Ancestry in the Americas

By Razib Khan | January 10, 2011 2:19 am

ResearchBlogging.orgThe populations of the African Diaspora have a particular interest in the new genomics, and its relationship to ancestry. Unlike other post-Columbian Diasporas they have sketchy, at best, knowledge of the regions from which their ancestors arrived. This probably explains the popularity of Roots and Henry Louis Gates Jr.’s various genealogical projects which have utilized cutting edge genomics. It may seem silly to hang one’s hat on one maternal lineage, but perhaps it seems silly if you are relatively assured of the broad outlines of your own genealogy. The fact that I am U2b is not very interesting to me, but I also happen to know that my maternal grandmother’s mother’s family were long resident in their region of Bengal (and, that her father was a migrant from northwest India). It would be a different matter if my ancestors had been enslaved and dispossessed of their heritage.

A new paper in PLoS ONE surveys the paternal (NYR), maternal (mtDNA), and autsomal (using 175 ancestrally informative markers), heritage of a range of African origin populations from across the Americans. Dissecting the Within-Africa Ancestry of Populations of African Descent in the Americas:

Our analysis revealed that both continental admixture and within-Africa admixture may be critical to achieving an adequate understanding of the ancestry of African-descended Americans. Whilecontinental ancestry reflects gender-specific admixture processes influenced by different socio-historical practices in the Americas, the within-Africa maternal ancestry reflects the diverse colonial histories of the slave trade. We have confirmed that there is a genetic thread connecting Africa and the Americas, where each colonial system supplied their colonies in the Americas with slaves from African colonies they controlled or that were available for them at the time. This historical connection is reflected in different relative contributions from populations of W/WC/SW/SE Africa to geographically distinct Africa-derived populations of the Americas, adding to the complexity of genomic ancestry in groups ostensibly united by the same demographic label.

There isn’t anything too surprising here. Blacks from Brazil have much more ancestry from the former Portuguese colonies of Angola and Mozambique. As we should expect. Because the New World African Diaspora dates to only the past 350-150 years even mtDNA should be a good snapshot of the genetic variation. And, because of the ability to construct clean genealogies due to lack of recombination, mtDNA can be even more informative than total genome surveys in terms of elucidating fine-grained geographical patterns. The map below illustrates the mtDNA results well:


But I was more interested in some patterns comparing the various African and European identified populations. In the figure which I stitched together below you have maternal ancestry on the left, paternal in the middle, and total genome ancestry to the right. The first panel has self-identified blacks from various nations, and the second has self-identified whites from Brazil and Philadelphia, USA. These results need to be taken with a grain of salt, because the samples from each nation need not necessarily be representative of the ethnicity for that whole nation (e.g., blacks in coastal Georgia have far less white ancestry than those in urban northern cities). But they give a rough picture of the differences and similarities.

Here the numbers with margins of error as well:


Self-identified black Self-identified white
African error European error Native error African error European error Native error
Brazil mtDNA 85 3 1 1 14 3 31 6 38 5 31 5

NRY 51 4 47 4 2 2 0 1 97 2 2 2

AIMs 58 30 12 20 64 17
USA mtDNA 93 1 5 1 2 1 6 5 92 7 2 1

NRY 77 2 25 2 0 0 2 1 97 2 1 1

AIMs 83 1.6 15 2 2 1 2 2 95 3 3 3

Similarities: a strong bias toward more male European ancestors, and more female African and Native ancestresses. This is what you’d expect. But look at the Brazil black sample. The disjunction between nearly total lack of female European ancestry and a substantial proportion of male European ancestry is rather striking. I think this is partly a function of the strong male bias of the Portuguese settler community. A process of “whitening” of the original mulatto and mestizo population of the colony probably occurred with each successive generation of male immigrants, who married into the hybrid communities and shifted the total genome content, though not the maternal background. The biggest difference of course is the much more clear and distinct difference between the races in the USA as opposed to Brazil. A minority of Brazilians identify as black, while a plural majority identify as white (the remainder are “brown” or mixed-race). And yet Brazilian blacks are ancestrally much whiter than American blacks, while Brazil whites are ancestrally much less white than American whites. Additionally, while Brazil perceives itself as a mulatto nation, there is a substantial Amerindian substrate which spans the black, white, and brown, populations.

