One quibble I'd make: Just because someone has an advanced and prestigious education does not mean that they can't be a crank. Some of the most famous and influential cranks have also been highly educated. Education does not necessarily over-rule ideology, particularly when there is a strong social or economic pressure to emphasize ideology over education.
prestigious education = brainwashed. the "best" schools are a joke. the one who learns by following her own nose will be the most knowledgable, and without the inherent bias of the establishment's institutions.
I especially love how, to defend themselves, they point to psychologists and others who make the exact errors the video describes. I wonder if there is a genetic basis for bad listening comprehension that predisposes them to hold on to long discredited ideas ;).
i cant believe ive been tricked into learning math.... i love how your videos are an intersection of biology, math, history, and social justice - tying together subjects that appear so separate but are in fact interconnected
@@PhukYu2 According to biology, human brains do not finish developing until one is in one's 20s. You might want to try learning biology before you start pretending to know about it.
Thank you for making this informative and important video! It's important to recognise that as much as we might quibble about how much exactly the narrow sense heritability due to additive genetic effects contributes to variance in IQ or educational attainment within any given population, whether it's closer to 10% or 50% should not change our views on eugenics because the main reason why we oppose it is not 'because it wouldn't work anyway' but because it is morally wrong, which is a reflection of our human values that science can't decide for us. I'm not going to quibble here (see my other comment), so I'm just going to end this by saying keep these videos coming!
Hi Zach, as usual, a great video. However, I would like to point out to the work of twin adoption studies, especially those by Kathryn Harden. As you likely know, this work tries hard to separate out heritable effects that are genetically transmitted, versus culturally (with some caveats). Her work suggests that for many traits there is a significant heritable contribution - that identical twins share many more traits than fraternal twins. This is true even when the twins are adopted (i.e. not raised by their biological parents). A second point I would like to make (and this is brought up by Harden herself, who is self-described as a progressive), is that just because there may be significant genetic contributions to a trait, it does not necessarily follow that we need to support eugenic principles. Finally, I'll also point out that Harden's work also suggests that stochastic effects (i.e. effects beyond cultural and genetic transmission from parents) are significantly stronger than what most people think.
Thanks! I gave some sources on bluesky, but I'll elaborate and share them here as well for other folks to see. Twin studies have long been known to be harder to interpret than is often presented, and, depending on the statistical model you employ, you can get heritability of IQ ranging from 10% (Bingley et al. 2023; Collado et al. 2023) to as high as 50% (Sunde et al. 2024). All use twins, so which is correct? It depends on your statistical modeling choices - the lower-end (which, it should be pointed out, are more in line with molecular measures) relax assumptions about identically shared environments between twins. By doing this, more of the correlation is soaked up by indirect genetic effects and the environment. If relaxing this assumption can reduce heritability by 40%, to me this is cause for suspicion of the higher estimates. For Harden's work, most of her claims are from GWAS studies (that's what her "Genetic Lottery" focuses on), and developing polygenic scores for educational attainment as a way to guide policy decisions. But critics of her book, like Coop & Przeworski (2022), note that she ignores that ALL estimates of heritability in humans are confounded to some degree by the environment, assortative mating, population structure, and indirect genetic effects. Indeed, as Barton et al. (2019) remind us: "Natural populations are never homogeneous... With respect to confounding by population structure, the key qualitative difference is between controlling the environment experimentally, and not doing so." The only way we can control for these effects in humans - even in twin studies - is statistically. And these are never perfect. Lastly, I absolutely agree that a trait having a genetic basis does not necessarily imply we should take a eugenic policy. Historically, it ~has~ meant that, and, if you read through some of these comments, you'll see others have come to that conclusion still today. But I hope I stressed in this video that even the genetic effects can be modulated by the environment as in the case of high vs. low SES households and their respective IQ heritabilities. Some sources for those interested: theinfinitesimal.substack.com/p/twin-heritability-models-can-tell academic.oup.com/evolut/article/76/4/846/6728440
@@talkpopgen This study on twins and homosexuality may be useful for your literature review and upcoming video, Zach. "Homosexual orientation in twins: a report on 61 pairs and three triplet sets" (Whitam et al. 1993).
Thanks for a very informative video. I wish the people who need and would benefit from it most-the Pinkers and Charles Murrays of the world-were more open to having their positions challenged, but sadly most aren't (and so you still see papers retreading old hereditarian arguments). But I used to be on their side when I was younger, misunderstanding the math I was (ab)using, and patient people took the time to teach me.
Zach, this was excellent work and more educational content like yours is paramount. Another topic needing genetic clarification is homosexuality. Many scholars now agree same-sex sexual behavior is influenced by numerous genes, and the enigma has been understanding how such genes maintain frequency across populations since homosexuals generally do not reproduce. Some have called homosexual behavior a Darwinian paradox, and many scholars have proposed various heredity models to explain how potential genes achieve and maintain frequency. Some believe the frequency increased later in the Homo sapiens lineage while others say the genes accumulated before bipedalism. The 2010 Hewlett paper, "Sex and searching for children among Aka foragers and Ngandu farmers of Central Africa" suggests homosexual behavior is not universal among all cultures, and later 2015 research by Barthes, "Male Homosexual Preference: Where, When, Why?" proposes a hypergyny model to account for frequency and regulation of influencing genes. In summary many believe homosexual behavior is highly nuanced on a spectrum of innate and determined to conditioned and learned. Cases of ambiguous genitalia at birth causing incorrect gender assignment suggest orientation is not necessarily fluid, and perhaps with certain individuals nature trumps nurture. Do you believe genes for same-sex behavior have always been present in our distant primate ancestry, or recently accumulated within our genus or species? I think this subject would be incredibly educational, especially for religious minds believing god doesn't make people gay and homosexuality is chosen. Thanks for taking time to review the papers and answer my question--and my apologies for the lengthy comment, sir!
Oh man this is an extremely nuanced topic that I don't think I can do justice to in a YT comment - I was actually going to cover it in this very video initially but it got too long. So, for now, I'm going to take a raincheck and say it is a topic I will definitely be covering in-depth in a future video because there is a bit of controversy surrounding this and I think it's worth engaging.
There's the root of your fallacy: "homosexuals generally do not reproduce." You could argue equally well that many heterosexuals do not reproduce, when given the choice, and that since many populations are experiencing falling birth rates, there must be a "gene" that has infected them to reduce desire. The fact is that gay and straight people have as many children as they want. Science has uncoupled, to a degree, sexual behavior and reproduction, which means that biology doesn't have to betray your sexual preferences anymore. Women, gay or straight, choose to have fewer children, but if they want them, gay or straight, they can have them. No paradox involved.
