A good piece on the ideological infection of biology

April 22, 2023 • 12:30 pm

I found this article in the Twitter feed of Manchester University developmental biologist Emma Hilton, a passionate defender of biological truth against ideological pollution. And because she said the article was great, I read it. It was.

The article is from Skeptic magazine, edited and published by Michael Shermer, and it’s well worth your while to read the piece. Author Robert Lynch, by the way, is identified as “an evolutionary anthropologist at Penn State who specializes in how biology, the environment, and culture transact to shape life outcomes.”

It’s also free, so click on the screenshot to access it.

The piece is loaded with all kinds of good stuff starting with the assertion and documentation that sex in humans is binary, something that is not just a definition, but a description of what evolution has done to the reproductive development of all animals including H. sapiens.  I’ll give a few quotes, but you could do a lot worse than read the whole thing.

I’ve left the footnotes in because he documents his statements extensively. And I’ve picked out three areas of special interest because they are controversial—not because of biology, but because the biological facts contravene fashionable “progressive” ideology. Lynch’s quotes are indented; my own takes are flush left.

Why sex is binary.

The assertion that male and female are arbitrary classifications is false on every level. Not only does it confuse primary sexual characteristics6 (i.e., the reproductive organs) which are unambiguously male or female at birth 99.8 percent of the time with secondary sexual characteristics7 (e.g., more hair on the faces of men or larger breasts in women), it ignores the very definition of biological sex — men produce many small sex cells termed sperm while women produce fewer large sex cells termed eggs. Although much is sometimes made of the fact that sex differences in body size, hormonal profiles, behavior, and lots of other traits vary across species, that these differences are minimal or non-existent in some species, or that a small percentage of individuals, due to disorders of development, possess an anomalous mix of female and male traits,8 that does not undermine this basic distinction. There is no third sex. Sex is, by definition, binary.

I’d add here that saying it’s binary “by definition” leaves out something important: the binary nature of sex didn’t arise because biologists decided to impose a strict binary on something quasi-continuous in nature. Rather, the presence in animals of only two sexes—producers of two distinct types of gametes—is a result of evolution, and the “definition” is more of a “concept”—an encapsulation in words of a dichotomy biologists see when they look at nature. (This also holds for “species”, which is why we have a biological species concept rather than a definition—an encapsulation in words of the discontinuities among plants and animals we see in nature.) There are two paths, and only two paths, for the development of gametes. There is no animal with three gametes. Human hermaphrodites, none of which has ever produced both sperm and eggs that can function, are not a third sex. Neither are the very rare individuals who represent disorders of sex development (DSDs). Transgender people, of course, don’t violate the binary of biological sex; indeed, by transitioning in one direction or the other, they serve to confirm it. Finally, we understand how the sex binary evolved. Once it did, species are resistant to the evolutionary invasion of any more sexes.

Why it’s important to recognize why sex is binary. The short answer is that it explains a ton of other observations about nature, all of them arising from the fundamental difference in gamete size, which leads to a difference in reproductive investment, to sexual selection, and so on.  And it also leads to testable predictions about biology:

It was [Robert] Trivers, who four decades earlier as a graduate student at Harvard, laid down the basic evolutionary argument in one of the most cited papers in biology.2 Throwing down the gauntlet and explaining something that had puzzled biologists since Darwin, he wrote, “What governs the operation of sexual selection is the relative parental investment of the sexes in their offspring.” In a single legendary stroke of insight, which he later described in biblical terms (“the scales fell from my eyes”), he revolutionized the field and provided a broad framework for understanding the emergence of sex differences across all sexually reproducing species.

Because males produce millions of sperm cells quickly and cheaply, the main factor limiting their evolutionary success lies in their ability to attract females. Meanwhile, the primary bottleneck for females, who, in humans, spend an additional nine months carrying the baby, is access to resources. The most successful males, such as Genghis Khan who is likely to have had more than 16 million direct male descendants,3 can invest relatively little and let the chips fall where they may, while the most successful women are restricted by the length of their pregnancy. Trivers’ genius, however, was in extracting the more general argument from these observations.

