fitness enhancing for the species because at some point, when environments change, the species needs an accumulation of diversity upon which natural selection can act.

    In that regard, I would also note that in the area of human genetics, “the third sex” is sometimes used as a term of art to refer to the genetic changes arising from de novo mutations in a new generation.

  20. Ilya says:

    Nick Lane and company think that 2 sexes are favored by (early stage) evolution for deep game-theoretic reasons:
    http://www.nick-lane.net/Hadjivasiliou%20Proc%20B%20two%20sexes.pdf

  21. Jason Malloy says:

    ” And humans, especially in the old hunter-gatherer phase, didn’t usually have fortress-nests.”

    Or homosexuality, for that matter.

      • Unladen Swallow says:

        Are there any documented examples of homosexuality in hunter-gatherers? I recall Jared Diamond mentioned some New Guinea tribe in the Third Chimpanzee allowing older men to have younger males as sex partners or something like that, although I think he implied it was not a long term arrangement for either. Did Henry ever see it in Southern Africa?

        • gcochran9 says:

          People in highland New Guinea aren’t hunter gatherers.

          I don’t think Henry saw it in the Bushmen. They’d heard of it, though, as happening in the mines in South Africa.

        • Jason Malloy says:

          In all SCCS cases homosexuality is “absent or rare” among foragers, with a stronger signal toward absent.

          http://blogs.discovermagazine.com/gnxp/2012/01/human-behavior-over-the-ages/#comment-791253593

          In cases where it exists (or may exist) at all, it could be an introduction. This is what the Aché people told Kim Hill, for instance, that such behavior was unknown before Western contact. And anthropologists like Jacques Lizot and Colin Turnbull were certainly eager to teach (or infect) such groups.

          • gcochran9 says:

            Can you direct me to that statement by Kim Hill?

            • Jason Malloy says:

              If I remember correctly it is in Aché Life History. Don’t have it on hand right now, but should be in the index.

              • “Some men in our [Ache] sample never had any children and others never acquired a wife. One category of men in Ache society opts out of the male mating pool altogether. These men, called panegi, take on a female socioeconomic role. … Panegi generally do not hunt, but instead collect plant resources and insect larvae. They weave baskets, mats, and fans, and make … female handicrafts. They spend long hours cooking, collecting firewood or water, and caring for children. Most informants stated that panegis did not ever engage in homosexual behavior prior to contact. A few informants said they were not sure. … One panegi of the southern Ache had children early in life and then later became pane[gi]. On the reservation settlement these men grow their hair long and act overtly effeminate. In 1970, the year before first contact … 2% [of men over twenty] were panegi. … Our observation … suggests that they were low status and not always treated well. … [But] a very high status hunter told us a story of how a panegi had saved his life during the contact period. When all of his band had become ill … a panegi stayed with the sick … until some recovered from the illness. The hunter told us the story with tears welling in his eyes, and he clearly had strong positive feelings toward the unrelated panegi who had nursed him back to health.”

                Kim Hill, Ache Life History pp. 276-277

  22. melendwyr says:

    I have no idea whether homosexual inclinations contributed anything in our ancestral environment. But judging that by looking at today’s world is foolish. A lot of human traits are maladaptive in the modern world but were clearly beneficial to our distant ancestors. Our love of fat, salt, and starch had obvious evolutionary benefits even though potato chips make us fat and unhealthy.

    • gcochran9 says:

      I’m sure that if we saw a few per cent of people jumping into fiery furnaces, you’d say the same thing.

      • melendwyr says:

        Religion obviously had benefits. And religious beliefs have resulted in people doing things just as remarkable as ‘jumping into fiery furnaces’. Magna Mater cult self-castrations, for example, as discussed in The Golden Bough. Or Roman Catholic priests promising celibacy.

        The biggest problem with your proposed explanation for homosexuality is that there’s no obvious pattern of transmission for the hypothetical bug to benefit from. To my knowledge, the idea that gays are molested by gays as children and so become homosexual has been pretty entirely abandoned. So where’s the benefit to the microbe?