@@PZMyersBiology Hopefully my comment did not sound biased or offensive and if so please accept my apology. I agree homosexuals can utilize donor gametes, surrogacy options, adopt and rear children, etc., but homosexuality has existed long before fertility options were available by which their genes could be transmitted. The question for researchers has been pinpointing the mechanism by which the genetic component is transmitted. It cannot be a Darwinian paradox because the genes in question suggest heritability, so considerable research has focused on maternal fertility, birth age, sibling order, etc. to isolate potential variables. The mechanism(s) regulating and sustaining these genes are utterly fascinating for inquiring minds. I'm no expert on this subject, but what I often hear is that homosexuals do not choose their orientation. This potentially implies the genetic component actively induces same-sex behavior in combination with environmental conditioning; however, outcomes appear highly nuanced. For example, despite family members/caregivers rearing a child as heterosexual he/she nevertheless identifies as homosexual. Such scenarios suggest in some cases the genetic component has greater influence than environmental conditioning, which was the focus of Zach's video--we are not our genes. There's another side to this discussion and that is hormonal effects on gene expression and neural pathways. Some have reported after engaging hormone therapy their sexual orientation switched, but this is a different topic also needing elaboration. Hopefully Zach can dissect all the subtle nuances in an upcoming video because I think education on the topic is critical. Thoughts?
@@talkpopgen That's great news, Zach. I believe a large percentage of Americans could benefit from education on this topic, and your content is always thorough and objective. I've wondered if orientation is mostly conditioned, but it seems unlikely sexual identity is learned and instead may be mostly genetic and/or hormonally induced in utero. Anyway, really looking forward to your video on the subject and thanks for replying, sir.
Is the G factor something like the PCA1 of several proxy measures of general intelligence? This reminds me of using aggregates to study the complicated behavior of deep learning models, because we have interpretability concepts that cannot be measured directly, only via several imperfect proxy measures. Your stuff is great, and easy to understand for a non-biologist!
In effect, it's a measure of the correlation across different kinds of cognitive tests and hence seeks to capture the variance across individuals, despite not itself being a feature of any single individual. Thus, an individual cannot have a g factor, because you cannot estimate correlations for a single point on a graph.
@@talkpopgen I see, so it's not referring to the primary axis in some PCA-like analysis but rather the amount that can be explained by the primary axis. Very interesting!
Just a few remarks on history: Galton did not invent linear regression; the least square method for instance was claimed by Gauss, whose proof was that he did find the position of Ceres, which would have been rather difficult to calculate using other methods. Also, the dichotomy between nature and nurture is due to Confucius, while Hippocrates was the first racist in history.
Great video, thank you. A few things your video reminded me of are the insistence of certain mythologies about the history of science that are perpetuated by hereditarians, eugenicists, and so on. For one, throughout the history of scholarly ideas there was never a generally widespread rejection of innateness in explaining human being. While you certainly did have scholars like David Hume who formulated the concept of humans born as tabula rasa, that was in direct response to the nativism in the philosophies of earlier scholars like Kant and Descartes. The persistence of this myth helps to continue selling hereditarianism and its ilk as aligning with the perception of "real" science as challenging orthodoxy, despite the longer and more established historical roots of innateness in science and philosophy. We really need to do a better job fighting this historical revisionism. For another, the continued compartmentalization of nature from nurture, which fell out of favor by most scientists *except* for those inclined towards hereditarianism, race realism, eugenics, etc. This rhetorical compartmentalization itself began with the father of eugenics himself, and it is, I think, imperative that we do a better job teaching more students (especially if we can get this taught along the way in primary and secondary biology education) and harping more about it in public that nature and nurture are inextricably intertwined. Real shame that so much of the narrative and characterization of science as it pertains to humans is pretty well controlled by the worst people pushing the dumbest possible ideas.
It's funny that genetic determinists lost track of the origin of the word "inheritabilty" when they decided that wealth is genetically inheritable but forgot that it's even more inheritable by way of a last deed and testament. Dr Hancock, would you comment on the status of twin studies in the whole heritability discussion? You don't say anything in your talk. From what I've read, there are also issues of environment and data selection bias in those studies.
Hi, is heritability measurement just suited for continues traits? I mean how about for instance heritability of certain diseases which seems to be binomials
While the presence/absence of a disease is dichotomous, most diseases that we study the heritability of have a potentially complex genetic basis, like cancer and heart disease. So, if you have, say, throat cancer, you may have certain variants known to be associated with it, but you may not have ~all~ the variants known to be associated (or none of them!). Because of this, people can be assigned different "risks" of getting it, since there's always a chance you never have it even if you have all the known variants associated with it. So, yeah, you can measure the heritability of disease, and this is one of the most common things folks do in these kind of studies.
Regarding your initial example, dealing with the possibility of a girl inheriting somehow the ability to play piano. I'm an avid listener of classical music and and when listening to violinist goddesses like Hilary Hahn or Julia Fischer you start asking yourself if there are a few geniuses who are actually born more gifted than others. However, if you look closely into their upbringing, you start seeing patterns which are common to everyone who excels at a human endeavor, being it music or sport or studying. Usually, people who excel in a field when adults are: - introduced to this activity at a young age - they really like it - and finally, they have the patience, perseverance and consistency to dedicate hours of their day, everyday, to perfect the same task. Hilary Hahn was introduced to the violin when she was 4 years old and Julia Fischer was born in a family of musicians, being introduced to music probably at the age of 3-4. So, if I had to guess, could it be possible that there's no gene for a specific talent, but rather there are children who are more prone to be focused at the same task for an extended period of time without being easily distracted?
Could be? No one knows because things like "perseverance" aren't standardized traits with a clear meaning that can be measured on a typical questionnaire. These large genetic studies for measuring heritability collect trait data that is volunteered from individuals, which means they are limited to things that you can ask in a survey. So the answer is: no one knows, but there will be plenty of people who try to tell you they do.
@@talkpopgen I once had dinner with James Watson, who complimented me on my good nordic genes, and explained that they (and also Asian people's genes) made them smarter than the Scots-Irish, his ethnic group. But then proceeded to explain that the Scots-Irish inherited greater persistence and stubbornness and ambition, which made his slightly lower IQ group *better*. When in doubt, invent a genetic parameter with no empirical justification to make yourself look superior.
