Genome Study Points to Adaptation in Early African-Americans

Nicholas Wade, New York Times, January 2, 2012

Researchers scanning the genomes of African-Americans say they see evidence of natural selection as their ancestors adapted to the harsh conditions of their new environment in America.

The scientists, led by Li Jin of the Chinese Academy of Sciences in Shanghai, report in the journal Genome Research that certain disease-causing variant genes became more common in African-Americans after their ancestors reached American shores—perhaps because they conferred greater, offsetting benefits. Other gene variants have become less common, the researchers say, like the gene for sickle cell hemoglobin, which in its more common single-dose form protects against malaria. The Shanghai team suggests the gene has become less common in African-Americans because malaria is much less of a threat.

The purpose of studying African-American genomes is largely medical. Most searches for variant genes that cause disease take place in people of European ancestry, and physicians want to make sure they have not missed variants that may be more common in African-Americans and helpful for developing treatments or diagnosis.

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The unusually common variants identified by the Shanghai team are associated with higher risk of hypertensionprostate cancer, sclerosis and bladder cancer.

“Most of the genes associated with African-American ethnic diseases,” they write, “may have played an important role in African-Americans’ adaptation to local environment.” But the authors have not yet been able to identify the benefits they believe such genes conferred.

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The Shanghai researchers used a method for studying admixture, a geneticist’s term for when two populations or races intermarry; China has several such populations, perhaps accounting for the team’s interest. Using gene chips that analyze common variations in the human genome, researchers can deconstruct the chromosomes of an African-American, say, assigning each chunk of DNA to an African or European origin.

The scientists found that of the African-American genomes in their sample, 22 percent of the DNA came from Europeans, on average, and the rest from African ancestors, a figure in line with other estimates.

{snip}

{snip} Meanwhile, the ancestry of each segment can be identified from its pattern of single-nucleotide polymorphisms, or SNPs, the sites on the human genome where there is commonly variation in the A, T, C and G units that make up DNA.

Among human populations, there are very few absolute differences, meaning those in which all members of one population will have, for example, unit T at a site and all members of another will have unit G. But populations do have characteristic percentages. Among Europeans, 70 percent may have C and 30 percent A at a particular SNP site, whereas in Africans the ratio may be 40 percent C and 60 percent A. So a section of genome with C at this SNP site is somewhat more likely to be European.

This is hardly decisive in itself. But take a row of 10 SNPs, and if European ancestry is more likely for most of them, then that section of DNA is probably European in origin.

Geneticists can thus deconstruct the genomes of admixed populations into a mosaic in which each segment can be traced back to one or the other of the two parent populations. This is the basis of the Shanghai team’s approach. {snip}

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  • Otherworld33

    It’s not surprising groundbreaking research on race is being done in China. Nothing like this will happen in White countries for fear of angering the gods of the Leftists who run Whites countries: the Blacks.

    And for the NYT author, did the “harsh conditions” of America include malaria, dengue fever, slave raids, cannibalism, muti, etc?

    Notice the obligatory remarks about how humans are still basically identical, in spite of the evidence. The veneer is cracking, folks. It will take time, but the current paradigm on race is destined for the grave.

  • Rob Girouard

    You see all kinds of racial differences reported and discussed (and
    accepted) by the mainstream media yet when it comes to the differences in
    behaviors or intelligence they stomp their feet in outrage at such an idea, as
    if the brain would be immune from the effects of natural selection while the
    rest of the body is not.

  • Beloved Comrade

    Blacks do not run White countries.  They have neither the intelligence nor skills to run anything. They are the useful idiots and battering ram of the NWO masters, used to terrorize White communities.
    Obama is in charge of exactly nothing.  He is given his marching orders, reads lines from a teleprompter and does as he’s told.

    • The cost of the black undertow is so high the US can’t afford NASA anymore.

  • Andy

    The differences set forth are suggestive of the distinct possibility that a very significant
    contributing cause to deaths in transit on slave ships from Africa to the Americas might have
    been the result of dietary disruptures?  

    • Staying in Africa would have lead to more deaths. The slaves sold by blacks in Africa where convicts or defeated rival tribes. There are no prison in sub saharan Africa so justice is swift. The Zulus genocided the Hottentots instead of selling them. Malaria still kills a kid in Africa every 6 sec even after the Europeans told them what plants cure malaria.

  • Its possible that the genes didn’t help them and only made women less likely to avoid rape. Not all genes that increase offspring are good. In fact with plentiful year round food in the tropics a gene that made men not stick around and rape lots of women would let them spread their genes around. It wasn’t until europeans shared the cure for malaria that Africa became crowded since they no longer had to have 9 kids so 2 could live till breeding age.