Oh the humanity, stringent requirements for evidence! We may actually have to wait until we have good data to make a conclusion! I’ll wait with baited breath!
Not surprisingly, your suppositions continue to have little to do with reality.
It certainly is.
As, for example, the reliance on overly stringent requirements for “race” to be biologically based:
From here.
“Relying on modern biology’s refutation of racial categories, contemporary social theory conceptualizesrace as a purely social construct that is both maintained and contested through a sociohistorical process thatinvolves politics and other social institutions (Omi and Winant 1994; Saito 1998; Shiao 2005) and thatresults in historically and nationally different racial classification systems (Almaguer 1994; Lie 2001 Telles 2004). However, there are several shortcomings to this refutation, especially in light of recent genetic research. The first and core problem is the reduction of a biological basis for racial/ethnic categoriesto the existence of categorical differences between groups. As the philosopher Neven Sesardic (2010) has noted in his critique of racial constructionism, this criterion for a biological basis is “so unrealistically demanding that . . . even the species concept would fail to pass muster” (p. 147). Arguably, the origin of the essentialist criterion for biological differences lies less in actual science than in its use in the historical
justifications for the categorical exclusion of nonwhites from political, economic, social, and cultural citizenship in the United States. By contrast, biological science does not require the white supremacist beliefin species-level, much less greater, differences between human subspecies.”
PS: I don’t disagree that you occasionally try to bait the oppostion, but I think you mean “bated” breath. That’s the pedant in me, and I apologize for letting it sneak out.
First of all I din’t say people in this thread,I spoke of people who discriminate by color. If you can show me where I stated anyone in this thread then please point it out. My intent was of any people who judge by color etc.
Thank you for your information. I do believe that genetics play a big part of our possible illineses, talents,etc.. My children have a different genetic make up than me, I have some chilldren who have high IQ’s, some look like my side of the family some like my husbands, I have brown eyes my husband has blue, all our children are blue eyed except one. My great grandchildren and grandchildren also have some traits from each of our families.
Some of the ancestral traits were passed on some not. our country of origin is European,as far bck as we can trace it to the 15th Century. But much further back in time according to genetists we all came out of Africa!
I never claimed that you did.
Here’s what I said:
You did not provide an example.
Then I asked:
Again, you were free to provide an example from outside the thread. You failed to do so.
Then I asked this:
(my bolding)
I made it 100% clear that I was not necessarily looking for an example from within the thread.
And what is your response?
:rolleyes:
I’m not sure if you are intentionally misinterpreting my question, but it doesn’t really matter at this point.
This exchange is concluded.
Bye.
Should have been “free consistent with the question”
No, monavis; we did not “all come out of africa.” Only people whose ancestral groups came out of africa can say they came out of africa.
As I mentioned in the post, many groups–almost all of the modern black sub-saharan groups–never “came out of africa.”
This split into “africans” and “non-africans” occurred about 75,000 years ago, in round numbers.
Any advantageous mutation arising after humans left africa would not be available to groups that did not leave africa. This is true for all populations reasonably separated for a long period of time. Various migration patterns, geographical obstacles, and natural disasters or climate changes have all contributed to lumping up human populations.
There are good examples of genes which spread widely to non-africans, but not africans, as a result of these sorts of migratory patterns. Look up Bruce Lahn’s research on MCPH1 haplogroup D variant as an example. We find that variant in 70% of non-african populations; not at all so far in african populations. Lahn tested the possibility this high degree of penetration was due simply to genetic drift, and determined positive selection pressure was the most likely cause. No function is known for MCPH1 other than its relationship to brain development. Svante Pääbo’s research suggests introgression of Neandertal genes into Eurasian–but not african–populations, again because the out of africa population had minimal gene flow back into african with the exception of an area around the central Sahel and the eastern coast.
The separation is not nearly so absolute as you imply here- it’s very possible advantageous mutations could spread back from any population to another- there has always been mixing of African and non-African populations, to one degree or another.
There is no evidence this is related to intelligence in any way.