        If infections are involved with at least some incidences of homosexuality, I suspect there’s no benefit to the infectious organism at all. Homosexuality is in my view most likely to be a birth defect, a failure of the normal processes of fetal development.

        • JerryC says:

          Is there any obvious benefit for h. pylori to cause ulcers and stomach cancer? It seems like the bacteria could get along quite nicely without killing anyone, and yet it does.

        • gcochran9 says:

          If you had a broad knowledge of infectious disease, you would have a different opinion. You would think about how polio, an intestinal bug, generates paralysis in a fraction of cases. Or you would think of rheumatic heart fever – where staph screws up your heart vales as a side effect of molecular mimicry, that mimicry being directly advantageous to the pathogen, even though the heart valve damage is not.

          But you don’t know that stuff.

          • melendwyr says:

            I don’t recall anyone ever suggesting that polio profited by inducing paralysis. But discussion of the possible role of infection in the development of homosexuality usually involves the suggestion of benefit to the organism.
            There’s little explanatory power to saying that an unknown microbe or parasite might sometimes induce gayness by accident. We might just as easily invoke chemical exposure or sheer randomness.
            I’m told that many ‘primitive’ and isolated societies had virtually no tooth decay. But it’s generally recognized that this isn’t due to infectious agents previously unknown in these populations, it’s because of diet.

            • gcochran9 says:

              Killing you is never directly beneficial to the organism, except perhaps for something like anthrax, that lives on long-term in the soil. But most fairly common fitness-reducing syndromes are caused by microorganisms. Most. It is possible for a key result of an infectious disease to confer benefit to the infecting organism – sneezing for example – but most do not.

              Moreover, since they spread, they can affect people globally. Since they adapt to our countermeasures, it’s hard for people to develop complete resistance: this is not the case for chemical insults and such. Moreover, the majority of dangerous chemical exposures are historically new: the Greeks never had to worry about vinyl chloride.

              Lastly, random errors happen – but homosexuality is very common compared to problems caused by mutations, chromosomal errors, and such.

              • melendwyr says:

                The birth defect rate in the US is supposedly about 3%. I have no idea what it would be in an ancient or ancestral society. Exclusive male homosexuals are thought to be what, 2-3%, and female less than 1%?

              • gcochran9 says:

                In other words, similar to the sum of all genetic disease. Look at the incidence of serious failures in other functions – for example, what fraction of people are born deaf? 1-2 per 1000, this in a function that sure looks to be a lot more complex than interest in the opposite sex, which works just fine in fleas.

                50-60% of those congenitally deaf kids, today, are due to genetic reasons: some mutational pressure ( mutations in many genes that affect hearing), a fair amount because of a single connexin-26 mutation, common in Southern Europe and the Middle East (it must go back to those early Anatolian farmers!) – probably a disease defense.

                the remainder: congenital infections. Today mostly cytomegalovirus, but rubella used to be a big cause before the vaccine. The rest – problems of pregnancy such as prematurity and severe jaundice.

                The failure rate for of hearing, due to simple mutation pressure, is less than 1 in 1500. At least for severe hearing loss.

                The failure rate for sexual orientation is something like 50 times higher.

              • melendwyr says:

                What does genetic disease have to do with most birth defects?

              • gcochran9 says:

                Assume a total of 3%. Maybe 0.5% of births have chromosomal disorders. A rough estimate (from 1999, WHO) has 1% suffering from single-gene disorders, many of which are caused by alleles that have been made common by selection (sickle-cell, thalassemias, G6PD deficiency, cystic fibrosis, connexin-26 deafness. So at least half are probably genetic, although in many individual cases we are not sure. AJHG published several new genetics diseases in every issue. Probably half of all significant genetic diseases also entail some degree of mental retardation.

                a number of infections during pregnancy cause birth defects: toxoplasma, other (syphilis, HIV, parvovirus), rubella, cytomegalovirus, and herpes (TORCH)

              • melendwyr says:

                We don’t know what causes most birth defects – it’s theorized to be a variety of causes, yadda yadda yadda.

