Brazilians, more European than not?

By Razib Khan | February 25, 2011 1:30 am


Credit: Dragon Horse

The Pith: Brazil is often portrayed as the second largest black nation in the world, after Nigeria. But it turns out that the majority of the ancestors for non-white Brazilians are European.

One of the more popular sources of search engine traffic to this website has to do with the population genomics of Latin America. For example, my post showing that Argentina is not quite as European a country as it likes to consider itself is regularly cited in online arguments (people of various “persuasions” are invested in the racial status of the Argentine people). But last week in PLoS ONE a paper looking at the patterns of ancestry in the Brazilian population came to a somewhat inverse conclusion as to the self-conception or perception of the preponderant racial identity of that nation. Let me quote from the conclusion of the paper:

Among the actions of the State in the sphere of race relations are initiatives aimed at strengthening racial identity, especially “Black identity” encompassing the sum of those self-categorized as Brown or Black in the censuses and government surveys. The argument that non-Whites constitute more than half of the population of the country has been routinely used in arguing for the introduction of public policies favoring the no-White population, especially in the areas of education (racial quotas for entrance to the universities), the labor market, access to land, and so on [36]. Nevertheless, our data presented here do not support such contention, since they show that, for instance, non-White individuals in the North, Northeast and Southeast have predominantly European ancestry and differing proportions of African and Amerindian ancestry.

ResearchBlogging.orgThe idea that Brazil is majority non-white, that is black, is one I’ve seen elsewhere. Using the American model of hypodescent, where children inherit the racial status of their most stigmatized ancestral component, no matter its magnitude, well over half of Brazilians are “black.” On the other hand, there’s the persistent trend in the recent analyses which show that black Brazilians have a much higher load of European ancestry than black Americans, while white Brazilians have a much higher load of Amerindian and African, than white Americans.

Let’s jump to the paper first. The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected:

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a “total ancestry” estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19th and 20th centuries – a phenomenon described and intended as the “whitening of Brazil” – is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations.

If you don’t know, the cartoon cut-out is that the northeast of Brazil is the most African inflected region, while the far South is predominantly European. Amazonia has more Amerindian influence, while there is local variation in other parts of the country due to rural to urban migration. Because the ancestry components that the authors were looking for are very distinctive, with the parent populations being separated for tens of thousands to hundreds of thousands of years, I assume 40 well selected markers are sufficient. Over 900 individuals is a large number. I jumped to the detailed methods, and was a little curious as to possible sampling bias introduced by their locations of collection, universities. Nevertheless, after 10 years of these sorts of papers I am convinced that there really does seem to be a fair amount of admixture in the Brazilian population across color lines.

The authors focused on three major color categories, white, brown, and black. These are self-descriptions for most of the participants, though the methods indicate that the southern sample was classified visually by the researchers. To get a sense of the relevance of these categories quantitatively the book Race in Another America: The Significance of Skin Color in Brazil, is useful (the low stars given on Amazon to this book seem to do with the reviewers being dumb or angry that the author didn’t have a big enough axe to grind). Roughly, Brazil shakes out as a “layer cake,” with (on average) blacks on the bottom, whites on top, and browns in the middle.

To the left you see the excepted triangle plots, with each vertex representing an ancestral component. The apex is European on each triangle (don’t deconstruct that!), with African to the bottom left and Amerindian to the bottom right. The leftmost column consists of self-identified whites, the right-most column self-identified blacks, and the middle column browns. Each row consists of a set of samples from a specific geographic region. To get a sense of national patterns the authors report that a 2008 survey indicated that of Brazilians 48.4% identified as white, 43.8% as brown, 6.8% as black, 0.6% as yellow, and 0.3% indigenous. These are social constructs. In fact, it seems likely that the indigenous genetic contribution to the total Brazilian population is actually 10-15%, relatively evenly distributed across the white, black, and brown categories. Additionally, American sociologists have generally observed that while very light-skinned individuals with some African ancestry self-identify as black in the USA, in Brazil the same individuals would probably identify as white. That’s a function of the differences between North American and Brazilian societies.