Watson would hate me then . I’ve got distant Scots ancestry and have 2 children both with high IQs , science degrees and a large percentage of African ancestry 🤷🏾♀️
One study actually show that genes could capture 10% to 15% of educational success. And that may not sound like a lot at first until you realize that wealth and equality accounts for only 11%. Basically, she says your genes play as much a role in your educational success as your parents' wealth.
@real_pattern "Predicting educational achievement from genomic measures and socioeconomic status" doi: 10.1111/desc.12925 PMCID: PMC7187229 PMID: 31758750 The study is free access too
@real_pattern "Predicting educational achievement from genomic measures and socioeconomic status" youtube keeps removing it when I have details but that's the title, you should find it when you Google that.
The debate over heredity vs environment has been going on for a long time. It will undoubtedly continue for a long time because there is no way to find out. Even if you took identical twins, raised one in a totally sterile environment, and the other in a more normal environment, you'd still be uncertain at to what extent the differences were either heredity or environment. Needless to say, that sort of experiment is out of bounds in any case. We do know that some things are definitely hereditary, and some things are definitely learned. Problem is, there's a lot of stuff which could be either/or, or both. Best thing is just to accept that.
Here is my comment for quibbling. You mention that a certain GWAS study found that only a few percent of the variation could be explained by the genetic variants they identified, but surely if the trait is highly polygenic like height then there could be many genetic variants of small effect that make up the missing heritability. This is not my field, so enlighten me if I am missing something.
Here's the source for the differentiation between populations (muse.jhu.edu/article/633715 ). Sure, it could be that there are many SNPs contributing to the variance in intelligence but their individual effects are so small as to be undetectable. But that still means that we don't have any positive evidence that genes are the prime driver of differences in intelligence. To me, if a dataset of 450,000 individuals ~still~ can't predict more than a percent of the variance (www.nature.com/articles/s41588-023-01398-8 ), maybe it's time to consider genes just aren't playing much of a role. At the very least, individuals who take a strong stance that they do are doing so without evidence.
I think you're presenting the science fairly, as far as I can tell. (Background in biochemistry and bioinformatics, but not specifically evolution/GWAS.) But I'm not sure you're being fair to Pinker, I don't believe he thinks something like "all of the variance of personal traits is at least partly explained by genetics" with his first law. I think he probably meant the quasi-truism that the genes give us brains, and brains are requried for personality traits, thus personality traits are grounded in genes. To anyone who read the book, am I wrong?
If that's what he meant, then we'd be in agreement. But he used the term "heritable," and appeals to studies on heritability of behavioral traits. Since these are measures of the heritable variance in traits, it seems pretty clear that he's talking about genetic variation as causal to variation in personalities. The more charitable interpretation also seems at odds with his second law on the greater impact of genes than families.
We can argue about the exact estimates of IQ heritability and the confounds of midparent-offspring regressions or GWAS all we want but I'm still convinced that hereditarians are right on the dysgenics question. My comment will be more relevant to last year's human mutational load video but since it's something online hereditarians build their case on I might as well say it here. Modern medicine is anti-natural selection, or at least relaxed selection, such that demographic transition has conferred low mortality but low fertility across the board. The direction of differential fertility is biased towards people of lower IQ contributing more to the next generation. And provided that in developed countries we see couples delaying childbirth, this only compounds the effect of dysgenic fertility because mutational load in the offspring increases with paternal/maternal age. The logic follows such that most non-neutral mutations are slightly deleterious, and since 84% of the genome is expressed in the brain, this only increases the contribution of genetic sources of variation to behavioural differences among the next generation. And even if we disregard behaviour altogether, because we are doing NOTHING to 'modify our stock', our system of equitable healthcare for all would only be detrimental to long-term population health as preserving deleterious variants would confine the next generation to a lifetime of chronic genetic disease. I don't find it to be a coincidence that esteemed evolutionary biologists like H.J. Muller, Bill Hamilton and more recently Michael Lynch and Alexey Kondrashov have expressed the same worry for our genetic future, especially since we have such an unusually high mutation rate compared to other taxa (attributable to our low Ne). I'm not condoning classical eugenics here. But what I am saying is that the natalist hereditarians have a case. The world's first baby has already been born thanks to embryo selection and polygenic screening, and only time will tell whether such investments into 'liberal eugenics' would even be viable if our estimates for positive genetic correlations are good enough. This is a topic that I've been conflicted over for quite a while but it's important that this conversation is had now rather than later. Really informative video nevertheless! It's nice to see some critique against someone else other than YEC low hanging fruit.
