FtBCon2: Evidence Based Feminism w/ full transcript

Here’s the talk presented Friday night by HJ Hornbeck. Below the fold is the full transcript including all notes and links, which he’s helpfully provided.

I believe if you visit the Youtube page you will see that HJ has adequately performed his intended task — dredging for MRA trolls and making them take anti-scientific positions. Because that’s what it takes to deny that feminism is right about its foundational claims: you’d have to be anti-science.

[This is a direct copy of my shooting script, including all my cues. It’s a condensed version of a much longer source document, which also contains all the bonus content, full citations, illustrations, and links to PDFs. To get your paws on that, click here.]

Hi, I’m HJ Hornbeck, a co-host of the Legion of Reason podcast and a former president of the UofC Freethinkers. Before I get talking about the evidence for feminism, I must let you know that I’ve made a rough transcript of what I’m about to say here [tablet]. This should a big help to the deaf, or the vast majority who think I’m talking too fast. I’ll also toss in a few footnotes, illustrations that you can actually see, and a little bonus content.

On with the show. Of all the published works I’ve looked at, Helen Woolley’s has been the most fascinating. The introduction to her second meta-analysis complains of a flood of new papers, mostly due to the feminist movement.

Summing up the wealth of data, she declares [tablet] “the truest thing to be said at present is that scientific evidence plays very little part in producing convictions.” She spends a fair bit of time discussing the contradictory theories, results, and interpretations that plague the current research.

One reason why I dig this review is that it was published in [tablet] 1914. Yes, for over 100 years science has been studying culture and gender. For twice as long, feminism has also been making claims about culture and gender. If feminism’s claims are out of step with the scientific evidence, then it’s at best a cargo-cult, taking the aspects of reality it likes and constructing wonderful fantasies around them.

So let’s cut through the fantasy and get to the fact. What does science have to say about the claims of feminism?

We’ll start big, with the feminist view of gender. The most definitive statement I know of comes from Simone De Beauvoir’s 1949 work, “The Second Sex.” I quote: [tablet]


“The biological and social sciences no longer admit the existence of unchangeably fixed entities that determine given characteristics, such as those ascribed to woman, the Jew, or the Negro. [tablet: 1949!] … But does the word woman, then, have no specific content? This is stoutly affirmed by those who hold to the philosophy of the enlightenment, of rationalism, of nominalism; women, to them, are merely the human beings arbitrarily designated by the word woman. Many American women particularly are prepared to think that there is no longer any place for woman as such; if a backward individual still takes herself for a woman, her friends advise her to be psychoanalysed and thus get rid of this obsession.”


A quick aside: most of what I’ll reference for the time being was written before the term “gender” was used to describe humanity. When you hear “sex,” think gender instead.

Anyway, the vast majority of the feminist movement still agrees with De Beauvoir. However, Woolley’s complaints about the pace of studies are even more true today, so I’m forced to rely heavily on meta-analyses. These take a big-picture approach, gathering as much high-quality data as they can and rigorously summarizing it. While the meta-analysis approach has issues, it remains the best method we have for digging up truth.

Helen Woolley’s 1914 paper was the first good meta-analysis of gender differences. She mentions two competing theories of difference: gender differences were either inherent to our biology, or they were socially constructed. [tablet]

“All of this group of men, in spite of their wide differences of opinion as to the nature of the psychological characteristics of sex, are convinced that they are inherent and are not to be explained by environmental influences during the life of the individual. … Differences which remain constant at different ages and in different countries must, they think, be inherent in sex itself. They do not seem to have considered whether or not there are factors in the social environment of sex which remain constant in all modern civilized countries.”

“When one turns to the books written more largely from the historical and sociological point of view, the trend of opinion is that mental differences of sex are of social origin. … They all lay stress on the view that social conditions account for most of the traits ordinarily considered feminine, and particularly for the limited accomplishment of women in art and science.”

Woolley gives no general summary, but she usually concludes there is no significant difference, or not enough data to conclude anything. Woolley does find some minor differences though: girls grew up faster than boys, but caught more diseases; girls were better at complex motor tasks, memory tasks; they occupied the higher parts of the IQ curve, and were absent from the lower parts; and finally, girls were better at school. =05:00= Boys had better reaction time, and excelled at simple motor tasks; better at reasoning, math and logic; better at exams; and better at free association, which might explain the gender gap in rap.

The next major review after Woolley’s came in 1927, from Florence Goodenough. Her overall conclusion: [tablet]

“The most outstanding impression which one gains from a comparison of these studies is the inconsistency of the various findings. Sex differences are shown, it is true, and while they are in general small, there are still a number of instances in which a sufficient number of cases have been included to give a reasonably high degree of reliability to the differences shown. The direction of these differences varies, however, according to the type of test used, and with the age and school status of the subjects.”

“As several writers have been at pains to point out, the practical import of sex differences in mental traits is negligible, since the amount of overlapping is so great that the small differences between the sexes are completely overshadowed by the great variations found to exist between members of the same sex.”

What about the non-significant differences? Again, we find girls excel in verbal skills, and boys exceed in math, but only in the later grades. Goodenough concurs with Woolley about memory, but is more cautious about motor skill, stating [tablet] “there is, unfortunately, but little in the data at hand which serves to indicate whether the popular opinion as to masculine superiority in tasks of this sort would be justified if the material used were equally familiar to both sexes.”

The next major review was from Harvey Lehman and Paul Witty in 1930, and they blast much of the literature for perpetuating falsehoods. They find seven key flaws, including: biased samples, small sample sizes, poor analysis, overgeneralizations galore, and an automatic assumption of differences being biologically innate, when social factors have not been ruled out. Overall, they agree with Goodenough’s review.

The next major one came in 1946. [book] The “Manual of Child Psychology” contained a single chapter devoted to sex differences. Titled simply “Psychological sex differences,” it was written by Lewis M. Terman, among others, and unlike the previous authors I’ve mentioned they favor biological explanations over social ones.

You sense this was a minority position, though; their leading theory was that hormone levels explained difference. While animal models provided good evidence for this, the technology didn’t allow them to accurately measure endocrine levels in human beings, depriving them of a smoking gun; in contrast, the social construct side had mountains of evidence in their favour, ranging from cross-cultural studies to the difference between stereotypes and actual performance. The best the innatists could do was declare the situation to be complicated and messy, with no single explanation for difference being sufficient.

Terman and his co-authors found significant sex differences, but for various reasons, they have been led [tablet] “to emphasize sex differences in central tendencies rather than the extent and frequency of sex overlap.” Besides, “the results are sufficiently consistent to leave little doubt as to what are the essential facts.”

When it comes to verbal ability, for instance, there is no difference. While small-scale studies sometimes contradict that, they usually have deep flaws that makes them unreliable.

As for memory, there is far more evidence for similarity than difference, with the studies that fail to find a difference outnumbering those that do. On general intelligence, the authors state that [tablet] “although the groups tested are often large[,] they can never be viewed as strictly random samples of the general population, since a number of factors affecting school enrollments[sic] are known to operate differentially for the sexes. In general, however, the sex differences found were so small and so inconsistent in direction that no positive claim could be made for the superiority of either sex at any age.”

They also have a brief note on variation. The notion that men vary more than women began fifty years earlier, to explain why the historical record contained nothing but high-achieving men. They just occupied the extremes, the rationale went, while women were less variable. As early as 1914, however, there was considerable evidence that showed little if any difference in variation existed. Every meta-analysis I know of concludes there’s no significant variation.

1974 brought us the most cited review of gender differences, creatively titled “The psychology of sex differences.” I feel bad about just quoting from the summary chapter, but I’ve gotta watch the clock. The following beliefs about gender were found to be false [tablet]

Girls are NOT more social than boys.

Girls do NOT have lower self-esteem.

Girls are NOT better at rote learning, and boys are NOT better at higher-level cognitive tasks.

Boys are NOT more analytic.

Girls are NOT less motivated to achieve than boys.

Girls are NOT biased to auditory sensation, and boys are NOT visual.

=10:00= The following are actual gender differences that Maccoby and Jacklin found good evidence for [tablet]:

Girls have greater verbal ability than boys. The differences don’t show until 11-ish, however.

Boys exceed in visual-spatial ability. Again, the differences don’t conclusively show until adolescence.

Boys excel in mathematical ability. There’s a lot of caveats, though; Maccoby/Jacklin admit the difference is small and could easily be explained by social factors.

Boys are more aggressive. The pair don’t give a magnitude here, but make it clear the difference is big, starts early, and gradually declines over time.

A number of claims didn’t have enough data to say either way, including [tablet]:

Tactile sensitivity. Apparently that was a thing?

Competitiveness. Culture, here, seems to be more important than biology.

Dominance. If the genders are segregated, boys tend to be more dominant. When they’re mixed, the evidence is ambiguous, and may point to any short term difference levelling out into long-term equality.

Maternal behavior. Cultural studies suggest girls are more nurturing, while observational studies show no difference whatsoever. If we use altruism as a proxy for nurturing, then there probably isn’t a difference.

Now, this meta-analysis marks the end of an era. Until until here, every review has been summarized by eyeball and intuition, permitting bias to creep in. The increasing spread of computers in the 1980’s, however, combined with easily searchable databases, gave us an effective tool for cutting through bias, and dramatically improved the quality of analysis.

The first to champion this new approach was Janet Shibley Hyde. In a 1981 paper, she reexamined the Maccoby/Jacklin review and found:

The main conclusion that can be reached from this analysis is that the gender differences in verbal ability, quantitative ability, visual-spatial ability, and field articulation reported by Maccoby and Jacklin are all small. Gender differences appear to account for no more than 1%-5% of the population variance.

Hyde next focused on the strongest claim of those two, that men are significantly more aggressive than women. More surprises appeared: adults displayed no difference in aggression, while pre-pubescent children displayed the most.

