You posted this about my views: “…your own belief that for thousands of years Africans have retained some cognitively disadvantageous traits compared to other modern humans…”
I am objecting to the use of the phrase “retained some cognitively disadvantageous traits…”
This implies that some disadvantageous traits are preferentially retained even when advantageous traits are available, as if evolution just kind of wanders along with only random happenstance dictating which traits are retained (as opposed to any sort of positive selection pressure for those traits which are advantageous). This is not my position at all.
I have not advanced any particular theory about why Africans are different from Eurasian populations. I have only advanced the notion that they are qualitatively different in a biologic sense; that where differences are found they are likely to be genetic. “Retaining” disadvantageous traits is not the same thing as never having the opportunity (by mutation or exogenous exposure) in the first place of acquiring more advantageous genes.
I would not object to the characterization of my view as follows:
“Sub-saharan Africans, as a group, have some cognitively disadvantageous, genetically-determined traits compared to the broad group of modern Eurasian humans…within both groups are numerous subpopulations for which this generalization at the African/non-African level may not hold true. Among the mechanisms by which “non-Africans” acquired cognitively advantageous traits are spontaneous mutations post-emigration out of Africa, retention of cognitively advantageous genes from an emigrating African sub-population, and injection of advantageous genes from admixing with existing non-African populations such as Neandertals.”
The important point is not how one lumps or splits (although I realize this is where all the sensitivity comes in); it’s that, where differences between any two groups are found, genetics is a predominant determinant. I am OK with splitters who want a hundred–or a thousand–different populations. I hold simply that differences found between any two reasonably large groups are typically going to be genetic. Lump all of humanity into one group, and we’re smarter than the group known as monkeys. The reason is not nurture. It’s nature, even if you don’t think “monkeys” is a very well-defined population, and even if chimpanzees are smarter than Appalachians.
Neandertal mitochondrial genes having a selective fitness disadvantage when inside a Homo sapiens cell is indeed a possible alternate hypothesis. Without doubt genes (and consequently traits) that have a fitness disadvantage do tend to disappear.
OTOH neutral traits tend to stick around, like male nipples, never going away because there is no fitness pressure against them. Neandertal genes in Homo sapiens could have been a selective advantage, perhaps the result of a rare interbreeding event that spread widely due to its distinct reproductive fitness advantage, or neutral, and widespread because the event occurred early in the founding population and there was no selective disadvantage against it.
As of now there is no way to know which is the case.
We know that Neander gene presence is spread across the Eurasian populations and not as widespread or not present at all in African populations. Either explanation is possible and none has more evidence to support it or to falsify it.
Unless … I have not yet studied the Science article in any detail but is there anything in there about how conserved the Neander genes are in the different Homo sapiens lines? Neutral genes are subject to genetic drift, genes that are a selective advantage are well conserved.
BTW, why the apparent immediate presumption that a hypothetical fitness advantage of these particular Neander genes would have anything to do with cognition? There is absolutely no reason to presume that in the least. If it was shown that the Neander genes are conserved across Homo sapien lines then the speculation as to what the advantage might be would be wide open and would include metabolic, physical features and abilities, sperm function, and a host of others.
I don’t see how that phrase implies what you’re suggesting. AFAIK, it is perfectly possible for non-advantageous traits or even somewhat disadvantageous traits to persist in a population, even while other, advantageous traits are developing under positive selection pressure.
Evolutionary change in genetic traits incorporates both advantageous developments due to positive selection pressure and random happenstance. There’s no reason it has to be entirely either one or the other.
Thanks, I’ll bookmark that approved description of your view for future reference. Aren’t you being a bit premature in definitely identifying Neandertal interbreeding as a source of cognitively advantageous genes for non-Africans, though? As you yourself noted a couple of posts ago, we don’t actually know yet what the specific function(s) or evolutionary impact(s) of Neandertal genes on modern humans were.
You know I hadn’t even read that part of what CP wrote.
Wow.
He believes that Eurasians, as a population group, have cognitive superiority over sub-Saharan Africans. Proven fact to him.
And “that differences found between any two reasonably large groups are typically going to be genetic” - not that “may be”, but typically are. So health of a Western population now and of a population two hundred years ago? Genetic. Nutritional changes, infectious disease differences for improved infrastructures for sewage and clean water and vaccines and antibiotics, etc - those are pretty inconsequential. And when you compare the health of Chinese in America with those who live in China (at least up until this last decade), well the rates of diabetes and heart disease that are much higher in the American Chinese are because of those intragenerational genetic changes.