I'm going to disagree with almost everything you've written here, but I appreciate the cogent way in which you delivered it. The argument relies on a strong assumption that this video (and studies cited therein) specifically address: the heritability of IQ. For us to even begin a discussion about dysgenics, we'd need to agree that we can "breed ourselves dumber." So little of the variance in intelligence can be explained by genetics, and so much of it is confounded by the environment, that there's simply no reason to start with this premise. Second, medicine has not "conferred" low fertility. Education and women's reproductive freedom has enabled people to choose to have children or not. This is why developed countries with access to birth control measures have lower fertility. This has exactly nothing to do with natural selection - relaxed selection and the accumulation of deleterious alleles didn't lead to women having less children. You're looking for a biological cause when there's a clear social one right there. Third, a mutation is deleterious based on its fitness effect. Poor eyesight would have been selected against in the Paleolithic, but glasses are readily available today. We've not so much "relaxed selection" as we have changed the fitness effects of the mutations. To "relax selection" is to assume the fitness effect stays the same but the ability of selection to purge it is weakened, as in the case of reduced population size. But wearing glasses have nullified the fitness effects of the mutation itself. Lastly, most people don't die from genetic diseases. The greatest threats to human health are cancer and heart disease, things that kill you later in life and have very little (if any) genetic component. In fact, most major diseases in humans we struggle to identify what the underlying genetic variation is at all (this has been remarked as the greatest failing of the Human Genome Project). TLDR: there's no reason to start by assuming IQ has a significant heritability in the first place, lower fertility is not the result of mutational burden but entirely the product of social choice, mutational effects aren't fixed but are modified as we modify the environment itself (e.g., with modern medicine), and there's no evidence that genetic diseases are a significant concern to human health in the first place, you're far more likely to die from eating too many cheeseburgers. I'd recommend this paper as a response to Lynch (2016): academic.oup.com/genetics/article/204/2/821/6046895
@@talkpopgen Cheers for the very prompt reply. I think you've established your stance on the true heritability of intelligence clearly enough that I'll turn my questions and comments to the other parts of your response. 2) Differential reproduction due to some people choosing not to have kids can itself be natural selection provided that the reasons for these conscious choices have a heritable genetic basis. Years of behavioural genetics research would be going down the drain if we concede that social traits, and hence expected social choices, are mostly environmental in variation. Aren't social interactions downstream from biology anyways? Also I should have clarified that yes increasing mutational load is not the cause of low fertility but can be a consequence of it because we see trends of delayed childbirth in developed countries, and older parental age is correlated with infertility and as it so happens greater germline mutational load. Ideally people if they want children should have them younger, and it's a shame that young people don't have the economic incentives to have children and when they have the resources to do so in their 30s or 40s, an unfortunate effect is the mutational burden on their child. This has to be dysgenic - funnily enough this is why Kondrashov advised for young men in their 20s to freeze their sperm for IVF later on, sort of like making a germline save game lol. 3 and 4) If there ever comes a point to where we raise living standards and environmental/educational interventions to a maximum, we can only progress life outcomes even more if we account for the genetics. Sure, we may have neutralised poor eyesight with glasses but god forbid if a big war were to destroy the eyeglasses supply chain. It's an extreme example but it's the basis for Bill Hamilton's idea of 'Great Planetary Hospital' where he posits that having to constantly attend to a population increasingly burdened by chronic disease is the definition of a metastable strategy. Humans are awful at predicting large-scale disasters, and if our system of healthcare were to shut down for whatever reason imagine the countless deaths. Perhaps it's better to have a genetically robust population that at least acts as a safeguard for this situation. Hereditarian arguments to do with between-population differences (i.e. races) don't interest me as much as the within-population or species-wide consequences of dysgenics. I only give it so much thought because I asked my undergrad evolutionary genetics professor about this exact issue, to which they did express the same fear from a mutation rate perspective. Not surprising actually, given that their doctoral advisor was a British Neodarwinian of which they are almost always of hereditarian leaning. Again thanks for the reply and the paper you linked. Just wanted to let you know too that your neutral theory video helped me so much with an exam earlier this year so I'm always looking forward to some more popgen content!
@@pol_io One thing you and all hereditarians who try to link intelligence to genetic inheritance utterly fail to do is provide a clear and concise definition of "intelligence" which is entirely free of cultural biases, and consistent across populations and time; let alone any method of consistently and accurately measuring such a factor. Until that can be accomplished, any discussion of a genetic basis for "intelligence" is nothing more than presuppositional noise.
I'd be really interested in data regarding what people think intelligence is. I'd love to ask a large group of random people to guess the IQ of a bunch of famous people, or rank them smartest to dumbest. I wonder how much variation you'd find.
First half of the video is good, the rest falls off after the strange sequence of strawmen and lack of self awareness. Dude argues "social status is inheritable genetically AND socially, so programs to lift up the poor largely fail because of that." You: "you said it's only/mostly genetic " I may disagree with his central point but yours manages to be worse.
Throughout the video, twin studies, adoption studies, etc. were not mentioned once. Are you intentionally being so dishonest, or do you honestly believe what you're saying? Differences between groups are difficult to investigate and we have little data on them, but differences within the group have been studied for the last 100 years, we have a ton of empirical data, this is the scientific mainstream. We can compare identical twins raised together and separately, fraternal twins raised together and separately, siblings raised together and separately, adopted children, their biological and adoptive parents, etc. Twins have a common womb, identical twins have on average about 100% of common genes (in practice, this number is slightly lower due to mutations), the remaining siblings have an average of 50% of common genes (this number varies from 40% to 60%). By combining genes with different environments during adoption, we can compare 4 groups of twins: identical-together, identical-separately, fraternal-together, fraternal-separately. It is possible to debate the validity of the g construct for a long time, but we can compare more objective indicators that correlate with g, for example, reaction speed or working memory. Now we gradually begin to learn how to predict IQ by neuroimaging using EEG and fMRI, we have network models that do not use a hierarchy of factors, etc. We have a bunch of experiments where we give people gambling, and then we inject one group with a placebo, and another with a certain hormone, and people with the hormone start making riskier decisions, do you really not think that genes affect hormone secretion?
Culture is downstream from IQ. ^^ Pretty good video. I learned a couple of things with the math. Slight leftist bent tho but considering the touchy subject of IQ it's to be expected. 50 years of rehashing the data to portray it under new terms and in a ''nice'' way. Everybody knows the group ranking in terms of IQ during the 20th century had first Ashkenazi Jews then south east Asian then ''caucasian/europeans'' and so on. Rushton-Jensen 30 years of IQ research is kinda where I stand.
"Culture is downstream from IQ." Said no sociologist or anthropologist ever. Also, why would you stand with a debunked paper from two dead pseudoscientists?
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One quibble I'd make: Just because someone has an advanced and prestigious education does not mean that they can't be a crank. Some of the most famous and influential cranks have also been highly educated. Education does not necessarily over-rule ideology, particularly when there is a strong social or economic pressure to emphasize ideology over education.
prestigious education = brainwashed. the "best" schools are a joke.
the one who learns by following her own nose will be the most knowledgable, and without the inherent bias of the establishment's institutions.
You should be required to watch this video before being granted a TH-cam account. One of the best videos on TH-cam!
I'm so sorry. I see the hereditarians have shown up in your comments to make excuses.
I especially love how, to defend themselves, they point to psychologists and others who make the exact errors the video describes. I wonder if there is a genetic basis for bad listening comprehension that predisposes them to hold on to long discredited ideas ;).
i cant believe ive been tricked into learning math.... i love how your videos are an intersection of biology, math, history, and social justice - tying together subjects that appear so separate but are in fact interconnected
Bro, your content is fire! Just be careful when touching this subject, as some of the nastiest people online are obsessed with this stuff.
oh I've done a video debunking race realism so I am intimately familiar with the sort of people this is going to attract!
@@PhukYu2 Did you create your account just 3 days ago with the sole purpose of trolling this channel?
@@PhukYu2 Found the incel.
@@PhukYu2 Run along, child, the grown-ups are talking.
@@PhukYu2 According to biology, human brains do not finish developing until one is in one's 20s.
You might want to try learning biology before you start pretending to know about it.
