Wednesday, August 27, 2008

Spencer Wells at Chautauqua

 
Spencer Wells is Explorer in Residence at the National Geographic Society. He has impeccable credentials: Ph.D. with Richard Lewontin, and postdoc with Luigi Luca Cavalli-Sforza and Sir Walter Bodmer. Wells heads the The Genographic Project, a project that collects and analyzes DNA samples from individuals around the world in an attempt to understand human evolution and migration.

Wells spoke last Wednesday morning in the amphitheater. He gave an interesting and informative lecture on "Deep Ancestry: Inside the Genographic Project." Most Sandwalk readers are familiar with the basic results of these studies. They indicate that modern humans originated in Africa and rapidly spread from there to all other continents. The controversy is about timing. Wells promoted the view that the last migration out of Africa took place only about 50,000 years ago.

Before the lecture, I explained to my students that this type of DNA sequence analysis relies on the fact that different human populations are genetically distinguishable. What this means is that scientists are able to tell what group you belong to by looking at your DNA. This establishes that there is a biological difference between races/populations. That's why you can trace migration routes.

Wells explained this very well without using the "race" word. Africans split from the groups on all other continents less than 100,000 years ago. Later on the migrating population subdivided into Europeans, Asians, and native Americans (+ others). In response to a question after the lecture he made the standard politically correct statement ...
Listen, I’m a scientist, and to the extent that people listen to scientists, I would like them to absorb this message, that scientifically speaking, races have no biological basis.
This got the expected round of applause from the audience. (They love that stuff at Chautauqua.) Nobody seemed to notice the discrepancy between what he said in his lecture and the idea that "races have no biological basis."

Aside from that minor glitch, Wells did a fine job of explaining the science behind these studies. The Genographic kits were on sale at the Chautauqua bookstore and I suspect they sold a lot of kits last week. According to Wells, the Genographic Project is the largest DNA typing program in the world and the information it returns to you on your ancestry is much more reliable—and cheaper—than many of the for-profit companies that have sprung up recently.


[Photo Credit: Chautauquan Daily]

12 comments :

  1. In my mind, the word "race" in the human-diversity context includes suites of correlated characters, as well as the unfortunate history of the word and the concept of patterns of human phenotypic variation. Inevitably, "race" is a word with a great many negative connotations, something that "molecular sequence variance" doesn't have to deal with.

    I don't know of any serious scientists linking probably-neutral variation in non-coding sequences (or synonymous substitutions) to phenotypic traits of obvious importance in modern societies. I've yet to see a serious paper that associates particular mtDNA sequences with performance on IQ tests, for example (and lets not even start about the problems of IQ).

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  2. Maybe race is a loaded and simplistic term in its commonplace use. Specially becuase it fails to note that one race can give origin to another, changing its phenotype.

    So two phenotypically different races A and B can be more closely related to each other than to a third C that under common notions of race you would have lumped with A.

    If we keep thinking cladistically, african populations gave origin to all other races. So, we would all be "black" even if we are not so phenotypically. A limbless snake does not cease to belong to the tetrapods just because it lost its limbs. It originated from a tetrapod, and that's what counts: its phylogenetic affinities.

    Commonly used notions of race hide the fact that many of the most basic clades of humans are all african, in other words, it fails to make the distinction between the different groups of "blacks" that have more scientific evidence to be called a "race" than for the more recent divergence between whites and asians.

    We originated from a black ancestor;
    in fact, not from all of africa, but from a particular subpopulation, a "clade" (a much better term perhaps than race) who of course are more closely related to their pale descendants, than to other clades of dark-skinned people within africa that diverged long way before the origin of white people, and that have striking phenotypic differences.

    All this is lost under commonly accepted, cultural definitions of race which emphasize only differences but fails to see the pattern of common ancestry leading us directly to africa.

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  3. I agree with thebrummell and sanders. He was avoiding the common, politically charged, and biologically incorrect use of the term "race".

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  4. jim says,

    I agree with thebrummell and sanders. He was avoiding the common, politically charged, and biologically incorrect use of the term "race".

    Then what meaning of "race" did he intend?

    Remember, he specifically said that he was speaking as a scientist. Is there any scientific use of the word "race" that is consistent with "no biological basis"?

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  5. the brummell says,

    I don't know of any serious scientists linking probably-neutral variation in non-coding sequences (or synonymous substitutions) to phenotypic traits of obvious importance in modern societies.