By replacing “female” with “the sex that invests more in its offspring,” he made one of the most falsifiable predictions in evolution — the sex that invests more in its offspring will be more selective when choosing a mate while the sex that invests less will compete over access to mates.4 That insight not only explains the rule, but it also explains the exceptions to it. Because of the initial disparity in investment (i.e., gamete size) females will usually be more selective in choosing mates. However, that trajectory can be reversed under certain conditions, and sometimes the male of a species will invest more in offspring and so be choosier.

When these so-called sex role reversals5 occur, such as in seahorses where the males “get pregnant” by having the female transfer her fertilized eggs into a structure termed the male’s brood pouch and hence becoming more invested in their offspring, it is the females who are larger and compete over mates, while the males are more selective. Find a species where the sex that invests less in offspring is choosier, and the theory will be disproven.

I love that last paragraph, for seahorses (and pipefish) are the exception that proves the rule.

The sex difference in gamete size, because of sexual selection, has led to sex-specific selection pressures that have given human males and females different behaviors. Yet the blank-slaters deny this because their ideology tells them that any differences they see in behavior between the sexes must have a cultural or sociological rather than a biological origin.  Yes, of course there are social influences that affect the sexes differently. But men and women are also biologically different in important ways. I’ll give one more nugget from this mother lode of an article:

Biological differences in behavior between men and women.

The evidence that many sex differences in behavior have a biological origin is powerful. There are three primary ways that scientists use to determine whether a trait is rooted in biology or not. The first is if the same pattern is seen across cultures. This is because the likelihood that a particular characteristic, such as husbands being older than their wives, is culturally determined declines every time the same pattern18 is seen in another society — somewhat like the odds of getting heads 200 times in a row. The second indication that a trait has a biological origin is if it is seen in young children who have not yet been fully exposed to a given culture. For example, if boy babies are more aggressive than girl babies, which they generally are,19 it suggests that the behavior may have a biological basis. Finally, if the same pattern, such as males being more aggressive than females, is observed in closely related species, it also suggests an evolutionary basis. While some gender role “theories” can attempt to account for culturally universal sex differences, they cannot explain sex differences that are found in infants who haven’t yet learned to speak, as well as in the young of other related species.

Many human sex differences satisfy all three conditions — they are culturally universal, are observable in newborns, and a similar pattern is seen in apes and other mammals. The largest sex differences20 found with striking cross-cultural similarity are in mate preferences, but other differences arise across societies and among young children before the age of three as boys and girls tend to self-segregate into different groups with distinct and stereotypical styles.21 These patterns, which include more play fighting in males, are observable in other apes and mammal species,22 which, like humans, follow the logic of Trivers’ theory of parental investment and have higher variance in male reproduction, and therefore more intense competition among males as compared to females.

If so, why then has the opposite message — that these differences are either non-existent or solely the result of social construction — been so vehemently argued? The reason, I submit, is essentially political. The idea that any consequential differences between men and women have no foundation in biology has wide appeal because it fosters the illusion of control. If gender role “theories” are correct, then all we need to do to eliminate them is to modify the social environment (e.g., give kids gender-neutral toys, and the problem is solved). If, however, sex differences are hardwired into human nature, they will be more difficult to change.

Acknowledging the role of biology also opens the door to conceding the possibility that the existence of statistically unequal outcomes for men and women are not just something to be expected but may even be…desirable. Consider the so-called gender equality paradox23 whereby sex differences in personality and occupation are higher in countries with greater opportunities for women. Countries with the highest gender equality,24 such as Finland, have the lowest proportion of women who graduate college with degrees in stereotypically masculine STEM fields, while the least gender equal countries such as Saudi Arabia, have the highest. Similarly, the female-to-male sex ratio in stereotypically female occupations such nursing is 40 to 1 in Scandinavia, but only 2 to 1 in countries like Morocco.

Note the play fighting in males, which become more overt aggression when boys turn into men at puberty. And this is certainly an explanation for the palpably greater degree of risk-taking of postpubescent men compared to women.  It takes all kinds of forms, including street racing, which is a male pursuit, and a dangerous one.

Do note the explanation for ideological resistance to biological facts given in the third paragraph. The “gender equality paradox” of the last paradox is resolutely ignored by “progressives,” who argue that any difference in representation of sexes in a profession must be due to sexism—most likely of a structural nature.

