January 15, 2005

Racial (and non-racial) differences

A recent protracted discussion over at Gene Expression gives me the opportunity to discuss an important issue in thinking about racial differences. We were discussing whether or not Mongoloids have a spatial genetic endowment for visuospatial (V/S) ability, or whether their high performance in V/S tests may be due to their use of the logographic system from an early age. During this discussion, the V/S performance of Eskimos was cited in support of the genetic explanation, to which I replied that Eskimos are hardly typical for Mongoloids, and we should not base conclusions for Mongoloids based on Eskimos, just as we would not base conclusions for Caucasoids based on Swedes. After many twists and turns, my counterpart in the debate came up with this illustrating quote, which will serve as the starting point in our discussion:
As Swedes are typical of Caucasoids broadly considered in terms of prognathism, so Eskimoes are typical of Mongoloids broadly considered in terms of visuospatial ability.
Any two populations will almost invariably differ in their distributions for almost any physical attribute (+), and this includes degree of prognathism, IQ scores, scores on tests of V/S ability, height etc. Many of these differences may be shown to be statistically significant based on sample sizes, and this will usually indicate differences in causal factors (genetic or environmental) between them. Some of them may also be shown to be "large" allowing us to differentiate between the populations, as in e.g., several measures of facial flatness would differentiate Swedes from several Mongoloid groups. It may also be that several attributes may not show large differences in themselves, but their correlated differences would.

Races, which as I have stated elsewhere exist as clusters of phenetic similarity, are special cases of populations which are (1) sufficiently differentiated and which show a relative persistence (2) in time to make them useful concepts. In this sense, Caucasoids and Mongoloids are races, and Swedes/Eskimos are identified as Caucasoid and Mongoloid.

The Swedish population differs from the Caucasoid population as does the Eskimo population from the Mongoloid one. This is a consequence of our observation (+) above. In some attributes, e.g., prognathism, Swedes may not be much different than Caucasoids in general, and this may also the case for e.g., frequency of epicanthic fold in Eskimos compared to Mongoloids. Hence, Swedes and Eskimos are typical for their respected races for this attribute.

If we take other attributes, e.g., the very low cranial index of Eskimos or the very light pigmentation of Swedes we see that these deviate from those of their respected races. Indeed, Swedes might resemble some Uralic groups in terms of pigmentation more than they do Armenians, and Eskimos resemble Negroids in terms of cranial index more than they do the Chinese.

The above discussion illustrates the distinction that needs to be made between racial differences such as the naso-dacryal subtense, a measure of nasal flatness, and non-racial differences such as the cranial index. The former differentiates Caucasoids from Mongoloids while the latter does not.

One must exercize caution when generalizing from the features of populations within races to the races themselves. This mistake was made in the past, when e.g., it was believed that Caucasoids and Mongoloids were differentiated on the basis of the cranial index, yet now we know that this is not the case.

There are two reasons why this mistake persists. Practically, one is rarely exposed to the full range of variation within a race, and thus tends to generalize from the subset to the whole. For example, many people tended to identify light skin pigmentation as a main feature of Caucasoids which led to naming them as "whites", and yellowish pigmentation as a main feature of Mongoloids, yet there are millions of yellowish or dark Caucasoids and many northern Mongoloids who are paler than southern Caucasoid groups.

The second reason is more sinister, as people often want the identified differences to be racial in character, since this allows them to practice the sort of politically-motivated racial essentialism that has been out of vogue in anthropology for several decades. Nasal flatness, the presence of epicanthus, or the presence of Y-haplogroups have a racial significance, yet they are value-free, and hence cannot be politicized, unlike things like V/S ability or other useful features.

Getting back to the original quote, we know that Swedes are orthognathic and that this is typical Caucasoid feature. We do not know that Eskimos have a genetic endowment for a high V/S ability, and we should not infer that their high V/S performance reflects a Mongoloid specialty. Such a generalization would be akin to a group of Polynesians being exposed to a group of blond English soldiers and concluding that Europeans are generally blond.

Once many Mongoloid groups have been sampled, especially those who have not been exposed to the logographic systems and are reasonably thought to be representative of Mongoloid populations, we will be able to conclude whether high V/S performance is a racial feature of the Mongoloids.

Until enough evidence points in that direction, we must not add to Rushton-like laundry lists of differences, which have been shown to be suspect. A much healthier (and honest) attitude is to differentiate among features known to be of racial significance, like nasal projection, features known to be of no racial significance, like the cranial index, and features whose racial significance is uncertain, such as V/S ability.

(1) There is no a priori definition of "sufficiently"; sufficiently with present-day technology will suffice as a working definition.
(2) Since gene flow occurs between races, these are not necessary permanent; on the other hand it makes little practical sense to name recently admixed groups of varying ancestral proportions such as African Americans or Latin Americans as races.

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