In any case, as you can see above there are differences between the color categories. Whites have more European ancestry, blacks more African, and browns are more mixed, with those in the north having more Amerindian quantum than those elsewhere. Here are the summary statistics by region & self-identification:




Color Assignment
Region Ancestry White Brown Black
North European 0.78 0.69 0.52
African 0.08 0.11 0.28
Amerindian 0.14 0.21 0.2
Northeast (Bahia) European 0.67 0.6 0.54
African 0.24 0.31 0.36
Amerindian 0.09 0.09 0.1
Northeast (Ceara) European 0.76 0.73 -
African 0.13 0.14 -
Amerindian 0.11 0.13 -
Southeast (Rio) European 0.86 0.68 0.43
African 0.07 0.24 0.5
Amerindian 0.07 0.09 0.08
South (Rio Grande do Sul) European 0.86 0.44 0.43
African 0.05 0.44 0.46
Amerindian 0.09 0.11 0.11

There’s nothing that surprising in this. The rank order is as you’d expect…except that blacks in the far south, where they are a much smaller minority, have less, not more, European ancestry. This is counter-intuitive because the presumption is that in blacker regions the threshold for being white is lower, while in whiter regions the threshold for being black is lower. You see the first in Bahia, where the typical white is about 2/3 European in ancestry, vs. Rio Grande do Sul, where European ancestry is at the level of Argentina genetically. I don’t think the authors have a good explanation for this, and even at their N there might be issues with representativeness that is distorting the results.

A common finding, which shows up in this research, is that there isn’t that big of a difference in the averages between some of the color categories in terms of ancestry. You can see that clearly in the figure to the left, from the paper Color and genomic ancestry in Brazilians: a study with forensic microsatellites. Again you have the three color categories, with their position on the y axis proportional to their “index of African ancestry.” The average rank order is perfectly correct, but there’s a great deal of overlap. The sample was from Sao Paulo. This is not typical in the United States. African Americans may be about ~20-25% European, with 10% being more than 50%, but the rate of non-European admixture in American whites is generally rather low. Only a small minority of American whites have anywhere near the median among of non-European ancestry among Brazilian or Argentine whites.

The main argument of the paper, which is in line with that of a long line of papers coming out of Brazil over the past ten years, is that assortative mating over the past 300 years has maintained phenotypic races, despite ancestral admixture. In other words, the physical difference between the color categories is much clearer than their ancestral quanta. Why? Because skin color, and perhaps traits like hair curl and nose form, as controlled by a small number of genes. In the case of skin color most of the variance is accounted for by less than half a dozen genes! We all know that among mixed-race siblings some individuals will resemble one race much more than the other, despite similar ancestral quanta. Rashida Jones regularly “passes” for white for her television roles, while her sister Kidada looks a bit more African American. As long as humans fix upon salient characteristics the “post-racial” idea is probably a delusion of idealism.

In any case, probably the most interesting and original aspect of the paper is the demographic one. I’ll quote:

We believe that the regional disparities in mtDNA ancestry were maintained because, once again, in the immigratory wave of Europeans there was a significant excess of males. When they admixed with the Brazilian women there was rapid europeanization of the genomic ancestry, but preservation of the established matrilineal pattern. There is demographic information to corroborate this possibility. First, of 1,222,282 immigrants from all origins that arrived in the Port of Santos in the period 1908–1936 the sex ratio (males/females) was 1.76…Second. the two most abundant immigrants, Portuguese and Italians, had sex rations of 2.12 and 1.83, respectively. census data of 1910 showed concordant results: there were 1,138,582 foreigners in Brazil, with a male/female ratio of 1.74, while there were 22,275,595 Brazilians with an even sex ratio of 1.0.

I’ve poked around for this sort of data before, and it is often hard to find. The Brazilian pattern, with a huge bias toward male migration, has probably been the pattern across much of human history with long distance travel. The United States is a great exception, with intact families settling New England early on (though the South exhibited a more Brazil like pattern, the admixed element was reabsorbed into the slave population). I think this has resulted in some weird inferences from historical population genetics derived from mitochondrial DNA, which passed through the maternal lineage (example: mtDNA of India didn’t predict very well how much closer Indians were going to be to West Eurasian populations when autosomal studies utilizing hundreds of thousands of markers came online).

Finally, a lot of these authors in these papers coming out of Brazil seem rather political when it comes to genomics, race, etc. I have no knowledge of the detailed back story, and I don’t believe that anything but conspiratorial manipulation could result in the consistent pattern in the data. But, in a heterogeneous population there’s always going to be worries about representativeness. From what little I know an awful lot of Brazilians are like Gisele Bündchen, the grandchildren or great-grandchildren of European immigrants. If so, they shouldn’t have any non-European ancestry. So I do wonder if there’s some conscious or unconscious undersampling going on because the researchers want to promote the idea of a racially admixed population.