              • gcochran9 says:

                I just said otherwise. Want me to say it again?

            • benespen says:

              Why wouldn’t the bacteria that live in your mouth be transmissible from person to person, and also subject to selection on what helps them spread?

              • melendwyr says:

                I wouldn’t be at all surprised. But the available evidence shows that it’s dietary changes which resulted in serious tooth decay among indigenous people, along with various metabolic illnesses previously rare. There’s no inherent reason it couldn’t be due to pathogenic bacteria, it’s just not the case that it’s so.

          • Henk says:

            A gay germ as proposed would exert selective pressure. For every mutation that would reduce the pathogen’s homosexualizing effect, the old, pre-mutation variant would technically be a gay gene.

            You say we can’t find a gay gene in homosexual men. I believe you.

            What does that say about the gay germ, if it exists, and if we presume it not to be novel, as I understood your point about Greeks to imply?

            It seems to me that it says that the evolutionary arms race has been run pretty much to completion, and being gay is a necessary, “nonnegotiable” part of the parasite’s life cycle.

            • gcochran9 says:

              Where do you get these ideas? There are infectious diseases that been causing trouble – killing or ruining a fraction of their hosts – for millions of years. TB, staph, malaria. Evolutionary arms races often don’t end at all.

              • Henk says:

                We find genes associated with malaria resistance, none with resistance to being gay. To pick another random example, I looked up rheumatic heart disease. It didn’t disappoint: “…genetic factors have been found to increase susceptibility to autoimmune reactions in RHD” says the Wiki.

                If there’s a gay germ, why can’t we find the gay genes?

                Does the absence of a visible genetic reaction to a disease you liken to “people jumping into fiery furnaces” really not strike you as unusual?

                Evolutionary arms races often don’t end at all.

                If they don’t end, they’re still on, thus visible in both genomes.

              • gcochran9 says:

                If we assume that some germ is causing male homosexuality, the fitness burden it causes is less than that of malaria in west or central Africa. In some areas, being a sickle-cell carrier can raise fitness by 20$. If you assume that 4$ of men are homosexuals, and that they never have any children, the fitness load is 2%. Ten times smaller.

                You know what? You’re wrong in an uninteresing way. Go study up.

              • Henk says:

                Arguing against male homosexuality as an extended phenotype of the mother, you said:

                resistance to that kind of manipulation is favored by selection

                Yet if the hypothetical manipulator is a gay germ, lack of evidence for such resistance doesn’t pique your curiosity. Why?

                It’s assumed to be the same homosexual phenotype in both cases, so the same selection pressure in both cases, except it’s even lower in the first case because mother is a close relative.

              • gcochran9 says:

                Pathogens have shorter generations than humans. Since you didn’t know that…

            • melendwyr says:

              If homosexuality has no genetic component, but we keep finding correlations to things like the number of older brothers, then it seems entirely possible that it’s the result of women’s immune systems reacting to some ‘male’ signal in the developing fetus. A lot of immune reactions are highly unpredictable in individual cases – we have no idea why any given person becomes allergic to peanuts, for example. Is there some pathogen that sometimes has proteins similar to those in peanuts? Maybe. Maybe there’s a bunch of pathogens that occasionally trigger it. Presumably there are reasons foods like peanuts and strawberries are relatively common allergens and beef isn’t.

              Perhaps we can’t find the ‘gay pathogen’ because there is no such single entity; as with allergies, a bunch of unknown factors result in some people being sensitive.

        • Toddy Cat says:

          “To my knowledge, the idea that gays are molested by gays as children and so become homosexual has been pretty entirely abandoned.”

          Possibly, but was it abandoned because it’s untrue, or because it was politically incorrect? I don’t know, but I know how I’d bet, given the modern world.