In conclusion, it appears that gender differences in aggression, like cognitive gender differences, are not so large as one might assume from the conclusion that they are “well-established” (Maccoby & Jacklin, 1974). Within-gender variation is far larger than between-gender variation.

But what really caught everyone’s attention was Hyde’s finding that the gender gap was narrowing with time. The floodgates opened, and everyone started pumping out their own large-scale meta-analyses.

In 1988, Hyde examined the verbal gender gap with improved methods and more data, and declared:

We are prepared to assert that there are no gender differences in verbal ability, … in American culture, in the standard ways that verbal ability has been measured.

This study also found no clear increase in verbal skill around age 11, contrary to Maccoby/Jacklin; that female researchers were more likely to find a gender difference; and yet again, the gender gap was decreasing over time.

In 1990, Hyde’s latest data told her the gender math gap was small, but when she only included studies that reflected the general population, it completely disappeared! Hyde did note a wider gap in some areas, but could explain those exceptions with social factors. And yet again the gender gap was decreasing with time.

Other authors have also studied the same topics, and more, and backed up Hyde’s findings of small-to-no gender differences.

Hyde, however, has been a favorite target of critics. Her infamous paper “The Gender Similarities Hypothesis” triggered four rebuttals in the very same journal it was published, of which I’ll mention two.

Richard A. Lippa criticized her for starting from the wrong hypothesis. He himself ascribes to what he terms the “gender reality hypothesis;” he assumes that there will be some gender differences, then once he finds a difference he tries to look for a reason it exists. Hyde’s assumption of the null hypothesis was too simplistic, for him; she should move past this heated and polarized debate over the existence of difference, and look instead for greater meaning.

G. E. Zuriff criticized Hyde for being too scientific. After all, everyone sees huge differences between the genders, including many keen observers of humanity. They don’t come to that conclusion by playing with numbers, running experiments, or weighing the evidence, they use psychology, not science. Hyde’s methodology is doomed to fail, and she should consider other ways of knowing. =15:00=

Whatever your stance, we find ourselves in a very weird place. It’s been over one hundred years since Woolley’s crack at the subject, yet we still don’t have a consensus on gender differences. Even the meta-analyses I’ve covered don’t always agree. Woolley found girls were better at language, Terman found no difference, Maccoby found they were better, Hyde and others found they weren’t. Woolley found almost difference in math ability, Terman and Maccoby found a difference in higher abilities, Hyde would flip between a difference due to higher education, no difference at all, then a difference due to high school. Outside of meta-analyses, we still find stark differences in individual studies that point every which way. How can we conclude anything from this mess?

Pretty easily, actually, with the help of firearms.

Machine guns are not precise weapons. Pull that trigger and bullets go flying everywhere. A rifle, in contrast, is precise; pull that trigger twice, and both bullets will land in roughly the same spot. That spot, however, may be a few feet to the right of where you were aiming. If the scope is misaligned or the barrel warped, a rifle becomes a biased and inaccurate weapon, even if it still precisely lands a bullet in the same spot.

OK, now let’s say I snag a paper bullseye from a shooting contest. [tablet] Bullets are scattered all over the place, but there are few clusters. What can you tell me?

Well, everyone could have used imprecise weapons. That’s not likely, and we’d expect an imprecise weapon to throw bullets around more randomly.

Or maybe they used very precise weapons, but on a very small target. A weapon’s accuracy would then dominate, and any bias would have a similar effect to imprecision, though we’d generally expect less clustering. Generally.

Or maybe the weapons were precise but inaccurate. The target was large, but bullets went almost every which way because everyone’s gun was biased. Almost, though, because bias itself can be biased.

I think you can see where I’m going here. If we were unbiased and accurate, we’d have long settled the sex difference question. If we were biased, or the differences were small, or our tools were inaccurate, then we’d have results all over the map. But the vast literature and use of meta-analyses rule out inaccurate tools, and the wild clusters of different and shifting conclusions point to significant bias.

So De Beauvoir called it; either the differences are so small they can be treated as non-existent, or we’re biased and in need of a shrink.

It’s important to note that “bias” isn’t synonymous with “personal prejudice.” [tablet] Here’s the standard deviation of variously sized random samples taken from a larger population. Note that it underestimates the population’s standard deviation for small values, making the distributions more concentrated and exaggerating difference.

Of greater concern is this horn surrounding the deviation. A random sample is a random sample, after all, and sometimes you pick values that have more or less variation than the overall pool. The inner horn is your 50/50 line; there’s a 50% chance you’ll pick a value from within there. The outer horn contains 90% of the values. Even with a sample size of 100, there’s a 50/50 chance your standard deviation will be off by 5% or more.

That’s a bit of a problem, thanks to the “file drawer effect.” Scientists are human, after all; we want to have an impact on our chosen field, push the boundaries and come to solid conclusions. Publishing a study that says “we couldn’t find anything” doesn’t seem to do that, so instead the results are stuffed into a file drawer.

[tablet] Problem: if the effect is relatively small, then tossing those null results distorts the scale of what we’re studying, letting the extremes dominate. My simulations show that published studies will tend to inflate the mean.

Similar effects apply to the standard deviation. [tablet] Publishing only the results that are statistically significant tosses out trials with high deviation, which underestimates the population deviation and exaggerates difference. This effect gets worse with smaller sample sizes, or effects. And random samples random – horns – et cetera.

That’s bad enough, but there’s another effect in play. Richard Feynman’s famous “Cargo Cult” lecture points out that scientists are more critical of their results if they’re unexpected or too different from the norm, causing them to look for ways to bring the data back “into line.” Flawed initial results do get corrected, but only slowly and gradually. =20:00= Feynman claims that nowadays “we don’t have that kind of a disease,” but Maccoby and Jacklin demonstrate a counterexample.

You might think the cost of a study would discourage tossing out results, but those two also point out that most studies aren’t targeting gender differences; their primary goal was to look at another question, the analysis around gender just happened to be on the path to that goal. They lose nothing by filing the gender analysis bit away.

[tablet-REDUX] We can now build up a picture of this system: a small study finds a big difference and publishes it. Other researchers jump on the bandwagon; those that get a weak effect will dustbin or “retool” their work, while those that agree, or disagree in a spectacular fashion, will get published. Later researchers increase the sample size or do a meta-analysis to cut through the confusion. Greater statistical power allows weaker effects to get published, and the observed difference shrinks. Disappointed, future researchers either look elsewhere, or split their meta-analyses into sub-populations in search of something they may have missed. Sample sizes drop, and suddenly differences re-emerge. The cycle thus repeats.

But just because our biases have a greater effect than gender differences, doesn’t mean gender differences are small. We need a way to judge the degree of difference. Let’s take a step back.

When we say “men are taller than women,” what do we really mean? I figure it declares “pick a random man and woman, and more often than not the man will be taller.” It says there’s this property that we call “height” that tends to be associated with men more often than women.

Note this goes both ways; if I was to hand you someone’s height, you should be able to predict their sex. Demographic data confirms this. For each possible height, we calculate the number of men and women who have that height. We chose our guess based on the biggest share, accept our losses, and then update the integral. In graphical form, we divide the biggest share by the total of all shares. [tablet]

For Australia in 1995, we find we can correctly guess if a person is male or female about 83% of the time. [tablet] Sri Lanka as of 2005 gives the same results. That means our failure rate is 17%, though, which seems pretty high next to the standard “p value” of 5%. Then again, height isn’t the sole way we determine gender. We’re fine with the existence of tall women and short men, because we have other ways of determining gender.

With our tool now in hand, we can measure gender differences! We’ll start with a null result, the difference in mathematical skill that Hyde found in 1990 within the general population. [tablet]

As you’d figure it’s 51/49, barely different from a coin toss. Hyde breaks down the studies into several categories, and not surprisingly found bigger differences in the smaller samples. Here’s the largest she found, which is for graduate students and certain colleges and has a solid social explanation: [tablet]

That’s still pretty small, we’d be wrong 40% of the time if we tried to predict gender that way. Still, it establishes the range of differences that could be explained or generated by social factors.

Let’s move on to spatial ability, a more fertile ground for gender differences. Here’s the difference in spatial visualization, the smallest according to the Voyer’s 1995 meta-analysis. [tablet]

That’s only 54% predictive. The largest difference they found was in “mental rotation ability:” [tablet]

Wait, our failure rate is 39%? How can they state “men are significantly better at mental rotation,” then?

Because the word “significant” has multiple meanings. A statistically significant result is one that we wouldn’t expect by chance. To properly test whether or not a coin comes up heads 11 times out of 20, I need to flip it over a thousand times. That result is highly significant, in a statistical sense, but is it personally significant? If I gave you a coin with that much bias and told you it was fair, would you ever notice I’d lied? I doubt it. A 60/40 split might be noticeable, in certain contexts, but if it only shows up with large sample sizes in laboratory conditions, we probably couldn’t detect it in our messy everyday lives.

But to some extent I’ve been talking from Mars while sociology has been focusing on Venus. Contemporary research has abandoned gender differences in favor of sex differences.

What’s the feminist view on those? Here’s what the Transfeminist Manifesto says: =25:00=

Though the second wave of feminism popularized the idea that a person’s gender is distinct from her or his physiological sex and is socially and culturally constructed, it largely left unquestioned the belief that there was such a thing as true physical (biological) sex. The separation of gender from sex was a powerful rhetorical move used to break down compulsory gender roles, but it allowed feminists to question only half of the problem, avoiding the question of the naturalness of essential female and male sexes. Transfeminism holds that sex and gender are both socially constructed; furthermore, the distinction between sex and gender is artificially drawn as a matter of convenience.

Sounds like there’s no consensus, with some branches of feminism content with sex differences. I don’t know which view is the most common feminist one, but within my peers and readings the Transfeminist view seems to rule the roost, so I’ll defend that.