Remember that we are talking about groups here. These debates always end up this way even though there is no proven cause on either side yet. Let’s not get away from the obvious, Eurasians as a group do have cognitive superiority over almost all indigenous groups of sub-Saharan Africans in any way that can be measured by our standards. No one has ever given a shred of evidence to the contrary even though people bend over backwards to make up explanations and excuses for it.
You can’t even raise populations of sub-Saharan children in a western environment and expect them to do as well as their European or Asian counterparts. It is one of the most consistent and repeatable social experiments in the world although it is unfortunate. It is impossible to make up any kind on non-specific cognitive test in which kids of sub-Saharan African descent do better than their European or Asian counterparts no matter how or where they are raised.
This is one area where the Ivy Tower types have gone off the rails. They ignore the most significant fact of all and dive straight into the minutiae while ignoring the obvious. That doesn’t mean much for individuals. There are plenty of sub-Saharan Africans smarter than me or you but the only way to claim that they are intellectual equals in population terms is to base it on mysticism and add lots of non-specific environmental factors on top of that.
Most people know this intuitively yet we get called bad things if we say it. There may be some biological basis for what we all see every day the testing always reports but I don’t know what the ramifications will be if something like Neanderthal genes means that there was a distinct split in the homo sapien family tree between sub-Saharan blacks and other groups.
I am not a white supremacist by any stretch but this topic always elicits an emotional response which doesn’t have much bearing on the scientific facts whatever they turn out to be. There is plenty of evidence that the differences in existing human populations is not just skin deep and it grows greater all the time. I think it would be more amazing if all groups turned out to be exactly equal for everything except skin tone.
If that’s so, then why don’t the test outcomes for African-American kids vary in accordance with how much European genetic heritage they have? I’ve never really understood why “sub-Saharan African genes” are supposed to explain cognitive underperformance just as well for black kids with significantly or even mostly white genetic ancestry as for black kids with no white genetic ancestry.
Well as this thread goes careening off the rails let me comment on this. Briefly. Yup: “measured by our standards”. Don’t get too far away from the obvious.
Look we’ve had plenty of inane GDs on “The Bell Curve” and its various acolytes; I really have no desire to engage in one here, nor to follow this thread as it gets kicked into GD and spawns a Pit thread in turn. Been there done that.
I’m thinking it would make sense that if there were Neanderthal gene advantage conferred to Eurasians, it would probably be physical. I mean, you have a group of heat-adapted people moving into cooler climes. If Neanderthals were hairier and stronger with paler skins more adept at absorbing sunlight and making Vit D, humans acquiring these traits would be a plus in their survival, right?
And if Neanderthals merged with sapiens by raping and pillaging (and I know this is really speculative), this would further select for strength. And also agressiveness, but perhaps that is a good thing to have if you’re in the cold.
Given that it is sapiens genes that dominate, would you not expect the reverse? That it was sapiens that raped, pillaged, and conquered neanderthalensis?
The hypothesis that Neanderthals were the rapers is suggested by the absence of a mitochondrial (maternal) DNA linkage to humans. But has been pointed out by others, these genes may been dropped for reasons other than just the lack of Neanderthal impregnation, which is why the rape theory is highly speculative.
Ah. Interesting observation and deduction. How do they know that the mitochondria were sufficiently dissimilar? After all, sapiens and neanderthalensis only split 500K years ago. There should be very significant cross-over.
Has anyone ever done an analysis to see if it does (or does not)?
I’m not advocating for either side here, just asking a question. I think it would be a pretty complex and difficult task, but definitely doable provided the motivation and the funding were there.
It’s true that there don’t seem to be fully conclusive studies on this yet, and it certainly would present a lot of difficulties to settle the issue conclusively. However, Richard Nisbett’s Intelligence and How to Get It (incomplete text at Googlebooks, sorry) discusses (pp. 223-232) various studies of the effect of European ancestry on IQ test performance for American blacks. The correlation of more European ancestry with higher test scores was slight or nil, and in some studies even slightly negative.
So far, at least, if there really is a cognitive disadvantage in African genes that makes African-Americans underperform on cognition tests, it seems to be almost completely unaffected by the amount of African genes present in the test subjects. Either we’ve got some weird genetically atypical phenomenon going on in the African genes, like DSeid’s (sarcastically suggested) “one-drop” effect, or else genetic explanations by themselves are not adequate to account for the measured performance differentials.
