Black Americans' Ancestors

[lpetrich]

DNA: Transforming African American Genealogy | Legacy Tree

Only about 65% of American black men's Y chromosomes are (recent) African. Many of the rest are European, and many are likely from (male) slaveowners. By Y-chromosome comparison, Thomas Jefferson has been successfully identified as the father of at least one of his slave Sally Hemings's sons (Thomas Jefferson's Y chromosome belongs to a rare European lineage. - PubMed - NCBI,  Jefferson–Hemings controversy).

Male slaveowners impregnating female slaves was something well-known, despite some slavery defenders' denials. At least one of those deniers, James Henry Hammond, a big defender of slavery, had done some of it himself. Not surprisingly, some abolitionists made a big issue about how, as one of them put it, the slave states were one big brothel.

Turning to mitochondria, most black Americans' mitochondria are African, and a few of them are Native American.

Autosomal chromosomes are those other than the sex-determining ones, the X and the Y. From autosomal DNA, American blacks have around 24% European ancestry and around 1% Native American ancestry.

So it is evident that most of the white contribution to American blacks' ancestry is male. Although slaveowners are an obvious and somewhat documented conrtibutor, a possible culprit in post-slavery years might be relationships between black women and white men being much more socially acceptable than between black men and white women. I don't know enough to say for sure, other than many black men having been lynched for being with white women. The first big film epic, "Birth of the Nation", depicted the Ku Klux Klan as protecting virtuous white women from lecherous black men.

The Genetic Ancestry of African Americans, Latinos, and European Americans across the United States: The American Journal of Human Genetics using data from 23andme.com. Has those and other results, like

We find that Latinos who, besides reporting as “Hispanic,” also self-report as Mexican or Central American, carry more Native American ancestry than Latinos overall; those also who self-report as black, Puerto Rican, or Dominican have higher levels of African ancestry; and those who additionally self-report as white, Cuban, or South American have on average higher levels of European ancestry.

They also have 13% less European ancestry in their X chromosomes than over their genomes in general, indicating that their white ancestors also tended to be male. That paper didn't mention Y-chromosome results, however.

 

[untermensche]

A system like slavery corrupts everything around it.

Systems of absolute power corrupt the humans with the power.

Huge pockets of poverty, inferior education, the lack of opportunity, the drug war and the for-profit prison system is the new slavery.

 

[Toni]

Happy New Year Let's Talk About Rape Because We Don't Do That Enough Around Here?

 

[untermensche]

The rape is long over.

What we have today are people with greater genetic diversity because of the rape.

Genetic diversity is good.

Inbreeding is bad.

 

[Politesse]

That's my family's history, straight up. Though, my grandsire tried to do his best by the resulting child at least, formally adopting him and sending him West with a bit of money during Reconstruction. Since the younger Beckwith had won the genetic dice roll, he was able to "pass" in Colorado, and our partially African heritage was a dark family secret known only to a handful of people, for more than a century.

 

[rousseau]

Happy New Year Let's Talk About Rape Because We Don't Do That Enough Around Here?

Not a knee-jerk thread about rape, it's (hopefully) about science.

Interesting thread actually, albeit depressing. I've sometimes wondered about the difference in tones you see between those of African ancestry in North America, vs Africa itself. In Africa many people are markedly darker, and where I live you don't often see people of that pitch.

Brazil is relevant here. Millions of slaves transported but throughout the late 19th / early 20th century there was a whitening of the population. Not just because of racism, but because even dark skinned people realized there was an economic advantage to having lighter skin. People tended to breed with others who were more white, and less so with people who were darker.

Now the result is the majority of the population isn't quite European white, but very close to.

 

[J842P]

We find that Latinos who, besides reporting as “Hispanic,” also self-report as Mexican or Central American, carry more Native American ancestry than Latinos overall; those also who self-report as black, Puerto Rican, or Dominican have higher levels of African ancestry; and those who additionally self-report as white, Cuban, or South American have on average higher levels of European ancestry.

That is definitely not surprising. Pretty much anyone from these areas could have probably told you this. One can see it.