43 thoughts on “A good piece on the ideological infection of biology

    1. If you mean why are males attracted to females (and vice versa) that seems obvious?

      If you mean why am I attracted to my wife (or why is any individual attracted to some individuals of the opposite sex but not to others), that’s very complicated but doesn’t seem relevant.

      If you mean why are some males attracted to males instead of females (and vice versa), there are some good ideas and data showing how same-sex attraction might evolve and be inherited as a trait in spite of leading to reduced individual fitness.


      1. If the whole ‘gays can’t procreate and therefore shouldn’t exist’ argument worked then there’d be far less people suffering from genetic diseases. Zero, in fact.

        1. Ok but I didn’t make that argument. What’s the connection between same-sex attracting and genetic diseases?

          1. Their argument normally revolves around ‘gays can’t procreate so you can’t inherit gayness’.
            The same is true for infertility, downs syndrome, etc. And yet they still exist.

            1. Yes, but gayness is much more common than the other conditions you mention. I haven’t looked at the literature about why gayness is so prevalent, but it is a good question why, if there is ANY genetic component to it, it hasn’t been driven to low frequency by natural selection. I don’t even know enough about it, though, to say anything about the heritability of homosexuality.

              1. Anecdotally, I have known of a neighbour who married and had two children, and later we suspected of being gay (no actual relationship, but lots of the usual clues). He had a son and a daughter, both of whom turned out to be gay. Not data, but I think most of us have come across or heard of similar stories.

            2. In the paper I linked to upthread, the authors use GWAS to show that some genetic variants associated with same-sex behaviour confer a mating advantage in individuals who are opposite-sex attracted. Basically, inheriting a few of those variants from your parents makes one sexy; inheriting a lot of those variants makes one gay. Could lead to evolutionary maintenance of those variants within a population, even if those variants sometimes meet a dead end in some same-sex-attracted individuals.

              I don’t do GWAS so I can’t say how good the data or analysis might be.

              Sorry for overcommenting.

        2. Evolution via natural selection is a numbers game from the genome’s point of view. The game is maximizing your (and the host organism’s that you built around you) reproductive success in the long term. It can’t select away every condition and disease because they are not the only selective pressures it needs to overcome. Very often it makes do with quick and dirty compromises which at one time work great (Subsaharan prevalence of sickle cell and malaria) but later are detrimental. So goint back to your point, the existence of a feature or condition doesn’t negate that it is under selection pressure.

  1. I think one can drill down even farther. Why are there two gamete types? Because two gametes are required for fertilization. Why just two – why don’t three or four or more gametes combine at fertilization? Because gametes are formed by dividing the genome in half, and exactly two are needed to restore the original genome size in offspring to match the genome size of the parents. Why is the genome divided in half rather than in thirds (with three gametes) or quarters (with four gametes)? Because all successful cell division is fundamentally binary – including cell division in meiosis.

    The molecular biology of that binary cell division in plants & animals and other eukaryotes was inherited from single-celled organisms that don’t have gametes or fertilization. Having to use that same cellular machinery for cell division and gamete formation in eukaryotes probably limits the options to just two daughter cells, splitting the genome in two, requiring two gametes at fertilization, and having only two sexes.

    Some cancer cells divide into three or more daughter cells, which seems like an exception that proves the rule.


    But if others know more than I do about those constraints and the possibilities for a three-way fusion of three (or more) gamete types it would be fun to learn I’m wrong.

    1. I recently picked up a book that delves into this pattern (known as anisogamy). The title is The Evolution of Anisogamy. Isogamy is the ancestral state, and is seen in fungi and many kinds of algae. Anisogamy evolved at least twice, from my reading (in plants and animals). The leading hypothesis is that gamete competition that led to disruptive selection for two different sizes is what reinforced the binary pattern. I don’t know, but suspect a three-way fusion would not be stable in the way that alternating between the haploid and diploid arrangement of chromosomes is evolutionarily stable.