Sigh…aren’t you being a bit premature in leaping to the term “definitely identifying…” when in my post I listed that as only one of at least three possible ways that Eurasian-descent populations might have ended up with a different gene pool from more archaic pools still persisting in modern Africa?
DSeid, we have, in fact, argued genes v. nurture endlessly on these boards. I’m surprised it’s a surprise to you that my own position is just what I’ve stated above. But on the other hand, these sorts of studies are no surprise to me and no threat to my core paradigm–that we are our genes.
Science will get to the resolution eventually, I think, and in my opinion not too far down the road. Baby steps…the first of which is to show that group genomes do differ. If, as I think, we get that far, I’ll let the PC crowd who hopes everything turns out to be nurture to decide how to spin the science then. Right now it’s easy to spin disparate outcomes because of a default assumption that all individuals are gene books from the same total library of available genes. We’ll see how much longer that supposition holds up.
Another potential test - use those “non-specific cognitive tests” on a Native American Population. Now that is a group that descended from an Asian migration and should therefore have that cognitive superiority gene(s) and perform comparably to the Asian population on these non-biased tests of cognitive function that are immune to cutural effects (both in scores and in pattern of scores), if it is true that differences in performance on these cognitive tests is genetic in origin. Which is why MIT is overrun with Native American engineers.
They do, as do any mixed population groups. See “The Global Bell Curve” for numerous examples. It makes sense that any large-enough hybrid gene pool is going to perform somewhere in between its source pools. IQs measured for American blacks falls in between those measured for US Eurasian populations and African populations.
Well okay, if you mean only that these are possible ways that Eurasians might have acquired cognitively advantageous traits, then that sounds perfectly reasonable. What you said before was “Among the mechanisms by which “non-Africans” acquired cognitively advantageous traits are […]”, which comes across as a definite assertion rather than merely an indication of possibility.
Yeah, but the point I was making is that IQs measured for American blacks don’t seem to depend on how much Eurasian genetic heritage they have. If the IQ differentials are indeed genetic, then you would expect African-Americans of pure African heritage not to do any better on IQ tests than African populations do.
Well I am sorry but there are really only a limited number of posters whose posts stand out to me, either for their wisdom or their stupidity, and your posts apparently didn’t make either list. Of course it is also true that those discussions get pretty old pretty quickly with positions staked out soon enough and then repeated ad nauseum so as I bug out I may have just missed your past … contributions.
These studies shouldn’t be a threat to that belief but neither should it be a reassurance to it. An honest assessment is that it bears naught on the question. It does allow for many possible speculations and gives the Eurasian line some extra genetic diversity to work out of and potentially select from (or not if they were neutral traits) - and previously the greatest genetic diversity was indisputably out of the African lines. That in itself is of significance, even if we don’t know what that significance is.
There are any number of subpopulations which differ from one another in outcomes, and it would be foolish indeed to assert that every population not in Africa has, on average, superior cognitive genes (or any other trait) to every African population. I’m not sure this single paper suggests that all those migrated populations are descended from the Neandertal-exposed ones, anyway. But in any case, populations are much more complex, and I realize that.
I don’t really try to lump or split. I make a much simpler assertion: Where you find differences, they are typically genetic. The “why” is being sorted out as we sort out the genome. We can already type various populations. We can already --in theory–find out what proportion of a given individual fits those purer ancestral population types. This study sheds light on at least one way we may have diverged, and it makes a further division: part-Neandertal and no-Nearndertal. Surely there are many, many others and the take-away is not how to lump or split. The take-away is that we are all packages of genes and genes vary even at a large group level. We are not all individual patchwork quilts created out of the same pool of possible patches.
This is not a comfortable observation for some. Indeed, counter-arguments to every study defining differences among human populations are advanced with vigor. To date, though–to the best of my knowledge–no one has advanced studies which simply correct prior observations. If, for instance, all the studies showing a diminished African v. Eurasian average IQ are flawed, why not simply run corrective studies demonstrating equivalent IQs instead of attacking the “unsound” ones?
The answer, I believe, is that we are genetic egalitarians by culture and by nature. We have had quite enough of rabid racists promoting their agenda of supremacism and bigotry, and we want no part of it. Unfortunately nature and evolution are uninterested in our altruism, and while our most dangerous enemies may be those who want to divide us, this is not evidence that we are therefore genetically equal.