How does sex differ from gender? Up until 1955, it didn’t; the meaning of “gender” relating to humans wasn’t even invented until then. Even afterwards, there was no consensus definition; depending on what you read, “sex” was anything that remained constant across cultures, or anything tied to biology, where “biology” meant anything from chromosomes to hormone levels. “Sex” was basically a synonym for ignorance. Time and time again, our knowledge would advance, an unexplained difference would get a cultural explanation, and it would be moved to the “gender” pile.

But the problem goes far deeper than that. Here’s Woolley again [tablet]

The ancient idea that the female is essentially an undeveloped male seems to be finally disproved by the fact that it requires more determiners—usually one more chromosome, or a larger sex chromosome—to produce a female than a male. When the additional sex chromosome was first discovered the assumption was that it determined maleness, doubtless because of the idea that the male was a more highly developed type.

The assertion that there are exactly two sexes is pretty new. The ancients observed that while humans generally fell into two categories, there was variation and exception. Plato thought there were three sexes: male, female, and “hermaphrodite,” or people who combined male and female characteristics. He thought category three was extinct, however other ancient historians note them as fact.

The most common solution to this problem was to declare there was just one sex, which developed in different ways. In the ancient Middle East, for instance, they thought everyone stored sperm in their brain. Coming from strong sperm meant you had hairy weights that drew your sperm down your spine to be ejected from a handy tube. If you came from weak sperm, your tube was inside out, no weights dropped, and you instead developed long hair on your head. This acted as a wick, drawing any sperm deposits into your body where they would compete with your own sperm.

Incidentally, that explains why Middle Eastern religions ask women to cover their heads; no-one likes it when you wave around your genitalia.

All variation was neatly explained: there was an ideal form, which we’ll call “male,” and all those “women” and “hermaphrodites” were just defective men!

That didn’t sit well in some quarters. By the 1800’s, scientists were trying to separate science from religion, and some proposed a newer model of sex that didn’t claim women were sin-filled defects: they were instead fundamentally different, a full-on second sex. Wanting to have and eat their cake, however, they argued the differences didn’t matter because the two sexes were equal where it counted most: our minds.

As a side effect, intersex people were tossed under the bus. The bigotry of the one-sex model came from asserting there was an ideal human nature; remove that, and the hate goes bye-bye without killing the model. In contrast, the two sex model demands a clean biological division, and those that don’t follow it must be defects otherwise they’d threaten the model. Opponents of the two-sex model used this to their advantage, and while the binarists looked for biological difference, they looked for biological similarity. For nearly a century, the one-sex hold-outs were victorious in biology, even as they lost ground in psychology.

That changed when sex chromosomes were discovered just before 1910. Many scientists including Woolley were quick to claim the X chromosome as the female counterpart to the Y. This belief pops up even today, and it’s absolutely wrong.

As far as we know, every single human being has an X chromosome. =30:00= It contains genes critical for the development of our skin, eyes, nose, intestines, muscles, and other necessary anatomy. The X even contains more genes related to testicular development than the Y chromosome. You cannot make a human being of any sex without an X chromosome.

On the flip side, you don’t need a Y chromosome to make a man. XX males are rare, constituting maybe 1 in 20,000 births, but they’ve been well documented by science. Nor, for that matter, does the presence of a Y chromosome guarantee maleness, as XY females also exist.

It’s tempting to ignore these exceptions. But how did we determine their sex? If chromosomes were the one true division, we’d have an error rate of exactly zero; instead, we’re overriding chromosomes and flipping the sex. This minority cannot be dismissed, if we want to discover a division of sex.

The next big hope was hormones. While there was some early work done in the 1850’s, the study of sex-related hormones didn’t take off until the 1930’s. Testosterone and estrogen compounds were found to have far-ranging effects on the human body, and in animal models were also found to alter behaviour. Scientists eagerly started digging here in search of difference.

This search has also carried into modern times. [tablet] Lauren Rosenberg and Sohee Park tested two groups of women, one set on the pill, one set not, and found a significant difference between them; one group was better at verbal memory tasks.

Wait a minute. I covered verbal ability earlier on, and back then we found no gender differences. But if there’s no difference between men and women, who have different estrogen levels, why would we find a difference within women? What’s the sample size here – oh, eight?! Wait, and they tried three different types of contrast analysis to extract a correlation? And- OOOOO, look what’s buried in the back: “we did not perform hormone assays to verify the actual hormone levels”

The field is littered with examples just like this, small sample studies which find sharp gender differences that larger studies have shown to be minimal or non-existent. On top of that, meta-analyses are few and far between here.

Take Premenstrual Syndrome. The science on mood and menstruation cycles is surprisingly lousy. Sarah Romans and her co-authors couldn’t even perform a meta-analysis on the evidence; out of 646 articles on the subject, only 41 reached their minimum requirements. The resulting old-school qualitative summary found only six studies of those 41 which demonstrated PMS as we think of it. Eighteen found a complicated relation between mood and menstruation, while 16 found no relation. PMS probably doesn’t exist.

Testosterone, though, provides a different story! There’s plenty of data for a meta-analysis, and so far four have been done. The latest is a rehash of an earlier analysis, done in 2001, which found a predictive rate of… [tablet] 54%.

I never did provide much detail on XY females. Some of them have “streak gonads,” or lumps of inert tissue. Others, however, have fully-functional gonads within their chest cavities, which pump out the same level of testosterone compounds you’d find in a man… and yet, no-one would dare call these people men.

But don’t worry, another potential division has come to the rescue: brain structure! See, the past few decades have given us some incredible tools for examining the brain, and a few neuroscientists have used them to dig for differences. As one study put it:

“Sex differences in brain anatomy may explain some documented differences in behavior. Women perform better than men on verbal and memory tasks, whereas men excel in spatial tasks”

Hmm, deja-vu. We’re presupposing a difference, and then searching for that difference. This is a big problem with neuro-imaging; these tools are fire-hoses of data, making them ripe for data-mining and false conclusions, such as discovering brain activity in a dead fish. And because of time and expense, these studies tend to have small sample sizes.

One major exception broke in December 2013. I’m sure you’ve seen the headlines: [tablet] “Male and female brains wired differently, scans reveal: Maps of neural circuitry show women’s brains are suited to social skills and memory, men’s perception and co-ordination.” The study in question is certainly the most definitive study of neurological difference to date, and it found that if you used brain wiring to predict the sex of a person, you’d get it wrong… [tablet] 40% of the time.


And that was the best-case scenario. There’s a lot more I and others have said about this study, but I’ll only mention one other objection. =35:00= Did these researchers find brain structure steering our social roles, or were social roles causing our brains to rewire and adapt? If you want these small differences to be intrinsic, you must assume the brain’s structure is static and eternal. Even a neuroscientist should know that’s poppycock.


But don’t worry, we’ve got ANOTHER candidate waiting in the wings: genes!


Decoding the structure of DNA started a minor revolution in biology. Thinking from a gene’s eye view explained many previously puzzling problems, like altruism or colonial insects.

Robert Trivers was at the forefront, and in the 1970’s he published an influential series of articles, one of which covered parental investment and sexual selection. A simple set of assumptions could be used to explain a wide variety of behaviour, which sparked a huge interest and created a new discipline: evolutionary psychology.

Trivers made three critical assumptions: there are only two sexes, fundamentally different from one another, and that a primary driver of that difference was sexual selection. Those assumptions weren’t necessary, but they made it easier to do the math and find examples.

As one, David Buss argues that men are bigger than women because parental investment demanded that men had the hunting duties, while women had no choice but to gather, which means that we should expect to find major biological differences in… spatial ability. Huh. He concludes a difference exists based on five studies, completely ignoring the Voyer’s meta-analysis of 286 studies, which as I showed earlier found a difference small enough to be explained by social factors.

Buss asserts that mental rotation is the best measure of hunting skill, arguing it was necessary for chucking spears and route finding. But mental rotation is just the ability to rotate things in your mind; that has nothing to do with manipulating objects while dealing with distractions, which is called spatial reasoning in the literature, or memorizing landmarks, which is a spatial memory task. In a remarkable co-incidence, mental rotation shows the largest gender gap of all types of spatial ability, while spatial reasoning shows less and Buss himself argues that women have better spatial memory than men.

Buss is cherry-picking the data to fit his theory. He must presuppose there are sex differences, though, as he’s using the same assumptions as Trivers. The theory predicts them, he believes they exist, so that settles it! If he doesn’t find a difference, he just keeps looking and waiting until one arrives.

Consider aggression. Scientists used to find big differences there, which they explained through evolutionary theory as the result of men competing for mates. Women weren’t thought to be aggressive, with David Buss himself declaring female aggression wasn’t worth studying. When they were studied, however, the difference in aggression disappeared. Not a problem! Human beings are social creatures who spend a lot of time in groups, hence getting along with one another would enhance our survival, and based on that evolutionary theory predicts there should be no difference in aggression. And hey, we don’t find a difference! Our theory is still correct.

If there was any difference in aggression, it had to be by type. Men preferred physical aggression, while women preferred indirect aggression through flexing their social superiority. But didn’t Maccoby and Jacklin fail to find superior social skills? Hmm.

No-one’s bothered to study female physical aggression exclusively, but they have studied aggression between the sexes in heterosexual relationships, and found… [tablet] women were just as prone to committing physical violence as men.

On the flip side, women have more parental investment than men, so we’d expect them think in terms of care-giving. Carol Gilligan proposed exactly that in her book “In a Different Voice,” which triggered a decade of research. Hyde neatly summed it all up in 2000. Based on 160 studies, she concluded that the sex difference in a moral orientation directed towards care was… [tablet] 56%.