There is no evidence to support the genetic explanation. I think Frank Sweet’s explanation (a combination of lesser parenting skills, lower teacher expectations, and “oppositional culture” peer pressure) is just as plausible as the genetic explanation, and has the advantage of no data that appears to disprove it (like the zero difference between first generation black and white immigrants test scores).
Would you be willing to provide a cite showing geneflow into parts of sub-saharan africa beyond the already-referenced (upthread) R1b-V88 group into the central Sahel, and a few others such as Y-DNA haplogroups G,J, M or T into a few places along the eastern coast?
I would be interested to read them. I have not seen studies showing significant gene flow into the vast majority of the sub-saharan parts of the african continent. In recent years, of course, there is a reasonable admixture for genesets in settings such as the United States, although even there persistent phenotypic differences for appearance, or physiologic differences for physiology, hemoglobin S and the like are good evidence the admixture is nowhere near homogenized.
Also, if the separation were much less absolute, do you have thoughts on the pronounced prevalence difference of MCPH1 variants (70% in non-african populations and close to 0% in sub-saharan populations)? With all the “mixing” you imply, how would that africa/non-africa prevalence difference persist in the haplogroup D variant of a gene that arose 35,000 years ago?
Thanks.
You misunderstand me. You were implying that there was essentially zero mixture back into Africa. I was simply saying that it’s obviously not zero- that if some advantageous mutation arose outside of Africa (and for it to be in all non-African populations, it would have had to arise in a specific time in a specific location during the first out-of-Africa Homo Sapiens migration, which would probably not have been that far from Africa) that it’s possible that it could have worked its way back in.
But it’s not particularly relevant to the larger discussion.
I’ll take that as a “No, I don’t have any cites.” I have not “implied” anything of which I am aware, and I am more comfortable having you actually quote me rather than summarize whatever I said into an implication.
Clutching at what is “possible” is fine, but if you want to argue that “there has always been mixing of African and non-African populations, to one degree or another,” it’s helpful to try and quantify that degree, and the evidence behind it where there is any.
As it turns out, it’s very germane to the larger discussion. At issue is whether or not there is sound scientific reason based on biological/evolutionary/migrational patterns that a SIRE group of “black” could somehow have a gene pool distinct from a SIRE group of “white” or “asian.” After all, how can we lump all “blacks” into one pool when there are obviously many distinct sub-groups within the sub-saharan population? Isn’t it ridiculous to talk about “races” if there’s more variation within “black” (african) sub-clades than within non-african human sub-clades? By what arbitrary criterion are we going to define a “race,” and if we can’t define that, how in the world does it make any sense at all to hold that such a grouping might have a different prevalence for genes?
The answer to all this is to understand first how we came to be here, and how our various populations descended within suprisingly separate populations of humans. When we understand that, we begin to understand why it’s not a counter-argument to genetically-based differences to simply define away “race,” or to point out that there isn’t a marker for races.
That’s irrelevant, and in my opinion those who advance that argument either don’t understand human migration or want to deliberately obfuscate the key point: SIRE groups have different genetic prevalences.
What there is, is evidence that many populations descended from a sub-group that left africa. That sub-group–or any of its descendant lines–had access to positively-selected gene mutations that occurred post-africa. African lines did not.
So if you want to casually throw out the notion that these post-africa genes “possibly” worked their way back into africa because a putatively advantageous mutation “probably” occurred near the exit point, it’s reasonable to cite evidence such backflow of genes occurred into the more ancestral populations. I’ve given you the handful of lines of which I am aware that made it back into the central Sahel and the eastern part of africa.
Are you aware of any other research showing a deeper penetration of non-african gene flow into the great majority of sub-saharan african lines, or are you just proceeding on faith again, like your faith that nature would only have positively altered non-important genes, and therefore any observed differences between these groups are more likely than not to be a result of disparate nurturing?
My children have different genetic make ups than I do.
Most mutations are neither helpful nor deleterious.