          • melendwyr says:

            It’s hard to know for certain, sure. We may be being Lysenkoized as we speak. But if there were actual clear evidence that sexual abuse was a causative factor in homosexuality, I think it’d be talked about in transgressive fora, much like HBD and this blog.

            On another note: has anyone ever explored the possibility that chicken pox has behavior-altering consequences?

            • Dr. Miller says:

              No, you are wrong, it would not be talked about in transgressive fora, guess what, because it is not talked about at all. Homosexuality is always linked to child abandonment or direct abuse. It is also then linked to masochism and sadism. There could be “gay genes”, that are under normal circumstances responsible for something else, even be positive selection-wise, but turn you gay under certain circumstances. But there is no pathogen that turns you gay, it is just that most people with gay genes do not turn gay. Get to know gay people first, talk about their history and THEN come up with your stuff. Not just assume things here. Same with mental illness and so on. You cannot understand that without having talked to many people that suffer from them. Blaming genes is the easy way, and a way to gain control over something that is uncontrollable (what turns empiricists mad).

              Most parents treat their children like shit, all over the world, even in the West, to different degrees. Even in the West middle-class I estimate that at least of 40% spend their childhood in mortal fear, the fear of being abandoned by their parents, and that is a biological death sentence that alters your brain structure if you experience it constantly. Western children manipulate their children psychologically. In other parts of the world there is direct violence. In Afghanistan it is common that close relatives rape the boys of the family, and no one cares (no data about Arabs e.g. – but that is because those guys who have suffered it have repressed memories and/or will never admit it, that’s why they turn to Islamistic macho culture and inflict pain into others, and sociologists will not touch these topics with a ten-footpole). And you wonder why people from Muslim countries are so crazy? No, not because of their genes that cause low IQ (albeit that does not help, as low IQ people have less impulse control and ability to reflect on their actions).

              That is the true secret society lies about, and not genes, HBD and pathogens. Everyone knows, subconsciously, that blacks are less smart, even blacks themselves. The general population knows that. HBD is just too obvious and nothing occult about. Child abuse is the true thing that matters and most people do not want to talk about it because it makes them uncomfortable and brings up their own bad memories (people usually think their childhood was “paradise”, being smacked a little is GOOD, but that is lying to yourself in most cases). You will not find empirical studies about this stuff, but that is the same reason why there is so much taboo when it comes to population genetics e.g. – not wanted! And yes, Freud was a brilliant guy who discovered many important psychological mechanisms. But then at some point he went off the rails, perhaps because he was scared of his own findings or simply choose fame over truth and did not want confront 19/20th century Austria with its dirty secrets and then put the blame on the “perverted child”. That was non-sense. But before the Freud bashing goes on on boards like these, first educate yourself about him.

              • Simmer down sport, you are tossing out wild unsubstantiated unrelated assumptions all over the place.

                1)”Homosexuality is always linked to child abandonment or direct abuse.”
                utter nonsense
                2)”Most parents treat their child like shit…even in the west to different degrees.”
                sorry to hear about the painful confession of your upbringing. the opposite is closer to the truth.
                3)”Freud was a brilliant guy who discovered who discovered many important psychological mechanisms.”
                all by his nutty self he set back the profession of therapy a generation at least.

              • teageegeepea says:

                Child abuse doesn’t seem to be that big of a factor. Knowing someone’s biological parents seems to impart more information than knowing their adoptive parents on most traits.

        • R. says:

          To my knowledge, the idea that gays are molested by gays as children and so become homosexual has been pretty entirely abandoned. So where’s the benefit to the microbe?

          Doesn’t lead to homosexual orientation, but possibly to fetishisation of homosexual behavior. Different thing entirely, may look a bit similar to an uninformed observer.

  23. not_an_economist says:

    Uh oh! Gender is more than just hormones. It looks like the immune system plays an important role in sexual differentiation.