Finally, going back to the main theme of the paper, African population structure, one of the main rationales is for purposes of medical research where stratification of ancestry within an aggregate pool may lead to spurious associations. In other words, mixing blacks with ancestry from Angola with those from ancestry from Nigeria may result in false positives in GWAS due to differences in predispositions of traits between these populations, which also track their genetic differences. The authors bring up the fact that African populations are the most genetically diverse in the world. But let me resurrect a comment from geneticist Nick Patterson:

I want to comment on Africa’s genetic diversity. There is a great deal of genetic diversity within many African populations. For instance more diversity within Yoruba than within Europe. But many African populations are quite similar. For instance divergence between Kikuyu (Kenya) and Yoruba (Nigeria) is just a little more than (Spain, Holland). This is of course caused by the Bantu expansion as Razib explained.

In other words, the great African genetic diversity is more a function of the intra-population variance, than inter-population variance. This sort of work is important for reasons of intellectual interest, but may not be quite so important for GWAS.

Citation: Stefflova K, Dulik MC, Barnholtz-Sloan JS, Pai AA, & Walker AH (2011). Dissecting the Within-Africa Ancestry of Populations of African Descent in the Americas PLoS ONE : 10.1371/journal.pone.0014495

CATEGORIZED UNDER: Genetics, Genomics, Human Genetics
  • http://ecophysio.fieldofscience.com/ EcoPhysioMichelle

    You have a knack for visualizing information.

  • http://washparkprophet.blogspot.com ohwilleke

    One of the major points of the “race is socially constructed” movement has been the point that the very same individual may be perceived visually as “black” in the United States, but as “white” in Brazil.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    it is a very valid point. that being said, they fall into the trap of inverse-platonism.

  • Ricky

    How to fact-check some of this information? Lot’s to consider there.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    how about using that internet connection ricky?

  • ryanwc

    I notice something else that could be a product of low sample size, or something else – among Philadelphia blacks, Philadelphia whites and USA black populations, the AIM proportion of native american ancestry is higher than the mtDNA and the y-dna, though you’d expect as with other ancestries, it would fall somewhere between.

    I can think of just-so-story reasons for this — that most of the initial pairings were between native females and white males (for obvious reasons); but then the daughters tended to stay within the tribe, while sons were able to make it out into the white world, passing on their white y-dna, and a 50% inheritance of native dna, but no mt-dna; I have more trouble inventing a rationale for why this would be anything but a statistical anomaly in the black community, though perhaps the same was true, that sons of mixed parentage (where the black parent was apt to be a male runaway) were more likely to return to the black community, while daughters were apt to stay within the tribal society.

    If either or both of these things are systematically true at a statistically significant level, it’s an interesting thing. Could also be a product of small sample size, though.

  • Antonio

    In my experience, most people who might identify themselves as whites in Brazil would not do so in US. They don’t needed anyone to tell them they are no longer white. It is obvious that: (1) the definition of white is much stricter in US and (2) US people are much more obsessed with race than Brazilian people. Oh! I almost forgot: thanks for the reference; I’ll send this out to people.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    US people are much more obsessed with race than Brazilian people.

    easily problematized :-) we don’t have hundreds of racial terms in common usage! also, do you know that the income gap between blacks and whites in the USA is much smaller than preto/ardos and brancos? i think brazilians and americans are obsessed, but in different ways.

  • Antonio

    Nope nope nope. They don’t nearly care as much as you. I believe that you really thinks otherwise but maybe the the available studies about this topic are just profoundly misinformed.

    To begin with, your data is probably comparing different things. By US standards many white people in Brazil would actually be non-white in US, so that I don’t really see the point of comparison besides causing confusion and misinformation. For instance, many important figures in Brazil have clearly non-white ancestry, as we can see just by looking at the newspapers or TV. Not a big deal. And the pattern is increasing over time.

    Brazilian don’t say that someone is black or white or whatever: there is no such an expression and it is just extremely offensive. We don’t refer to people by their “race”. There is no hate crime against blacks or whatever, let alone Klu Klux Kan. And there is not talk about white nation, not now nor in the past (this in itself already made Brazil light-years ahead of US).

    Moreover, not even in their best moments Portuguese descends said that other Europeans are non-white, a common US non-sense. There is no different box for other Europeans in the census. They might discriminate poor Germans or Italians or Turks but not on racial terms.

    Blondies are not usually the sex symbols. Actually most Brazilian sex simbols have obvious non-white ancestry. (And I am taking about sex symbols of the white people.) Many whites try to burn their skin desperately, often sacrificing their own health (I can show you in my facebook ) so it is total foreign to Brazilians white skin is more beautiful than brown. We may discriminate against “pure” blacks but people who look (and probably are) 100% european decendents can *easily* marry people with obvious non-european anscentry. Race and racial ancestry is not even mentioned in these cases. From what I saw here in US, this is already a big advantages over you.