Ok, what about risk-taking? Women invest quite a bit more in their offspring than men, so you’d expect them to be more cautious. There was a meta-analysis on this back in 1999, and the difference found in gambling risk was [tablet] 54% predictive.

The observed difference in risky physical activities, like climbing steep hills or playing in the street, was [tablet] 53% predictive:

The difference in risky sexual activities was [tablet] 51%:

But the biggest difference was in observed risks taken based on physical skill, like deciding which peg to toss a ring on, which was [tablet] 58% predictive:

=40:00= Ok, rewind a bit: there wasn’t much difference in sexual activities? Admittedly, that statistic is a bit misleading, because it groups all age categories together. If you divide the data down into smaller chunks, you can get a sex difference that’s [tablet] 62% predictive:

However, that’s based on a single study of 183 individuals, aged 10-13. While it’s tempting to ignore the small sample size, since that age range is roughly when menstruation begins, if you have a good diet, you then have to explain why a much larger sample pool of slightly older children showed a difference in sexual risk-taking that was only [tablet] 54% predictive:

The sex differences in… well, sex were at least interesting. Maybe here we’ll find the differences predicted by EvoPsych? Hyde has crunched the numbers, and the sex difference in the number of sexual partners was… [tablet] 55% predictive.

The sex difference in attitudes to extramarital affairs was… [tablet] 56% predictive.

This is freaky. We’re talking about sexuality, an area where EvoPsych claims to reign supreme over all other theories, and yet we’re not finding the sex differences it says should be there. Maybe we need to focus on specific claims.

Consider casual sex. In 1989, Russell Clark and Elaine Hatfield unleashed a few “confederates” onto a college campus, who would size up random strangers in an area, then walk up and proposition them. The results were striking: three-quarters of men agreed to an out-of-the-blue offer of sex, while not a single woman did the same. Conclusion: men are far easier to get into bed.

Problem: Women have been told, repeatedly, that men could sexually assault them and thus can’t be trusted. Maybe this social difference is at fault? Terri D. Conley decided to find out; by substituting written tests for the live experiment of Clark and Hatfield, she was better placed to figure out why women were rejecting these men. Sure enough, men were consistently perceived to be far more dangerous by women, then women were by men. Conley then spent quite a bit of time playing around with the basic scenario. When the person proposing sex was someone the person knew, and therefore trustworthy, the sex difference disappeared entirely. She also found that women preferred attractive men to wealthy men, by quite a margin, and that men ignored whether or not a woman was fertile when deciding to share the sack, both of which contradict the predictions of EvoPsych.

Women are also claimed to be more discriminating about potential mates, because of their greater cost in child rearing. Several large studies, most notably one by Robert Kurzban and Jason Weeden in 2005, have consistently found that in speed dating, men are less choosy than women. Their study in particular had a huge number of participants, in contrast to Clark and Hatfield’s piddling sample size. It looks like a solid result…

… but, Eli Finkel and Paul Eastwick noticed that every speed dating session had women stationary, while the men moved around. Their study flipped that around, and observed what happened when men sat around instead. The men not only became the choosy sex, they became just as choosy as women. This difference wasn’t due to sex at all, but a seemingly trivial social custom.

Now, you do not create consensus through a single study. Those two studies need multiple follow-ups before we can treat them as anything beyond interesting. The only way to achieve more in a single step is to kick out a core premise.

[book] In the intro to one of his textbooks on EvoPsych, David Buss writes:

It is part of the male lion’s nature to walk on four legs, grow a large furry mane, and hunt other animals for food. … It is part of the porcupine’s nature to defend itself with quills, the skunk’s to defend itself with a spray, the stag’s to defend itself with antlers, and the turtle’s to defend itself with a shell. All species have a nature; that nature is different for each species.

Buss is arguing some things related to sex are universal for all human beings. We’ll call these objective sexual truths.

But how would you establish their existence? Suppose I assert that all women possess vaginas, and find that out of 100 women, 100 possess vaginas. Have I demonstrated that the 101st woman will possess a vagina? Nope. How about a million? A billion? For what value of X do I demonstrate that example X+1 possesses a vagina, and why do I fail at example X-1? =45:00=

Philosophy majors know this as the problem of induction, and demonstrating objective sexual truths exist would solve it. What are the odds of Buss succeeding where two thousand years worth of philosophers have failed?

But there’s a bigger problem here. No other animal has the genetic code I do, and given how many possible genomes there are, none probably ever will. The same is true for you, your sisters and brothers, your pets, the fly zipping around your room, and so on. How then can you and I share an essential nature, but not our pets or that dang fly? I suppose you could argue parts of our genetic code are unique to us, but which parts? And if a future human being is born without a part, do they still share our nature? Ten thousand years ago we would have declared that drinking milk was contrary to our essential nature, and yet today quite a few of us enjoy a cold glass, because we…. “evolved.”

For the mind encased in Platonic blinkers, a rabbit is a rabbit is a rabbit. To suggest that rabbitkind constitutes a kind of shifting cloud of statistical averages, or that today’s typical rabbit might be different from the typical rabbit of a million years ago or the typical rabbit of a million years hence, seems to violate an internal taboo. …

The word “essentialism” itself wasn’t invented till 1945 and so was not available to Darwin. But he was all too familiar with the biological version of it in the form of the immutability of species, and much of his effort was directed towards combatting it under that name. Indeed, in several of Darwin’s books – more so in others than On the Origin of the Species itself – you’ll understand fully what he’s on about only if you shed modern presuppositions about evolution, and remember that a large part of his audience would have been essentialists who never doubted the immutability of species.

David Buss has been pushing evolutionary psychology for thirty years. What does it say about EvoPsych if their most vocal advocate doesn’t understand evolution? I think it says this is a cargo-cult science, which goes through the motions but only when they reinforce an existing bias.

Now, where does that leave feminism? Let’s return to XX males. From a gene’s eye view, the most plausible explanation is that some of the sequences on the Y chromosome jumped ship for the X. This means we could find a division between the sexes by analyzing the genes of an XX male.

Science has done that, and found the minimum number of genes you need is one. Sex-determining Region Y, or “SRY” as I prefer to call it, kicks off a long, complicated trail of dominos which alter fetal development. Cool! Except, there are about 20,686 other genes in the human genome, the vast majority of which are not contained on the Y. My body has the complete instructions for building a uterus, plus every gene that controls an evolved behaviour in women. What’s stopping it from activating the behaviour genes, by accident or design? Having a single switch sex determiner is actually an argument for similarity, not difference.

So it’s too bad we don’t have that single switch. While about four fifths of XX males have genes known to be unique to the Y chromosome, the remainder do not. We have no idea what’s up with that, but we do know there’s at least six genes involved in sex determination, bare minimum, and only two are on the Y. Human development is just a very messy, complicated affair, and most of us are ignorant of its diversity. Have you heard of micropenises? Aphalia? Ovo-testes? Mosaicism? And I’ve deliberately steered clear of sexuality and transgender people, as their inclusion adds entirely new dimensions of complexity.

At the same time, there are patterns in how we develop, some of which are more likely to happen than others. To represent these patterns, we have jointly developed some terms to tame the complexity, terms like “male” and “female.”

Sex really is a social construct, then, exactly as the Transfeminist Manifesto claims.

There are a lot more claims out there I could cover, like rape culture and objectification, but I see I’ve run out of time. Another time, perhaps?

In the meantime, any questions?

FtBCon2: Evidence Based Feminism w/ full transcript

28 thoughts on “FtBCon2: Evidence Based Feminism w/ full transcript

  1. 1

    You’d think YouTube would act as an incubator for trolls, causing them to gradually ratchet up their game in order to stand out from the crowd.

    Nope. 😛

    So far, the best critiques I’ve received have been that I slipped back into cissexist thinking during the Q&A (and I even TOLD myself to be careful of that! Grrr), that I was too boring, and that I tried to cram too much in.

    No-one has managed to critique the ACTUAL content of my speech so far, which I’m taking as a compliment.

  2. 2

    Also, one of my comments is worth copy-pasting over here, at least in part:


    Secondly, THANK YOU for bringing up the “man the hunter” claim! I desperately wanted to cover that, but had to dustbin it to make room for other, more important points. Rather than overwhelm you, I’ll just cover three key points:

    1. Hunting doesn’t require maximal power, only SUFFICIENT power. To hear most people talk, hunting is a lot like a WWE cage match. Total bullshit; even a modern hunter given a primitive bow, despite having no-where near the training of our hunting ancestors, can fire a home-made wooden arrow straight through a deer. That’s not necessary to earn a kill, and doesn’t provide any extra meat, meaning the energy used to drive the arrow past the vital organs and out the other side is completely wasted. Hunter-gatherers on the edge of starvation couldn’t afford to expend that; instead, they only used about as much power as they needed to earn a kill.

    What counts as “sufficient” power depends entirely on the technique used. How much strength does it take to set up a snare? Dig a pit? Heck, at the extreme end we have the “buffalo jump,” where North American natives would simply cause a herd of buffalo to stampede off the edge of a cliff. Total energy expenditure: a little bit of running.

    Speaking of which, there’s a new theory that’s gaining traction which argues humans specialized in persistence hunting: we’d spook our prey, then chase after it in the hot midday sun until it went hyperthermic and was rendered defenseless. Note that speed isn’t a concern here, we outclass the endurance of every other mammal we co-existed with by a huge margin, so larger limbs don’t provide much benefit. And defenseless prey doesn’t require strength to subdue, by definition.

    2. We’re a social, tool-using species. Tools augment our natural abilities, allowing us to exceed what the next mammal over could pull off without bulking up our muscles. If our tools can bridge the large gap between us and other species, why can’t they render the smaller gap between tall and short people irrelevant?

    Remember the buffalo jump? Human beings have no problem coordinating with one-another, which reduces the amount of strength each individual needs to chip in. A single human being verses a bear is suicide, even if you give them a spear; three human beings is a different story, and six would even allow children to participate.