    2. Never mind the molecular genetics. [Edit: Sorry, I don’t mean to be dismissive of molecular genetics. Bad wording. I just meant, “even before we get down into the molecular understanding….”. ] (But we do know that early miscarriages are often aneuploid.) The drawback to needing 3 gametes is that it requires those 3 gametes to find each other during whatever period of time the first “2 out of 3” intermediate form would survive despite being unable to develop further while it awaits the arrival of the third type. The fertilization mechanism would have to handle the possibility that either of the two different motile types might get there first. The 2/3 form would have to remain receptive to the so-far missing form but not to another arrival of the form already fused. It is fun enough to contemplate how this would work in external fertilization, with thousands of eggs released into the sea and millions of each of two forms of motile gametes trying to find them. What proportion of oyster eggs get fertilized by even one sperm? Now imagine that each of that small fraction can’t develop until another fertilization event occurs. How many oyster egglets would get eaten because unable to grow to where filter feeders can’t get them?

      Now imagine how mammals and birds would pull this off with internal fertilization. Human families that produce children would look very different from (and be much rarer than) we are accustomed to. How many couples would be barren because the female egg harbourer was unable to find a suitable second motile producer needed to consummate each pregnancy? Remember the female would have to be able to recognize reliably that the second male was of the different type yet she would still have to be receptive, willing, and capable of sexual intercourse with him. In practice his genitalia would have to be highly distinctive yet still fit.

      Finally, the resulting tripartite unions would have to be capable of producing any of the three types of offspring in a suitable ratio, who would have to be distinguishable to their parents and later to their sexual partners. Says woman, “OK, I’m going steady with a Malething1. Now I have to recognize a Malething2 without having to pull down his pants.”

      And what if some plague caused differential death or infertility among one of the male forms? Needing three seems more vulnerable to disaster than just two.

    3. There are a couple hypotheses about why anisogamy, or “why are there males”? Males contribute nothing more than the necessary set of chromosomes, while females, with their larger gametes, provide chromosomes + lots of organelles + often food energy (yolk, for example). So why are there males?
      One hypothesis comes from a game theory argument. One needs big but energetically expensive gametes (eggs) to provision embryos for development. But those gametes cannot be terribly numerous because they are more expensive. This is why females have a restricted reproductive potential. Tiny and numerous gametes (sperm) are therefore also needed to ensure that as many eggs as possible get fertilized, as unfertilized eggs are a waste in energy and that reduces fitness. So the most fit strategy is anisogamy.
      The other hypothesis has to do with a solution to the evolutionary arms race that would arise if both gametes were similar in size, and both contributed to provisioning the offspring. Among those provisions would be mitochondria, and those have their own DNA and their own ability to replicate in cells. If mitochondria from both parents lived together in the same embryonic cells, they would genetically compete with each other to take over, to the detriment of the embryo. So the solution is that one gamete simply does not provide mitochondria, and these are the sperm cells.
      I think there is evidence for both scenarios.

  2. Good stuff. Why have we so far been spared polemics about karyotype justice? After all, the existence of Turner (XO), Klinefelter (XXY) and Down (trisomy 21) Syndromes could lead polemicists to insist that human chromosome number, varying as it does in rare cases to 45 or 47, lies on a spectrum.

    As the article implies, a popular, over-simplified form of Left politics tends to come into conflict with Biology. This has been shown repeatedly, from Lysenkoism in that galaxy far away, to the doctrinaire egalitarianism behind opposition to academic testing. It was exemplified to perfection in that Sci Am article which denounced the normal distribution, revealing discomfort with any distribution other than uniformity. Maybe there is a reason why societies dominated by Leftish slogans skew (like the USSR) to uniformity.

      1. It used the gulags to enforce conformity. I don’t think any humanity skews toward conformity on its own. But it can be made to submit to it.

        1. So conservatives that have prisons to enforce laws forcing people to be devout followers, like say a christian americas constant attempts to undermine reproduction rights or muslim countries all out war on women or homosexuals, are secretly lefty communists?

          1. You’re just being argumentative, poorly. We were talking about communists and gulags. Go live in North Korea if you like. I’m not getting into a Twitter war with you. I have to get to church.

  3. The “gender equality paradox” of the last paradox is resolutely ignored by “progressives,” …

    I once put this to a woke academic (an educated person with a PhD), pointing out things like:

    … the female-to-male sex ratio in stereotypically female occupations such nursing is 40 to 1 in Scandinavia, but only 2 to 1 in countries like Morocco.

    He replied, entirely seriously, that such statistics just showed how dire life was for women in the “white, racist, sexist, capitalist, patriarchal” Western countries. He argued that they were the result of the pervasive “systemic” sexism inherent in all “white, capitalist” systems.