But I thought that folk racial classifications are totally useless, indeed, they are racism, and have no external or internal validity.

 

[Bomb#20]

Brazil is relevant here. Millions of slaves transported but throughout the late 19th / early 20th century there was a whitening of the population. Not just because of racism, but because even dark skinned people realized there was an economic advantage to having lighter skin. People tended to breed with others who were more white, and less so with people who were darker.

That doesn't work out mathematically. For every person who bred with someone more white, there was a person who bred with someone darker.

According to what I've read, the reason the population in Brazil is so white is because of the millions of slaves transported -- Brazil is close enough to Africa that it was cheaper to work them to death and kidnap new ones than to keep them alive and healthy enough to breed. As untermensche said, systems of absolute power corrupt the humans with the power.

 

[J842P]

Brazil is relevant here. Millions of slaves transported but throughout the late 19th / early 20th century there was a whitening of the population. Not just because of racism, but because even dark skinned people realized there was an economic advantage to having lighter skin. People tended to breed with others who were more white, and less so with people who were darker.

That doesn't work out mathematically. For every person who bred with someone more white, there was a person who bred with someone darker.

According to what I've read, the reason the population in Brazil is so white is because of the millions of slaves transported -- Brazil is close enough to Africa that it was cheaper to work them to death and kidnap new ones than to keep them alive and healthy enough to breed. As untermensche said, systems of absolute power corrupt the humans with the power.

You are assuming Hardy Weinberg equilibrium, e.g. non-assortative mating (highly doubtful), and no differences in fitness (again, highly doubtful when being black had such extreme social consequences).

 

[rousseau]

Brazil is relevant here. Millions of slaves transported but throughout the late 19th / early 20th century there was a whitening of the population. Not just because of racism, but because even dark skinned people realized there was an economic advantage to having lighter skin. People tended to breed with others who were more white, and less so with people who were darker.

That doesn't work out mathematically. For every person who bred with someone more white, there was a person who bred with someone darker.

According to what I've read, the reason the population in Brazil is so white is because of the millions of slaves transported -- Brazil is close enough to Africa that it was cheaper to work them to death and kidnap new ones than to keep them alive and healthy enough to breed. As untermensche said, systems of absolute power corrupt the humans with the power.

I'm talking about a time period after slavery was abolished in Brazil.

 

[Bomb#20]

Brazil is relevant here. Millions of slaves transported but throughout the late 19th / early 20th century there was a whitening of the population. Not just because of racism, but because even dark skinned people realized there was an economic advantage to having lighter skin. People tended to breed with others who were more white, and less so with people who were darker.

That doesn't work out mathematically. For every person who bred with someone more white, there was a person who bred with someone darker.
...

You are assuming Hardy Weinberg equilibrium, e.g. non-assortative mating

Show your work.

Granting that mating was assortative and the population did not achieve Hardy Weinberg equilibrium, how do you figure it is physiologically possible for people to have tended to breed with others who were more white, and less so with people who were darker? What, was the darker member of an act of copulation breeding while the lighter member of that same act was remaining childless?

(highly doubtful), and no differences in fitness (again, highly doubtful when being black had such extreme social consequences).

It's certainly likely that being black reduced one's odds of reproducing, but that doesn't change the fact that an interracial coupling doesn't change the ratio of black to white alleles in the gene pool.

I'm talking about a time period after slavery was abolished in Brazil.

The whitening in that period might have something to do with the massive immigration from Europe.

 

[rousseau]

You are assuming Hardy Weinberg equilibrium, e.g. non-assortative mating

Show your work.

Granting that mating was assortative and the population did not achieve Hardy Weinberg equilibrium, how do you figure it is physiologically possible for people to have tended to breed with others who were more white, and less so with people who were darker? What, was the darker member of an act of copulation breeding while the lighter member of that same act was remaining childless?

(highly doubtful), and no differences in fitness (again, highly doubtful when being black had such extreme social consequences).

It's certainly likely that being black reduced one's odds of reproducing, but that doesn't change the fact that an interracial coupling doesn't change the ratio of black to white alleles in the gene pool.

