Intelligence, race and related issues.

[ronburgundy]

So let me try to understand the upshot of a few recent posts.....

There is no scientific/genetic basis for racial categories according to skin colour.

Someone tell me if I’ve got that wrong.

What about other supposed racial characteristics, physical features I mean (thick lips, wiry hair, big noses, big ears, etc)?

Despite being more similar to each other in skin tone and most these other "racial characteristics" than they are to northern Europeans, black Africans are less genetically similar to each other than they are to Eurasians or than Northern Europeans are to Asians and Native Americans. Most of the genetic diversity in the human population exists within Africa, b/c the human lineage split into several branches (6-14 depending on method) before migration out of Africa, and only a portion of 1 or 2 branches left Africa while others in those same branches stayed, and then migrated came back into Africa (not counting what's happened post-civilization).

Thus, the black vs white or African vs. European categories within the colloquial/social racial framework have the least validity in terms of genetic variability and proximity in evolutionary branching.

But is it still the case that racial differences in something like intelligence could still have a genetic component, just not directly because of skin colour?

For example, take two hypothetical populations, one dark-skinned the other light-skinned, reproducing over time in different environments. Would it not be the case that different selection pressures might result in differences in intelligence between the two populations?

I replied to barbos' strawman version of this, but since you're likely to actually reason about it, I'll do it here and try to expand and reword it, b/c multiple ways of saying the same thing helps get the point across. The question is not whether it's possible (no one denies it's possible), but whether it's probable or as barbos claims highly improbable that intelligence wouldn't have evolved to different levels among different groups. The default result when environments differ is NOT biological difference but similarity. Humans are far more similar to each other than different, and this is especially true is traits that are fundamental and a core aspect of how humans interact with the world. Skin color, hair type, etc., have no general adaptiveness to humans, but are adaptive or maladaptive depending on specific context and environment. In contrast, general intelligence is, by definition, something that is fundamental to being able to predict and manipulate any type new information in whatever environment you're in. Thus, it would be adaptive in every environment where avoid harm and achieving goals in useful (aka all environments). This makes it highly implausible that subgroups in different environments would evolve to different levels of general intelligence.

Now, one reason you might get a trait variant in one group and not another is that the random variation for the variant just happened to occur in only 1 group. But that applies more to traits that are determined by 1 or small number of genes.

This is highly implausible for intelligence b/c is not a biological trait but a behavioral byproduct of hundreds of biological features of the brain and nervous system, like "gymnastic skill" is byproduct of countless biological features. Each biological feature that impacts intelligent mental performance is shaped by it's own collection of relevant genes, each of which undergoes random variations. By definition, those random variations would not all systematically vary in favor of the intelligence of on group over the other. Some favorable variations would happen to benefit one group and some the other. If you take 2 individuals, then due to the sampling error of small samples, you are likely to have one person who benefited from more variations than another and thus is more intelligent. But when you average across instances at the group level, random errors cancel out, and the groups will not differ on average despite the huge variance among individuals.

 

[ronburgundy]

Nope. that's not bold claim at all. The bold claim which you keep making is that brain/intelligence is not subject to evolution.

No one has made that claim. That is a strawman based upon your laughably wrong assumption that every single selection pressure that might possibly exist and might possibly have an effect an any existing trait did in fact exist and did in fact impact every trait in every possible way.

I already explained this to you, but let's see if this time can penetrate your wall of blind anti-science faith. By definition, general intelligence entails the most fundamental aspects of human cognition that would be relevant to reasoning and decision making in every probable environment in which pre-civilization humans existed. Thus, completely unlike highly environment dependent traits like skin color, height, etc.., general intelligence would be similarly adaptive across environments and thus would increase in all subgroups rather than diverge by increasing in some but decreasing in others. Different environments do not put different pressures on a given trait, unless those differences determine whether that given trait is adaptive.

IOW/TL;DR:

All environments humans live in will strongly select for intelligence, even if they do not select cultural changes that cause the advancement of technology.

Sure, that's the conclusion, but I find it important to actually explicate the premises that lead to it, and point out the error in thinking that leads one to wrongly equate environmental differences with selection pressures.

I'll leave assertions without any supporting argument to barbos.

 

[ruby sparks]

Ok the way I’m going to clumsily (I don’t know a great deal about genetics, and I’ve had two very large brandies) reason about it is.....

This suggestion, that all environments are equally stimulating (as regards selecting for general intelligence) ....that doesn’t feel right. In other words, surely (ruby said) some environments are more stimulating than others?

Which, in a way links to what jahryn said, except he’s drawing a distinction between ‘general intelligence’ (what is that?) and ‘technological intelligence’, I think.

And as to this point that ‘racially’ separate environments are merely hypothetically possible, but may be unlikely in practice (because as poli said, populations mingle geographically) I’m not sure about that. There is and has been at least quite a bit of segregation, so...that might lead to partial disparities.