    Of course the whole point of accusations of “systemic” racism and sexism is that one is not obliged to produce any evidence at all for their existence, the disparity in outcomes is all the evidence required.

    1. I wonder if the academic pondered whether life for women was far more “dire” in countries like Saudi Arabia. Or if pre-capitalist societies were far more sexist and patrirachal than modern ones. But this academic is undoubtedly under the delusion that everything will be better once the world becomes a university town.

  4. What of the urge of natural selection to solve the inbreeding problem. Who wants that? Biological sex is fundamental to biological fitness in humans
    “Charles II was dubbed for his overlarge tongue, epilepsy and other illnesses, had a whopping inbreeding coefficient of .25, about the same as the offspring of two siblings.”
    now that is a cultural stuff up not unlike the arguments and discussion going on here.WEIT. We could call this an ideological disfigurement of what it is to be a women and why women and for that matter, males exist. To my mind we’re still figuring out what values and meanings to apply, position yourself as any gender you like until you want a viable off spring but enough of the acting plain stupid… we need to move on.

  5. Nothing to add unless to say that it’s a great article, very clear in the arguments and scientific background.

  6. Not directly relevant and somewhat anecdotal, but I used to see patients with neurodegenerative disorders affecting the visual cortex and visual association areas such as posterior variant Alzheimer’s or CJD. Despite good angular resolution these unfortunate people couldn’t manage simple perceptual tasks. For example, which out four different sized squares was biggest or pick out a differently coloured dot in a simple cluster of dots. Among the tests was was two passport sized photographs in black and white, one of a man and the other of a woman. The pictures were not especially masculine or feminine yet the ability to correctly identify the pictures as male and female persisted after the ability to complete many other visual tasks was lost and people were rarely unsure. I suspect our perception of the sex binary is pretty deeply ingrained. I wish I had kept better records but at that time it didn’t seem that surprising.

    1. That is very interesting, and it could be an aspect of pareidolia. The ability of recognize faces is certainly seen in infants, and interesting that it seems to lie deep in our minds, even as they deteriorate.

  7. “Note the play fighting in males, which become more overt aggression when boys turn into men at puberty.”

    I would also note that, even when grown men get into physical altercations, literally coming to blows, they often make up immediately after the fight has ended. I believe this is where the phrase “hugging it out” originates. Men often shake hands and/or hug as soon as the altercation ends, even asking if the other is injured and often sharing in a bonding activity like having a drink together.

    In contrast, women very rarely get into physical fights and, when they do, the fights often (1) are the result of long-term disputes resulting in a culmination from rising tensions, and (2) do not normally result in “making up,” but rather either complete withdrawal from one another or continued hostility.

    I’ve often wondered why this occurs, and can see myriad explanations.

  8. Would be interesting to see if “choosiness”, that which is driven by parental investment relative proportions, would hold the same skew among paired transexual men and women.

    So that: Transsexual men with a sexual attraction to men should be choosier than transsexual men with a sexual attraction to women (a lesbian type relationship).

    And that: Transexual women with a sexual attraction to women should be on equal “choosiness” footing with transsexual women with a sexual attraction to men (gay type relationship).

  9. Lynch’s piece is an excellent defense of sex as a binary and it offers a very plausible analysis of why the concept is so threatening to some. As he says, it’s political.

    Those who are working so hard to discredit science don’t seem to understand that their efforts, in fact, will not make the biological basis of sex go away. Nature doesn’t care what they think or believe, and nature does not conform to their delusions. What they are doing will only harm the role that science can take in helping to solve real, rather than imaginary, problems.

    Some day, these same people will need real science to come to the rescue—in a medical emergency, in wartime, in the work needed to save us from climate change—but, alas, if they are successful, science won’t be there to help. A world without science is a world on its way to ruin, and we’ll have these postmodernist zealots to thank.

  10. I’m an applied mathematician, and a colleague has asked to call her Eric and instead of Erica. He was lesbian and is married. Okay, he has large gametes in him, but he lives in a society that struggles with his abilities in applied math, and he appreciates his wife who is comfortable with her husband. I’m not going to be talked out of honoring his decision.

