A couple hundred thousand years ago, anatomically modern humans appeared in Africa. Somewhere around 70K ya, some of them started leaving. Since then, various descendant populations have peopled the world. Many of those populations have been mostly isolated from one another for tens of thousands of years. As a crude first approximation, the physical barriers between populations have allowed evolution to generate enough differences that the concept of “race” (i.e., the human equivalent of “breeds”) has arisen.
Since humans are pretty clever at traveling, and reasonably prone to boinking whoever they meet, gene flow across populations has resulted in a significant blurring of any “pure race” concept, and so there is no such thing as biologically defining a race.
However self-identification with traditional race groups does correlate with the odds of having a particular gene. Self-identification with “black,” or even just a history of being from a source population of “blacks” such as western africa, markedly limits the chance you’ll have the MCPH1 haplotype D variant gene, for example, because this variant is thought to have arisen in populations which already left africa. Self-identification with “white” or “asian” gives you about a 70% chance of having that gene, possibly because a functional advantage drove its positive selection in descendant groups. And so on, for many, many genes, including the ones coding for phenotypical appearances.
Because it is exactly the sort of thing one might say if trying to pick a racially motivated fight. In fact, saying it in the right tone of voice would make blows and bruises inevitable. Even if the white person were a Quaker and the Indian were a Jain and they were both Girl Scouts.
No. Nobody migrated because wherever they were going would be healthier for them. In fact, nobody migrated (or, at least, migrations and volkswanderungs are only a marginal part of the story). The diffusion of humanity from its original homeland in East-Central Africa was more like, this village is crowded so some of the younger generation set up a new one a few miles down the road, and so on. Repeat often enough, and humans are living everywhere humans can live. And once humans got to place X, then they genetically adapted to its conditions by natural selection. Those who wound up farther north needed light skins – not to take cold better, because light skin does not take cold any better than dark, but to admit a sufficient amount of sunlight into the skin to drive the metabolic process that produces vitamin D. Those who wound up in equatorial climates needed melanin to prevent, not heatstroke (remember, white clothes are cooler than black clothes), but sunburn; and even with the melanin still got quite enough light into their skins to make their vitamin D.
I’ve got a question about racism in the “it’s not racist if we do it” vein. A person was looking for a cheap place to host a board game event and suggested this place in Minneapolis. I read through the guidelines of using the space and felt that there was a huge disconnect between two of them:
Hey that’s great. I totally agree with that…but then it continues later:
It has been my reading that many people migrated to different parts of the world, Lite skinned people did better than their darker skinned people in colder climates. It didn’t mead that only lite skinned people migrated Just the dark skinned dealt better in hotter climates, lite skinned in colder. I make no claim to being an authority on Race, or anything else for that matter.
N.B.: Those who left Africa form a genetic “bottleneck” – there could not have been more than 100,000 of them and all non-Africans of all colors are descended from those 100,000. There is actually more human genetic diversity in sub-Saharan Africa than in all the rest of the world combined.
That’s interesting. How does it manifest itself? Pygmies vs Masai? I’d wager at least the physical “diversity” is visually apparent in the non-Africans.
But that doesn’t have much of anything to do with the general concept of “race.”
If, for example, a sub-population of the non-africans gets a significant gene change, that change would only accrue to their descendants. If the nature of that change (skin color, say) is what is used to create a category of “race,” then it doesn’t matter which of the two groups otherwise has greater genetic diversity in terms of which “race” is more likely to have that particular gene.
Race is definitely an arbitrary grouping. But the fact that it is an arbitrary way to group does not mean that all races have about the same gene pool. The extent to which those gene pools differ depend on how long the sub populations have been separated, and which groups have been lucky enough to have their ancestors generate genes advantageous enough to have been driven to a broad representation in that sub-population.
As an example, we could call the Mbuti a “race” and the Bantu a “race” if we wanted to. We’d find genes coding for tallness more widely represented in the Bantu. We wouldn’t be able (necessarily) to biologically define an Mbuti, and the overall relative “genetic diversity” might be greater in one group over the other. But, have created those two “race” categories (self-describing as Mbuti or Bantu), it will now be the case that the gene(s) for tallness is not equally represented in both “races.”
It’s a common thing to confuse the notion of “genetic diversity” with an argument against biological differences among races. They are two quite different things, and the one has no bearing on the other.