Oh hang on. Before saying all the above I should first have said thanks for the explanation ron. I think I understand ......some of it. It’s hurting my brain, which is usually a good sign.

 

[ronburgundy]

Ok the way I’m going to clumsily (I don’t know a great deal about genetics, and I’ve had two very large brandies) reason about it is.....

This suggestion, that all environments are equally stimulating (as regards selecting for general intelligence) ....that doesn’t feel right. In other words, surely (ruby said) some environments are more stimulating than others?

How stimulating an environment is wouldn't select for different levels of intelligence.
Stimulation might impact whether the full level of development that is possible for a person is realized, but it doesn't change the fact that more intelligence is better.

Intelligence allows you to predict and manipulate your environment. When your wrong about what to expect or what to do to do you die. No matter how "stimulating" your environment, if you don't eat the right things, know how to get those things, know how to protect yourself from environmental threats, and know how to predict and manipulate others people around you, then you won't do well.
Environments differ in their types of challenges, but they all have challenges and intellect is relevant to all challenges. Whether the the life or death decisions you make occur 1000 or 2000 times per year isn't going to change the fact that everyone is wrong sometimes and any amount of wrongness reduces success, so there is always room for increased intellect to improve success.

Another way to think about it is that every natural environment that humans evolved in had so much information that could be processed to improve success that no human mind was ever remotely close to being able to process enough of it that more processing power would not have been an advantage. For there not to be selection pressure for more intelligence an environment would have to be so simplistic, controlled and unchanging that most people already had enough intellect to process every piece of available information relevant to survival and reproductive success. It is highly implausible that any sizable human subgroup existed and evolved within such an environment.

 

[ruby sparks]

So continuing to wing it.....

It surely would matter how often you faced life or death decisions.

In an environment where a population faced them less often, there would be lower selection pressure on making the right decision. And vice versa; in an environment where there were more life or death challenges, there’d be higher selection pressure on making the right decisions.

Or alternatively, to put it as jarhyn did (I think) if you lived in an environment where more technological solutions and innovations were needed in order to thrive.....

By the way, I do doubt that this hypothetical would be a standout explanatory factor, even if true. There would be too many other possible factors.

And all these factors, whatever they were (and one of them might have been chance or luck) may have added up to being the reasons Western (white) Europe ‘took off’ from the 16th century onwards.

And of course I am risking conflating ‘technological prowess’ with ‘general intelligence’, partly because I’m not sure what the latter is or how it can be measured.

 

[Politesse]

So continuing to wing it.....

It surely would matter how often you faced life or death decisions.

In an environment where a population faced them less often, there would be lower selection pressure on making the right decision. And vice versa; in an environment where there were more life or death challenges, there’d be higher selection pressure on making the right decisions.

Or alternatively, to put it as jarhyn did (I think) if you lived in an environment where more technological solutions and innovations were needed in order to thrive.....

By the way, I do doubt that this hypothetical would be a standout explanatory factor, even if true. There would be too many other possible factors.

And all these factors, whatever they were (and one of them might have been chance or luck) may have added up to being the reasons Western (white) Europe ‘took off’ from the 16th century onwards.

And of course I am risking conflating ‘technological prowess’ with ‘general intelligence’, partly because I’m not sure what the latter is or how it can be measured.

That's the whole problem. Intelligence is not an objectively measurable trait, but rather a subjective judgement always made in a social context.

 

[barbos]

No, we never started with anyone implying that genes are irrelevant or that people are born the same. We started with your scientifically illiterate claims that evolution makes it "IMPLAUSIBLE" that racial groups would not differ in intelligence, and your claim that the "environment is not a factor [IOW, accounts for 0% of variance in intelligence]". I then exposed your immense ignorance of evolution, genetics, statistics, and how random variations are impacted by aggregation over large samples vs. at the individual level. Being incapable of responding to those facts, your now back peddling, directly contradicting yourself by now saying environment is a factor accounting for 25%, and claiming that I took the opposing extremist position that would be as scientifically illiterate as your position.



IQ is the measure used to measure intelligence in all the genetic studies and all studies showing differences between racial groups. So, your now arguing something that implies there is no valid evidence that genes are at all linked to intelligence or that racial groups differ at all in actual intelligence (just on IQ tests your rejecting as invalid). That makes the entire thread about the source of racial differences intelligence moot.

And, even the variance that does correlate with genes likely includes mediating causal roles of the environment. This, is why the size of the correlation is rather small at young ages and increases with age and experience.

You are trying to make this obviously bad fact sound good. The fact that environmental factors fades with age suggest that genes are systematically underestimated in these studies.

