On Monday the NY Times ran an op-ed pice by Armand Marie Leroi, an evolutionary developmental biologist, on the concept of “race.” This paper reproduces an argument which has been gaining wider currency as a result of genetic studies: that, contrary to what anthropologists have to say on the subject, perhaps “race” isn’t a purely social construct, but does have some scientific validity after all.

After reading the article, it turns out that Leroi is playing word games.

The physical topography of our world cannot be accurately described in words. To navigate it, you need a map with elevations, contour lines and reference grids. But it is hard to talk in numbers, and so we give the world’s more prominent features – the mountain ranges and plateaus and plains – names. We do so despite the inherent ambiguity of words. The Pennines of northern England are about one-tenth as high and long as the Himalayas, yet both are intelligibly described as mountain ranges.

So, too, it is with the genetic topography of our species. The billion or so of the world’s people of largely European descent have a set of genetic variants in common that are collectively rare in everyone else; they are a race. At a smaller scale, three million Basques do as well; so they are a race as well. Race is merely a shorthand that enables us to speak sensibly, though with no great precision, about genetic rather than cultural or political differences.

Leroi is acting like Humpty Dumpty in Through the Looking Glass:

`When I use a word,’ Humpty Dumpty said, in rather a scornful tone, `it means just what I choose it to mean — neither more nor less.’

`The question is,’ said Alice, `whether you can make words mean so many different things.’

`The question is,’ said Humpty Dumpty, `which is to be master — that’s all.’

The sad fact is that race is not simply a shorthand for Leroi’s maps with elevations, contour lines, and reference grids, but refers to all kinds of cultural and political differences that have nothing to do with genetics. More importantly, these genetic difference map rather poorly on to our common sense notions about “race,” in ways that do nothing to help us understand the many important genetic issues that Leroi believes the term will help us face.

In order to make this point clearer than I ever could, I’ve invited my friend, population biologist Fredrick Gentz, a Ph.D. candidate at Temple University, to comment on the article.

Below are quotes from the article, followed by Fred’s commentary:

But this is not true when the features are taken together. Certain skin colors tend to go with certain kinds of eyes, noses, skulls and bodies. When we glance at a stranger’s face we use those associations to infer what continent, or even what country, he or his ancestors came from – and we usually get it right. To put it more abstractly, human physical variation is correlated; and correlations contain information.

Nothing new here. This is the anthropmetry of the early part of this century. It’s true that looking at a vast number of faces, body types, one can have a pretty good guess of continental origin. But what geneticists want to know is not “guess” estimates, but what is the error rate. Let me explain. Suppose I have a test for determining ‘race’ that is 75% accurate, and suppose I have another test that ascribes ‘disease type’ based on race that is 75% accurate. The chances of my picking the right race and picking the right disease for the race is (.75)(.75) = 0.563, or slightly better than flipping a coin.

Many European ‘racial’ diseases are quite restricted, but not entirely. Tay Sachs and other such afflictions are localized to various European groups, but also found elsewhere. If I was going to go by phenotype observations alone, I am quite sure most of my guesses of European ancestry would be quite erroneous (i.e. less than 75%). I would be better off asking each person where their parents and grand parents considered the ancestral home.

Indeed, a 2002 study by scientists at the University of Southern California and Stanford showed that if a sample of people from around the world are sorted by computer into five groups on the basis of genetic similarity, the groups that emerge are native to Europe, East Asia, Africa, America and Australasia – more or less the major races of traditional anthropology.

This is stuff done on Principle Components. The cluster analysis is rather interpretive, and alternative groupings can be generated. One must ask if the population origins were unknown would the same groupings be generated? Furthermore, if the study (I am not familiar with it) subdivides populations along continental lines, then it is a poor study as it obscures major regions of migration: like where are the Altaic genes among the Turks?, where is the region where the Europeans and Asians interact in Central Asia?; what about the slave trade from western Africa into southern Arabia and India? If all this study did was separate populations into five basic contiental masses, then it is useless as it obscured major events in human history.

Study enough genes in enough people and one could sort the world’s population into 10, 100, perhaps 1,000 groups, each located somewhere on the map.

Already we can theoretically distinguish one person from any other, alive or dead or unborn. Imagine 64 genes with 2 possible alleles each: then on the first gene you can separate the world into two populations, on the second an equal two (2×2 = 4), on the third gene, 2x2x2 = 8, and so on till 2^64, or 1.8×10^19 (more people then ever and will exist). So is everyone a unique ‘race’?

Soon it may be possible to identify your ancestors not merely as African or European, but Ibo or Yoruba, perhaps even Celt or Castilian, or all of the above.

‘Celt’ what is a Celt? The Celts were spread out across much of Europe, including Spain. Are the Spanish then Celts? If one says the Spanish derive a certain percentage of ancestry from the Celts, then are Latinos Celts?

The physical topography of our world cannot be accurately described in words. To navigate it, you need a map with elevations, contour lines and reference grids. But it is hard to talk in numbers, and so we give the world’s more prominent features – the mountain ranges and plateaus and plains – names. We do so despite the inherent ambiguity of words. The Pennines of northern England are about one-tenth as high and long as the Himalayas, yet both are intelligibly described as mountain ranges.

Names of topographical features are not ‘shorthands’ for geological inexpertise by the masses. The names are cultural products of an historical process by the people living in the regions. Too many people make the erroneous assumption that ‘race’ is a shorthand for scientific descriptions which are too complex for the majorities’ understanding. “Race’ is a cultural descriptor which serves multiple purposes. The above metaphor does not assist in the argument about ‘race’. Indeed, I could rewrite the above metaphor: there exist hidden strata which counfound the topological boundaries we commonly perceive on the surface. Likewise, there are hidden genetic ‘strata’ which confound our easy expectations of racial division we see on peoples faces.

One of the more painful spectacles of modern science is that of human geneticists piously disavowing the existence of races even as they investigate the genetic relationships between “ethnic groups.”

No geneticists are determining ‘genetic distances’ between populations. ‘Populations’ are abstract mathematical entities for which ethnic groups substitute. Identification of ethnic group is not made by the researcher, but by the group under study.

Such differences could be due to socioeconomic factors. Even so, geneticists have started searching for racial differences in the frequencies of genetic variants that cause diseases. They seem to be finding them.

This is important. By focusing research on racial differences (i.e. looking for genetic differences) social factors are likely to be overlooked or dismissed as irrelevant. There is only a limited amount of research money. Since the nineteenth century, the greatest advances have been made by relating health to living condition. Where genetics has played a significant role has been in programs to eradicate debilitaing genes from a population: e.g. Planned Parenthood.

That, it turns out, is much easier to do in people whose ancestors came from very different places. The technique is called admixture mapping. Developed to find the genes responsible for racial differences in inherited disease, it is only just moving from theory to application.

What researchers want is not ‘racial’ difference, but genetic distance. Quite different.

UPDATE: More from Alex Golub. Especially this article on “pharmacogenetics.”

UPDATE: More from Leroi here. With responses here. (via Gene Expression)