Race is non-existent

Great Debates
301

It’s not “pro-creationist” in the least; you just attach it to make a convenient (yet ridiculous) slur. Considering how closely related all humans are, genetically speaking (compared to other animals like chimpanzees), it’s not unreasonable at all to suppose that the genetic differences between different populations are mostly superficial, until there’s actual contrary evidence. Considering the huge number of human genetic characteristics that definitely don’t differ between populations, why are we supposed to assume that intelligence does? Apparently you don’t even need test-score data to know that human populations have different genes for intelligence- you just use the test scores to sort them. How ridiculous.

No it doesn’t.

So it’s your position that for every human genetic characteristic, every human population has significant genetic differences?

I don’t hold either of those positions, though the second one depends on one’s definition of the word “essentially”. There is certainly more genetic diversity within a population’s gene pool then there is between two different populations.

No, you’re definitely trying to find a convenient, pithy label. It’s comical considering you’re supporting a hypothesis with no evidence.

302

[QUOTE=CP]
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?
[/QUOTE]

http://boards.straightdope.com/sdmb/showpost.php?p=15893367&postcount=294

303

That’s exactly right, and a much better way to put it, although it’s not just the fossil record; it’s also the genetic record.
There are a couple of residual fine points:

  1. Was the source of the first anatomically modern humans (somewhere around 200K years ago) east africa or southern africa? Right now the typical party line is “east africa” but some argue that southern africa can have a case made for it.
  2. Was there introgression of Neandertal and/or Denisovian genes into the Eurasian descendant lines post africa? This would suggest interbreeding with archaic homo species who had already left africa before anatomically modern humans arose there. If it turns out there was such introgression, it would then be inaccurate to say those populations (the ones with Neandertal and Denisovian genes) “had a common anatomically modern homo sapiens ancestor in africa.” They would still have a common african ancestor, but the presence of post-african introgression of archaic humans would push that common ancestor back much further in time.
304

Every human alive has a common ancestor, and the most recent common ancestor was (probably) in Africa, and would (probably) pre-date the departure of our species from Africa. Whether or not there was later admixture by archaic species such as Neanderthal and the Denisovans (and there probably was) this does not change at all the most recent common ancestor of all humans. You’re incorrect that this pushes the common ancestor further back in time.

305

No.

If you just want a Most Common Recent Ancestor, meaning a great grandpa-type ancestor from a family lineage perspective, some mathematical models have such MRCA back only a few thousand years. But one should be careful not to confuse that to mean that genetic makeup from that kind of MRCA is present in any sort of homogenized distribution all over the world. In fact, that sort of MRCA may have no genetic contribution at all to a given individual, and the geneflow from such a MRCA has markedly different proportions by populations.

If you are talking about a “common ancestor” for our entire gene pool, Neandertal or Denisovian introgression pushes the time back to an ancestor which predates the splits into those groups. Anatomic humans arose about 200K years ago in africa, and every human on earth owes their entire genetic makeup to descendant genes from that population, unless there was recent introgression of genes from populations more archaic than anatomically modern homo sapiens.

Now suppose that the Neandertal introgression is correct, and that Neandertal populations were in turn descended from archaic humans that predate anatomically modern homo sapiens. Suppose that those archaic homo groups left africa 500,000 years ago. If introgression of those genes occurred, you have to go back at least 500,000 years to find the common ancestor for our entire gene pool.

The estimate for how far back you need to go for a common ancestor to homo sapiens, Neandertals and Denisovians is about a million years, I believe.
The results suggest the (Denisovian) hominin diverged from a common ancestor well before Neanderthals and modern humans did – about one million years ago."

306

You are wrong. The answer is yes. I am talking about Most Recent Common Ancestor (as should have been very clear by the words I used). You are talking about something else.

And to reiterate, there is no evidence for the genetic explanation for the test-score gap, and it doesn’t even fit all the facts. Frank Sweet’s hypotheses, at least, fit the facts.

307

Originally Posted by CP
*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?*

Thank you for this study showing at least some of the 70,000 (relatively distinct) Lembas may represent an asian migration back into southern africa. They are a good example of how gene pools tend to remain isolated (in this case, for religious and cultural reasons), aren’t they?

What I’m really looking for is reasearch showing a deeper penetration of non-african gene flow into the great majority of sub-saharan african lines.

But thanks for trying.

