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Notes -
I am skeptical of the race and IQ narrative mostly because Africa has an average IQ so much lower than everyone else. It's fairly easy to come up with just-so stories about Europe and East Asia. But nearly the entire world, including the pure indigenous populations of the Americas, scores notably higher than pure blacks do, on average.
It seems like the answer is as much about "the places where blacks with no European ancestry are to be found are extremely badly run societies with very high rates of child malnutrition and a high parasite load, and this depresses IQ scores. This problem is shared with a few other areas that are not majority black, but purely black populations probably have an average IQ similar to the averages in southeast asia and among native americans, while east asians and most whites underwent selection effects for higher IQ" as it is about genetics. Unless there's some selection effect for all nonafrican populations but not subsaharan africans that I've missed(and before "Ice age", humans were already pretty widely dispersed by then).
To put it another way, it doesn't pass my smell test that every population not considered black scores higher than every population considered black with no white admixture, when neither are monogenetic groups in ways that the entire human race is monogenetic.
Your premise is not sound. Australasian aboriginals are worse off. Poorest Central Asians like the Kyrghizstani are around black level, judging by PISA results. Ditto, it seems, for lower-caste Indians, which is a group bigger than any majority-black nation. Some purely black populations score higher than some non-blacks; Igbos are stereotyped as crafty and big-brained by Africans and they do comprise a big part of those high-performing Nigerians in the Anglosphere. I suspect that Tutsi are smarter than Hutu and indeed pretty smart in general, which is why they eventually suffered a genocide, as it happens. And the lowest results for specific African nations are suspect. Anyway, someone is bound to end up at the bottom of the totem pole.
On the level of rhetoric, it can be said everyone else are overwhelmingly descendants of a single out-of-Africa migration event (hence the popular factoid that there's more "genetic diversity" in Africa than elsewhere). It stands to reason that everyone else might also be close – and different from the left-behind African population – in some important phenotypic traits. Though of course in actuality Africans we talk about are almost 100% Bantu, and thus fairly homogenous.
But yeah, even hardcore hereditarians allow that with continued successes to eliminate causes of deprivation and sickness, along the lines of GiveWell/Gates Foundation, populations that currently report those absurd scores will almost converge with African Americans. E.g. here's Emil Kirkegaard, who himself believes the B-W gap in the US to be 100% genetic, citing the oft-demonized Lynn:
And Emil himself:
The problem is that the gap may be more than 100% genetic, so to speak. That is, with deliberate interventions to close the gap we can raise individuals from the lower-IQ group above the performance they'd have had, given equal treatment; and on a population level, with humanitarian efforts, we may improve environments of African societies beyond the level they'd be able to sustain on their own, so new South Asian-like averages won't hold if aid program is terminated on account of its success. Still, maintaining optimal African performance would probably be a net moral (and economic) win for humanity.
Is that not true?
It's true inasmuch as we literally talk about "genetic diversity" in the context of anthropological research, but implications that people try to smuggle in with these words are false. I'll just quote Cochran again.
On African genetic variation:
And the venomously sarcastic Economists and biology:
TL;DR: Africans do have greater genetic diversity, but "genetic variation is mostly in neutral loci", i.e., greater genetic diversity does not imply greater phenotypic diversity, and even if there is greater variation in one phenotypic trait (e.g. height), this does not imply that there is greater variation in all traits. Correct?
Pretty much. Actually it's four points.
Most of the asserted "genetic diversity" of Africa as a whole is due to peoples from ancient population clusters, which make up less than 1% of African population and are not associated with colloquial "black people". They are anthropological marvels, but frankly they're not the guys anyone is talking about. Related Razib Khan post.
"Genetic diversity" for a given population is overwhelmingly a measure of ancestral population size and diversity of interchangeable variants that have spread by genetic drift. Out-of-Africa populations have passed through a series of severe bottlenecks, so they've shed some genetic markers we can find in African Bantus. Doesn't have much to do with anything consequential. It's like a JPG that's gone through lossy compression: there are color bands now, and less diversity of color patches or raw pixel values, but it doesn't mean the semantics of the image is altered, or that the range of any color channel is diminished, in fact the opposite can be true.