    Brain’s ‘gender’ may be quite flexible: Mechanism that plays key role in sexual differentiation of brain described
    https://www.sciencedaily.com/releases/2015/03/150331121249.htm

    “Intriguingly, the latest study also found that inflammatory immune cells known as microglia appear to play a role in masculinization, in part through their production of prostaglandins, a neurochemical normally associated with illness. In recent years, scientists have increasingly realized that the immune system is integral to the development of the brain; Prof. McCarthy and her group are the first to show that it is also important for establishment of sex differences in the brain. The current discovery is another piece in that puzzle; they showed that Dnmt enzymes control expression of genes that play a role in inflammation and immunity, and also in the sexual differentiation of the brain. Prof. McCarthy is now doing additional research on the links between the immune system and brain sex differences.”

    • I might be missing something here, but this seems to suggest that the immune system is is important for establishing sex differences in the brain. Unless there is something about male immune-systems and female ones that operate differently at the early-development level, then genitalia would be a completely unreliable guide to gender. This seems, uh, unlikely.

      • not_an_economist says:

        The study suggests that if the immune system goes haywire during pregnancy brain development, specifically related to gender will be impacted.

        • Greying Wanderer says:

          “The study suggests that if the immune system goes haywire during pregnancy brain development, specifically related to gender will be impacted.”

          wild thought so whatever but…

          read recently that the rate of homosexuality varied by race with white least

          above comment makes me curious if the white homosexuality rate varies with lactose tolerance?

          (on the basis/theory/hypothesis/whatever that stem cells in milk are there to repair mistakes caused by rapid brain development)

          • not_an_economist says:

            It might correlate with lactose intolerance or a hundred other things but it’s against the law to do research to find out.

            • Greying Wanderer says:

              only if you were honest about it

              set up a study into lactose tolerance and just so happen to ask about sexuality in passing

  24. Darien says:

    What you think about asexuality? About 1-1,5% of population are asexual, this means no interest in sex at all. This is about the same population size as exclusive homosexuals, but these lucky/unlucky people do not fight for their rights and do not organize as repressed minority, so they are invisible to all.

    • gcochran9 says:

      I think your numbers are crap.

        • For people who aren’t interested in sex, asexuals sure do talk about it a lot. Let’s see how many remain when we parcel out those who are gay but unable to admit it, playing the age old game of “invest heavily in me, I’m worth it”, or are somehow damaged.

        • jasonbayz says:

          It may be true, asexuality may be a result of the (undesirable) selection against excess sexual desire.(see my comment above) It’d be harder to prove than homosexuality, the absence of something(sexual desire) is going to be more difficult to prove than the existence of something(homosexual acts). But my intuition tells me that it’s mostly crap. There’s always an interest in inflating the numbers, get your paper published and once it’s published bigger numbers get people’s attention. It reminds me of something I noticed when reading the LessWrong reader survey results, following their question about sexuality(3.9% of readers were asexual, it’s that type of place), they said:

          “[This question was poorly worded and should have acknowledged that people can both be asexual and have a specific orientation; as a result it probably vastly undercounted our asexual readers].”

          http://lesswrong.com/lw/lhg/2014_survey_results/

          I was taken aback because I thought “lacking an orientation” was the whole point of being asexual. But Wikipedia tells me that:

          “Many people who identify as asexual also identify with other labels. These other identities include, but are not limited to, how they define their gender and their romantic orientation.[24] They will oftentimes integrate these characteristics into a greater label that they identify with. Regarding romantic or emotional aspects of sexual orientation or sexual identity, for example, asexuals may identify as heterosexual, lesbian, gay, bisexual, queer,[17][18] or by the following terms to indicate that they associate with the romantic, rather than sexual, aspects of sexual orientation:[16][18]”

          My BS detector is ringing.

          • jasonbayz says:

            “It may be true, asexuality may be a result of the (undesirable) selection against excess sexual desire.”

            Should be “asexuality may be an (undesirable) result of the selection against excess sexual desire.”