308

The first group of anatomically modern homo sapiens to permanently leave africa left africa around 75,000 years ago. Can we agree on that (60-80K years ago, anyway)?
Archaic homos from which Neandertals and Denisovians descended left africa substantially earlier–100s of thousands of years earlier. Can we agree on that?
Before leaving africa, anatomically modern humans had already split into several lines, perhaps beginning about 150K years ago. Can we agree on that?

I want to know if you are talking about the concept of Most Recent Common Ancestor in a family lineage sense, in which case gene pools and prevalences are quite irrelevant, or if you are talking about common ancestor in the sense of the common ancestor from which all modern humans derive all of their genes.

Mathematical modeling (by Rohde, for example) suggests a MRCA of a few thousand years ago; probably somewhere in asia. This is a mathematically-based speculation–I have cited the paper upthread, as I recall–that has almost nothing whatsoever to do with genes; the genetic contribution of such an ancestor to some populations would be something between trivial and zero.

If we are talking about gene pools, common ancestors are those from whom all our present genes derive (again, if we were to unwind the mutations).

In this latter sense, the common ancestor to all modern humans is from africa (east or south) on the order of 150-200K years ago. If Neandertal and/or Denisovian introgression is correct (as you agree it is), the common ancestor to all humans is between 500K and 1M years ago.

The reason you don’t want to confuse the two types of ancestors is that a common impression taken from the MRCA concept is, “Oh; apparently we’re all pretty closely related since it’s only been a few thousand years since we had a grandpappy in common.” That’s a completely incorrect impression. In fact, a “common” grandpappy ends up having almost nothing at all do do with gene prevalence differences among populations.

From Rohde’s paper on (mathematically modeled) MRCA (“On the Common Ancestors of All Living Humans”):
“In fact, an individual’s DNA may retain none of the genes specic to a particular ancestor who lived many generations in the past…
The ancestry of a central African is shown in Figure 15…
The African sim has almost entirely African ancestry, with 0.00092% Eurasian ancestry, primarily from the border countries. Due to the greater isolation of Africa, this sim has much less Indonesian, Australian, and American ancestry than did the Eurasians.
The total South American ancestry, for example, amounts to just 1 part in 1.4 trillion.”

309

Yes, and I have not been confused in this entire discussion. I don’t know why this is so confusing to you- I have been using very simple words and phrases. The Most Recent Common Ancestor of all humans alive, at earliest, lived in Africa around the time of the first departure of homo sapiens out of Africa (or, as some modeling suggests, possibly a lot later).

And to reiterate, there is no evidence for the genetic explanation for the test-score gap, and it doesn’t even fit all the facts. Frank Sweet’s hypotheses, at least, fit the facts.

310

But not the common ancestor for all of our gene pool. As it’s typically used, MRCA says almost nothing about the genetics of any descendant population.

If introgression for Denisovian genes is a correct hypothesis, we have to go back between 500K and 1M years to find a common ancestor from whom a human with Denisovian genes got his gene pool. He might be able to find a geneological tree which takes him to a more recent common ancestor for some (or maybe even, none) of his genes that he shares with other humans, but that sort of “MRCA” simply means that that individual is in his geneological tree. It doesn’t mean that individual is the common ancestor for his entire gene pool.

And so when we are comparing populations, the important thing to understand is that MRCA is irrelevant. When monavis says, “we all had a common ancestor in africa” it’s important to distinguish the two concepts. If monavis means, “a geneological ancestor,” that common ancestor is more likely a eurasian, and possibly reasonably recent (but genetically irrelevant). If monavis means “the common ancestor from which all modern humans derive all their genes”–i.e. the evolutionary branching point for the gene pool of modern humans, then Denisovian and Neandertal introgression pushes the point back to 500K-1M years.

That’s why the article I gave you just upthread says, “The results suggest the (Denisovian) hominin diverged from a common ancestor well before Neanderthals and modern humans did – about one million years ago.”

My intention is to make sure Monavis’ question gets answered clearly, and the intent of it is not lost in misleading terminology that makes it sound like it’s been orders of magnitude less time than is correct before we get back to the source of our gene pools. The whole point of this thread (I think) is to understand how the separation of those gene pools affects our groupings.

311

That individual is, however, the most recent common ancestor for the vast majority of the human gene pool.

312

I recommend further reading on the concept of “Most Recent Common Ancestor.”