    The spacial segregation is not based on race but income instead. Obviously, poor neighborhoods are mostly populated by persons with large fractions of non-European ancestry but and blonde persons can easily walk over these place as long as they look poor.

    Of course, there is lots of racism down there. Of course, those with large fraction of fraction of African blood are worse off. But this is true any country in the world. On the other hand the rich is Brazil have more non-white ancestry than the rich in US and other places. I would go even further and, perhaps, raise the claim that the Brazilian mixing is the closest thing to the racial democracy in the world (though I am not sure how the Russia/Soviet Union would stand here). It may still be terrible but I believe far better than US have done so far.

    Finally who said Brazil has hundreds of racial terms in common usage?! I don’t even understand what people meant by that. On the contrary, US censuses have *far* more box than Brazilian. We can count, if you wish. The lack of this type of basic information about the country tell us more about the knowledge of the “specialists” than anything else.

    I am *not* claim that US will be ever behind Brazil in that matter nor that you haven’t made any progress. I am just trying to tell you what is the situation so far. I don’t think I am nationalist and, to be sincere, I am not specially proud of Brazil. As a society, US is clearly superior in many respects like meritocracy, the value of the work and education, etc. No doubt. But racism, racial assimilation and societal integration in general are superior down there.

    Best,

    Antonio.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    antonio, yeah, i’ve heard plenty of brazilians claim some of these things. i don’t really accept them for various reasons. btw, are you joking about russia/soviet union? it’s one of the most scary places for a dark skinned person to visit right now in the world. dark skin = someone who is a brunette white person like you. they call people from the caucasus blacks there! :-)

    Many whites try to burn their skin desperately, often sacrificing their own health (I can show you in my facebook ) so it is total foreign to Brazilians white skin is more beautiful than brown.

    well, is this stuff yankee propaganda then?

    http://msmagazine.com/blog/blog/2010/06/11/blonde-beauties-and-black-booties-racial-hierarchies-in-brazil/

    (i’ve read of the idea of ‘whitening’ in plenty of other places btw)

  • Antonio

    I know this is not a space to discuss Brazil and I will stop with this post but I really think my claims are more like facts than claims. Have you live in Brazil to the point of actually understand what is going on, I really don’t think what I am saying is something polemic and new. If my claims are generating repeated diatribes it is mostly due to the low quality of the social science research than anything else.

    “So, while women of African descent in Brazil may be considered “hot” or “sexy,” they are not considered “beautiful” enough to be models. In fact, as Barrionuevo states, “more than 70 percent” of Brazil’s models are from the “three southern states” that have had the heaviest influx of European immigration.”

    This is for *external* consumption, not for Brazilian themselves. I would say this yankee deeply ignorance, not necessarily propaganda. (btw, being ignorant is fine, but sometimes it seems some people in US are prone to believe they know much more than they actually do thus disseminating misinformation). The beauty of the brown skin is something that I suffer on regular basis at home with my wife telling me how beautiful I was when I was tanned. You can also check my facebook to see how my young cousins and their friends are destroying their skin to meet the standards.

    So the idea of whitening needs lots of detail when the focus is Brazil as it can be easily misunderstood. Compare to what I’ve seen here and I also learn about other places like Korea, the idea of whitening in Brazil seems now rather inclusive to me. In fact, many Brazilian see this in a negative fashion – include me in the past – but now I am not so sure because it allowed for ( or it is correlated to) less stricter definition of race, which I see as the core of US racism.

    From my perspective, the most odd thing about the US hypodescent definition of white is that it looks like it is a big deal being white, as if you automatically become the king of France just for being white. The main problem with this is not just the extremely ignorance about what white people suffered in places like Europe very recently. In fact, one of the most surprising things I saw when I moved to US is the huge number of poor-uneducated-ugly white people around. In Brazil, if you white in US sense you are actually better off, with a superior conditions than most US whites here will ever have . But here…so what is the point? Maybe because these people are actually nothing important at all they tried to make something out of their “race”.

    Yet, we still have lot’s of racism there but Brazilian society is just infinitely less concerned with race than US was and is. We do discriminate but less so in racial terms. Old aristocrats discriminate in terms of surnames and families history; new riches in terms of money. Many conflicts but no racial dived. Many important symbols of the Brazilian society like the Bandeirantes – those who extend Brazilian border west – are mixed people. The Brazilian music, including the made-by-whites bosa nova have clearly non-white roots.