    3. Women had no problems fighting in wars. If it’s true that women were bad hunters, you’d expect them to be poor soldiers. That’s patiently false; Viking invaders of 900AD England were gender balanced. Shaka Zulu had a women-only fighting force of 1,200. Piracy? Women did that too. Amazons? They were historically fictional, but a group in the Ukraine is making them a modern reality. Modern armies have no problems incorporating women into combat roles; if anything, sexism is what’s keeping them out.

    I could go on, but I think you get the point.

  3. 4

    This was a really fantastic presentation. Having grown up in the 80’s-90’s it feels like I’ve been seeing Evo Psych headlines about sex differences in just about every week of Time/Newsweek/Slate etc. I had heard many people point to the dubious nature of Evo Psych and especially the gender claims that often resulted from it, but I never really knew what the criticisms of it were. Your lecture did a fairly good job of laying out many of the problems in a way that was very accessible even to those of us outside of the fields, and even with limited knowledge of feminism. The only suggestion I have is that you could have gone through the statistical stuff just a little more slowly for those of us who barely passed Stats 101 (despite it being open book!) But anyways, very well done. I had no idea that the “differences” that are so often declared and believed by the mainstream public, were based on such small predictability. I would be curious to know: How do the proponents of these differences typically respond to arguments like yours? Also I know one of the big problems with alot of Evo Psych in general, as PZ mentioned in a post, is based on the fact that the studies so often rely on Western college students (covering very little in the way of cultures outside of that.) I assume that much of the material specific to gender differences would suffer from the same myopia. Is that true?

  4. 5

    Uncle Ebeneezer @4:

    I would be curious to know: How do the proponents of these differences typically respond to arguments like yours?

    I alluded to something like that during the lecture, and fleshed it out further in the bonus content. Those four responses to Hyde’s work were in the September 2006 issue of American Psychologist. I quote the key bits of three in the bonus content, but if you want the full deal you’ll have to hit the library. One contrary study I didn’t cover anywhere was “The Distance Between Mars and Venus: Measuring Global Sex Differences in Personality,” by Marco Del Giudice et al, which is a shame because I found it absolutely hilarious.

    The key criticisms I’ve seen are:

    1. The studies which show similarity are done in laboratory conditions; field studies are more in line with how we normally behave, and they show greater differences.

    2. Meta-analyses combine multiple data streams into one, effectively blurring out difference and biasing the findings towards similarities. In the more technical terms of Del Giudice, they are univarate measures of multivarate descriptions.

    3. The responses I mention in the lecture and bonus content: that’s answered in book X, the shear number of studies that find difference are staggering, you misunderstand EvoPsych, why didn’t you study topic Y, your methodology is wrong, and so on.

    4. While I haven’t seen anyone make it, I also allude to one possible counter-argument in my lecture: we can spot very small differences, in certain contexts, so while the absolute difference may be very small, in a personal and relative sense they feel quite huge.

    If you’re curious, I’ll summarize what Hyde’s response was to those falling under point 3. In my own opinion, though, all four fall flat.

    [incidentally, thank you; when I went back to the bonus content to grab an answer, I noticed I never cited those articles. Whoops!]

    I assume that much of the material specific to gender differences would suffer from the same myopia. Is that true?

    Oh yeah, a LOT of it does. Heck, many of my refutations also come from the WEIRD paradigm. Even good international studies have issues. Take “Cross-national patterns of gender differences in mathematics: a meta-analysis,” which covered an impressive range of cultures… but only gathered data from literate school children, which are not representative of the population as a whole. Getting a truly unbiased sample is freaking difficult, and few organizations have the deep pockets needed to sample the mental rotation skills of rural Chinese farmers and Himalayan Sherpas.

    Anthropological studies have been the best avenue out of that, but they can have big problems with small sample sizes and sexist researchers. While EvoPsych proponents love those studies, they freely equivocate between them and WEIRD sources, and the latter outnumber the former by quite a margin. I wish I’d looked harder at anthro sources, but I simply didn’t have enough time.

  5. 6

    Also, I really do recommend everyone at least glances at the bonus content, if only to grasp just how much research I put into this lecture. I can’t help but share a little postscript I meant to attach to the very end before presentation day, but only finished today, as a little teaser:

    You probably noticed I was using terms and language that are usually specific to atheist or religious communities. That wasn’t just a rhetorical tactic, it was to hint that atheism and feminism share a common bond. It’s not religion, though.

    It’s skepticism.

    You can think of feminism as the skeptical method applied to claims about sex, gender, and sexuality. Many people are sexual realists, thinking “sex” is an immutable and normative property of the world. For instance, they state there are only two sexes and thus exactly two bathroom types, or that women are nurturers and thus must be resposible for raising children by default. Fair enough, but what evidence supports those claims? Are the claims self-refuting by employing logical fallacies? Since Mary Wollstonecraft in 1792, feminists have turned a skeptical eye on various claims.

    You can also think of atheism as the skeptical method applied to religious claims. What evidence do you have for your god? Is the definition logically consistent? Matthias Knutzen is the first known person to be a non-believer in any gods, thanks to three pamphlets published in 1674, and he came to that by critically examining the vast contradictions within the bible. True knowledge could only be arrived at by the conscience, also known as “common science.”

    A common method implies common tools, however. If skepticism can reject any essential or universal claim, then it can reject claims of an essential gender, or universal morality.

    Of course, you can try to define “atheism” or “feminism” without resorting to skepticism. But if “atheism” means nothing more than a lack of belief in a god, what do you mean by “god?” If “feminism” is nothing but equality between the sexes, what is “sex?” How do you define those terms without referencing knowledge of the human condition, at least in part, and how did you acquire that knowledge? It must be through invoking the skeptical method on religious or sex/gender/sexuality claims.

    Or in other words, by accepting the definitions I asserted. That means that the ties between atheism and feminism aren’t coincidental.

    They’re inevitable.

  6. 7

    I completely agree with your assertion about the common underlying bond between atheism and feminism being skepticism, and it’s why I’ve always been a bit surprised when self-described skeptics end up being so credulous on topics like gender, sex, and equality.

    I suspect privilege explains a lot of it. People just are not always aware that they have a blind spot. I would have hoped that for most of them, their skepticism would kick in once an incongruity is highlighted. But, sadly, a lot of people sucummb to motivated reasoning to justify thier biases, and they use the language of skepticism and science, just as Intelligent Design proponents do, to allow themselves to feel ration about their opinion.

    I suspect my blind spots are when it comes to race and social status. I’m white and upper-middle class (a good programmers income, own my own home, two cars, etc). One of the most powerful things that has been told to me was a variation on ‘but that’s not what we were asking for’. That only gets set to people that are trying to help, but who are also ignoring the people they are trying to help.

    I’ve gone off on a tangent. I guess my point is, once you see the pattern of thought that hits that you’ve made unjustified assumptions, it becomes easier to spot in novel situations. Usually. I think. I’m probably blind to something though. *sigh*

  7. 8

    besomyka @7:

    I guess my point is, once you see the pattern of thought that hits that you’ve made unjustified assumptions, it becomes easier to spot in novel situations. Usually. I think. I’m probably blind to something though. *sigh*

    One thing that I do to minimize my own blindspots is to dismantle my own arguments in my head, in search of weak spots. Not attack, but dismantle, as if you were taking apart a car or bicycle. What are the key premises? How well are they supported? Are there any redundancies? If you practice that enough, you’ll start doing the same to other people’s arguments automatically, and quickly get a handle on the quality of the argument.

    Anyway, I finally have a substantial reply! It’s…. not very good. Like “you didn’t understand core portions of my speech despite both reading and watching it” not good. Like “I can refute your arguments by quoting my lecture back at you” not good.

    But it’s something, and some people may enjoy reading it. So there’s that.

  8. 9

    Oh my goodness, I just stumbled on the stupidest YouTube troll! I was getting bored of their attempts to grief me, from two sock-puppets, so I started quoting old lines from one sock back to the other.

    AND THEY FELL FOR IT!!! I can barely see the screen, I’m crying from laughing so hard!

    Let that be a lesson: always feed the trolls, because then you can start trolling them back. 😀

  9. 10

    After being blanketed by brain-dead questions, I’m finally getting some good ones. Cavanaugh himself asked me about using gamete size as a division for sex. My response, slightly edited:

    If you use sexual reproduction as your division of sex, then yes, you can have two sexes.

    Those that can create offspring, and those that can’t.

    Oh wait, you want to divide further by gamete size? Well then you have three sexes: large gamete, small gamete, and those incapable of creating gametes (I’ll term these “non-reproducers”).

    Hang on though, are you mixing in sexual attraction as well? Well then, we have: large gametes attracted to large gametes, large gametes attracted to small gametes, large gametes attracted to non-reproducers, large gametes with no attraction, small gametes attracted to small gametes, small gametes attracted to large gametes, small gametes attracted to non-reproducers, small gametes with no attraction, non-reproducers attracted to non-reproducers, non-reproducers attracted to large gametes, non-reproducers attracted to small gametes, and non-reproducers with no attraction. That’s twelve sexes.

    I challenged him to show one of those divisions was non-arbitrary, but I’m kicking myself for not asking this: And once you’ve settled on a division, how do we assign “male” and “female?” Can you do it without violating our common definitions of “man” and “woman?”

  10. 11

    2. Meta-analyses combine multiple data streams into one, effectively blurring out difference and biasing the findings towards similarities.

    And here my silly pink ladybrains thought that this was a feature, not a bug. The combining part. The rest is “but I want my data to be weak so it points in my direction”.
    The whole point of a meta-analysis is to counter alpha-mistakes and publication bias (aka the drawer effect).
    Because “signisicant” means that there’s only a 5% chance that this finding is a coincidence. That means if 20 studies are done, and only one is published, it’s going to be the one that found something.
    Also, significant does not mean large.
    Actually, large sample sizes are good at finding small differences.