The MRCA for “the vast majority of the human gene pool” would have lived at the onset of anatomically modern homo sapiens, about 200K years ago. The humans now populating the non-african world left africa about 70K years ago. You use the phrase “or, as some modeling suggests, possibly a lot later.” If you are using that to refer to mathematically-modeled MRCAs, then that kind of MRCA contributes almost nothing to the gene pool for whole populations (africans, for instance).

An “MRCA” used nonspecifically is an ancestor from who everyone is considered to be descended in the sense that such an MRCA is somewhere in their ancestral pool. It’s not the person they got their gene pool from, and in fact that kind of MRCA may not contribute any genes at all to a given descendant.

Nor does such an MRCA have anything to do with how closely various descendant groups may be related to one another. It’s really just a way of saying “Joe Schmoe is my 200th-great grandpa in my family tree.” As it turns out, you may have inherited none of your genes from Joe. You are just too far removed. I gave you an example upthread from Rohde’s paper (which uses mathematical algorithms to arrive at a MRCA date of perhaps 5-15K years), and goes on to say that an african in such a model would have with 0.00092% Eurasian ancestry and share just 1 in 1.4 trillion parts with a south american.

I think the concept you are wrapping up into a nonspecific “MRCA” is the concept of a common ancestor for a specific gene, or set of genes, or even “the vast majority” of human genes. A MRCA for any specific part of our genes goes back much further in time than the unspecified geneological MRCA, and by definition is a common ancestor for whichever part of the genome you are specifying it to be the MRCA for. Getting to the MRCA for the the “vast majority” of our genes requires going back further still.

If we want to look at specific parts of our genetic makeup, we sometimes talk about a mitochondrial eve or a Y chromosomal adam. Mathematical modeling using the average rate of random DNA mutations lets us project backward in time. Mitochondrial DNA is easier to play with, since it’s 16K base pairs against tens of millions of base pairs for the Y chromosome. Dates for a mtDNA eve (the most recent common matrilineal ancestor for all present humans) are in the range of 150K years. You have to go back far enough to pick up the intra-africa splits before you get to the L3 mtDNA line which spawned the N and M mtDNA lines that populated the rest of the world. Time to the MRCA for L3 is around 70K years, but of course that’s not the MRCA for all the mtDNA lines, since L0, L1 and L2 had already split off. (That mtDNA MRCA is sometimes called “out of africa Eve.” )

If we want the MRCA for the entire anatomically modern homo sapiens genome (i.e. “the vast majority of the human gene pool”), we have to go back at least 200K years. As I said to monavis, we did not all come out of africa, so to get to the MRCA for everyone’s genes, we have to go back further before the intra-african lines split. If we want the MRCA for the genome that includes Neandertal and Denisovian genes, we push the clock back closer to 1M years.

313

Ok. There remains zero evidence for your genetic explanation, and it doesn’t even fit all the facts. Frank Sweet’s hypotheses, at least, fit all the facts.

314

Frank Sweet offers the following three hypotheses for a black-white gap:
Little black kids have (relatively) incompetent parenting. This explains an early-age gap.
Black kids from ages 6-18 have low teacher expectation.
Black kids from 11-18 suffer from oppositional culture influences.

Mr Sweet discards the following as completely wrong explanations, devoid of evidence:
The gap is not real, and it is narrowing.
Test score (including IQ scores) gaps exist because test are culturally biased.
Ignorance, disparate wealth and disparate education contribute to the gap.
Public schooling differences contribute significantly to the gap.
Adolescent peer pressure explains the gap.

Mr Sweet asserts that, “The gap is not “racially” genetic, not even a little.” He bases this assertion on a number of limited and uncited studies, including immigrant “sub-saharan” and British West Indies grade-school children scores compared with whites. He is very skeptical ([http://thestudyofracialism.org/index.php]see this discussion board) that “Blacks are genetically different from Whites in a sense deeper than superficial appearance.” It appears with respect to this last quote that his fundamental position is that races cannot be “genetically defined” and therefore any categorization made according to race does not have a potentially biological basis. He adds this: “Millions of ethnically Black Americans lack sub-Saharan genetic markers.”