Local adaptation can very quickly act on non-neutral loci, a few thousand years are more than enough to change a typical polygenic trait by 1 SD. We have no grounds to presume that ancestral (>50KYA) diversity explains modern diversity for groups that have evolved in different environments.
By the same logic, yes, traits are independent products of selection. Just like all Sub-Saharan Africans are pretty dark relative to other races, they can be pretty ... fast runners, putting aside their internal ranking and their variation in toxin resistance or deep-diving talents or cricket skills.
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Thank you, that was the TDLR of an effortpost I was looking for.
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The Indigenous populations of the Americans came primarily from Asian populations around 18K years ago who underwent one hell of a trek. Funnily enough, 2 day old Navajo and Japanese babies show similar responses on the cloth over nose cognitive test (near complete docility) which would be extremely abnormal in caucasians. The separation between Africans and every other group is over 50K years. Given the standard theory that we all came out of Africa, it makes intuitive sense for the least cognitively capable members of our species to be the ones that didn't make it elsewhere. The Saharan desert is not exactly tolerant of the unintelligent.
Evidence for the horribly run nature of African societies, or malnutritution and parasite load doesn't exactly counter the validity of the genetic hypothesis. All of these are highly indiscriminate, killing the smart at similar rates to the stupid. You need particular conditions for selection pressures to favour intelligence over the simpler traits they might favour (speed, muscle, and high testosterone for example). Note that these are all areas where Africans excel, with African infants showing greater muscle control at birth than caucasians or asians (but not aboriginals).
I think the second half of your first paragraph has a bunch of issues.
I don't think it logically follows that the smartest would be the ones to leave first, especially in the context of simple, pre-agrarian hunter-gatherer societies. It could very easily be that the ones who left first were the least aggressive, and thus least likely to defend their territory. Inuit folklore mention the Dorset and state that their response to outsiders was simply to flee. I don't see why that wouldn't have been the case during the first human migration from Africa. I'd judge the argument that leaving Africa in the first place is a sign of intelligence to be false. Indeed, I think the low aggression hypothesis is actually more likely, given that there are experts who argue that drought in Africa is what first spurred the out-of-Africa migrations. That's a point in favour of aggressiveness/docility being the distinction between stayers and leavers, as conflict over increasingly scarce resources would have been inevitable.
Also, the first migrations out of Africa were fundamentally different than any that came after, as the original out of Africa population was traveling through areas where there were no Sapiens Sapiens, only Denisovans and Neanderthal. Once the first group leaves and is in the way, it becomes significantly less simple to push them out and then migrate, as you have to go through potentially(probably) hostile societies to do so. The first group to leave was incredibly lucky, and if they had been the second group due to minor changes in inter-tribe politics or random chance, they might never have made it out.
Finally, some parts of Africa are close to the Middle East and some are not. Any group that ended up in Southern Africa simply wasn't going to leave, and that is entirely circumstance and has nothing to do with any of their group characteristics. There's no reason the smartest humans 70,000 years ago couldn't have been denied the opportunity to colonize the world due to their location.
The Sahara was unlikely to have been a barrier to the first humans leaving, either. It has cyclical wet/dry periods, and it seems that a wet period ended ~70,000 years ago, which is right in line with the out-of-Africa migration that led humans into Eurasia and beyond. I find it more intuitive, given this fact, to suggest that the drought and desertification of the Sahara region was the impetus, and that it only became a hurdle for migration after the humans had already left Africa. On top of that, the Sans of Southern Africa have been successfully living in the Kalahari desert for 20,000+ years, despite scoring even lower on IQ tests(55 on average!) than other African groups.
With all that in mind, I find it very unlikely(I'd posit 95% confidence that this is the case) that the intellectual differences between Sub-Saharan Africans and non-African populations are the result of genetic differences that existed before humans migrated out of Africa. Any such differences are probably the result of selection pressures after the fact.
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That hypothesis, to be clear, was that high malnutrition rates and poor general sanitation leading to high parasite load take IQ points off of Africans. It's a competing explanation for African underperformance relative to other parts of the world which also produce few nobel prize winners. The explanation isn't evidence against competing hypotheses; I don't think that South Sudan with the social conditions of Holland or Japan would have an IQ of 100, I think it would have an IQ similar to blacks in rich countries(which is itself similar to southeast Asian and native American IQ).
