Nicholas Wade and race: building a scientific façade

“…for he has no right to give names to objects which he cannot define.” –Charles Darwin

Do “races” exist as meaningful biological categories? Physical anthropologists and human biologists have been studying race (i.e., blacks vs. whites, or Europeans vs. Asians) for centuries. For most of that time, they subscribed to the perspective that race was a taxonomic category, and they sought to identify the biological characteristics (such as cranial shape or skin color) that characterized and defined these different groups. This perspective assumed that each individual was a member of a single racial category, that the differences between racial categories were biological, and that these categories were predictive of other traits (such as ancestry, temperament, intelligence, or health).

But it gradually became clear that this understanding was not scientifically sound. Groupings of people by skin color did not produce the same result as groupings of people by skull shape, nor of blood type. Furthermore, as scientists began to study human variation with the tools of genetics (in the process creating my fields, anthropological genetics and human population genetics), it became apparent that human genetic variation does not divide humans into a few discrete groups. There are virtually no sharp boundaries, either with physical features or with patterns of genetic diversity, that show where one population “ends” and the next “begins”.

These observations have led the majority of physical anthropologists, human biologists, and human geneticists in recent decades to conclude that the racial groups we recognize are social categories constructed in a specific cultural and historical setting, even if we consider physical features when categorizing people. These social categories can have biological consequences (for example, someone who experiences the stress of racism may be more likely to develop high blood pressure and hypertension than someone who does not).

Racial groupings differ from culture to culture. For example, although in the United States Chinese and Japanese peoples are usually viewed as one “race” (Asian), they are seen as members of different racial groups in South Africa. Racial groupings also vary over time within a single culture, as can be seen below in the United States census classifications of race over several decades.

The United States census classifications of race or color, 1890-1990. Table 1 from Lee, S. (1993) “Racial classifications in the US census 1890-1990.” Ethnic and Racial Studies Volume 16 (1).
The United States census classifications of race or color, 1890-1990. Table 1 from Lee, S. (1993) “Racial classifications in the US census 1890-1990.” Ethnic and Racial Studies Volume 16 (1).

 

However, according to former New York Times science writer Nicholas Wade, we should never have stopped thinking of race as a biological taxonomic category. In his new book, “A Troublesome Inheritance: Genes, Race and Human History”, Wade takes it upon himself to educate scientists about the errors of our interpretations of human genetic diversity.

Wade claims that the latest genomic findings actually support dividing humans into discrete races, and that the genetic makeup of different races contributes to behavioral and economic disparities.   In a spectacular failure of logic, he asserts that those who disagree that races are meaningful biological categories in humans must ALSO think that human populations do not differ genetically, or have not been affected by evolution.

 

Plus ça change, plus c'est la même chose
Plus ça change, plus c’est la même chose

 

There is a lot to criticize in this book, particularly Wade’s imaginative storytelling in chapters 6-10 (“a much more speculative arena,” as he puts it). He explains that English populations have a “willingness to save and delay gratification”, which “seems considerably weaker in tribal societies” (pp. 184-185), and these differences must be genetically based, despite his admission that “the genetic underpinnings of human social behavior are for the most part still unknown” (p. 15), and numerous critiques of this hypothesis. In chapter 8, he asserts that Jews are adapted for capitalism in a manner analogous to the Eskimo’s adaptation to survival in an Arctic environment (p. 214) — an assertion unsupported by scientific evidence, to put it mildly. (Wade seems to be unaware of the consequences of laws prohibiting Jews from owning land and farming over much of Europe for centuries – and instead speculates that “their genes were adapted for success in capitalism”).

But others have already critiqued these aspects of his book. I’m far more interested in the central premise of Wade’s argument, which is passing unchallenged by all but a few reviews: “At least at the level of continental populations, races can be distinguished genetically, and this is sufficient to establish that they exist” (p. 122). If Wade is right and races are distinct biological categories, then we would reasonably expect that they would be unambiguously different from each other genetically and physically (as well as behaviorally, according to Wade). One should be able to define each race with a set of objective criteria, which could be used by any person to independently reach the same classifications (and number of classifications) as Wade. Furthermore, these categories should have predictive power; that is, features that define race should be in concordance with new discoveries of genetic diversity.

What is race?
To begin with, Wade can’t provide a clear definition of “race.” He tries to rely instead on loose associations rather than definitive characteristics, which forces him to conclude both that physical traits define race but that the traits can vary from person to person: “races are identified by clusters of traits, and to belong to a certain race, it’s not necessary to possess all of the identifying traits” (p. 121).