OK…

I am uninterested in any debate that starts by arguing what “race” is. It is self-evident to me that if you want to look for the possibility that black-white difference might be based in difference for gene prevalences, you have only to point to the history of the human race. If Self-Identified “blacks” are more likely to have a larger percentage of their gene pool derived from L haplogroups, and self-identified whites are more likely to have a larger percentage of their gene pool derived from N,M or later haplogroups, you are done with that part of the argument. Two different gene pools for average prevalences; 40K years or so of relative separation. This does not make a prima facie case for genetically-driven outcomes, but it does create a reasonable scenario for them consistent with evolution and migratory patterns. And there is incontrovertible evidence that those gene pools do differ for gene prevalences (again; haplogroup D MCPH1, e.g.). Yes, there is admixture. No, it is not nearly homogenized. Yes, black-white self-assignment largely correlates with L versus non-L haplogroups.

Obviously, I’m pleased with the tired explanations Mr Sweet discards, and I commend you for discarding them with him. It is so tedious to repeat over and over again that SES is not an explanation for race-based outcome differences.

I find the explanations Mr Sweet does grasp at to be wanting. The idea that a whole group of people cannot count backward as well as a different group because they have incompetent parents or live with oppositional cultural influences strikes me as lame. I am underwhelmed about the difference between adolescent peer pressure (not an explanation) and oppositional culture. I am skeptical that oppositional culture is not overcome by wealth and status, nor all-black learning environments. Beyond that I am suspicious of the need for one explanation for little kids, and a second for high-schoolers. Does Mr Sweet want to advance a third explanation for college students and a fourth for adults in the working world? Which explanation of his fits the nearly universal working-world differences so neatly illustrated in Ricci v DeStefano, where two adult groups with identical exams covering a known body of material have such disparate outcomes? That scenario is repeated thousands of times over–I am tempted to say universally–in employers across the nation and the world. And always, the same general rank order: you will not see asians dragging up the rear.

Finally, where does Mr Sweet’s explanation fit sprinting and basketball examples?

He, like you, knows one thing: It ain’t the genes.

315

I don’t care if it strikes you as lame. You’ve shown a remarkably poor understanding of how science works in a broad sense.

Mr. Sweet was attempting to find explanations that, unlike your genetic explanation, actually fit the data. It’s funny how you so gleefully lunge for anything Sweet says that fits your narrative, but the second he diverges, suddenly it’s “lame” and your “skeptical”.

Wow, this ridiculous anecdotal crap is just so weak. Your explanation has no evidence, and it doesn’t even fit the facts. Statistical differences by themselves provide zero evidence for causation- and all you have is a statistical correlation. You have no genetic evidence. Science is hard.

316

Well yes, that is already something that is occuring in terms of height. And as Hsu notes other complex heritable traits could also be found in the next 5-10 years.

317

This is a fact. Why embarrass yourself be refusing to recognize it?

318

Thanks for pointing this out.
I’d actually like to understand it better. Out of 40 million blacks, is it 3 million? 30 million who have no sub-saharan markers?

Is it the case that these millions of ethnically black americans have no sub-saharan ancestry, or is this simply one of those sneaky little ways to word things–in this case to imply that these ethnically black americans aren’t african at all?

Suppose, for example, that one cites a study where the the “sub-saharan markers” in question did not represent a broad enough cross section of africans…this statement would leave the impression that millions of ethnically black americans are actually scandinavian, or asian, or something.

Which is it?

Is it your contention that “millions of ethnically black americans” do not have substantial sub-saharan ancestry? If so, would you mind giving me an idea where you think the rest of their genome came from, and a cite to review?

Let me give you an example. In 2009, Tishkoff and Bustamante did a study looking at the content of West African genes in US African-Americans and Europeans.

Science Daily carried the prepublication snippet. Notice their wording in the story:
“People who identify as African-American may be as little as 1 percent West African or as much as 99 percent – just one finding of a large-scale, genome-wide study of African and African-American ancestry.”

If you look into the actual article, here’s what you read:
"Among African Americans, analysis of genomic admixture by a principal component-based approach indicates that the median proportion of European ancestry is 18.5% (25th–75th percentiles: 11.6–27.7%), with very large variation among individuals…estimated mean West African ancestry was 77%, consistent with prior studies…it is important to note that other African populations not sampled, including those from Sierra Leone, Senegal, Guinea Bissau, and Angola, may also serve as good (or potentially even better) proxies for the ancestral population of some African Americans "

This is a pretty common admixture estimate; about 20% of the genome of US self-identified blacks is european, and the actual percentage varies. I can’t find where it suggests there are millions of blacks with no sub-saharan markers at all. Obviously, that wouldn’t change the overall percent of genome coming from africa, but I’d still like to understand what is actually supported.