    1. I don’t think anyone is trying to talk you out of honouring Eric’s decision. If his lesbian wife is OK with suddenly finding herself married to a heterosexual man who still loves her, that ought to be good enough for the rest of us. Call him Eric and use he/him in his hearing at least, and everywhere if your employer says you must. But you do have a responsibility to truth as an objective good to answer “No” (at least silently, in your heart) if you are asked “Do you believe that Eric is a man?” “None of your business” would also be an acceptable answer. If your employer says you must answer “Yes” out loud, then you no longer live in a free country.

    2. There’s a difference between being nice to someone like eric and denying objective reality.
      If anything transexuals show there’s a sex and gender binary.
      People like eric shouldn’t be used by an ideological few to undermine science.

  11. I am not sure the species concept is a good analog to sex, as AFAIK there really are fuzzy boundaries between at least some species in the same genus, and the assignment of species status is historically somewhat arbitrary, in a way that sex isn’t. Lots of traditional species, among baboons, for example, turned out to mate with each other in the wild. In the process of speciation, there is a “spectrum” from perfect fertility and fitness of offsping over reduced fertility and fitness to absolute reproductive incompatibilty.

  12. I really like the final paragraph of the article:

    “The push for a biologically sexless society is an arrogant utopian vision that cuts us off from our evolutionary history, promotes the delusion that humans are not animals, and undercuts respecting each individual for their unique individuality. Sex is neither simply a matter of socialization, nor a personal choice. Making such assertions without understanding the profound role that an initial biological asymmetry in gamete size plays in sexual selection is neither scientific nor sensible.”

  13. Everyone should read this. Fantastic article. Of course, it doesn’t capture the big picture, but then I never seem to see any contemporary writing that does. I might take time to get to the trans debate, but bear with me. The fact that we evolved demands a fundamental revaluation of what it is to be human that has barely even begun. We are animals, more accurately we are social primates, more accurately still we are great apes. Studies of non-human great apes have shown that chimpanzees behave differently from bonobos, both species behave differently from gorillas and all of them even more markedly from orang-utans. Underpinning these differences must be the way they think and feel about the world they live in, or in other words they have what I call a deep nature, which means that, if we are animals, our species must have one too. Part of our deep nature is that, unfortunately, we are a tribal species. Our deep nature didn’t evolve in the world we live in today: and what follows is a significant simplification of the case I’d make if I had more time and space, but tribalism (technically in-group/out-group behaviour) has cursed our species, causing all wars, division and discrimination throughout history. So, perhaps we should think of it as anachronistic hangover behaviour from when we lived on the African plains in the Pleistocene. This current muddle over trans-identities is just the latest manifestation of it. We, rightly, want to oppose discrimination, but the enthusiasm of some about doing this, has led to the absurdity of denying basic biology. Of course, it is part our deep nature to want to belong, to feel safe, protected and settled within whatever identity group to which we feel attached. The trick is to find some way of achieving this without othering those outside of our identity group (which inevitably includes apes – which in contemporary culture, compared to humans, are thought of as smelly, hairy and stupid). I suspect we will never understand how to perform the trick effectively until we understand who we are, why we are the way we are, and where we came from: and in that respect, denying biology definitely won’t help.

    1. This is a complicated question, and one that’s discussed in a jointly authored paper that will come out at the end of June. For the time being I’d suggest you read this post, and the links to earlier posts within it, to see my take on the issue.

      1. Very helpful and I appreciated the line regarding the location of East Asians.

        On a personal note, I am of Mexican descent. As a third generation American, I had a lower to middle class upbringing in overwhelmingly white majority neighborhoods. My parents chose not to teach us Spanish because they didn’t want it to get in the way of our academics. I married a white girl. My visits to Mexico have been day trips to border towns as a tourist.

        So culturally, I’m white. What puzzles me is my interest in music. It’s broad with jazz being my favorite genre.

        Yet, I melt when I hear Mexican ranchera and mariachi even though I understand only about 10 percent of the lyrics. It affects me like no other.

        I’ve often wondered if this attraction is biologically based.

        Thank you.

    2. We still use the race structure victorians imagined, and that’s different to the race structures the Chinese imagined (it wasn’t that long ago all Chinese people were taught that they were a separate human species to everyone else), the race structures Indians imagined and the Africans above and below the Sahara, etc etc blah blah blah.
      In that sense race is a social construct.

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