No, I am applying basic scientific reasoning about what the most plausible explanation is for the fact that overall genetic similarity only weakly predicts similarity in intelligence at young ages, but increases with age. The 60%-75% estimates are based upon adults and represent the highest estimates that include every possible direct and indirect heritable trait that has some influence on intellectual performance. That includes an infinite number of possible indirect pathways, mediated and moderated by environmental factors. The massive role of environment in mediating and moderating genetic effects is a consensus fact among those with even basic understanding (clearly not you) how biological variables are manifested in outward behavior. Thus, the a priori most probable reality is that only some portion of the variance in intelligence that is "heritable" is tied to variables that directly determine the cognitive system. Your argument which presume 100% of heritability is due to such direct influence is improbable, carries the burden of proof, and has no evidence to support it.

A plausible account of this is that genes that code for things unrelated to cognition (e.g., skin color) lead people to either seek out or have different experiences imposed upon them (e.g., racism), and those experiences in turn causally shape intellectual development.

IOW, not only is some individual variance completely independent from genes, but a sizable portion of the variance related to genes is actually caused by environmental factors that enhance genetic effects or allow genes unrelated to intellect to have an indirect influence.

That role of environment is more than enough to be able to give rise to any group level differences without genes that actually code for aspects of intellect playing any role in those group differences.

This conclusion does not follow from anything.

Add basic evidence based reasoning skills to the many aspects of scientific literacy that you lack.

The variance between racial groups is only about 10% of the total variance in intelligence. Thus, even considering only the 25%-40% of variance that is not broadly "heritable" by direct OR indirect pathways, 100% of between race differences could easily be environmental. That's doesn't even count the most obvious, probable, and evidence supported environmental pathways, such as genetically determined skin color and other racial physical traits triggering differential environments within a racist culture.

I am not claiming that we know that 0% of racial group differences are genetic. You are the only one that has taken a 100% vs. 0% position. I am claiming that your position has no scientific basis or empirical support, b/c the known facts mean that even with a 75% within-population heritability estimate, there is more than enough unaccounted for variance for most and even all the between population variance to be environmental. Plus, we know for a fact that a number of genetically determined physical traits indirectly impact intellectual development via mediation from racist social systems, which means we know that the "heritability" estimate is an over-estimate of actual directed biological influence on cognitive development. The only rational question for which we have no good data is just how much it is over-estimated by.

Stop with this word salad and comment on studies which found that environment has zero effect on adult IQ.

 

[Trausti]

I replied to barbos' strawman version of this, but since you're likely to actually reason about it, I'll do it here and try to expand and reword it, b/c multiple ways of saying the same thing helps get the point across. The question is not whether it's possible (no one denies it's possible), but whether it's probable or as barbos claims highly improbable that intelligence wouldn't have evolved to different levels among different groups. The default result when environments differ is NOT biological difference but similarity. Humans are far more similar to each other than different, and this is especially true is traits that are fundamental and a core aspect of how humans interact with the world. Skin color, hair type, etc., have no general adaptiveness to humans, but are adaptive or maladaptive depending on specific context and environment. In contrast, general intelligence is, by definition, something that is fundamental to being able to predict and manipulate any type new information in whatever environment you're in. Thus, it would be adaptive in every environment where avoid harm and achieving goals in useful (aka all environments). This makes it highly implausible that subgroups in different environments would evolve to different levels of general intelligence.

Oh, come on. The cold calculus of natural selection is the ability to reproduce and have your offspring survive. Full stop. You can't imagine an environment that applies selective pressure to cognition and behavior? Say, agriculture in temperate and northern climates, where you must have future orientation and delayed gratification or you die or your children die? Or say, Jews in medieval Europe, who could not own land, were kept in ghettos, and were limited to occupations that involved high cognition? What is the explanation why Ashkenazi Jews are so wildly over-represented with Nobel Prizes? Or, say, East Asians whose ancestors development a civil system that required reading, writing, and large memory retention to ascend to the civil ranks. Might the descendants of these civil servants have inherited higher intelligence from their ancestors? It is purely coincidental - coincidental! - that Ashkenazi Jews and East Asians sit at the top of global IQ. Or, say, just the urban environment itself. The intelligence and behavior necessary to survive in an urban environment is not the same as the Serengeti. And evolution can be a fast process.

In Cities, Wildlife Evolves Astonishingly Fast

Animals, plants, and insects adapt to the extreme urban environment—and even to specific subway lines.

 

[barbos]

Animals, plants, and insects adapt to the extreme urban environment—and even to specific subway lines.

These ducks are better "germans" than many immigrants.

 

[fromderinside]

Probably because their previous life experiences are more similar to that of Germans than from which immigrants came. No need for genetics here. Learning capacity and experience serves quite well for many species.

Both sets have learning capacity while only one set has similar past experience.

 

[barbos]

Probably because their previous life experiences are more similar to that of Germans than from which immigrants came. No need for genetics here. Learning capacity and experience serves quite well for many species.