With such a shifty, casual footing, it’s no surprise that Wade’s conclusions are unsound. He can’t keep the number of races straight:

Screen Shot 2014-05-20 at 8.21.17 PM

Wade can’t settle on a definite number of races because he can’t come up with a consistent, rigorous definition of what “race” means. He uses terms like “major race”, “race”, “subrace”, “group”, or “population,” but doesn’t provide any serious, objective ways to distinguish between these terms for arbitrary groupings of people arbitrary groups.

Rather than just announcing his subjective opinions about race, Wade wants to ground them in science. He tries to use genetics: “Such an arrangement, of portioning human variation into five continental races, is to some extent arbitrary. But it makes practical sense. The three major races are easy to recognize. The five-way division matches the known events of human population history. And, most significant of all, the division by continent is supported by genetics.” (p. 94)

To support his claim, Wade relies heavily on a 2002 paper (by Rosenberg et al.) that used a program called structure to group people based on similarities in markers distributed across the genome. He notes that the program identified five major clusters in this 2002 study, which corresponded to the major geographic regions (Africa, Eurasia, East Asia, Oceania, and America) of the world. Therefore, Wade argues, these results clearly show that humans are divided up into racial categories that match continents.

Charles Murray, author of The Bell Curve, who recently reviewed Wade’s book in the Wall Street Journal, agrees:

A computer given a random sampling of bits of DNA that are known to vary among humans—from among the millions of them—will cluster them into groups that correspond to the self-identified race or ethnicity of the subjects. This is not because the software assigns the computer that objective but because those are the clusters that provide the best statistical fit.

But Wade and Murray are both wrong. Structure didn’t simply identify five clusters. It also identified two, three, four, six, and seven clusters. (Rosenberg et al. 2002 actually identified up to 20 divisions, but 1-7 are the primary ones they discussed. They also divided their worldwide sample up into regions, and then ran structure within those regions, to look at more fine-scale population structure.)

 

Figure 1 from Rosenberg et al. 2003 showing Structure runs at 2, 3, 4, 5, and 6 populations. Each population is separated by a black line. Each thin vertical line represents one person. Ancestry groupings inferred from the program on the basis of genetic similarity are represented by different colors, so that a thin vertical line that is ~60% purple and 40% orange indicates a person who was inferred to have 60% ancestry from the “purple” genetic cluster and 40% ancestry from the “orange” genetic cluster.
Figure 1 from Rosenberg et al. 2002 showing structure runs at 2, 3, 4, 5, and 6 populations. Each population is separated by a black line. Each thin vertical line represents one person. Ancestry groupings inferred from the program on the basis of genetic similarity are represented by different colors, so that a thin vertical line that is ~60% purple and ~40% orange indicates a person who was inferred to have 60% ancestry from the “purple” genetic cluster and 40% ancestry from the “orange” genetic cluster.

 

Why? Researchers using structure have to define the number (K) of clusters in advance, because that’s what the program requires. The program was designed to partition individuals into whatever pre-specified number of clusters the researcher requests, regardless of whether that number of divisions really exists in nature. In other words, if the researcher tells structure to divide the sampled individuals into 4 clusters, structure will identify 4 groups no matter what–even if there is really only 1 group, or even if there are really 14 groups.

So, when Rosenberg et al. (2002) told structure to use K=6? They got six clusters, with the sixth corresponding to a northwestern Pakistani group, the Kalash. Does this make the Kalash a separate race? Wade doesn’t think so. When they told structure to use K=3? They got three clusters back, corresponding to Africa, Europe/Middle East/South Asia, and East Asia/Oceania/Americas. So are Native Americans and Australians not separate races? Rosenberg et al. never published any statistical evidence that justifies picking 5 races instead of 7, or 4, or 2 (although such methods do exist–see Bolnick et al. 2008). Wade seems to like K=5 simply because it matches his pre-conceived notions of what race should be:

“It might be reasonable to elevate the Indian and Middle Eastern groups to the level of major races, making seven in all. But then many more subpopulations could be declared races, so to keep things simple, the five-race, continent-based scheme seems the most practical for most purposes.” (p. 100)

Practical. Simple. Wade wants us to cut up human diversity into five races not because that’s what the statistical analyses show, but because thinking about it as a gradient is hard.
Wade isn’t even using the tools of genetics competently. The authors of the paper he relied on, as well as subsequent studies, showed that different runs of the program with the same data can even produce different results (Bolnick, 2008). Structure’s results are extremely sensitive to many different factors, including models, the type and number of genetic variants studied, and the number of populations included in the analysis (Rosenberg et al. 2005). When Rosenberg et al. (2005) expanded the 2002 dataset to include more genetic markers for the same population samples, they identified a somewhat different set of genetic clusters when K=6 (Native Americans were divided into two clusters and the Kalash of Central/South Asia did not form a separate cluster). In fact, Rosenberg et al. (2005) explicitly said:

“Our evidence for clustering should not be taken as evidence of our support of any particular concept of ‘biological race.’”