Citation: Pena SDJ, Di Pietro G, Fuchshube-Moraes M, Genro JP, & Hutz MH (2011). The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected PLoS ONE : 10.1371/journal.pone.0017063

CATEGORIZED UNDER: Genetics, Genomics
MORE ABOUT: Brazil, Genetics, Genomics
  • Antonio

    Interesting that the the part you liked the most I found the most uninteresting one, perhaps because I am already familiar with this information and argument. What I would like to see is a full demographic model simulating how we got to our current population from the settlers; I would like to see how the differences between reproduction ratios among early settler groups played out in more detail, including their intermixing.

    From what I got, they sample what they could and I wouldn’t be surprise if this is not nationally representative: in each place they got data from individual from different backgrounds; I would guess the sample from the north region came from mostly poor people while the northeast includes many university students; also, the sample from the south was “racially” classified by others than the individuals under analysis themselves, which actually might explain why the south sample has more between “race” variation.

    I also am a little surprise about the total lack of meaning of the racial categories in some places. Sure, we don’t have some whites should have non-european anscestry, but why, for instance, I european person would self-classify as non-white, and, specially, as black? This makes me a little suspicious about the sample representativeness but… who knows?

    Finally, it would be nice to try to explain some with discrepancies with socioeconomic information about the individuals but it seems these are lacking.

  • John Emerson

    Without claiming that Brazil is utopia, this supports the claim that the color line is less sharp there, more of a continuum. This is supposed to be a Latin (Catholic) as opposed to Germanic (Protestant) pattern. (Huguenots may fit in with the Germanics, in the US and South Africa, in which case it would be a Catholic/Protestant split).

    Hawaii’s racial politics is alos a different pattern. The lines are differently drawn. For example, I’ve been told that Portuguese tend to get lumped at the bottom with Filipinos, not because of race but because of settlement patterns, historical sequences, and class.

    A litmus test here is “what counts as a mixed marriage”. In the Caucasus, for example, the main line is Christian / Muslim. Marriages across language groups are not necessarily mixed marriages unless there are historical enmities. When I was growing up it was Catholic / Protestant and was taken very seriously (people were disowned and expelled from families in the generation before mine). Now I would guess the line here is Christian / non-Christian and white / non-white, though many people would be accepting of anything but black American and some would be accepting of that.

    So anyway, in Hawaii and Brazil, what is a mixed marriage?

    P.S. A Kenyan once told me that the people of Madagascar, or some of them, are xenophile and are happy to bring new ethnicities into the family. Grain of salt, but I’d like to hear more.

  • dan

    yeah, i remember reading about that recruitment of white immigrants from Europe because they’d brought about 6 million slaves over and weren’t happy about the mix of the country. the writer i was reading implied the gene mixing was a result of slave masters having their way with the slaves but i don’t know if that’s accurate. i think he said it was a far larger group of slaves then America had brought over (650,000 vs 6 million) if i remember correctly. also, he wrote that they have a saying that was something like “money lightens” or something like that which refers to the correlation between income in Brazil and a lighter skin tone and went on to describe the massive amount of plastic surgery, etc. to look whiter. i’d love to know whether this correlation is accurate and is according to percent of admixture. that would be very very interesting if the whitest made the most, mixed earn in between and the darkest earn the least.

  • pconroy

    Razib said:

    From what little I know an awful lot of Brazilians are like Gisele Bündchen, the grandchildren or great-grandchildren of European immigrants.

    Yeah, I knew a Brazilian guy whose Great-Grandparents were all German, but grew up in a remote farming community in Rio Grande Do Sul, and he told me that when he went to school for the first time at 7 yo, he only spoke German?!

    My brother’s wife is from Rio Grande Do Sul, and her mother is a 100% Northern Italian* Light Brown hair/green eyes, while her father is 50% African, 50% Portuguese/Amerindian – which makes for an interesting look. Incidentally, she is the most African looking of her siblings, one of her brothers looks completely European.

    * It’s funny how Northern Italians seem to have emigrated to South America, while Southern Italian emigrated to North America?!