    We don’t have TV programs or soup operas exclusively for blacks and, for that matter, we don’t have different racial status quo like in US you have for hispanics, black, whites. Everybody wants to be a star in the same soup opera. Contrary to what happened in US, the Brazilian “minorities” never tried to create parallel words but they always tried to conquest the “white” status quo instead (quotation because we never refer to the status quo in racial terms, this is translation for American people).

    I understand that this doesn’t make to much sense to you, giving your default society. It is a totally different way to see people, I know. My wife currently works in one of these big online US “matching” companies which just open operations in Brazil. She is having a very difficult time explaining Americans that the race question (which is or race/ethnicity ? which would be the race/ethnicity of your match) doesn’t make sense for people there, let alone in the context of finding a mate! At best sounds odd, at worse it looks that the company is promoting racial discrimination. Brazilian people just look at pictures to see person’s beauty and style. Of course race is also considered but in a very elusive, flexible and distant way. They just don’t think “oh I need someone with 1/3 Amerindian ancestrality and 2/3 northwestern European”. This is just non-sense for them.

    Still there is lots of discrimination down there: being European descent is better than not but, like I said, this is also true elsewhere so that we cannot rank down Brazil as a consequence of it. On the other hand, much of the non-European ancestry live in quite good conditions. Finally, Brazil still have lots of non-racial discrimination, like by income and education, which is a real problem.

    Best,

    Antonio.

  • Antonio

    Soviet Union/Russia. I have a friend, an Russian ethnic born i Soviet Union that told me there is no racial discourse there. I asked him about the recent events in the Caucasus and the racial discrimination there and he told me these are new developments. And he told me stories, for instance, about the election of Black mayors, the seemed to confirm his point. By reading books, I already knew that many soviets “president” where not russian ethnics and that Soviet Union was good in including different ethnic groups ( do you disagree?). Also this seems common knowledge about my colleagues who are more informed about Russia than I am. But I don’t know much about Russia so that I can really debate with you about.

  • Latifundiário

    Brazil perceives itself as a Brazilian nation, a New People, a New Construction, a New Amalgama, a New Synthesis, just read the Brazilian sociology and anthropology. Brazil is a more racially integrated community than the United States because the Brazilians share the same genetic history, although not in the same proportions, but they are the same people, with the same components, in the same giant territory conquered by the Brazilians against other European rivals. The relationship between Brazilian Y DNA and a very homogeneous European Nation State is unique in the world, so the central basis of the Brazilian unity is the same Community of Men, the same Manhood with the same distinct language, the same racially integrated Armies and the same sense of Ethno-National Brazilian identity crossing different phenotypes with the same genetics, culture and National Spirit throughout the same historical process. New Amerindians, New Africans, New Europeans and New Asias were anthropophagically eaten, integrated, absorbed and assimilated in the Brazilian New People.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    I asked him about the recent events in the Caucasus and the racial discrimination there and he told me these are new developments.

    yes, they’re new. but it doesn’t mean that moscow isn’t scary for colored people. the violence is widely reported in the media, but i know of colored people who avoid adding russia to their tourism travel itinerary because of racism.

    the soviet union also was officially atheistic. but russia is now chauvinistically orthodox. so things change quickly.

    to finish up, i agree that i’m influenced by american presuppositions. though we’re talking on a blog where most people are american. that being said, i would like to see quantitative and more rigorous analysis of racism. e.g., are brazilians less or more racist on implicit association tests? what’s the race discrimination effect on brazilian dating sites vs. american ones? not just qual, but quant.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    also antonio, i bask in the admiration you have for my natural brownitude. it’s hard being the pearl of creation :-)

  • Antonio

    Razib, I am in academic game right now but sometimes I feel there is no space for this type of analysis. Those wh0 disseminate misconceptions about Brazil ( and probably by other countries too) dominate the game in the area in US. My own advisor told me to stay away from these area. The task of explaining one culture to another in huge and without community support or even interest is difficult. Also, from a Brazilian perspective, since we still have lot’s of problems with people with majoritarian black ancestry – and I am white – I don’t wanna sound I am denying racism down there. These populations have special needs that remains to be adressed ( and I think we are behind US for that matter). That said it would be not difficult to operationalize top-not research on the topic (experiments on racial identification, genetic information to properly compare populations and also reconstruct their history, etc). And I would love to do that.

    Latinfundiário! Eu lhe devo um email!

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

ADVERTISEMENT

See More

ADVERTISEMENT

RSS Razib’s Pinboard

Edifying books

Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »