Reddit reviews Evolution and the Genetics of Populations: Genetics and Biometric Foundations Vol. 1

"Just in case anybody was taking this seriously, several of the links provided are to alt-right (read, fashy) sources." Explain how? Because they're scientific sources that you need an account to go to?

"Also worth noting that this is a poster to r/the_dimwit who has a frog meme as their banner, so I doubt that this is a good-faith effort to engage." Uh no I never posted to that subreddit unless you're just trying to do an ad hominem here.

"And just to counterpoint their thesis: intra-racial genetic diversity is higher than inter-racial diversity. That is to say, there is on average more variation within "black people" than there is between any given black population and white population. Turns out, skin color is kind of a shitty indicator." Ok, are you making the common argument against the taxonomic validity of race is that there is more genetic variation within than between races and so races must not be genetically different enough to be subspecies? This argument comes from a 1972 paper by the Harvard geneticist Richard Lewontin (Lewontin 1972). As will be shown, Lewotin’s argument fails because the metric of genetic differences he used has no obvious relevance to subspecies and because human races are equally or more genetically differentiated than recognized subspecies from other species are.

To understand Lewontin’s argument you have to have a conceptual grasp of a metric used in population genetics called an Fst value. Say we take two random animals from the species and look at what variant they have for some specific gene. There will be some probability, called the species’s total heterozygosity, that these gene variants will not be the same. Now say we do the same thing, but this time the two people are picked from the same sub-population within the species. This time the probability that their genes variants will not be the same will be called the sub-population heterozygosity. To calculate an Fst value you subtract a the sub-population heterozygosity from the total heterozygosity and then divide by the total heterozygosity:

Fst = (Ht-Hs)/Ht

In other words, an Fst value tells us how much the probability of picking different gene variants increases is the gene variants are picked at random from the entire species instead of the same sub-population. When calculating an Fst value, geneticists run this analysis for many genes and then find the average increase in heterozygosity.

When an Fst value is calculated for a species with multiple proposed sub-populations the values are averaged. So, for instance, if we conducted a study and found that two people having different gene variants was 10% less likely if they were both picked randomly from the Asian population instead of humanity at large, 8% less likely if they were both from the European population instead of humanity at large, and 6% less likely if they were picked from the African population rather than humanity at large, we might assign humanity an Fst value of (10%+8%+6%)/3% = 8% under this 3 race model. And this is what we would mean if we said something like “Only 8% of human genetic variation is between races while 92% is within them”. (The proportion of variation within groups is just 1 – the Fst value.)In 1972, Richard Lewontin became the first person to empirically measure the human Fst value and found it to be 6.3%. Based on this finding, Lewontin  declared that categorizing humans racially has no “genetic or taxonomic significance”.

Unfortunately, Lewontin never explained why an Fst value of 6.3% should mean races have no taxonomic or genetic significance. And it isn’t obvious that it should. In fact, Sewall Wright, a founder of population genetics and the man who invented Fst values, thought that they had nothing to do measuring taxonomic significance and continued to believe in Human races long after Lewontin’s famous article (Wright 1984).

That Lewontin’s idea never took hold in the world of biology can be seen by looking at a 2006 report be the U.S Geological Survey which reviewed more than a century of popular proposed criteria for when a population counts as a sub-species. It never mentioned Fst values let alone Lewontin’s paper (Haig et al. 2006).

Since Lewontin’s paper, research has suggested that the Human Fst value is actually about twice as large, 12%, as what Lewontin suggested (Elhaik 2012). This has not altered the stance of Lewontin on races. Indeed, it isn’t obvious that his stance is open to changing because he has never said how high an Fst value would need to be in-order for a population to be of taxonomic signficance. Instead, he has just said that the human Fst value is too low.

Furthermore, Lewontin has never adressed the fact that there are many species with recognized subspecies which have Fst values lower than Humans. As can be seen below, I was easily able to find 8 other species with recognized subspecies which have Fst values no higher than humans.  In fact, it isn’t hard to find researchers in the nonhuman literature taking any Fst value greater than zero as evidence that a population is a subspecies. See, for instance, Lorenzen et al. 2007 and Williams, Homan, Johnston, and Linz, 2004. Given this, it is clear that most biologists do not use Lewontin’s criteria, whatever exactly that is, for subspecies. And given that he has never made any argument for using it, neither should we.

Jackson et al. 2014, Elhaik 2012,  Lorenzen, Arctander, and Siegismund, 2008, Pierpaoli et al. 2003, Lorenzen et al. 2007, Jordana et al. 2003, Hooft, Groen, and Prins, 2009, Schwarts et al. 2002, and Williams, Homan, Joshston, and Linz, 2004.

Instead, many biologists use a criteria of subspecies based, in part, on the idea that a population can only be a subspecies if you can analyze the traits of an organism in that species and accurately predict whether or not it is a member of a proposed subspecies.

Based on this traditional understanding of subspecies taxonomy, multiple geneticists have pointed out that an Fst value of 6% is just the average increased probability of a single gene being different and that, by combining data from multiple genes at once into our analysis, we can very accurately predict whether or not someone will be a member of a given race (Mitton 1977). To get a conceptual understanding of what this means, imagine that you were told to guess whether a person was a male or a female based on whether they were taller or shorter than average, or hairier or less hairy than average, or whether their voice was higher or lower pitched than average, etc. If only one of these facts were told to you, you could make an educated guess but there would be a decent chance that you would be wrong. But if you combined data on, say, 20 such sex differences, your chances of correctly guessing the person’s sex would become quite high. By the same principle, a singe gene might not be a very good predictor of someone’s race, but that doesn’t mean that the combined data of many genes wont be.  It was on this basis that the famed population genetic A. W. F. Edwards dubbed this argument against race “Lewontin’s Fallacy” (Edwards 2002).