If you read the Nature link you gave, instead of scanning through it and cherry-picking information from it, it’d dawn upon you that
So what about the remaining mutations that go uncorrected?
Well, if you stopped believing in creationist gospel …
light would again shine upon where it hasn’t yet shone. Of about 175 mutations per generation in humans, 3 are deleterious.
http://www.genetics.org/content/156/1/297.abstract
P.S.: This is the third-grade education in me speaking, and I apologize for letting it sneak out.
If you want me to admit “sure, it could be”, then I already have. But I’m not going to waste much effort on things for which there is no evidence, and there is no evidence for your genetic explanation. Maybe there will be someday- but there ain’t none today.
Shhh…iiandiiii or Honesty might hear you, and they’ve been lobbying vociferously for the idea that beneficial mutations aren’t all that likely. See, if they are, then it increases the chances that separated populations will have disparate outcomes based on genetics because they happen to be descendants of just such lucky beneficial mutations in their unique ancestors.
One poster, Honesty, was routed out of the thread after he decided all humans have exactly the same genes and refused to retract it. I’m the anti-Creationist here, arguing for evolution and beneficial mutations.
A word about “mutations.” Most mutations of single nucleotides don’t do anything. They get repaired, or they don’t actually affect the protein (or protein interaction) being coded for enough to make a difference. Some are deleterious. Some are beneficial.
Here’s a link looking at a study in Drosophila, for example.
“Our analysis suggests that ≈95% of all nonsynonymous mutations that could contribute to polymorphism or divergence are deleterious, and that the average proportion of deleterious amino acid polymorphisms in samples is ≈70%”
If we’re just talking about SNP mutations, I don’t have any trouble agreeing that only a small percent end up being deleterious; perhaps an even smaller percent beneficial. If we are talking about mutations at the gene level–i.e., a mutation that changes the function of a gene, I doubt only 3 out of 175 are deleterious. But whatever that number is, one thing’s for sure: many mutations do end up being beneficial, and that’s why separated populations evolve to have disparate outcomes. I’ve already pointed out a couple examples of SNP substitutions that have a beneficial effect. One creates a red cell that resists malaria. Another (C for T in the right part of a HMGA2 gene) confers a brain size and IQ advantage such that homozygotes have 2.6% bigger brains and higher IQs than folks without the single C substitution.
Look through the thread, and you’ll see me arguing for a point of view that says beneficial mutations are at least common enough to make it unlikely that separated populations have equivalent gene pools. The separation starts new evolutionary games of chance for various skillsets, and the winning population of any given game now have beneficial genes for that skillset. I appreciate you adding weight to that notion by suggesting that beneficial mutations are quite common.
Opposite viewpoint of old Henry Morris and the viewpoint that DNA only degrades. I’ve repeatedly critiqued iiandyiiii for his pro-Creationist stance, and Honesty has already long since bolted for the door.
So, yeah, CP, you’re wrong. Again. But keep up the bad work.
I’ve said no such thing.
No, you’re the one with extreme confidence in a hypothesis with no supporting evidence (hint- in this argument, you’re the creationist).
You’re sticking to this canard pretty desperately, aren’t you? Perhaps it makes you feel better to imagine that you’re arguing with such cretins… perhaps it keeps you from dwelling on your complete lack of supporting evidence. From a scientific perspective, you’ve reached your conclusion arbitrarily. There’s no legitimate reason why anyone would take your hypothesis over Frank Sweet’s, and quite a few reasons why they wouldn’t. But even without evidence, you stick to it like glue.
I think it’s probable that the best explanation for the test-score gap is a combination of lesser parenting skills, lower teacher expectations, and “oppositional culture” peer pressure, as Frank Sweet proposes. Unlike the genetic explanation, these hypotheses actually fit all the facts. The fact that black and white 1st generation immigrant children have show no test-score gap makes it pretty unlikely that the explanation is genetic, and strongly points to the “nurture” side (which I’ll admit doesn’t actually count as positive evidence even for Sweet’s conclusion). On the other hand, the genetic explanation has no evidence in support, and the aforementioned lack-of-a-gap in 1st generation immigrant kids is a big strike against the genetic explanation.