Thank you for making this informative and important video! It's important to recognise that as much as we might quibble about how much exactly the narrow sense heritability due to additive genetic effects contributes to variance in IQ or educational attainment within any given population, whether it's closer to 10% or 50% should not change our views on eugenics because the main reason why we oppose it is not 'because it wouldn't work anyway' but because it is morally wrong, which is a reflection of our human values that science can't decide for us. I'm not going to quibble here (see my other comment), so I'm just going to end this by saying keep these videos coming!
Hi Zach, as usual, a great video. However, I would like to point out to the work of twin adoption studies, especially those by Kathryn Harden. As you likely know, this work tries hard to separate out heritable effects that are genetically transmitted, versus culturally (with some caveats). Her work suggests that for many traits there is a significant heritable contribution - that identical twins share many more traits than fraternal twins. This is true even when the twins are adopted (i.e. not raised by their biological parents). A second point I would like to make (and this is brought up by Harden herself, who is self-described as a progressive), is that just because there may be significant genetic contributions to a trait, it does not necessarily follow that we need to support eugenic principles. Finally, I'll also point out that Harden's work also suggests that stochastic effects (i.e. effects beyond cultural and genetic transmission from parents) are significantly stronger than what most people think.
Thanks! I gave some sources on bluesky, but I'll elaborate and share them here as well for other folks to see.
Twin studies have long been known to be harder to interpret than is often presented, and, depending on the statistical model you employ, you can get heritability of IQ ranging from 10% (Bingley et al. 2023; Collado et al. 2023) to as high as 50% (Sunde et al. 2024). All use twins, so which is correct? It depends on your statistical modeling choices - the lower-end (which, it should be pointed out, are more in line with molecular measures) relax assumptions about identically shared environments between twins. By doing this, more of the correlation is soaked up by indirect genetic effects and the environment. If relaxing this assumption can reduce heritability by 40%, to me this is cause for suspicion of the higher estimates.
For Harden's work, most of her claims are from GWAS studies (that's what her "Genetic Lottery" focuses on), and developing polygenic scores for educational attainment as a way to guide policy decisions. But critics of her book, like Coop & Przeworski (2022), note that she ignores that ALL estimates of heritability in humans are confounded to some degree by the environment, assortative mating, population structure, and indirect genetic effects. Indeed, as Barton et al. (2019) remind us: "Natural populations are never homogeneous... With respect to confounding by population structure, the key qualitative difference is between controlling the environment experimentally, and not doing so." The only way we can control for these effects in humans - even in twin studies - is statistically. And these are never perfect.
Lastly, I absolutely agree that a trait having a genetic basis does not necessarily imply we should take a eugenic policy. Historically, it ~has~ meant that, and, if you read through some of these comments, you'll see others have come to that conclusion still today. But I hope I stressed in this video that even the genetic effects can be modulated by the environment as in the case of high vs. low SES households and their respective IQ heritabilities.
Some sources for those interested:
theinfinitesimal.substack.com/p/twin-heritability-models-can-tell
academic.oup.com/evolut/article/76/4/846/6728440
@@talkpopgen This study on twins and homosexuality may be useful for your literature review and upcoming video, Zach. "Homosexual orientation in twins: a report on 61 pairs and three triplet sets" (Whitam et al. 1993).
Thanks for a very informative video. I wish the people who need and would benefit from it most-the Pinkers and Charles Murrays of the world-were more open to having their positions challenged, but sadly most aren't (and so you still see papers retreading old hereditarian arguments). But I used to be on their side when I was younger, misunderstanding the math I was (ab)using, and patient people took the time to teach me.
A video of impressive length/depth, but I wish you talked about twin studies. Would appreciate a part 2
Zach, this was excellent work and more educational content like yours is paramount. Another topic needing genetic clarification is homosexuality. Many scholars now agree same-sex sexual behavior is influenced by numerous genes, and the enigma has been understanding how such genes maintain frequency across populations since homosexuals generally do not reproduce.
Some have called homosexual behavior a Darwinian paradox, and many scholars have proposed various heredity models to explain how potential genes achieve and maintain frequency. Some believe the frequency increased later in the Homo sapiens lineage while others say the genes accumulated before bipedalism.
The 2010 Hewlett paper, "Sex and searching for children among Aka foragers and Ngandu farmers of Central Africa" suggests homosexual behavior is not universal among all cultures, and later 2015 research by Barthes, "Male Homosexual Preference: Where, When, Why?" proposes a hypergyny model to account for frequency and regulation of influencing genes.
In summary many believe homosexual behavior is highly nuanced on a spectrum of innate and determined to conditioned and learned. Cases of ambiguous genitalia at birth causing incorrect gender assignment suggest orientation is not necessarily fluid, and perhaps with certain individuals nature trumps nurture.
Do you believe genes for same-sex behavior have always been present in our distant primate ancestry, or recently accumulated within our genus or species? I think this subject would be incredibly educational, especially for religious minds believing god doesn't make people gay and homosexuality is chosen. Thanks for taking time to review the papers and answer my question--and my apologies for the lengthy comment, sir!
Oh man this is an extremely nuanced topic that I don't think I can do justice to in a YT comment - I was actually going to cover it in this very video initially but it got too long. So, for now, I'm going to take a raincheck and say it is a topic I will definitely be covering in-depth in a future video because there is a bit of controversy surrounding this and I think it's worth engaging.
There's the root of your fallacy: "homosexuals generally do not reproduce." You could argue equally well that many heterosexuals do not reproduce, when given the choice, and that since many populations are experiencing falling birth rates, there must be a "gene" that has infected them to reduce desire.
The fact is that gay and straight people have as many children as they want. Science has uncoupled, to a degree, sexual behavior and reproduction, which means that biology doesn't have to betray your sexual preferences anymore. Women, gay or straight, choose to have fewer children, but if they want them, gay or straight, they can have them. No paradox involved.
@@PZMyersBiology Hopefully my comment did not sound biased or offensive and if so please accept my apology. I agree homosexuals can utilize donor gametes, surrogacy options, adopt and rear children, etc., but homosexuality has existed long before fertility options were available by which their genes could be transmitted.
The question for researchers has been pinpointing the mechanism by which the genetic component is transmitted. It cannot be a Darwinian paradox because the genes in question suggest heritability, so considerable research has focused on maternal fertility, birth age, sibling order, etc. to isolate potential variables. The mechanism(s) regulating and sustaining these genes are utterly fascinating for inquiring minds.