        • jasonbayz says:

          Here’s another reason to doubt the claims of the asexuals, there are a large group of humans who really are asexual: young children. When young children first learn about sex, the typical reaction is disgust. You can see why, it’s an unhygienic, privacy-invading practice. If asexuals really had no sexual orientation, you’d expect them to view it in a similar way, much as heterosexuals see homosexual behavior or homosexuals claim to see heterosexual behavior.* Do they?

          *I’ve read that homosexuals watch certain pornography which depicts heterosexuals, but with a focus on the man rather than the woman, reflecting an attraction to the “alpha male.” Don’t know how true it is.

    • JayMan says:

      Asexuality is vastly overstated in terms of true prevalence.

      But then, the number you gave is typical of the crap that is sex research.

  25. mapman says:

    OK, Greg!

    Menopause. Since you tend to explain everything with adaptation, what’s your explanation for a menopause?

    • gcochran9 says:

      I don’t know of a convincing explanation.

      • mapman says:

        Thanks 🙂
        (I was expecting one of your trademark snarky relies).
        Agree that there does not seem to be an obviously true adaptive explanation available

        • jasonbayz says:

          The point at which a woman’s reproductive machinery degrades to a level where it’s a better investment for her to take care of existing children than risk having more?

    • Greying Wanderer says:

      no doubt wrong but…

      seems to me menopause would be a relatively simple halfway house between solo female provisioning and male provisioning

      1) easy gathering environment: solo female provisioning – women with random mutation that stopped ovulation before death selected against

      2) harder gathering environment: males gradually moving to male provisioning (slowly) – but now women who stopped ovulating before death could help feed their daughter’s kids instead of having to worry about their own – so only one change needed compared to the (however many it needed in men)

  26. st says:

    D-r Cochran, it must have taken some time, many generations (thousands of years? hundreds of thousands? more?) and some intermediary or transitional stages for a two-gender specie to become eusocial. How would this transitional stages would have look like in terms of reproduction and could entering a transitional stage from two-gender to eusociality or stepping on the path to eusociality be driven by a… pathogen interference in the life cycle of the predecessors of the naked mole rats or the ants?
    In “The Social Conquest of Earth” Wilson says that the evolutionary establishment of an eusocial specie from math standpoint is so hard it’s nearly impossible and that is why very few species have made it.

  27. dearieme says:

    95 comments so far: it’s wonderful what “Sex” in a headline can achieve.

  28. j says:

    I imagine cats are on the path of developing a three-gender species. Cats already have induced ovulation, meaning that agreeable sex between a sweet, suave male and a willing female will rarely cause pregnancy. Cats need prolonged violent copulation, causing abrasion and inflammation of the uterus to ovulate and get pregnant. I could imagine two kinds of males: one, a raping race with large spiked penises, that prepare the female and induce ovulation, and then a second kind, males that follow up the first ones and fertilize the haemorrhaging females. In my times in the pampas, this second copulation was called “repaso” and it was considered necessary to ensure pregnancy of milch cows. As you know, a cow without a calf is dry, produces no milk, so failed copulation means economic loss. So you could have two kinds of males and one female = a third sex.

    • j says:

      Addenda: This scenario could be also present in humans. You have males personality type alpha that seduce, force and excite the females, and you have males personality type beta, that offer their shoulders to the seduced females to cry on. Humans are equipped with pump-like penises causing the sweet beta to suction off the alpha’s semen and inject his own. I would be interesting to know if personality types are genetic, I think so.

      • teageegeepea says:

        That would result in three sexes of cats, the first one which “prepares” the female isn’t producing any offspring. Orangutans do have a “rape morph”, but this is essentially just another strategy in a competitive equilibrium with the flanged male one.

        • teageegeepea says:

          Sorry, would not result in three sexes of cats.