  11. 12


    I never said gamete size per se determined sex. I invited you to explain why, if sex in not binary, gametes come in only two varieties: sperm (male) and eggs (female). Your snarky response was evasive.

    It so happens that sperm are indeed very small and eggs very large — do you know why that is? It’s actually quite central to the very origin of sexual reproduction.


    Skep Tickle (an M.D.) has refuted your claim that sex is determined by hormones levels, and that intersex conditions = multiple sexes. She writes:

    “People who are XY are genetically male. People who are XX are genetically female. No matter what they look like, what gonads they have, or what hormones they make.

    “There are several variations on this theme – several patterns of abnormalities in chromosomal segregation (“nondisjunction” during meiosis) that result in a different number of sex chromosomes but aren’t incompatible with life. These are named syndromes (e.g. Turner’s and Klinefelter’s), as people with the characteristics were recognized as having certain features even before karyotyping was widely available. The biological sex is determined based on the person’s phenotype (external genitalia at birth, which matches the later secondary sex characteristics): Turner’s = female, Klinefelter’s = male.

    “People who have external genitalia and secondary sex characteristics that look female are phenotypically female. People who have external genitalia and secondary sex characteristics that look male are phenotypically male. There are any number of variations that can occur, including external genitalia that appear ambiguous (usually first noticed at birth), but with secondary sex characteristics developing in puberty that display a phenotype that may be different from the sex the external genitalia were assumed at birth to suggest. 5-alpha reductase deficiency is one such condition.

    “Hormone levels are never used to determine someone’s sex, but they can sometimes help sort out what syndrome or condition a person has. People who are XY & thus produce testosterone, but who carry a mutation in the AR (Androgen Receptor) gene can have high testosterone levels yet have female external genitalia and female secondary sex characteristics. This is not some argument against there being no difference between the sexes. This is androgen insensitivity syndrome (AIS), and it just goes to show that without testosterone receptors, the body develops as female. (Not everyone with AIS has “complete” AIS; the phenotype can be male or intersex, depending on the degree of function of the androgen receptors.)

    “So, biologically:
    – genetic sex is determined by the sex chromosomes
    – sex phenotype is determined by (a) certain genes, which control (b) the production of or response to sex hormones
    – most people’s genetic & phenotypic sex match at birth & beyond, including through the pubertal changes, with (XY male, or XX female), with a few people choosing (usually after puberty) to take hormones and/or undergo surgery to change their secondary sex characteristics and/or genitalia
    – Indeed, there are some people who have any of several conditions considered to be abnormal variations on the normal process, whether chromosomal (XO, XXY, etc) or genetic (translocation of the SRY gene from Y to X chromosome, any of ~600 known mutations in the AR gene on the X chromosome, any of ~50 known mutations of the SRD5A2 gene on chromosome 2). These variations don’t disprove the existence of 2 biological sexes – in fact they help elucidate the normal processes.”

    Do you care to respond to this?


    In an attempt to clarify your claims, I posed four specific questions to you:

    1) Can you cite any scientific papers claiming that intersex conditions are not what the American Academy of Pediatrics terms “disorders of sex development”, rather additional sexes?

    2) Can you cite any scientific papers claiming that sex determination in humans is not regulated by chromosomes? Or that human gametes are not sex-specific?

    3) Do you refute that humans reproduce sexually?

    4) Do you claim that sexes and reproduction in humans differ from those in other species of our class?

    Are you prepared or able to reply?

  12. 13

    Gah, Cavanaugh, you’re mucking up my plan! Carrying on one conversation in two places will lead to a lot of cross-talk (I’ve already responded to SkepTickle’s post, for instance), so I’m answering your questions over there exclusively. It saves on Thibeault’s moderation load, and your blog is a more comfortable environment for SlymePitters to participate. Anyone coming to this page will see my link to your blog, and hop over there if they’re curious. If I’m not responding, it’s for at least one of three reasons:

    1) Other tasks are preventing me. As much as I love discussing my talk, I have a number of deadlines coming up and will have to quiet down for a bit in order to hit them.

    2) The questions I’m being asked either have answer so obvious I figure the typical person could answer them after a moment’s thought (“Well, has your article been peer reviewed?”), are completely irrelevant (” I invited you to explain why, if sex in not binary, gametes come in only two varieties: sperm (male) and eggs (female).”), or could be answered by merely re-quoting my lecture (“These variations don’t disprove the existence of 2 biological sexes – in fact they help elucidate the normal processes.”). Answering those are a waste of my time, even if a few people interpret that as being evasive.

    3) I didn’t see them, because comment threading and inconsistent placement of replies made it difficult.

    Speaking of which, I have to apologize to you: while I praised “windy” for quoting an omission in my lecture, I didn’t realize you’d spotted it and explicitly pointed it out a day earlier. Sorry about that! You deserve full props for finding a legit problem, that I never backed up my assertions about Triver’s assumptions.

    And speaking of re-quoting my lecture at you:

    Can you cite any scientific papers …

    Please please please PLEASE read the bonus content! This is the THIRD AND FINAL time I’m quoting the first paragraph of my lecture back at you:

    [This is a direct copy of my shooting script, including all my cues. It’s a condensed version of a much longer source document, which also contains all the bonus content, full citations, illustrations, and links to PDFs. To get your paws on that, click here.]

    I do not accuse you of arguing in bad faith lightly. Just for ignoring the obvious yet again, I am NOT going to reply back on your blog for at least 24 hours, to you or anyone else. The lot of you will have to stew until I decide to return.

  13. 14

    Oh dear, someone from the SlymePit is going around claiming I quote-mined de Beauvoir. Let’s nip that in the bud, shall we?


    … sigh …. First off, here’s the intro to de Beauvoir, so everyone can decide for themselves.

    Now, if I may copy-pasta, as I’ve already answered this charge elsewhere (warning, long):

    In “A Defense of Abortion,” Judith Jarvis Thomson writes:

    We are told that performing the abortion would be directly killing the child, whereas doing nothing would not be killing the mother, but only letting her die. Moreover, in killing the child, one would be killing an innocent person, for the child has committed no crime, and is not aiming at his mother’s death. And then there are a variety of ways in which this might be continued. But as directly killing an innocent person is always and absolutely impermissible, an abortion may not be performed.

    Does this mean she’s against abortion? No, it just means she’s a philosopher. They’re trained to obey the principle of charity, which means they must not only be willing to think from their opponent’s view, they must be willing to repair their opponent’s argument to make it tougher to defeat. This lead to a distinctive writing style, where they bounce back and forth between opposing views, mapping out weak spots in both in search of the greater truth. de Beauvoir was an excellent philosopher, and so “The Second Sex” will also hop between tearing down and building up a division between the sexes. You need to carefully read over a large chunk to get a true sense of what she’s talking about.

    Her primary target is the idea of women as the “other”, as a slave, as a “Second[ary] Sex:”

    if nevertheless we admit, provisionally, that women do exist, then we must face the question “what is a woman”?

    To state the question is, to me, to suggest, at once, a preliminary answer. The fact that I ask it is in itself significant. A man would never set out to write a book on the peculiar situation of the human male. But if I wish to define myself, I must first of all say: ‘I am a woman’; on this truth must be based all further discussion. […]

    Thus humanity is male and man defines woman not in herself but as relative to him; she is not regarded as an autonomous being. … Benda is most positive in his Rapport d’Uriel: ‘… She is defined and differentiated with reference to man and not he with reference to her; she is the incidental, the inessential as opposed to the essential. He is the Subject, he is the Absolute – she is the Other.’ […]

    Now, woman has always been man’s dependant, if not his slave; the two sexes have never shared the world in equality. And even today woman is heavily handicapped, though her situation is beginning to change. Almost nowhere is her legal status the same as man’s, and frequently it is much to her disadvantage. Even when her rights are legally recognised in the abstract, long-standing custom prevents their full expression in the mores. In the economic sphere men and women can almost be said to make up two castes; other things being equal, the former hold the better jobs, get higher wages, and have more opportunity for success than their new competitors.”

    But she’s aware that discrimination and othering may be covert, in the notion of “equal but separate,” and this forms a secondary target:

    In proving woman’s inferiority, the anti-feminists then began to draw not only upon religion, philosophy, and theology, as before, but also upon science – biology, experimental psychology, etc. At most they were willing to grant ‘equality in difference’ to the other sex. That profitable formula is most significant; it is precisely like the ‘equal but separate’ formula of the Jim Crow laws aimed at the North American Negroes. As is well known, this so-called equalitarian segregation has resulted only in the most extreme discrimination. The similarity just noted is in no way due to chance, for whether it is a race, a caste, a class, or a sex that is reduced to a position of inferiority, the methods of justification are the same. ‘The eternal feminine’ corresponds to ‘the black soul’ and to ‘the Jewish character’.

    As my lecture points out, though, she was writing in 1949. de Beauvoir was very knowledgeable of contemporary science, so she knew of chromosomes and hormones. But the defeators I use to argue against those as divisions, genes and rare combinations of chromosomes, had not been discovered or fully understood yet. She was faced with what seemed like a solid division between sexes, and being a woman of science had to accept that. So she instead took the approach of the two-sex advocates, acknowledging a sex difference but doing her damnest to demolish gender difference.

    As I mentioned, the concept of “gender” would not be invented until 1955 (and wouldn’t be commonly accepted for some time; if you had sharp ears, you noticed Maccoby and Jacklin still using “sex” in 1974), so she had to make do with then-current terminology.

    This explains the confusion: she was arguing against gender differences, but using the terminology of sex, and because she was a philosopher she would occasionally switch sides and argue from the essentialist view.