I'm no expert on this subject, but what I often hear is that homosexuals do not choose their orientation. This potentially implies the genetic component actively induces same-sex behavior in combination with environmental conditioning; however, outcomes appear highly nuanced. For example, despite family members/caregivers rearing a child as heterosexual he/she nevertheless identifies as homosexual. Such scenarios suggest in some cases the genetic component has greater influence than environmental conditioning, which was the focus of Zach's video--we are not our genes.
There's another side to this discussion and that is hormonal effects on gene expression and neural pathways. Some have reported after engaging hormone therapy their sexual orientation switched, but this is a different topic also needing elaboration. Hopefully Zach can dissect all the subtle nuances in an upcoming video because I think education on the topic is critical. Thoughts?
@@talkpopgen That's great news, Zach. I believe a large percentage of Americans could benefit from education on this topic, and your content is always thorough and objective. I've wondered if orientation is mostly conditioned, but it seems unlikely sexual identity is learned and instead may be mostly genetic and/or hormonally induced in utero. Anyway, really looking forward to your video on the subject and thanks for replying, sir.
Is the G factor something like the PCA1 of several proxy measures of general intelligence? This reminds me of using aggregates to study the complicated behavior of deep learning models, because we have interpretability concepts that cannot be measured directly, only via several imperfect proxy measures. Your stuff is great, and easy to understand for a non-biologist!
In effect, it's a measure of the correlation across different kinds of cognitive tests and hence seeks to capture the variance across individuals, despite not itself being a feature of any single individual. Thus, an individual cannot have a g factor, because you cannot estimate correlations for a single point on a graph.
@@talkpopgen I see, so it's not referring to the primary axis in some PCA-like analysis but rather the amount that can be explained by the primary axis. Very interesting!
Neurobiology teaches us that there is a variation in everything, and everything is an individually determined value.
Yeahhhh! Zach, You have no idea how much I missed you, man :)
Just a few remarks on history: Galton did not invent linear regression; the least square method for instance was claimed by Gauss, whose proof was that he did find the position of Ceres, which would have been rather difficult to calculate using other methods.
Also, the dichotomy between nature and nurture is due to Confucius, while Hippocrates was the first racist in history.
Great video, thank you.
A few things your video reminded me of are the insistence of certain mythologies about the history of science that are perpetuated by hereditarians, eugenicists, and so on.
For one, throughout the history of scholarly ideas there was never a generally widespread rejection of innateness in explaining human being. While you certainly did have scholars like David Hume who formulated the concept of humans born as tabula rasa, that was in direct response to the nativism in the philosophies of earlier scholars like Kant and Descartes. The persistence of this myth helps to continue selling hereditarianism and its ilk as aligning with the perception of "real" science as challenging orthodoxy, despite the longer and more established historical roots of innateness in science and philosophy. We really need to do a better job fighting this historical revisionism.
For another, the continued compartmentalization of nature from nurture, which fell out of favor by most scientists *except* for those inclined towards hereditarianism, race realism, eugenics, etc. This rhetorical compartmentalization itself began with the father of eugenics himself, and it is, I think, imperative that we do a better job teaching more students (especially if we can get this taught along the way in primary and secondary biology education) and harping more about it in public that nature and nurture are inextricably intertwined.
Real shame that so much of the narrative and characterization of science as it pertains to humans is pretty well controlled by the worst people pushing the dumbest possible ideas.
It's funny that genetic determinists lost track of the origin of the word "inheritabilty" when they decided that wealth is genetically inheritable but forgot that it's even more inheritable by way of a last deed and testament.
Dr Hancock, would you comment on the status of twin studies in the whole heritability discussion? You don't say anything in your talk. From what I've read, there are also issues of environment and data selection bias in those studies.
34:52 "published in 2023"
...what the fuck?
Hi, is heritability measurement just suited for continues traits? I mean how about for instance heritability of certain diseases which seems to be binomials
there are a few diseases which are genetically inheritable.
While the presence/absence of a disease is dichotomous, most diseases that we study the heritability of have a potentially complex genetic basis, like cancer and heart disease. So, if you have, say, throat cancer, you may have certain variants known to be associated with it, but you may not have ~all~ the variants known to be associated (or none of them!). Because of this, people can be assigned different "risks" of getting it, since there's always a chance you never have it even if you have all the known variants associated with it. So, yeah, you can measure the heritability of disease, and this is one of the most common things folks do in these kind of studies.
Regarding your initial example, dealing with the possibility of a girl inheriting somehow the ability to play piano.
I'm an avid listener of classical music and and when listening to violinist goddesses like Hilary Hahn or Julia Fischer you start asking yourself if there are a few geniuses who are actually born more gifted than others.
However, if you look closely into their upbringing, you start seeing patterns which are common to everyone who excels at a human endeavor, being it music or sport or studying. Usually, people who excel in a field when adults are:
- introduced to this activity at a young age
- they really like it
- and finally, they have the patience, perseverance and consistency to dedicate hours of their day, everyday, to perfect the same task.
Hilary Hahn was introduced to the violin when she was 4 years old and Julia Fischer was born in a family of musicians, being introduced to music probably at the age of 3-4.
So, if I had to guess, could it be possible that there's no gene for a specific talent, but rather there are children who are more prone to be focused at the same task for an extended period of time without being easily distracted?
Persevarence and patience are also mostly genetic
Could be? No one knows because things like "perseverance" aren't standardized traits with a clear meaning that can be measured on a typical questionnaire. These large genetic studies for measuring heritability collect trait data that is volunteered from individuals, which means they are limited to things that you can ask in a survey. So the answer is: no one knows, but there will be plenty of people who try to tell you they do.
@@talkpopgen I once had dinner with James Watson, who complimented me on my good nordic genes, and explained that they (and also Asian people's genes) made them smarter than the Scots-Irish, his ethnic group. But then proceeded to explain that the Scots-Irish inherited greater persistence and stubbornness and ambition, which made his slightly lower IQ group *better*. When in doubt, invent a genetic parameter with no empirical justification to make yourself look superior.