I'm talking about a time period after slavery was abolished in Brazil.

The whitening in that period might have something to do with the massive immigration from Europe.

Possible. I'm going by a History of Brazil I read a few weeks ago, but don't recall them accounting for European immigration.

I definitely wouldn't be surprised if colour of skin was selective in a situation like that, though.

 

[J842P]

You are assuming Hardy Weinberg equilibrium, e.g. non-assortative mating

Show your work.

Granting that mating was assortative and the population did not achieve Hardy Weinberg equilibrium, how do you figure it is physiologically possible for people to have tended to breed with others who were more white, and less so with people who were darker? What, was the darker member of an act of copulation breeding while the lighter member of that same act was remaining childless?

(highly doubtful), and no differences in fitness (again, highly doubtful when being black had such extreme social consequences).

It's certainly likely that being black reduced one's odds of reproducing, but that doesn't change the fact that an interracial coupling doesn't change the ratio of black to white alleles in the gene pool.

I think I don't understand what you are saying, because it sounds to me like you are saying that it is impossible for darker or lighter skin to evolve in a population over time, whether it be by natural or sexual selection.

Anyway, it isn't a single act of a darker skin person mating with a lighter skin person that changes the allele frequencies in the population (it may or may not, but this would fall under the category of genetic drift, since the children's actual inheritance of lighter or darker skin isn't going to be 50-50, although it may on average be so). It is the tendency for lighter skinned people to be preferred as mating partners by the breeding population generally, or the tendency of the children of lighter skinned people to survive to adulthood and reproduce.

I don't think we are actually disagreeing, I'm probably just not understanding exactly what you are objecting to.

 

[ruby sparks]

Anyway, it isn't a single act of a darker skin person mating with a lighter skin person that changes the allele frequencies in the population (it may or may not, but this would fall under the category of genetic drift, since the children's actual inheritance of lighter or darker skin isn't going to be 50-50, although it may on average be so). It is the tendency for lighter skinned people to be preferred as mating partners by the breeding population generally, or the tendency of the children of lighter skinned people to survive to adulthood and reproduce.

I read in the abstract of one study that available evidence suggests that in each society a lighter-than-average skin colour is preferred in a sexual partner.

 

[Toni]

The rape is long over.

Is it?

What we have today are people with greater genetic diversity because of the rape.

Because people just 'naturally' prefer to reproduce with lighter skinned people? Which explains white men raping black women...how, exactly?

Genetic diversity is good.

Inbreeding is bad.

Indeed. At least we can revel in the sound knowledge that genetic exchange between groups never happens unless rape is involved and that therefore rape is a good thing.

 

[untermensche]

Is it?

The legal rape is long over.

Crime is not over.

Because people just 'naturally' prefer to reproduce with lighter skinned people? Which explains white men raping black women...how, exactly?

The genetic diversity is more about protection from disease and recessive defects.

Nobody wants to be raped. But nobody living today is legally raping anyone.

The diversity would occur without the rape. The rape is not necessary. But the rape is long over.

At least we can revel in the sound knowledge that genetic exchange between groups never happens unless rape is involved and that therefore rape is a good thing.

Doesn't follow from anything I'm saying.

I'm talking about what did happen, not what should have happened.

What should have happened though leaves Africans in Africa and the millions of descendants of slaves living in the US never exist.

 

[Politesse]

The legal rape is long over.

Crime is not over.



The genetic diversity is more about protection from disease and recessive defects.

Nobody wants to be raped. But nobody living today is legally raping anyone.

The diversity would occur without the rape. The rape is not necessary. But the rape is long over.

At least we can revel in the sound knowledge that genetic exchange between groups never happens unless rape is involved and that therefore rape is a good thing.

Doesn't follow from anything I'm saying.

I'm talking about what did happen, not what should have happened.

What should have happened though leaves Africans in Africa and the millions of descendants of slaves living in the US never exist.

Rape most certainly does still happen, indeed it's rate is currently on the increase. It is considerably more likely that a socially disadvantaged person will be the victim of rape. Race is a common factor, there are others such as wealth, age, and sexual/gender identity. Rape is an act of violence, not attraction.