  14. 15

    I’m rather puzzled by your use of the terms “social construct” and (@10) “non-arbitrary”, with respect to sex (I’m saying nothing about gender). Admitting that there are a considerable number of human individuals who don’t fit into a purely binary division, that does not seem sufficient grounds for designating the female/male distinction a “social construct” or “arbitrary”, if these terms mean that there is no reason why we could not just as well recognise only one sex, or 7 billion sexes, or continuous gradations between two extremes without any actual divisions (as with height), or whatever. It does appear to be just a fact that most people can be unambiguously classified as either female or male, just as it is a fact that some cannot. Most terms and systems of terms, whether from everyday language or scientific terminology, lack the kind of absolute tidiness and rigidity that essentialism wants to find; but some are very much closer to it than others. Failure to recognise the reality of distinctions because of the existence of boundary case, doubtful cases or exceptions is as much an error as essentialism.

  15. 16

    Whoops, I’ve been neglecting this page a bit.

    Giliell, professional cynic -Ilk- @11:

    The whole point of a meta-analysis is to counter alpha-mistakes and publication bias (aka the drawer effect).

    Not only that, but proper science requires considering the “balance of evidence;” you do not get to ignore findings contradictory to your view, you must consider everything. By denouncing meta-analyses, you’re essentially saying “we should ignore some of these studies and focus on those of type A.” You need to have a damn good reason for doing so, better than just “difference is multivarate.”

    Which it really isn’t, as you can tell from the mere existence of words like “intelligence.” What is intelligence? It’s a fuzzy mish-mash of various mental abilities which we aggregate together under a general rating. That’s univarate. If it were multivarate, we wouldn’t lump those together and we’d never have the general term. We’d speak exclusively of “spatial visualization” or “algebraic ability” instead of “intelligence.”

    John Archer is an interesting counter-example. It was he who did the meta-analysis of testosterone I referenced in the lecture, yet he’s a evo-psych supporter. I suspect he was hoping to demonstrate genes are more important for aggression than hormones, which would solve the problem of prepubescent boys being very aggressive even though their hormone levels are low. He certainly succeeded there.

  16. 17

    Nick Gotts @15:

    It does appear to be just a fact that most people can be unambiguously classified as either female or male, just as it is a fact that some cannot. Most terms and systems of terms, whether from everyday language or scientific terminology, lack the kind of absolute tidiness and rigidity that essentialism wants to find; but some are very much closer to it than others. Failure to recognise the reality of distinctions because of the existence of boundary case, doubtful cases or exceptions is as much an error as essentialism.

    You’re not the only person to make a similar argument, and on the surface it’s quite appealing.

    That line of thinking, though, argues we should stick with Newtonian Mechanics.

    It explains a ridiculous amount of the universe, after all. NASA still uses it more often than General Relativity, because its failure rate is so small. The precession of Mercury is very subtle, and it took us centuries of close observation to notice it. Light bending around an eclipse? Newtonian Mechanics can predict that if you assign some mass to light, though it doesn’t predict the same amount of bending as GR. GPS satellites are an interesting corner case, as Newtonian Mechanics fails spectacularily, but I suspect we could solve even that by switching to geosynchronious orbits.

    So why not dismiss those exceptions as disorders or abnormalities, and dump GR in the dustbin?

    Here’s where Cavanaugh and I diverge strongest. I view the two-sex model as exactly that, a model and human construct. These exceptions are signs the model isn’t complete, and there’s a better one out there. Binarism is a good model (I even hint as much in the transcript), but it’s not a complete description of sex. I want to examine these corner cases to see if there’s a better model out there, so I refuse to dismiss them. And if I convince enough of my peers of the utility of my model, it transitions from a human construct to a social construct.

    Cavanaugh, and many other people for that matter, view the two-sex model as reality. These exceptions aren’t signs the model is incomplete, they’re signs we live in a messy, sinful world. If anything, they actually demonstrate the reality of the two-sex model. They’re rare! If you drop your standards, you can stuff the exceptions back into the binary! See? No further study is needed, because we’ve arrived at the fundamental truth. Any attempts to show otherwise constitute arguing against reality, and are ridiculous by definition.

    The amusing part is that Cavanaugh and I mostly agree. We don’t teach the Quantum Field Theory model of the atom to school children, because it’s freaking difficult to understand; we instead present them with the Bohr model and concede we’re simplifying things. Any multi-sex model would have to be binary for the most part, and a simple model like the two-sex one works remarkably well most of the time.

    So I don’t have a problem with people believing the two-sex model, I have a problem with them trying to stop progress on coming up with a more complete model. I have a problem with people treating models as reality.

  17. 18

    That line of thinking, though, argues we should stick with Newtonian Mechanics.

    No, it really, really, doesn’t suggest anything of the kind. Try rereading what I said, without the prejudicial additions of terms such as “sinful”, “no further study is needed”, “ridiculous by definition” and so on, none of which I used or even hinted at.

  18. 19

    Nick Gotts @18:

    Try rereading what I said, without the prejudicial additions of terms such as “sinful”, “no further study is needed”, “ridiculous by definition” and so on, none of which I used or even hinted at.

    I did. It’s still arguing for Newtonian Mechanics. Here, let’s try some word substitution:

    It does appear to be just a fact that most [scenarios can be unambiguously described by Newtonian Mechanics], just as it is a fact that some cannot. Most terms and systems of terms, whether from everyday language or scientific terminology, lack the kind of absolute tidiness and rigidity that essentialism wants to find; but some are very much closer to it than others. Failure to recognise the reality of distinctions because of the existence of boundary case, doubtful cases or exceptions is as much an error as essentialism.

    You are arguing in favor of a flawed model of sex, when the exceptions are telling you there must be a better and more complete one out there. If someone else did the same about any other model, like the fundamentals of physics or biology, you’d wonder why they lacked a sense of exploration, why they didn’t want to come to a greater understanding.

    I didn’t use the religious and exaggerated language to mock you, as that would be like mocking religious believers for believing in religion, but I used them to bring the dual standard into sharper relief via analogy.

  19. 20

    Hmm, I’ve been neglecting this thread again.

    Must of my time since the last post has been spent in this thread over at Fogg’s, until it descended into PRATTing and camping. There’s only one thing worth sharing from over there, as it sheds a light on how much work I put into researching this talk. It’s been slightly edited and expanded on from the original.


    There are 78 URLs in the full script. That’s only a subset of the citations, as many of the papers I reference are hidden behind pay-walls and therefore could not be linked to. A half-decent count of MLA-style citations that excludes URLs adds 31 more. There’s also six non-MLA citations that I could eyeball. That makes for 115 citations, give or take a few (as I’m not sure I properly counted double-citations).

    I only linked to 17 Wikipedia pages, of which I only relied on one for my argument (and even then only because it was a minor, uncontroversial point), and slipped in two to shore up a post-talk YouTube comment (see comment 2 above). The remainder were intended as an overview of a subject for those reading the script.

    That leaves 98 non-Wikipedia citations. There’s also this casual throwaway line in the script:

    Hyde’s done quite a bit more, too, and her published work had a major impact on this document.

    Which was very true; her “Gender Similarities Hypothesis” paper led me to track down Woolley via Google Scholar at least four months ago, which got me hooked on historical views of gender. With one or two exceptions due to Hyde’s excellent citations, I used Scholar to track down the historic meta-analyses. Each of those were grabbed via the University of Calgary’s library, either electronically or in hardcopy. Off the top of my head, I think I read or skimmed about dozen physical books, of which only eight or so made it into the final citation list. They formed a stack about a foot and a half high, which I planned to show off if anyone asked for citations during the Q&A.

    That’s how the full script wound up peppered with long direct quotes and page references, as I either copy-pasted or manually typed them in.

    If you paid close attention during the video, you would have noticed that copy of “The Greatest Show on Earth” didn’t have a library tag on it. That’s my own copy, one of six books by Dawkins that I own. Other than that one quote, and some flipping through during the post-talk discussion, I didn’t have much use for them.

    And there’s still a few bits that never made the lecture. There were failed numeric simulations, and both those and the simulations that did make it were hand-coded by me and run continuously for a few weeks; I calculated a method to convert Terman’s favorite metric, the Critical Ratio, into Cohen’s d; and I spent a week charting old numeric values to asses the historic size of some gender differences, which led to the creation a few scripts to automate some of those charts.

    All told, it took roughly two months of intensive research, not counting the earlier background snooping I’d done for fun.

  20. 21

    And while it’s somewhat tangential, this comment is worth the copy-pasta.


    During the months of research I did, this was my favorite find:
    Sherriffs, Alex C., and R. F. Jarrett. “Sex differences in attitudes about sex differences.” The Journal of Psychology 35.1 (1953): 161-168.
    The authors had their tongues firmly planted in cheek, admittedly, but the implications are quite profound. If strong sex differences existed, that could demonstrate that one gender was more aware of reality. Conversely, they could be promoting stereotypes and misinformation, presumably following an unconscious agenda of dominance.
    That’s not what these researchers found, though.

    There is surprising agreement between men and women both with respect to the behaviors and characteristics which they attribute to males and females and to the values they place on these qualities. Moreover, there are remarkably few behaviors and attributes which are not uniformly ascribed by both men and women to one or the other of the two sexes.

    Everybody is sexist, to a first approximation, even if that’s experienced quite differently by some of us. On the other side of the coin, no-one intrinsically knows more about the subject, and thus anybody could study up on the subject and speak on it.

  21. 22

    Worth noting, the Google Docs document for this talk loses all of the comments if you download it as a PDF; and so when I returned to obtain the open document format, I found it has been slightly revised with an addendum that replicates comment 2 of this comment thread.