  • MPerry

    Regarding the “money whitens” phrase. The first time I heard that was from a Brazilian friend in college. The way she explained it was that it didn’t mean a literal whitening but that with acquired wealth skin color tended to matter less. Or reversing it, for very poor whites, their skin color didn’t get them many advantages.

    She also told me about a popular joke regarding Brazil’s affirmative action programs. The question was that in a country with so many people with African ancestry, how can you tell who is truly black for AA purposes. The joke was let the police decide, they always seem to ne able to figure it out.

  • John Emerson

    In Taiwan in 1983 I met a beautiful rosy-cheeked blonde Spanish teacher who, it turned out, was German, Polish, and Jewish in descent but had grown up in Brazil as a Brazilian (her parents were pretty much deliberate renegades, as I remember). Her behavior struck me as purely Brazilian (according to my stereotypes): high spirited, lively, and outgoing. She was also a snappy dresser.

    Even for me, just seeing her around town was sort of a jolt. For the Taiwanese it must have been ten times that.

    Point? In this case I haven’t got one . I’m just being Tom Friedman for a bit.

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

    john, i don’t think it is a latin vs. germanic thing. rather, the iberians just had colonies in areas not as suitable for “settler colonies” for europeans (also, portugal has a tiny population). remember that purity of blood arose in spain. and multiple white latin americans, who have no strong racial bias that i can tell, have asserted to me their “pure spanish blood.” in other words, i think miscegenation in latin america was structural, not ideological.

  • Antonio

    I wrote very late at night: can I fix my (many) typos? :(

  • John Emerson

    Well, the French in Canada intermarried a lot, so that in early Minnesota history “French” usually means mixed-race (Matis).

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

    john, again, they had a demographic shortage. the same admixture occurred in english colonies when there was a woman shortage (india in the 18th century, to some extent parts of the american frontier and upper south). the difference is that the british homeland entered into a period of MASSIVE demographic growth around 1800, and international transport got better in the 19th century. the dutch protestants hybridized plenty in the netherlands. again, lack of women.

  • pconroy

    John,
    I took Tango lessons years ago, from an authentic Argentinean Tango instructor, who had just come to New York. She seemed typically Latin in behavior and barely spoke English. Then it turned out her name was Julianna Kelly, and she was of 100% Irish descent…

    Speaking of which, my father had two 1/2 Argentinian relatives, now he has his first full Argentinian relative.

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

    I wrote very late at night: can I fix my (many) typos?

    i sympathize, but i don’t control the edit feature. also, there is a reason to have a statue of limitations on how late you can edit…lest people just reedit past comments and disrupt the flow of conversation :-)

  • http://lablemming.blogspot.com/ Lab Lemming

    How do they control for selection bias in the sampling? (I’m not finding the ‘free article” tab clickable) One of the things that struck me from my field work in NE brazil was that the rural areas were much ‘blacker’ than the cities, while in the cities, the racial mix was strongly dependent on the affluence of the neighborhood.

    So I suspect that by doing these studies in cities, they already whiten their results geographically. And how they selected people in those cities for analysis could easily further bias their sample.

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

    How do they control for selection bias in the sampling?

    they didn’t do anything robust and systematic from what i can tell. that being said, don’t be too skeptical, look at their citations and you see the same pattern from some papers in rural areas too. i think there may be significant differences on the margin, but i’m willing to bet $100 that brazilian “blacks” are at least 50% or more whiter than american blacks in terms of ancestry. that is, if american blacks are 20% white, on average, i think brazilian blacks are 30% white, on average, as a low bound. on the other hand, you can find a significant number of “pure” white brazilians. i think it has to do with the fact that blacks arrived earlier, and so have been more subject to panmictic processes.

    also, keep in mind that the point of many of these genomics papers from brazil is to illustrate the significant disjunction between appearance and ancestry. everyone who goes to brazil seems to note the layer cake of racial strata. the authors’ (along with others earlier) seem to be suggesting one should be careful of phenotypic cues as too predictive.

    off-topic, you made an assertion about the absolute increase in people in poverty months ago. i asked for a cite, and i don’t recall you gave one. i spent 20 minutes looking and i saw papers/estimates in both directions and couldn’t ascertain which set were more credible. can you give a citation you had in mind for your assertion? if you don’t have one, that’s fine, i don’t care about your personal opinion so don’t bother elaborating in detail.