Both sets have learning capacity while only one set has similar past experience.

The point is, environment affect genetics (through natural or not so natural selection). That's how evolution works.

 

[ruby sparks]

And of course I am risking conflating ‘technological prowess’ with ‘general intelligence’, partly because I’m not sure what the latter is or how it can be measured.

That's the whole problem. Intelligence is not an objectively measurable trait, but rather a subjective judgement always made in a social context.

When I said what I said, I was thinking that it can be measured, that it was just that I didn't know how. You are going further.

Without saying that complete objectivity can be obtained (as in almost anything, if not indeed anything) there must surely be objective differences in intelligence, not just between species (I hope I am more intelligent than a poodle) but within species (there are surely differences in intelligence between humans).

So I am going to agree with your point about subjectivity and social context making it more difficult to measure intelligence, without going as far as you seemed to.

 

[ruby sparks]

...... studies which found that environment has zero effect on adult IQ.

Citation?

I have only found studies which suggest that differences in heritability (in the genetic sense) account for some differences (in IQ), and that environmental differences also seem to account for some differences (in IQ).

 

[Trausti]

Ya know, the recent replication crisis in psychology knocked down many a supposed finding on human behavior, like priming. But not IQ. IQ findings are consistently and reliably replicated. To say there are no objective measures for intelligence is uninformed.

 

[ruby sparks]

Probably because their previous life experiences are more similar to that of Germans than from which immigrants came. No need for genetics here. Learning capacity and experience serves quite well for many species.

Both sets have learning capacity while only one set has similar past experience.

That seems to assume equal learning capacity. For all members of the same species? That doesn't sound likely.

However, it also seems improbable that the learning capacities of one of those groups would differ significantly from the other, at the group level. In other words, at group level, it would seem to make much more sense for the learning capacities to be very similar. As if, to analogise, both groups are born with very similar underlying 'computer processing power', but that the two groups may have learned to use it in different ways.

What would change that would be if different environments had resulted in different 'computer processing powers' among different groups. Which is the hypothetical I was exploring yesterday. I haven't yet convinced myself it has made a significant contribution. I'm not even totally convinced it has made any contribution.

 

[barbos]

...... studies which found that environment has zero effect on adult IQ.

Citation?

I have only found studies which suggest that differences in heritability (in the genetic sense) account for some differences (in IQ), and that environmental differences also seem to account for some differences (in IQ).

https://en.wikipedia.org/wiki/Nature_versus_nurture
Adoption studies found no effect of nurture on adult IQ.

 

[ruby sparks]

Probably because their previous life experiences are more similar to that of Germans than from which immigrants came. No need for genetics here. Learning capacity and experience serves quite well for many species.

Both sets have learning capacity while only one set has similar past experience.

The point is, environment affect genetics (through natural or not so natural selection). That's how evolution works.

Which suggests that saying either that genetics are 100% responsible, or that environment is 100% responsible, for differences in intelligence, seems untenable, does it not?

Speaking for myself, I tend to rule both of those out. That doesn't make things much easier though, because it seems almost as difficult to say which of the two sets of factors has the more influence, and almost impossible to come up with anything like reliable proportions.

Saying that there are differences due to race (by which I mean due to the racial differences, not merely 'found between different races') seems even harder again.

 

[ruby sparks]

...... studies which found that environment has zero effect on adult IQ.

Citation?

I have only found studies which suggest that differences in heritability (in the genetic sense) account for some differences (in IQ), and that environmental differences also seem to account for some differences (in IQ).

https://en.wikipedia.org/wiki/Nature_versus_nurture
Adoption studies found no effect of nurture on adult IQ.

That's a wiki page which seems to say there's a debate about it.

 

[ruby sparks]

This study seems to suggest a mixed influence:

Sources of human psychological differences: the Minnesota Study of Twins Reared Apart.

https://www.researchgate.net/profil.../02e7e530fc6cceec1b000000/IQ-and-Heredity.pdf


"Since 1979, a continuing study of monozygotic and dizygotic twins, separated in infancy and reared apart, has subjected more than 100 sets of reared-apart twins or triplets to a week of intensive psychological and physiological assessment. Like the prior, smaller studies of monozygotic twins reared apart, about 70% of the variance in IQ was found to be associated with genetic variation. On multiple measures of personality and temperament, occupational and leisure-time interests, and social attitudes, monozygotic twins reared apart are about as similar as are monozygotic twins reared together. These findings extend and support those from numerous other twin, family, and adoption studies. It is a plausible hypothesis that genetic differences affect psychological differences largely indirectly, by influencing the effective environment of the developing child. This evidence for the strong heritability of most psychological traits, sensibly construed, does not detract from the value or importance of parenting, education, and other propaedeutic interventions."

 

[ruby sparks]

These ducks are better "germans" than many immigrants.

But would you put that down to genetics? Surely not.