ORIGINAL FRENCH ARTICLE: Les « races » sont d’abord une construction sociale
by Bertrand Jordan
Translated Sunday 4 April 2010, by Gene Zbikowskiand reviewed by
For some years, we have known that the analysis of human DNA makes it possible to define a person’s genetic ancestry, to know whether most of one’s ancestors are African, Asian or European.
By Bertrand Jordan, molecular biologist and geneticist. (*)
What does our DNA reveal about our genetic ancestry?
For some years, we have known that the analysis of human DNA makes it possible to define a person’s genetic ancestry, to know whether most of one’s ancestors are African, Asian or European. This requires in-depth study (far beyond the “genetic fingerprints” used by the police), and the ancestries thus revealed do not correspond to “races.” Moreover, such a genetic approach can also differentiate, just on the basis of their DNA, Belgians, Swiss, Italians, and French people, who, however, are obviously very closely related. A recently-published scientific article (*), the fruit of the collaboration of American, African and French researchers, gives the results of the analysis of several hundred Africans, Europeans and Afro-Americans. The authors examine the (rather limited) diversity of the ethnic and cultural groups in Western Africa and South Africa, but they also look into the Afro-Americans (the U.S. citizens who declare themselves to be “blacks”), and they obtain data which reveal the difference between genetic ancestry and “race.”
First of all, you need to bear in the mind the fact that, in the United States, “race” is an officially-recognized personal characteristic, and that, when censuses are taken, each individual fills out a form and checks the box of his choice: hence the Afro-Americans in this study are people who have checked the ad hoc box (Black, African American, or Negro) on the census form. Their DNA, exactly like that of the Europeans and Africans, was analyzed using the latest techniques; and the data were then processed using powerful computer programs in order to calculate the “genetic distance” separating all of the people being analyzed: that is to say, in sum, the degree to which they are related. Because, we are all related, since our species, homo sapiens, appeared in Africa about 200,000 years ago and we are all the product of migrations which, over 50,000 or 60,000 years, have progressively peopled the entire globe. The results of such an analysis can be represented in different ways, depending on whether you want to underline all the details or else, on the other hand, comprehend the general lines of distribution. If you opt for a general view, without getting hung up on small genetic differences, you find that the Europeans form (on that scale) a compact group; the African populations also are found to be grouped together, and are clearly separated from the European group. The Afro-Americans, on the other hand, are spread from one end of the diagram to the other. Consequently, some of them are 100% of African ancestry in terms of their chromosomes, others are mixed, and some could very well, from the genetic point of view, be considered Europeans. More precise studies, which examine every chromosome in detail, have been able to confirm this; nevertheless, all declare themselves to be Afro-Americans, just the same.
These results demonstrate the very particular conditions in which the Afro-American community was formed in the United States. Indeed, for a long time it lived under the conditions of the “one drop rule,” according to which “a single drop” of “black blood” (that is to say a single black ancestor, even very far removed) was enough to make you a black. It goes without saying that in those days, the census form was filled out by an official, and not directly by the person concerned... For the most part, those who were called “blacks” remained in that social category, in that culture, and today consider themselves to be Afro-Americans. Here, we put our finger on the dissociation between genetic ancestry and social “race,” even if it is self-proclaimed. This divergence, which is important in political and sociologigal terms, also has medical implications. There is often a question, at least in the United States, of an “ethnic medicine” in which “race” is used to understand the patient’s genetic constitution and to choose the treatment to be administered. And yet, we know that the differences (sometimes real) in pathologies among different population groups are more often linked to their living conditions than to their genes; above all, we see, with the recent data, that a single “racial” heading can cover a population that is very diverse genetically, and consequently cannot in any case determine the choice of a treatment.
Sometimes using the new genomic tools to look into the possible genetic differentiation of human groups is frowned on, especially in France. People get hung up on a simplistic phrase: “we are all 99.9% identical, so races do not exist,” which does not take reality in all its complexity into account. The work commented on above not only shows that our DNA bears the trace of our ancestors – there’s nothing amazing about that – but also that it reveals all the distance between our genetic history, our personal constitution, and the racial categories. Until recently, racial categories were supposedly founded on biology, whereas, and the history of Afro-Americans shows this, they are above all a social construct...
(*) The author of “L’Humanité au pluriel, la génétique et la question des races.” Published by Éditions du Seuil. This opinion article is an adaptation of an article that appeared in the February, 2010, issue of the magazine Médecine/Sciences.