  • http://lablemming.blogspot.com/ Lab Lemming

    I was probably referring to the negative correlation between per capita GDP and population growth for countries on the whole, which may be (a) out of date and (b ) non-rigorous without relating GDP to actual population % in poverty.

    I’m sorry if I’ve lost track of the comment, but my blog activity is sporadic these days.

  • http://ironrailsironweights.wordpress.com/ Peter

    Brazil is often portrayed as the second largest black nation in the world, after Nigeria.

    I thought it was the fourth largest black nation, behind Ethiopia and Congo as well as Nigeria. Brazil has also claimed to be the world’s third largest white nation, behind the United States and Russia.

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

    meant population peter. jesus ethiopia has a huge population!

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

    I was probably referring to the negative correlation between per capita GDP and population growth for countries on the whole, which may be (a) out of date and (b ) non-rigorous without relating GDP to actual population % in poverty.

    the big error margin is going to be chinese estimates. when you weight by population china has a huge impact.

  • Diogenes

    It would be interesting if we could find out if phenotypically “white” Brazilians with no recent “black” ancestry but more significant African admixture, actually do worse in financial and educational terms than equivalent phenotypical whites without African ancestry.
    Likewise if phenotypically “black” Brazilians with substantial white ancestry do better in life than people of equal visible “blackness” without much European ancestry.

    Could admixture be a source of positive novelty in general? Shouldn’t more genetically diverse populations have larger standard distributions for any trait?
    Intelligence has after all been selected more often than not in all human populations for the past million years.

    How about for very high IQ individuals?

  • Diogenes

    To be clearer, I suspect in both cases more admixed individuals will generally fare better at the top end than less admixed ones provided both groups have equivalent visible “social race” stigmatization levels for what is worth.

    Ashkenazi Jews for instance were/are a very admixed/diverse population within their North European context. This means they both had larger numbers of very high IQ individuals to start with AND had the diversity to enable faster evolution to novel conditions…

  • Matt

    Could admixture be a source of positive novelty in general? Shouldn’t more genetically diverse populations have larger standard distributions for any trait?

    I don’t think there’s much of a relationship in terms of intelligence, in terms of the general pattern of overall genome diversity I know about (Africans>West Eurasians>East Eurasians>Oceanians>Native Americans, with the big gaps between Africans and Eurasians and New World populations). This is possibly because the reduction of diversity away from Africa due to serial founder effect has less effect on variation in intelligence related genes as they’re under selection (neutral genes can’t push back up to frequency due to gene flow after the serial founder effect, because they’re neutral and the overwhelming pressure is against them, while stuff with a selective advantage can and has).

  • onur

    Ashkenazi Jews for instance were/are a very admixed/diverse population within their North European context. This means they both had larger numbers of very high IQ individuals to start with AND had the diversity to enable faster evolution to novel conditions…

    I don’t think the situation in Ashkenazi Jews has anything to do with the situation in Iberian (i.e., Spanish or Portuguese)-speaking America (I never use the term “Latin America” as the word “Latin” has in origin nothing to do with the Americas, it is a term belonging solely to Caucasoids): different racial (including sub-racial) mixes, different cultures and different histories.

  • Diogenes

    ”I don’t think there’s much of a relationship in terms of intelligence, in terms of the general pattern of overall genome diversity I know about (Africans>West Eurasians>East Eurasians>Oceanians>Native Americans”

    I’m not trying to compare very different populations with very different histories. I’m comparing Brazilian whites with 0% African admixture to Brazilian whites with 10% African admixture
    If you postulate that European populations evolved intelligence promoting genes A, B and C after Out of Africa; and Angolan Blacks gene D; it follows that a Brazilian admixed individual could possess A, B, C AND D, to put it in the most simplistic scenario. Or maybe some of the European intelligence genes have adverse affects like increased probability of bipolar disease that an African gene supresses.
    Obviously most admixed individuals will not hit the lottery genes, and obviously some would have NEGATIVE feedback between genes that didn’t evolve toghether, but for the few that do, the returns would be large.

    As for the returns of diversity on comparable populations, you might want to take a look at
    “Buj, V., 1981, Average IQ values in various European countries, Personality and Individual Differences, 2, 168-169″
    Couldn’t find the original article pdf but Dienekes published some of the data years ago.
    http://dienekes.110mb.com/articles/greekiq/
    In this study, average IQs between Northern Europeans and Southern Europeans were equivalent, but Southern Europeans, a more diverse population, had higher standard deviations, thus larger numbers of both very smart and very dumb individuals.