So you’ve got no evidence for it, and it doesn’t even fit all the facts… well, at least you can still pretend you’re arguing with creationists.
I’ve been reading this thread avidly, and have never seen the slightest hint of any such stance.
Isn’t this pretty much the equivalent of Godwin’s law, in any biology thread?
Here’s the part of the argument I find pro-Creationist:
We are all more likely than not to have pretty much the same skillsets coded for by the same genes.
Such a position discounts the effects of evolution and migration over tens of thousands of years of separation.
At issue is this question:
Is it it more likely than not that evolution drives separated groups apart for all of the things for which their genes code?
The answer is, “Yes” and it is a pro-Creationist viewpoint that evolution is a minor effect, or only degrades. It is a pro-Creationist viewpoint that all humans are essentially the same gene pool, aside from the occasional degradation of the original DNA.
I acknowledge it’s better not to use labels. I am trying to point out a fallacy, not fling an epithet.
May I get some more clarity from you about just what it is I am wrong about?
I don’t argue that all populations are absolutely isolated, and that genes never flow between two populations. I don’t argue there was never any back migration of any post-africa genes into sub-saharan african populations.
What I argue is that sub-saharan populations represent gene pools containing prevalences that are markedly different from gene pools in other parts of the world, because of the historic separation.
It’s a pitiful clutching at straws to find exceptions to this broad rule and then pretend that, if we find exceptions, we’ve suddenly shown there are no real differences and separations, after all.
Here’s a fuller quote from the paper you find so persuasive:
“In sub-Saharan Africa, the recent spread of a set of haplotypes partially erased pre-existing diversity, but a high level of population (PhiST=0.332) and geographic (PhiCT=0.179) structuring persists. Correspondence analysis shows that three main clusters of populations can be identified: northern, eastern, and sub-Saharan Africans. Among the latter, the Khoisan, the Pygmies, and the northern Cameroonians are clearly distinct from a tight cluster formed by the Niger-Congo-speaking populations from western, central western, and southern Africa. Phylogeographic analyses suggest that a large component of the present Khoisan gene pool is eastern African in origin and that Asia was the source of a back migration to sub-Saharan Africa. Haplogroup IX Y chromosomes appear to have been involved in such a migration, the traces of which can now be observed mostly in northern Cameroon.”
Three main clusters. Partially erased (internal to sub-saharan) diversity with recent (internal) migration. Persistent structuring. Khoisans derived from eastern Africa. One back migration for one haplogroup marker for one of the Lemba clans.
If you think this data somehow creates a case for the homogenization of sub-saharan africa with the rest of the world…well; enjoy your delusion. A quick glance at the chart from your own cite might dissuade you from the idea that these populations are anything close to homogenized with the rest of the world. They aren’t even homogenized among themselves.
It’s all about broad, average separations and consequent broad, average gene prevalence differences. Isolated gene flow here and there is not evidence we are homogenized, and in particular, the flow of genesets from post-africa descendant lines back into most of sub-saharan africa has been limited. An example is the marked prevalence difference of haplogroup D MCPH1 variant in african and non-african populations.
You might find this article on the Khoisan an interesting example of how clustered human populations are.
“African neighbours divided by their genes:
Geographically close human populations in southern Africa have been genetically isolated for thousands of years.
By considering the similarities and differences among the SNPs in the various click-speaking peoples, and comparing them with patterns from other African populations, the teams were able to identify ancestral relationships. Both teams deduced that the southern African click-speaking populations (known generally as the Khoisan) actually belong to two genetically differentiated groups, one in the north and and one in the south of the Kalahari, which went their separate ways around 30,000 years ago. The discovery of this genetic divide is raising numerous questions about how it could have come about.”
I suspect the One Big Genetic Family approach is not going to be a fruitful avenue for you to pursue. But have at it.
Thank you for your explaination. It was my understanding according to archeologists that humans all had a common ancestor in Africa. according to the latest remains they have found.