Here is a second paper, also by Tishkoff, on “The Genetic Structure and History of Africans and African Americans.” I am unable to figure out where it says “millions of ethnically black americans lack sub-saharan markers,” although I may have missed that data point.

So I just want a cite for Mr Sweet’s statement (and your confirmation) that "millions of ethnically Black Americans lack sub-Saharan genetic markers). It wouldn’t change the rough percentage (20%) of the average genome that’s European, but I would still find it interesting data, so I’d like to see it.

319

I am sorry science is hard for you. But I think it is fairly easy to wrap your head around some reasonably simple science and statistics here regarding the black-white gap:

  1. Statistically, about 80% of the overall geneset for black americans derives from sub-saharan gene pools based on typically-used ancestral population markers.
  2. Statistically, well over 80% of the overall geneset for white americans derives from european gene pools based on typically-used ancestral population markers.
  3. On average, the performance gap between blacks and whites and asians in the US is constant and persistent; unrelated to SES status or parental education.
  4. The handful of claims Mr Sweet offers against a biologically-based explanation use immigrant populations. Such a population can hardly be expected to be a statistically random sampling of a source population. Mr Sweet did not offer his cites, so I can’t tell if these are newspaper articles about British school grades, or if these are formal studies. I cannot tell, for example, if he’s comparing the best subset a source population has to offer (those who are accomplished enough to get to the front of the emigration line) against the weakest subset a comparison population has to offer (those in school districts where immigrants typically settle).
  5. I find the idea that educated and wealthy blacks are incompetent parents to be a lame idea. In my (relatively educated) circles, it’s been my observation that well educated black parents are indistinguishable from the rest of us.
  6. I find the idea that an “oppositional culture” is a good explanation for crapping out in teenage years to be a lame one. It essentially argues that black children from wealthy and educated families perform poorly because their non-conformist teenagers have a special degree of non-conforming related to stereotypical expectations of underperformance. On his YouTube video, Mr Sweet uses an IQ example of counting backward. So you can’t count backward well because you are feeling an oppositional culture? (!) Mr Sweet himself argues that “peer pressure to not act white” is an inadequate explanation. This is a pretty thin distinction to draw from “oppostional culture.” Moreover, worse black scores are seen in HBCUs compared with black scores from more prestigious colleges. Does Mr Sweet hold that oppositional culture is somehow worse at an HBCU? Wouldn’t the simpler explanation be that HBCUs get lesser-abled students? As it turns out, Mr Sweet does think the skillset for academic achievement is hereditary:
  7. “This is not to say that the ability to get high scores is not hereditary. It is. Dumb parents have dumb kids and viceversa.” Mr Sweet’s entire anti-genetic argument rests on a conviction that you cannot “define” race genetically. As we have seen in this thread, this may be technically correct. But there is a marked correlation between SIRE group and ancestral population, and a marked separation of those ancestral populations over tens of thousands of years. There are strong examples of disparate gene prevalences. The fact that the term “race” is a nearly useless term is not evidence that SIRE groups have no biological correlation with historically separated ancestral populations.

Your persistent charge that “how science works” is beyond my grasp is not as persuasive as presenting a specific counter argument based on your own science citations.

320

Though it’s changed significantly over time. There is no reason to believe that the gap will be the same in 50 years.

He also offers the fact that while the gap correlates with self-identification, it does not correlate with actual sub-Saharan African genetic markers. That’s a big piece of data that your explanation doesn’t fit.

And I find the idea that educated and wealthy blacks have inferior genes for intelligence to be a lame (and evidence-free) idea.

LOL. I don’t care if you find it lame or not. I’m not trying to change your mind- I’m just demonstrating the incredible weakness of your arguments for all to see. You’ve argued essentially that different populations (that have been mostly separated for long periods) must necessarily differ in quantity and quality of genes for intelligence (though there’s no evidence for this, of course), and you just use the test-score gap to sort them into the smart and dumb races (or populations). It’s just sad and ridiculous that you’ve convinced yourself that this must be so.

No it doesn’t.

And self-identification correlates far more with the actual test-scores then genetics does. You have no evidence, and can do nothing but pick away ineffectually at “competing” arguments. Your extreme confidence in a hypothesis with no evidence that doesn’t even fit all the facts does not speak well of your capacity for objective analysis.