    “I don’t think the situation in Ashkenazi Jews has anything to do with the situation in Iberian-speaking America”

    Maybe not in terms of evolutionary pressures. That is not my point though. I’m not denying Ashkenazi Jews underwent unique ecological niche pressures. I’m just arguing they, as a diverse population with: Middle-Eastern (including both Egyptian and Mesopotamian), Anatolian, Italian, Iberian, multiple Northern European and Central Asian (Khazar) admixture, already had advantages versus local populations of Northern Europeans to take up opportunities and respond to the resulting pressures much more quickly.

    Sorry for being so provocative, particularly as I’m Portuguese and may seem to be defending my turf. But I actually just took up the Brazilian case because I’m more familiar with it.
    My point is under selective pressure large scale admixture can only be a positive thing long term. And under such conditions, for admixed individuals, phenotypic race may not a useful guide to personality and mind traits. Populations today in all continents live increasingly in cities too, with increasingly equivalent lifestyles and immediate contact with ideas from across the world. People will still be different, maybe more so, but more from the person with different tastes and occupations next block and less to like-minded people in the antipodes. New niches are being formed today and they’re GLOBAL.

  • onur

    I’m just arguing they, as a diverse population with: Middle-Eastern (including both Egyptian and Mesopotamian), Anatolian, Italian, Iberian, multiple Northern European and Central Asian (Khazar) admixture, already had advantages versus local populations of Northern Europeans to take up opportunities and respond to the resulting pressures much more quickly.

    Your model seems to largely ignore the negative effects of admixture and only focus on the positive effects. If, for instance, the average IQ of Egyptians is lower than Jews, admixture with Egyptians will have negative effects on Jews.

  • onur

    i

  • Diogenes

    I’m talking about individuals at the very intelligent end of the spectrum only. Admixed populations would tend to have more individuals further away from the mean. The average admixed individual may not be more intelligent, and there would be larger numbers of low IQ individuals too. If pop A has average IQ 105 and std dev 20 and pop B average 95 and std dev 25, the resulting pop could have, as an example, average IQ 100 BUT std dev 35. This means individuals with either IQ>120 or IQ<80 should be more common in the resulting admixed pop than in either parent one.

    But as long as selective forces are effective, and we have little evidence they're not or wont be in the future, those average and low IQ admixed individuals have to compete with the few extraordinarily intelligent ones who belong to the very same admixed population. So the intelligence promoting genes from both parent populations, and the average IQ of the admixed population would increase if given time. Nobody has any evidence Jews were ,ON AVERAGE already more intelligent as little as 1000 years ago. Even today Ashkenazi Jewish IQ is not extraordinarily higher than other Europeans. It is the (small) number of very smart AJ individuals which is manyfold higher.
    They were however more diverse already 1000 years ago. Thats what probably allowed them to take off under the very strong evolutionary pressures they experienced from then on.

    Basic evolutionary theory.
    BTW these arent my theories, they've been about I'm merely collating them.

  • onur

    Diogenes, if we are going to discuss Jews, in their case not only admixture with different populations but also the very low population density of Jews and special selective pressures working on them throughout history should be taken into account, and of course also their specific culture, religion and history in general. Jews likely were exposed to genetic drifts and selective pressures due to their small population size and relatively isolated and hard life, and this should be especially true for Ashkenazi Jews as they were a tiny and despised non-Christian minority dispersed in an enormous Christian land throughout their history.

  • Diogenes

    Ashkenazi Jews have reduced diversity today in several alleles probably due to strong selective forces, very different reproductive rates among different individuals, and population explosion in the last 200 years or so. It is not their current genetic diversity for a number of allelles that is important though, in my opinion…

    What is important was their genetic diversity when their special intelligence promoting selective conditions began to act. It was likely far higher than for most Europeans back then.
    Persecutions, founding effects and differential reproduction may have wiped out many of the neutral and negative diversity, but likely the alleles promoting intelligence were preserved entirely and also absorbed from neighbouring populations in small quantities. New mutations may have added as well.

