The pozzing about race is horrifying even in scientific, para-medical textbooks. I have here on my table a book called
Evolutionary Medicine (
Sterns and Medzhitov, 2016, Sinauer -- a very good publisher of biological texts). In Chapter 2, after presenting a detailed trajectory (with a cladogram) how modern human evolved since they left Africa, the authors give a subsection entitled "
Support of the concept of race is weak" (p.34). The idea is that, when you pick two random people in the world and examine their genes, you'll find that only 10% of their genetic differences are accountable by race. The percentage difference depends on how you look at things, and I reproduce the table (p.36) in the book, with minor modifications
| Polymorphism | Author | Number of Loci | Number of groups (i.e. races) | Diff. within populations / samples (%) | Diff. among populations within same groups (%) | Difference among groups (%) |
| Protein | Lewotin (1972) | 17 | 7 | 84.5 | 8.3 | 6.3 |
| Protein | Ryman (1983) | 25 | 3 | 86 | 2.8 | 11.2 |
| DNA (RFLP) | Barbujani (1997) | 109 | 4 or 5 | 84.4 | 4.7 | 10.8 |
Single-nucleotide
Polymorphism (SNP) | Li (2008 ) | 650000 | 7 | 88.9 | 2.1 | 9 |
(I'm not allowed to add hyperlinks in a table, so I have to list the papers separately. Fortunately, all are available for free.)
Lewotin (1972). The approportionment of human diversity.
Ryman (1983). Differences in the relative distribution of human gene diversity between electrophoretic and red and white cell antigen loci.
Barbujani (1997). An apportionment of human DNA diversity.
Li (2008 ). Worldwide Human Relationships Inferred from Genome-Wide Patterns of Variation
So in summary, current research show that race can account for 6-11% of the difference found between humans. So can we say, as Sterns and Medzhitov did, that "Support of the concept of race is weak"? My first complain is terminology. The authors seems to have confused "weakness" with "lack of magnitude". When you say that the support of something is (statistically) weak, we
don't mean that the observed differences are small; what we mean is that the observed difference are likely to be due to chance (in statistical parlance, we say the p-value is insignificant). So we can say "there is a strong support of a tiny difference" and vice versa. Of the four papers, only Barbujani presented the p-values (and they are often significant). Li uses various high-powered statistical tests and interpretation is not straightforword (SNP analysis itself carries oodles of statistical problems anyway). So in conclusion, Sterns and Medzhitov are NOT justified to say that "
support of the concept of race is weak"; at most they can say, "race accounts for a small difference of human biology, though the strength of the support is untested."
My second complain concerns the validity of
quantitative analysis. The two protein studies only measured a handful of proteins expressed in the red and white blood cells, which are poor shadows of the vast variety of human proteins. Comparisons between DNA sequences and especially SNPs can tell us only so much. We know there is a difference, but we don't know whether, or how much of the difference in DNA are actually expressed, or contribute to (or even correlate with) gene expression. In other words. we don't know whether the differences matter.
To further alleviate the rage of SJW harpies, Sterns and Medzhitov added that in the summary of the section (p.36):
Biological support of the concept of race is weak; race is primary a social construct.
Yet they want to have their cake and eat it too, for in the next sentence:
Because of the huge size of the genome, however, there are genetic difference associated with ethnicity that contain useful medical information about drug metabolism and disease resistance.
So race is "primary a social construct", but said "social construct" somehow informs us about drug metabolism, etc. Riddle me that! I conclude that 1) race is almost certainly a biologically real phenomenon, and 2) pure
quantitative assays, noting just how DNA sequences differ but NOT whether they differ in places that matter, may not represent the true magnitude of difference between races (for which we need to compare, say, the transcriptomes of various cell types for a large number of people, and that's tedious and expensive even today).