"What should have happened" is up for debate, but you would have to change a lot more things than the Transatlantic slave trade to substantially reduce genetic diversity in the Americas, already interestingly complicated by other political traumas and economic migrations.

 

[J842P]

The legal rape is long over.

Crime is not over.



The genetic diversity is more about protection from disease and recessive defects.

Nobody wants to be raped. But nobody living today is legally raping anyone.

The diversity would occur without the rape. The rape is not necessary. But the rape is long over.

At least we can revel in the sound knowledge that genetic exchange between groups never happens unless rape is involved and that therefore rape is a good thing.

Doesn't follow from anything I'm saying.

I'm talking about what did happen, not what should have happened.

What should have happened though leaves Africans in Africa and the millions of descendants of slaves living in the US never exist.

Rape most certainly does still happen, indeed it's rate is currently on the increase. It is considerably more likely that a socially disadvantaged person will be the victim of rape. Race is a common factor, there are others such as wealth, age, and sexual/gender identity. Rape is an act of violence, not attraction.

"What should have happened" is up for debate, but you would have to change a lot more things than the Transatlantic slave trade to substantially reduce genetic diversity in the Americas, already interestingly complicated by other political traumas and economic migrations.

He is talking specifically about the rapes of slaves by slave owners. That happened in the past.

Why is it so difficult to understand such a straight-forward statement?

 

[Politesse]

Rape most certainly does still happen, indeed it's rate is currently on the increase. It is considerably more likely that a socially disadvantaged person will be the victim of rape. Race is a common factor, there are others such as wealth, age, and sexual/gender identity. Rape is an act of violence, not attraction.

"What should have happened" is up for debate, but you would have to change a lot more things than the Transatlantic slave trade to substantially reduce genetic diversity in the Americas, already interestingly complicated by other political traumas and economic migrations.

He is talking specifically about the rapes of slaves by slave owners. That happened in the past.

Why is it so difficult to understand such a straight-forward statement?

You may be, but he is not, if by "he" you mean lpetrich. The original post cites this as a possible reason for the correlation, but does not stop there, nor should we. Racial violence and coercion is not and has never been strictly bounded by the current legal status of slavery. Indeed, I doubt very much that a black woman in 1890 felt at all more free to prevent or report a rape by a white man than her counterpart in 1820 would have; either way, the crime would be almost certainly impossible for her to prevent or gain legal redress for. We gain nothing by trying to whitewash the cruelties of our national history, or paint triumphal narratives of wholesale moral victories over realities that were much more grim for those actually involved with them.

 

[Toni]

The legal rape is long over.

Crime is not over.



The genetic diversity is more about protection from disease and recessive defects.

Nobody wants to be raped. But nobody living today is legally raping anyone.

The diversity would occur without the rape. The rape is not necessary. But the rape is long over.

At least we can revel in the sound knowledge that genetic exchange between groups never happens unless rape is involved and that therefore rape is a good thing.

Doesn't follow from anything I'm saying.

I'm talking about what did happen, not what should have happened.

What should have happened though leaves Africans in Africa and the millions of descendants of slaves living in the US never exist.

You make many assumptions, including that the presence of genetic markers identified as ‘european’ could only have found their way to to the genome of African Americans through the rape of African slaves and their decendants through the rape of slave women by white men of European descent. This fails to take into consideration any intermarriage between Africans and Europeans prior to the institution of slavery in what became the US, the mutual and consensual relationships between black and white Americans post slavery and whether these markers are really unique only to defined geographic areas.

Further, your postulation that these rapes increased ‘genetic diversity’—presumably only for African Americans as you seem to ignore that any whites women might have had children by black men, is based upon the assumption that there is significant genetic differences between European and African populations compared with variations between individuals within African populations and within European populations. You seem to ignore millennia of human migration and cultural exchange along with the inevitable exchange of genes. Frankly it sounds as though you are making the argument that white slave owners raping their black slaves improved the stock by increasing their genetic diversity.

All in all I find your line of thinking flawed and disgusting.