    Their diversity in those genes is well exemplified by their measured IQ. The average IQ of Ashkenazi Jews is only some 5-10 points higher than Northern Europeans, but the number of people with very high IQs is, depending on where you set the bar for high IQ exactly, some 10-30 times higher per 100000 people than Northern Europeans.
    No other explanation occurs to me other than higher diversity among intelligence promoting genes.

    This together with related environmental reasons (more emphasis in high education) is why Ashkenazi Jews have won about a third of academic Nobel Prizes, despite being a much smaller population than say, non-Jewish Germans.

  • Antonio Santos

    Não percebo a surpresa.Os Portugueses chegaram ao Brasil em 1500, a política dos reis Portugueses sempre incentivou a mistura genética com os locais, de forma a povoar território.

  • onur

    Diogenes, I don’t think high genetic diversity past or present has any significant role in the rise of the Ashkenazi Jewish IQ. Their genetic potential (regardless of high genetic diversity) + genetic bottlenecks + selective pressures + their peculiar history seems enough to me to explain their high average IQ.

  • onur

    Their genetic potential (regardless of high genetic diversity) + genetic bottlenecks + selective pressures + their peculiar history seems enough to me to explain their high average IQ.

    BTW, in Ashkenazi Jewish genetic potential and history I include their European admixture.

  • Pingback: Linkage is Good for You: Last of the Old Edition

  • Matt

    hypodescent is possibly the most insidious of rascist ideas.

  • dan

    pretty good movie on the subject here:
    http://www.youtube.com/watch?v=Xo9p2lQ7GXk

  • Hermenauta

    Razib,

    The Wikipedia article about immigration in Brazil is pretty good and brings relevant information to people not familiarized with brazilian history:

    1. 1820-1876: small number of immigrants (about 6,000 per year), predominance of Portuguese (45.73%), with significant numbers of Germans (12.97%);
    2. 1877-1903: large number of immigrants (about 71,000 per year), predominance of Italians (58.49%);
    3. 1904-1930: large number of immigrants (about 79,000 per year), predominance of the Portuguese (36.97%);
    4. 1931-1963: declining number of immigrants (about 33,500 per year), predominance of the Portuguese (38.45%).

    Before that we had mainly portuguese colonizers starting in the XVI century and, of course, african slaves, against a background of amerindian populations. So I bet that these four newer immigration waves didn´t had enought time to mix with the older ones. This explains the “Gisele Bundchens” you mentioned.

    [just for curiosity, there is also a huge japanese colony in Brazil, the greatest outside Japan itself; they arrived mostly between 1908 - 1940; also, there is a significant sirian-libanese colony also, starting in the XIX century]

    Conclusion: it is true that we had a lot of miscigenation in Brazil, but the bulk of miscigenated population arised among the older population waves (I´m not saying that you will not find people of black+italian or black+german ascendancy, but this will be probably rarer, since the later waves _ particularly the german and italian ones _ didn´t had time to mix and used to be more self-centered). Geografically, the more mixed population occurs from the north to the center of the country, more or less encompassing also the states of Rio de Janeiro, Minas Gerais and something of São Paulo; the less mixed populations are the black people of Bahia, and the south of the country, encompassing also many areas in São Paulo (where the bulk of italian immigration came to).

    I myself am a good example: my father was born in Brazil in 1919, and his parents were portuguese that arrived at the beginning of the XX century to work in the remodelation of downtown Rio de Janeiro by Major Pereira Passos; my mother was a mix of portuguese, blacks and amerindians of much older miscigenation, essentialy lost in the streams of time.

    http://en.wikipedia.org/wiki/Immigration_to_Brazil

  • JL

    “Buj, V., 1981, Average IQ values in various European countries, Personality and Individual Differences, 2, 168-169″

    Buj’s study is garbage. He recruited his samples from capital cities, and apparently did nothing to ensure that they were representative. The standard deviations for some countries were >30, which is ridiculous. Buj’s data also fail a crucial test of convergent validity:

    “But the data of Vinko D. Buj seem not to be ideal for differences within Europe because these data yielded correlations with student assessment studies of only around r=-.10 to .07. In contrast, the mean IQs of the Lynn & Vanhanen collection (including Buj) correlated with student assessment studies within Europe at r=.61 (N=31; grade), r=.71 (N=29; age) and r=.67 (N=35; student assessment sum, all corrected).” (H. Rindermann)

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 »