    HJH, many thanks for such a well-prepared talk. I was especially curious about one of the XY women, whom you alluded in the lengthier notes had given birth. From my own previous reading I was aware that most women who have a genetic failure preventing the Sry gene from expressing, or who have complete androgen insensitivity or gonadal dysgenesis, usually do not end up with non-functional gonads (‘streak gonads’); so was very surprised to find an XY woman not only fertile, but reported to have had a child, seeing as the standard binary dogma would have it that it is impossible for a 46-XY person to give birth, or in particular, impossible to pass on a Y chromosome to her offspring – in such circumstances with a 46-XY karyotype, a fertile woman might capable of producing ova with either an X or Y chromosome; but only fertilisation by sperm with an X chromosome of an ovum carrying the Y chromosome would result in a viable zygote, as a zygote without a X chromosome would be non-viable and almost certainly result in miscarriage.

    So I went looking for your citation of this – found no links, so downloaded the version of the document which hadn’t lost all the citations! – and discovered the XY woman in question was chimeric and in possession of an ovo-testis; 96% XY but phenotypically female. Did you discover any more about her case and the genetics of her children? For example, were her ova (and ovary) characteristic of the 96% XY chimera or of XX?

    Finally, PZ has a new post today over on his blog touching on the complicated gene signalling that most of the time, results in differentiation of the bipotential genital ridge into either ovary or testis. It still strikes me that people think they know so much about how this process works based only on the successes, when they often know comparatively little of how the same process turns out when it doesn’t work (in a small but significant number).

  22. 23

    Damn, I left in a double negative; please read the clause about streak gonads as “usually do not end up with non-functional gonads”.

    (I nearly lost the entire comment by hitting the wrong keyboard shortcut for changing tabs, and so after breathing a sigh of relief when the comment was still sitting intact in the page buffer, didn’t proof-read as careful as I would have liked.)

    Incidentally, how does one catch up with what you’re doing? (I didn’t notice any publicising of a Twitter or blog.)

  23. 24

    Xanthë, Amy of my threads @22:

    HJH, many thanks for such a well-prepared talk.

    No prob, it was a blast to research and write! As for the citation issue, you’re in luck; a former women’s studies professor of mine expressed an interest in incorporating some of that lecture into a course, so I crafted a citation-only version.

    Did you discover any more about her case and the genetics of her children? For example, were her ova (and ovary) characteristic of the 96% XY chimera or of XX?

    I’ve got the case report in front of me; all they say about the child is:

    At 39 years of age, she conceived spontaneously [HJH: from context, this likely means pregnancy via pleasurable methods] and had an uncomplicated term pregnancy delivered by cesarean section. Her child was a normal male. Two years later, she requested gonad ectomy to prevent future germ cell malignancy. […]

    In 2004, blood from the patient and her son were sent to University of California, San Francisco (UCSF Medical Center), for mitochondrial DNA studies. These confirmed the genetic identity of mother and child.

    I have a helluva lot more info about her ova, though:

    Laparoscopic evaluation of the pelvis demonstrated an enlarged left ovary with normal contour and a small right ovary, confirming the ultrasound findings. A wedge biopsy was taken from the left gonad. Histopathologic evaluation demonstrated an ovotestis with ovarian tissue overlying testicular tissue. The ovarian components consisted of many corpora albicantia showing focal degeneration and large corporalutea within a variable cellularstroma. Primordial oocytes were not apparent. Within the interface between the ovarian and testicular tissues there were irregular duct like structures resembling mesonephric or wolffian ducts and focally resembling epididymal tissue.

    The testicular component of the tissue was composed of well-formed seminiferous tubules. No spermatogenesis was identified. There were also seminiferous tubules with partially thickened membranes consisting of vacuolated germ cells containing variably sized and mildly pleomorphic round nuclei with prominent nucleoli, features consistent with a gonadoblastoma. … Karyotype of the ovotestis was 60% 46XX and 40% 46XY.

    From what I can parse out, that means the ovo-testes showed no signs of sperm or egg generation, but had many of the same structures that ovaries and testes possess.

    Xanthë, Amy of my threads:

    so was very surprised to find an XY woman not only fertile, but reported to have had a child, seeing as the standard binary dogma would have it that it is impossible for a 46-XY person to give birth, or in particular, impossible to pass on a Y chromosome to her offspring

    The case study never says where the boy’s Y came from, but odds are it wasn’t from his mother. I don’t see why a 46,XY female couldn’t form a 46,XY egg in theory, but I’m not a biologist. I might ask one, though…

    I’d also been led to believe intersex wasn’t hereditary, but a quick look on Google Scholar shows quite a few case studies of hereditary androgen-insensitivity intersex, at least in the past. I can’t find much recent research, and there may be good reason for that:

    In one third of patients with mixed gonadal dysgenesis, a gonadoblastoma tumor will develop by the fourth decade of life, and 30% of these tumors will be malignant. In contrast to patients with mixed gonadal dysgenesis, true hermaphrodites have a lower risk, 10%, of development of a gonadoblastoma, and generally this occurs only in those patients with mosaic genotypes.

    Because of the potential for malignancy in both dysgenetic gonads and in intra-abdominal testes, true hermaphrodites and patients with mixed gonadal dysgenesis are generally advised to have the gonads removed and usually do so. The prevalence of gonadectomy in adolescence or young adulthood may partially explain the extreme rarity of fertility in true hermaphrodites. In contrast to patients with mixed gonadal dysgenesis, in whom fertility has never been reported, pregnancy is possible in true hermaphrodites.The likelihood of malignancy in the gonads of true hermaphrodites appears to be lower than in those of patients with mixed gonadal dysgenesis.

    The case history notes this woman was offered gonadectomy three seperate times, any one of which would have prevented her from giving birth to a boy. At the same time, the increased risk in tough-to-find cancers that comes with some forms of intersex explains why doctors would push gonadectomies so heavily. The doctors behind this case recommend they lay off a bit for true hermaphrodites, which seems sensible and could lead to more cases coming to light. The authors note the following:

    We were able to locate only 10 prior reports of pregnancy in a true hermaphrodite. Seven were patients with normal female (46XX) karyotypes, two were mosaics (46XX/46XY), and one was unknown. Both of the mosaic patients became pregnant after their ovotestis was removed.

    In other words, even with doctors pushing for gonadectomies, and even among the rare cases of true hermaphrodism, she’s not alone.

  24. 25

    Xanthë, Amy of my threads @22:

    Worth noting, the Google Docs document for this talk loses all of the comments if you download it as a PDF; and so when I returned to obtain the open document format, I found it has been slightly revised with an addendum that replicates comment 2 of this comment thread.

    I’ve been issuing small corrections and updates. I thought that comment was worth tacking onto the end of the full transcript, and with a presentation that large and complex it’s only inevitable that some errors would pop up. Speaking of which, I have two corrections to issue, one relating to my last comment here:

    I don’t see why a 46,XY female couldn’t form a 46,XY egg in theory, but I’m not a biologist.

    Silly me of an hour ago, you spent so much time trying to parse that medical case report that you forgot human gametes are haploid, in comparison to the remainder of our cells which are diploid. I should have said “23,Y egg” instead, as I knew the odds of a gamete winding up with a 46,XY diploid karyotype were very, very, very unlikely (though in defense of my past self, not impossible either).

    The scripts already contain the second correction, which I’ll print here too. It’s a comment to my first usage of “meta-analysis:”

    CORRECTION: I’m being loose with my terminology here. Technically speaking, “meta-analysis” refers only to reviews of multiple studies that have been quantitatively combined through well-defined means. No-one did a meta-analysis as-per the technical meaning before 1980, since (as I hint at later) computers were needed to develop the math behind all meta-analysis. An interesting “transitional form” was Maccoby and Jacklin’s review of 1974, which labeled each study as “voting” towards a hypothesis and presented them in table form. The credit for spotting this goes to J.S.Hyde.

  25. 26

    Thanks for picking up your own error; while it’s certainly possible for an ovum to have no sex chromosome at all or more than one, the norm is 23,X – however if the ovary is mosaic between a 46,XX/46,XY karyotype then it doesn’t seem impossible for a proportion of ova to have been laid down that are 23,Y, in which case the mother might be able to pass on a Y chromosome – which seems rather incredible. Even if this is not the case, fertility and birth is quite remarkable. As you said there’s more than one individual who’ve given birth but up to about ten prior cases.

  26. 27

    Interesting convo Xanthe and HJ!

    Looking myself about the 23,Y oocyte I found what looks like a bit of Koranic/Xtian apologetics about Mary and the virgin birth. [CN: Biological essentialist view of “woman” that is clearly confused given it talks about intersex individuals, and even talks about being “reared” female. Also concludes Mary was a woman regardless of her chimeric intersex possibilities. So god according to at least one Muslim/Xtian apologetics wonk is semi trans inclusive!]
    This person explores the idea that Mary was chimeric and spontaneously produced a Jesus, not from a 23,Y oocyte but a chimeric Mary who can produce both gametes. Doesn’t really add to the reality of if it’s possible as the writer is clearly not an expert in biology. But interesting nethertheless.

  27. 28

    I’ve got some interesting follow-up for my lecture. As I pointed out over at Pharyngula, mosaicism is scary frequent:

    As scientists begin to search for chimeras systematically — rather than waiting for them to turn up in puzzling medical tests — they’re finding them in a remarkably high fraction of people. In 2012, Canadian scientists performed autopsies on the brains of 59 women. They found neurons with Y chromosomes in 63 percent of them. The neurons likely developed from cells originating in their sons.

    In The International Journal of Cancer in August, Eugen Dhimolea of the Dana-Farber Cancer Institute in Boston and colleagues reported that male cells can also infiltrate breast tissue. When they looked for Y chromosomes in samples of breast tissue, they found it in 56 percent of the women they investigated.

    You might own an animal with a genetic mosaic, or for that matter even be one.

    I also have to give a hat-tip to the article that introduced me to gynandromorphs, or animals that are exactly half one sex and half another.

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