I beg to differ. As a matter of fact, any number of researchers beg to differ. Or just plain differ, without begging.
Some variants of the gene nicknamed “MCPH1” result in microcephaly. The assumption that you appear to be making is that if a variant does not result in microcephaly, it’s not “functionally different.” This claim is erroneous and unsupported by the evidence on two counts.
First is the indirect evidence. The haplogroup D variant of MCPH1 is widely penetrated into descendant populations from the time of its putative origin. See Bruce Lahn’s research into it if you are interested. However the takeaway is that a new random mutation achieving 70% penetration is most likely positively selected for, and therefore offers some sort of reproductive advantage.
Second is the more direct research on variants of microcephaly genes. See here, for example. The fact that a new mutation is not dysfunctional does not mean it is equivalent to the original gene. That’s why evolution generally stumbles its way into improving a function. And the tiniest change may confer a surprisingly large improvement. For example, substitution of a single C for T in the HMGA2 gene creates a measurable difference (2%, if I recall correctly) in brain size and measured intelligence in those individuals with two cytosines and no thymine for just that tiny little section of DNA.
We are evolving like mad, and as our human population has grown, the total number of experimental variants mother nature tosses out there has equivalently increased. To the lucky descendant populations of the beneficial variants fall the spoils of advantage. Not all polymorphisms are functionally equivalent simply because they are not directly harmful polymorphisms.
Chief Pedant, you’re wrong, and the cite you cherry-picked is quite damning compared to the mountain of evidence suggesting that polymorphisms of the MCPH1 gene does not correlate with brain volume. You can start here, here, here, and here. At best, you’re “making fact” about something that has no scientific consensus, at worst, you’re attempting to distort the evidence to mesh your erroneous viewpoint.
You get so confused when it comes to genes. Your implication that a polymorphism like the haplogroup D variant of MCPH1 which has been so positively selected that it has penetrated 70% (!) of a descendant population is not suggestive of an advantageous variant is not defensible. It isn’t whether or not the exact mechanism has been worked out; it’s whether or not a given gene variant is advantageous. And with respect to self-identified race and ethnicity, the overwhelming evidence is that many many gene variants are not only disproportionately represented (that is, they cluster by SIRE group), but the gene variants are positively selected for. In turn, that positive selection is excellent evidence that the gene must be advantageous in some way.
Wrt MCPH1, you quote 4 studies, all several years older than the research I gave you, and then suggest I’m cherry picking?
You appear to want to talk yourself into the idea that we are not evolving, that mutations cannot be beneficial, that variants which have achieved marked penetration are not positively selected, or some other such nonsense. I hope you’ve at least learned that (contrary to a prior assertion of yours), all humans do not have “exactly the same genes.” That would be a start on your road to education.
As the climate change debates showed me, yes you are cherry picking, a single study doers not overturn the past ones, much more are needed for the consensus to change.
As past experience showed us, you even discount the conclusions for researchers that advice people like you to not use medical research for justifications on finding race differences useful for your sorry societal solutions.
I don’t. I see people as fellow humans who happen to look different than me. Part of the human race. Yes, there are many who would agree with you, That is a human trait as well.
Thank you for this excellent, well-supported, and insightful summary of why my position is wrong that genes vary by SIRE groups, and that those genes can be shown to have been positively selected for (suggesting that they are advantageous).
You da man when it comes to effective debating!
ETA: I can’t remember saying much about climate change, though, other than a general observation that it’s a Great Cause sort of psychology.
Thank you, and I do accept that praise even in jest because when one looks at the methods of the study they concentrated on Norwegians, indeed the authors concentrated on a medical factor that has virtually no use when the subject is race and you only attempted to use misleading points as usual.
And you do have to check if genes are doing that loss of memory :).
Suffice to say, you got a note in a previous from management for just not having anything useful to say and posting ignorant stuff just to use psychology to upset a poster.
Mind you, I do look at what scientists report, so the reason I post is not much to convince people like you , but to report what is the actual consensus and actual solutions proposed, in the end, regarding climate change you only showed all that your ignorance does not stop you from claiming to know more or better than the scientists, and as I have found out, many that have that issue with a scientific topic also do the same in others, like in this issue of race.
The fact that you forget about your shown ignorance in climate change and even in the race issue is a problem, but at least you are humble enough to acknowledge your limitations.