@@PZMyersBiology Haha this is a classic
Watson would hate me then . I’ve got distant Scots ancestry and have 2 children both with high IQs , science degrees and a large percentage of African ancestry 🤷🏾♀️
One study actually show that genes could capture 10% to 15% of educational success. And that may not sound like a lot at first until you realize that wealth and equality accounts for only 11%. Basically, she says your genes play as much a role in your educational success as your parents' wealth.
include the citation
@real_pattern "Predicting educational achievement from genomic measures and socioeconomic status"
doi: 10.1111/desc.12925
PMCID: PMC7187229
PMID: 31758750
The study is free access too
@real_pattern "Predicting educational achievement from genomic measures and socioeconomic status"
doi: 10.1111/desc.12925
PMCID: PMC7187229
PMID: 31758750
@real_pattern "Predicting educational achievement from genomic measures and socioeconomic status" youtube keeps removing it when I have details but that's the title, you should find it when you Google that.
@@real_pattern Predicting educational achievement from genomic measures and socioeconomic status
Not in your genes by Oliver James is great book on how we "inherit" traits from our parents
The debate over heredity vs environment has been going on for a long time. It will undoubtedly continue for a long time because there is no way to find out.
Even if you took identical twins, raised one in a totally sterile environment, and the other in a more normal environment, you'd still be uncertain at to what extent the differences were either heredity or environment. Needless to say, that sort of experiment is out of bounds in any case.
We do know that some things are definitely hereditary, and some things are definitely learned. Problem is, there's a lot of stuff which could be either/or, or both. Best thing is just to accept that.
Here is my comment for quibbling. You mention that a certain GWAS study found that only a few percent of the variation could be explained by the genetic variants they identified, but surely if the trait is highly polygenic like height then there could be many genetic variants of small effect that make up the missing heritability. This is not my field, so enlighten me if I am missing something.
Here's the source for the differentiation between populations (muse.jhu.edu/article/633715 ).
Sure, it could be that there are many SNPs contributing to the variance in intelligence but their individual effects are so small as to be undetectable. But that still means that we don't have any positive evidence that genes are the prime driver of differences in intelligence.
To me, if a dataset of 450,000 individuals ~still~ can't predict more than a percent of the variance (www.nature.com/articles/s41588-023-01398-8 ), maybe it's time to consider genes just aren't playing much of a role. At the very least, individuals who take a strong stance that they do are doing so without evidence.
I think you're presenting the science fairly, as far as I can tell. (Background in biochemistry and bioinformatics, but not specifically evolution/GWAS.)
But I'm not sure you're being fair to Pinker, I don't believe he thinks something like "all of the variance of personal traits is at least partly explained by genetics" with his first law. I think he probably meant the quasi-truism that the genes give us brains, and brains are requried for personality traits, thus personality traits are grounded in genes.
To anyone who read the book, am I wrong?
If that's what he meant, then we'd be in agreement. But he used the term "heritable," and appeals to studies on heritability of behavioral traits. Since these are measures of the heritable variance in traits, it seems pretty clear that he's talking about genetic variation as causal to variation in personalities. The more charitable interpretation also seems at odds with his second law on the greater impact of genes than families.
@talkpopgen Makes sense, thanks for the clarification!
Re: Galton, I think you mean “polymath,” not “polyglot.”
@@aryamanshalizi7131 lol yep you right that’s on me
We can argue about the exact estimates of IQ heritability and the confounds of midparent-offspring regressions or GWAS all we want but I'm still convinced that hereditarians are right on the dysgenics question. My comment will be more relevant to last year's human mutational load video but since it's something online hereditarians build their case on I might as well say it here.
Modern medicine is anti-natural selection, or at least relaxed selection, such that demographic transition has conferred low mortality but low fertility across the board. The direction of differential fertility is biased towards people of lower IQ contributing more to the next generation. And provided that in developed countries we see couples delaying childbirth, this only compounds the effect of dysgenic fertility because mutational load in the offspring increases with paternal/maternal age. The logic follows such that most non-neutral mutations are slightly deleterious, and since 84% of the genome is expressed in the brain, this only increases the contribution of genetic sources of variation to behavioural differences among the next generation.
And even if we disregard behaviour altogether, because we are doing NOTHING to 'modify our stock', our system of equitable healthcare for all would only be detrimental to long-term population health as preserving deleterious variants would confine the next generation to a lifetime of chronic genetic disease. I don't find it to be a coincidence that esteemed evolutionary biologists like H.J. Muller, Bill Hamilton and more recently Michael Lynch and Alexey Kondrashov have expressed the same worry for our genetic future, especially since we have such an unusually high mutation rate compared to other taxa (attributable to our low Ne).
I'm not condoning classical eugenics here. But what I am saying is that the natalist hereditarians have a case. The world's first baby has already been born thanks to embryo selection and polygenic screening, and only time will tell whether such investments into 'liberal eugenics' would even be viable if our estimates for positive genetic correlations are good enough. This is a topic that I've been conflicted over for quite a while but it's important that this conversation is had now rather than later.
Really informative video nevertheless! It's nice to see some critique against someone else other than YEC low hanging fruit.
I'm going to disagree with almost everything you've written here, but I appreciate the cogent way in which you delivered it. The argument relies on a strong assumption that this video (and studies cited therein) specifically address: the heritability of IQ. For us to even begin a discussion about dysgenics, we'd need to agree that we can "breed ourselves dumber." So little of the variance in intelligence can be explained by genetics, and so much of it is confounded by the environment, that there's simply no reason to start with this premise.
Second, medicine has not "conferred" low fertility. Education and women's reproductive freedom has enabled people to choose to have children or not. This is why developed countries with access to birth control measures have lower fertility. This has exactly nothing to do with natural selection - relaxed selection and the accumulation of deleterious alleles didn't lead to women having less children. You're looking for a biological cause when there's a clear social one right there.
Third, a mutation is deleterious based on its fitness effect. Poor eyesight would have been selected against in the Paleolithic, but glasses are readily available today. We've not so much "relaxed selection" as we have changed the fitness effects of the mutations. To "relax selection" is to assume the fitness effect stays the same but the ability of selection to purge it is weakened, as in the case of reduced population size. But wearing glasses have nullified the fitness effects of the mutation itself.
Lastly, most people don't die from genetic diseases. The greatest threats to human health are cancer and heart disease, things that kill you later in life and have very little (if any) genetic component. In fact, most major diseases in humans we struggle to identify what the underlying genetic variation is at all (this has been remarked as the greatest failing of the Human Genome Project).
TLDR: there's no reason to start by assuming IQ has a significant heritability in the first place, lower fertility is not the result of mutational burden but entirely the product of social choice, mutational effects aren't fixed but are modified as we modify the environment itself (e.g., with modern medicine), and there's no evidence that genetic diseases are a significant concern to human health in the first place, you're far more likely to die from eating too many cheeseburgers.