    You may want to re-phrase that sentence. There's an entire industry of SNP analysis on microchips that refutes it.

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  6. Wells spoke too broadly, but his statement may have a kernel of truth with regard to the work that he does.

    I remember a television program about Wells' research in which he searched for bearers of the oldest versions of certain patrilineal genes. The program showed Wells meeting with one such person living in mid-Asia. The fellow was a sort of Everyman, bearing features of all of what we think of as the various human "races" (the slightest suggestion of epicanthic folds, medium skin pigmentation, etc.).

    Thus, groupings of features we identify as belonging to certain races may not easily correspond to distinct subpopulations throughout recent human evolutionary history, and I think it's in this sense Wells may have meant his remark.

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  7. People are prone to confuse and mix diferent meanings of the words and "race" is no exeption.

    Here is a best definition of biological race that I so far found:

    American Heritage Dictionary
    5 Biology
    1. An interbreeding, usually geographically isolated population of organisms differing from other populations of the same species in the frequency of hereditary traits. A race that has been given formal taxonomic recognition is known as a subspecies.

    Obviously, in the context of biology saying that "race" has no biological basis is absurd. The only interesting thing here would be to know if Wells truly, deeply believes what he said. Regardless the answer, it's quite illuminating. If yes, it shows the power of self-delusion; if no, it shows the power of self-preservation instinct.

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  8. In response to Larry Moran

    Then what meaning of "race" did he intend?

    Remember, he specifically said that he was speaking as a scientist. Is there any scientific use of the word "race" that is consistent with "no biological basis"?


    The whole quote...

    Listen, I’m a scientist, and to the extent that people listen to scientists, I would like them to absorb this message, that scientifically speaking, races have no biological basis.

    You will have the advantage on this one, having been there. I am keying off the use of "races", and interpreting it to mean the commonly used versions based on skin tone and eye shape. As mentioned by others, the term is so broadly used in common dialogue, that I can't help but think of that first. So I believe that he was using that as well.

    But yes, that lead-in to the statement could imply something else. I guess I'm giving him the benefit of the doubt by my interpretation.

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  9. Jim says,

    I am keying off the use of "races", and interpreting it to mean the commonly used versions based on skin tone and eye shape.

    Just out of curiosity, do you think there's no biological basis to skin color and eye shape?

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  10. Just out of curiosity, do you think there's no biological basis to skin color and eye shape?

    Now you're talking about individual phenotypes (do we want to get into the definition of "phenotype"?), which is a discussion at a different scale than a discussion of race. The widely-used discussion of "race" includes suites of phenotypes. Hence the earlier comment by Jud about individuals with apparent combinations of features.

    I talked about scientists associating neutral variation in sequence with socially-important phenotypes, to which Dr. Moran replied:

    You may want to re-phrase that sentence. There's an entire industry of SNP analysis on microchips that refutes it.

    We may be needlessly splitting hairs here - I'm not interested in variation in non-coding sequences that may be very near to coding sequences of interest.

    What I meant was I have yet to see a serious paper that links, say, particular microsatellite alleles with success or failure on standardized tests of intellectual performance. I have heard of some studies linking extreme sequence variants, like repeat regions hundreds of times longer than the population average, to such behavioural phenotypes, but those are usually in the context of disruption of basic cellular processes like DNA double-strand break repair.

    I would be grateful if you could point me at a paper that clearly associates (correctly or incorrectly) variation in non-coding sequences or synonymous substitutions in coding sequences with human behavioural variation.

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  11. The Brummel asks,

    I would be grateful if you could point me at a paper that clearly associates (correctly or incorrectly) variation in non-coding sequences or synonymous substitutions in coding sequences with human behavioural variation.

    Are you serious? Why are you focusing on human behavior? Is that the only kind of biological variation that you can think of?

    I don't give a hoot whether or not there are heritable differences in behavior between different races. Do you?

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  12. The brummell said:

    "I would be grateful if you could point me at a paper that clearly associates (correctly or incorrectly) variation in non-coding sequences or synonymous substitutions in coding sequences with human behavioural variation."

    Here you go:
    http://www.ncbi.nlm.nih.gov/pubmed/18212819
    Arguably, promoter region is a non-coding sequence.

    MAOA is linked to aggressive behaviour:
    http://www.ncbi.nlm.nih.gov/pubmed/18463263

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