Finally, the creators of structure themselves caution that it will produce rather arbitrary clusters when sampled populations have been influenced by gene flow that is restricted by geographic distance (i.e. where more mating occurs between members of nearby populations than between populations that are located farther apart, a pattern we geneticists refer to as isolation by distance). As this pattern applies to the majority of human populations, it makes the results of structure problematic and difficult to interpret in many cases. These limitations are acknowledged by anthropological geneticists and population biologists, who interpret the results of structure cautiously. It’s very telling that Wade, a science reporter, chose to ignore the interpretations of the experts in favor of his own.

Human biological variation is real and important. I’ve studied it my entire professional career. We can see this variation most easily in physical traits and allele frequency differences between populations at extreme ends of a geographic continuum. Nobody is denying that. Let me repeat this: no one is denying that humans vary physically and genetically. All anthropologists and geneticists recognize that human differences exist. But Wade, and others who agree with him, have decided that certain patterns of variation—those which happen to support their predefined notions of what “races” must be—are more important than others.

Wade’s perspective fits with a larger pattern seen throughout history and around the world. Folk notions of what constitutes a race and how many races exist are extremely variable and culturally specific. For example, the Bible claims that all peoples of the world are descended from Noah’s three sons, mirroring the popular concept of three racial divisions (Caucasians, Africans, and Asians). On the other hand, the five-part division of races seems most “logical” to Wade. Anticipating confusion on this point he claims: “Those who assert that human races don’t exist like to point to the many, mutually inconsistent classification schemes that have recognized anywhere from 3 to 60 races. But the lack of agreement doesn’t mean that races don’t exist, only that it is a matter of judgment as to how to define them” (p. 92).

A matter of judgment. So, rather than being defined by empirical criteria, as Wade had asserted so confidently earlier in the book, it really is just a subjective judgment call. The differences between groups are so subtle and gradual that no objective lines can be drawn, so Wade draws his own on the basis of his own preconceptions.

How subtle is the gradient that Wade is chopping up? Humans are incredibly similar genetically. We only differ by about 0.1% of our genome. Compare that to chimpanzees, our closest relative. Individual chimps from the same population show more genetic differences than humans from different continents.

The genetic differences that exist in human populations are important, because they help us understand our evolutionary history. The most genetic diversity is found in populations in Africa, where our species originated. Subsequent migrations across the continents resulted in sampling a subset of the genetic diversity present in the ancestral populations; thousands of years of localized evolution and cultural practices have produced region-specific adaptations, such as the ability to thrive at high altitudes. These adaptations have influenced particular genes and traits, but the overall pattern of genetic variation is clinal, meaning that for the most part it varies gradually with geographic distance.  Groups that live close together are more closely related to each other (and more genetically similar) than they are to groups farther away. (People marry and have children more frequently with people who live close to them than they do with people who live farther away). Other evolutionary forces (founder effects, selection, drift, and migration) have all contributed to patterns of genetic diversity that we see in populations today.

But these patterns of human diversity don’t give us a scientifically viable definition of race as a taxonomic unit. As Agustin Fuentes puts it, with emphasis added:

“when you compare people from Nigeria, Western Europe and Beijing you do get some patterned differences…but these specific groups do not reflect the entire continental areas of Africa, Europe, and Asia (the proposed “continental races” of African, Caucasian and Asian). There are no genetic patterns that link all populations in just Africa, just Asia or just Europe to one another to the exclusion of other populations in other places. If you compare geographically separated populations within the “continental” areas you get the same kind of variation as you would between them. Comparing Nigerians to Western Europeans to people from Beijing gives us the same kind of differences in variation patterns as does comparing people from Siberia, Tibet and Java, or from Finland, Wales and Yemen, or even Somalia, Liberia and South Africa— and none of these comparisons demonstrates “races.”
In fact if you use the common level of genetic differentiation between populations used by zoologists to classify biological races (which they called subspecies) in other mammals, all humans consistently show up as just one biological race.”

(Also see Templeton AR, 2013. Biological races in humans. Studies in History and Philosophy of Biological and Biomedical Sciences, http://dx.doi.org/10.1016/j.shpsc.2013.04.010)

Wade even seems to agree with population geneticists that there aren’t any races, just clinal distributions of genetic diversity: “Because there is no clear dividing line, there are no distinct races—that is the nature of variation within a species.” (p 92).