I'd recommend this paper as a response to Lynch (2016): academic.oup.com/genetics/article/204/2/821/6046895
@@talkpopgen Cheers for the very prompt reply. I think you've established your stance on the true heritability of intelligence clearly enough that I'll turn my questions and comments to the other parts of your response.
2) Differential reproduction due to some people choosing not to have kids can itself be natural selection provided that the reasons for these conscious choices have a heritable genetic basis. Years of behavioural genetics research would be going down the drain if we concede that social traits, and hence expected social choices, are mostly environmental in variation. Aren't social interactions downstream from biology anyways?
Also I should have clarified that yes increasing mutational load is not the cause of low fertility but can be a consequence of it because we see trends of delayed childbirth in developed countries, and older parental age is correlated with infertility and as it so happens greater germline mutational load. Ideally people if they want children should have them younger, and it's a shame that young people don't have the economic incentives to have children and when they have the resources to do so in their 30s or 40s, an unfortunate effect is the mutational burden on their child. This has to be dysgenic - funnily enough this is why Kondrashov advised for young men in their 20s to freeze their sperm for IVF later on, sort of like making a germline save game lol.
3 and 4) If there ever comes a point to where we raise living standards and environmental/educational interventions to a maximum, we can only progress life outcomes even more if we account for the genetics. Sure, we may have neutralised poor eyesight with glasses but god forbid if a big war were to destroy the eyeglasses supply chain. It's an extreme example but it's the basis for Bill Hamilton's idea of 'Great Planetary Hospital' where he posits that having to constantly attend to a population increasingly burdened by chronic disease is the definition of a metastable strategy. Humans are awful at predicting large-scale disasters, and if our system of healthcare were to shut down for whatever reason imagine the countless deaths. Perhaps it's better to have a genetically robust population that at least acts as a safeguard for this situation.
Hereditarian arguments to do with between-population differences (i.e. races) don't interest me as much as the within-population or species-wide consequences of dysgenics. I only give it so much thought because I asked my undergrad evolutionary genetics professor about this exact issue, to which they did express the same fear from a mutation rate perspective. Not surprising actually, given that their doctoral advisor was a British Neodarwinian of which they are almost always of hereditarian leaning.
Again thanks for the reply and the paper you linked. Just wanted to let you know too that your neutral theory video helped me so much with an exam earlier this year so I'm always looking forward to some more popgen content!
@@pol_io One thing you and all hereditarians who try to link intelligence to genetic inheritance utterly fail to do is provide a clear and concise definition of "intelligence" which is entirely free of cultural biases, and consistent across populations and time; let alone any method of consistently and accurately measuring such a factor. Until that can be accomplished, any discussion of a genetic basis for "intelligence" is nothing more than presuppositional noise.
Great video doctor zach !!
Aaaaand another loss for the hereditarian camp. Profoundly informative video👍
Very informative video. Thanks!
isn't the cloning plot the same in the movie the Boys from Brazil but they cloned hitler
Based
Hereditarianism - Herr-Reddit-Aryanism
I'll see myself out.
But you wouldn't be you without your genes...
You wouldn't exist without genes. But that doesn't mean genes are the cause of why you like watching YT videos while others watch tiktok.
47:58 Why are you referencing correlations only from GWAS studies and not including the figures found from twin studies?
There be dragons
I'd be really interested in data regarding what people think intelligence is. I'd love to ask a large group of random people to guess the IQ of a bunch of famous people, or rank them smartest to dumbest. I wonder how much variation you'd find.
I think ranking people they know personally might be more meaningful than celebrities.
First half of the video is good, the rest falls off after the strange sequence of strawmen and lack of self awareness.
Dude argues "social status is inheritable genetically AND socially, so programs to lift up the poor largely fail because of that."
You: "you said it's only/mostly genetic "
I may disagree with his central point but yours manages to be worse.
Throughout the video, twin studies, adoption studies, etc. were not mentioned once. Are you intentionally being so dishonest, or do you honestly believe what you're saying? Differences between groups are difficult to investigate and we have little data on them, but differences within the group have been studied for the last 100 years, we have a ton of empirical data, this is the scientific mainstream. We can compare identical twins raised together and separately, fraternal twins raised together and separately, siblings raised together and separately, adopted children, their biological and adoptive parents, etc. Twins have a common womb, identical twins have on average about 100% of common genes (in practice, this number is slightly lower due to mutations), the remaining siblings have an average of 50% of common genes (this number varies from 40% to 60%). By combining genes with different environments during adoption, we can compare 4 groups of twins: identical-together, identical-separately, fraternal-together, fraternal-separately. It is possible to debate the validity of the g construct for a long time, but we can compare more objective indicators that correlate with g, for example, reaction speed or working memory. Now we gradually begin to learn how to predict IQ by neuroimaging using EEG and fMRI, we have network models that do not use a hierarchy of factors, etc. We have a bunch of experiments where we give people gambling, and then we inject one group with a placebo, and another with a certain hormone, and people with the hormone start making riskier decisions, do you really not think that genes affect hormone secretion?
0:47 WWII cr@pzis chose to clone a person with one of the most popularly known Jewish surnames??????
🙄
your content may be good, I don't know. A thumbnail with that utter m&£_n means instant ban though. Goodbye.
Great, now look a transracial adoption studies and racial admixture studies.
Just did, and neither support hereditarianism. Is that what you wanted us to see?
What do you believe that would tell us?
Turning two blog posts by Gusev into a one hour video doesn't make the argument more correct.
It makes it more consumable rather.
Are you a hereditarian?
Culture is downstream from IQ. ^^
Pretty good video. I learned a couple of things with the math. Slight leftist bent tho but considering the touchy subject of IQ it's to be expected. 50 years of rehashing the data to portray it under new terms and in a ''nice'' way. Everybody knows the group ranking in terms of IQ during the 20th century had first Ashkenazi Jews then south east Asian then ''caucasian/europeans'' and so on. Rushton-Jensen 30 years of IQ research is kinda where I stand.
"Culture is downstream from IQ."
Said no sociologist or anthropologist ever. Also, why would you stand with a debunked paper from two dead pseudoscientists?
When one stands on shit, they will inevitably sink into it.😂
@@Liliquan We are but hankeys on the mushy shoulders of dung giants...
_"Slight leftist bent"_
Reality has a liberal bias. Deal with it.