The argument is more "there's probably a world baseline somewhere in the 80's, and black countries limbo under it by being in youtube ads asking for money to save the children rather than for genetic reasons". I'm open to the alternative that blacks just have genetically low IQ's, but I want to see the explanation for a common selection pressure on Indonesians and Irishmen but not Bantus.
And I believe the sahara was not a desert when early man crossed it.
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Could you rephrase this? It sounds interesting but reads to me like "I'm skeptical of HBD because every single black country has a low IQ, and every black minority population in other countries also has a low IQ." To me this sounds like pretty good first-glance evidence that the HBD story makes sense, even before you look at the genes themselves. Forgive me if I'm tired and completely misreading you.
Could you give a few examples? I'm under the impression that the IQ in say, Afghanistan, is quite high despite the institutions in those areas being incredibly dysfunctional forever. (EDIT: Woah, dead wrong alert. Afghanistan looks to be in the mid eighties. This table looks to be sourced to Richard Lynn's work.)
I left this out because it's pure speculation, but the "Cold Winter" hypothesis is the one you run into the most. Populations incapabale of planning many months into the future died off any time their migration crossed a temperate climate. For example, this also explains why Mesoamerican civilizations which were also tropical or subtropical have such a high IQ and had sophisticated premodern science and maths. (Their ancestors had to pass through Siberia and over the Bering Strait.)
Did the path taken from africa to europe really pass into 'cold winter' areas? Africa -> the Levant -> Turkey -> Greece ends in europe without passing through any places that even really receive snow. Plus there are temperate climates in Africa. Are there really any climates on the way to Europe from Africa that you couldn't find i.e. in the temperate regions of south africa? If so, why aren't i.e. Zulus as high average IQ as white europeans, considering their ancestors would have had to make similar migrations? And furthermore, 'cold winters' aren't the only source of long famines. Couldn't there be plenty of (and different types of) causes of famines in the tropical parts of africa to encourage selection toward individuals capable of long-term planning?
Europe itself was the cold winter area, leading to a population bottleneck. Pop-sci link.
The more dubious and interesting question would the Middle East and India. It's worth noting though that populations do not move in a linear direction, and those regions have at various points gotten heavy admixture and even outright population replacement from the north -- especially after 3500 BC or so.
I'm completely ignorant of Zulu history, but I'm not really seeing devastating unsurvivable winters anywhere along the migration path. As for the temperature on the highlands and mountains I'm assuming they would descend for winters like foragers, nomadic farmers, and pastoralists have throughout history. Are there any mountain ranges that would take multiple years to cross to South Africa? How was the ice age in middle Africa, I thought pretty mild?
Maybe. I'd be interested in seeing if there was a population bottleneck akin to what happened in Europe above.
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Nepal, Guatemala, and Nicaragua are the three non-black countries in the bottom ten in the world by IQ score. All three are desperately poor, badly run countries that plausibly have environmental factors causing loss of IQ points in kids that grow up there. And really 7/10 countries being African sounds not too far off from a sample of 3rd world countries.
The main thrust of my argument is that since non-black is not a monogenetic group, and black isn't either, the pattern of every non-black group outperforming every black group demands an explanation. I'm aware of the cold winter hypothesis, and that's why I included southeast asia- why does the dumbest country in SE Asia(Indonesia) have an average IQ roughly on par with the smartest country in subsaharan Africa(Sudan)? Since we know that childhood malnutrition and parasite burden and all sorts of other things black countries usually do badly on lower IQ, it accords with available evidence to suggest that the average IQ of blacks would be in the eighties if they lived in countries that were as nice as Thailand or the Philippines. To my knowledge, it doesn't require a cold winter to reach either of these countries from Africa, and neither of them has undergone some kind of selection effect for high IQ, and if anything biased sampling probably makes Africa look relatively better than more urbanized SE Asian populations rather than explaining the gap.
All of these countries had quite dark-skinned populations several thousand of years ago. Then, populations originating from territory of modern China came and largely displaced them, sometimes without a trace of preceeding population. A large fraction of area of modern China was permafrost or under glaciers at some point.
Why do you think Indonesians literally living at equator have such light skin?
A diet based almost entirely on rice would tend to lighten the skin over generations, but the Chinese replacement also makes sense.
In general, it almost never occurs that some recent non-African population had its ancestors follow shortest path from Africa.
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