In other words, he can’t define distinct races. He just knows them when he sees them

I’ve focused a lot of this review on numerous technical details because I think that it’s very important that non-geneticists understand the degree to which Wade is distorting the results of recent research on genome-wide human variation. I won’t speculate whether this distortion is deliberate or a result of simple ignorance about genetics, but it is serious. There is a great deal more in this book that also needs to be critiqued, such as Wade’s assertion that the genetic differences between human groups determine behavioral differences, resurrecting the specter of “national character” and “racial temperaments”. But as I’ve shown here, Wade’s book is all pseudoscientific rubbish because he can’t justify his first and primary point: his claim that the human racial groups we recognize today culturally are scientifically meaningful, discrete biological divisions of humans. This claim provides a direct basis for the whole second half of the book where he makes those “speculative” arguments about national character.  In other words, the entire book is a house of cards.

It’s also worth noting the extent to which Wade’s argument here is a variation on the Galileo fallacy: the fact that one bravely holds a minority view in science is considered to be sufficient evidence of the worth of one’s position. I’ve seen it used over and over again in responses to my criticisms of pseudoscience, and it’s no more persuasive for Wade than it is for creationists or homeopaths.


Further reading:

“If scientists were to make the arbitrary decision that biological race is real, can you think of a positive outcome?” –a nice piece by Holly Dunsworth: http://ecodevoevo.blogspot.com/2014/05/if-scientists-were-to-make-arbitrary.html

Agustin Fuentes’ online debate with Wade: (https://aaanetevents.webex.com/ec0606l/eventcenter/recording/recordAction.do?theAction=poprecord&AT=pb&internalRecordTicket=00000001fcaac3649dadd2c6e78a2511ed436c75acea0fcceaf7ff0731dc4216dec6996b&isurlact=true&renewticket=0&recordID=8614987&apiname=lsr.php&needFilter=false&format=short&&SP=EC&rID=8614987&RCID=e801bfd96855006077205e3d2e023699&siteurl=aaanetevents&actappname=ec0606l&actname=%2Feventcenter%2Fframe%2Fg.do&rnd=4944230866&entactname=%2FnbrRecordingURL.do&entappname=url0108l)

“The troublesome ignorance of Nicholas Wade”, also by Agustin Fuentes:
http://www.huffingtonpost.com/agustin-fuentes/the-troublesome-ignorance-of-nicholas-wade_b_5344248.html?utm_hp_ref=tw&utm_content=bufferfad4c&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

“On the origin of white power” by Eric Michael Johnson:

http://blogs.scientificamerican.com/primate-diaries/2014/05/21/on-the-origin-of-white-power/

A critique of Structure:
Bolnick DA. Individual ancestry inference and the reification of race as a biological phenomenon. In: Koenig BA, Lee SS-J, Richardson SS, editors. Revisiting Race in a Genomic Age. New Brunswick, NJ: Rutgers University Press; 2008. pp. 77–85.

Jon Marks: “The genes made us do it: The new pseudoscience of race.”
http://inthesetimes.com/article/16674/the_genes_made_us_do_it

Barbujani and Colonna, 2010. Human genome diversity: frequently asked questions.
http://www2.webmatic.it/workO/s/113/pr-1400-file_it-Barbujani-Colonna.pdf

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Many thanks to Deborah Bolnick, Colin McRoberts, Jay Kaufman, Jonathan Kahn, Troy Duster, and Rick Smith.

 

Please review my Site Policies before commenting. Disagreement with me is fine; bigotry is not.

577 thoughts on “Nicholas Wade and race: building a scientific façade

  1. dallas November 21, 2014 / 2:16 pm

    ” If Wade is right and races are distinct biological categories, then we would reasonably expect that they would be unambiguously different from each other genetically and physically (as well as behaviorally, according to Wade). ”

    No, we don’t. You are making the same old continuum fallacy that is in every egalitarian article.
    Vagueness alone does not necessarily imply invalidity.
    Just because something cannot be defined precisely it doesn’t mean that it doesn’t exist.
    Can you tell me for example where the color red commences on a rainbow? No, you cant but it doesn’t mean that the color red doesn’t exist.

    • Mike Ward March 3, 2015 / 10:40 am

      Jennifer is not committing this fallacy. It’s not that the boundaries between colours (or “races”) are fuzzy. It’s more like the question: “how many colours are there in the rainbow?” – which has no objective answer. But for some even better examples, see my link.

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