          • j says:

            Sex One: Female. Sex Two: Semisterile Raping Male. Sex Three: Seductive Fertile Male.
            The species a whole could have an oscillating equilibrium. One generation, too many Twos and too few Threes are being born. The females sense the existence of a pheromone disequilibrium in the air and compensate giving birth to more Threes and less Twos. There are cases of stable/oscillating equilibria in nature, specially in predator/prey systems. If the model makes sense in our minds, someone will surely find it in the wild.

  29. st says:

    How do we know that a “gay germ” does not transmit sexually? There are, say 5 or 10 % of human males that would be in a position of contracting it during their lifespan – nowadays. So, the rest of the males – about 95% would stay straight in any given epoch and in any given society – which, more or less, is the state of affairs in human history. Has anyone done any follow-up research on the acquired homosexualism in prisoner population? How many of them stay this way, say, for the rest of their lives? None? Few? 1%? 10%? I doubt such research exists. But let say a prisoner enters a sexual relation with another prisoner. He won’t contract the gay germ if they both don’t have it in advance. So, upon returning to society, neither of them would stay gay and it will look that homosexuality is not sexually transmittable.
    But it certainly did not look like it 5 centuries ago. The founder of seljuk empire was brought as a sex slave in Persia from central Asia. He could not live a biological legacy – nore he wished. Instead he kept buying young males from central asia and turned them the core of his military guard – and his lovers. One of the gay lovers would inherit the crown of the seljuk empire – but would keep the tradition to supply the army with central asia youngsters, which would rose to military prominence – or die trying. I doubt any of them would have been born gay; but they would quickly change their sexual preferences and became strictly gay for the rest of their lives.

    It became even weirder in the times of ottoman empire, which inherited seljuk empire. At a certain point the entire ottoman military was consisted of gays – the so called janissaries. Actually, at one point ottoman army was consisting entirely of janissaries – the rest of population was forbidden to serve in the army (there were cases when families would bribe the authorities so their sons would serving in the army, dreaming of a military career, pretending that the sons were gay or offering them for sex). Now, janissaries were “recruited” from among the children of subject people in the ottoman caliphate. On every 3 to 5 years the recruiters would collect most first borns from the villages of the christian minorities, aged five to ten (the so called “blood tax”) and send them to Constantinople, where they would be trained for professional soldiers and converted to islam. Janissaries did not have a right to marry – not that they wished it. Before they enter military service and turn 16, they – or many of them – were supposed to serve as male prostitutes. There is an accounting document from 16th century that meticulously describes things like number of orgasms per day that the male prostitutes have given to its customers as a base for financial evaluation of a bath house in Constantinople. As Lawrence of Arabia would testify few centuries later from his brief encounter with a couple of ottoman soldiers, janissaries would stay gay forever and would strictly prefer males.
    The importance of this entirely gay army for the ottoman caliphate can be evaluated from the fact that two generation after the practice of collecting youths and turning them into gay soldiers, the entire empire fell apart. However, my points are: janissaries stayed gay to the rest of their lives (the numerous fights amongst them upon competition for the best lovers available sometimes would turn into large scale rebellions and bring Constantinople into chaos, which was one of the reason the practice of janissaries to be discontinued and forbidden in the beginning of 19th century) and my other point is – at that point of time and at this place homosexuality would have looked like sexually transmitted disease – unlike today.

    • MawBTS says:

      ^ if you’re wondering whether the above comment is worth reading, it’s not.

      • st says:

        But of course its not worth, my dear – ignorance is a bless. As well as the arrogance.
        Besides, US society is world-famous for its comprehensive erudition – i mean, you can see the signs of this erudition all over the the world map.

        • Erik says:

          Why not just come out and say that US society has lots of blacks, rather than snarking about circumlocutions like “comprehensive erudition”?

  30. et.cetera says:

    I am bored enough to think that anything other than what we have is better. It can be a lot of fun in the looney bin you know. A lot! I like these madmen.

  31. Cpluskx says:

    ”A similar pattern in humans would, I think, drive us all crazy.”
    We will see.

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