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January 14, 2003

Human Biodiversity Redux

Long time readers can basically ignore this post-it deals with general and specific points and the logic behind my ideas about human biodiversity. Not too long or detailed.

1) As Jason Soon notes, there is a persistent difference in "g" between a variety of groups (Ashkenazi Jews at the high end-various tribal peoples in the Old World the low end)

2) We know IQ is 30-80% genetic (I'm giving the most wide range, though somewhere on the high side of 50 is probably the modal value that would come up if you polled "experts")

3) The black-white IQ gap in the United States has been rather steady (shifting between 10-15 points) for about 100 years

4) Social conditions (and the income gap between) of both blacks and whites have changed, but the IQ gap has remained

5) Some new immigrant groups, and some non-white groups overseas, especially those of Northeast Asian extraction (Chinese, Japanese and Korean) seem to score high on g-loaded tests. Especially in visual-spatial skills

6) Blacks from middle and upper-middle income backgrounds score rather low-even compared to low income whites and Asians

7) Some groups initially scored rather low (southern and eastern Europeans during World War I), but later came up to the mean of their new nation (or higher, as in the case of European Jews). Others on the other hand perform poorly on g-loaded tests. This indicates that bias and acculturation are factors, but some groups may lack aptitudes that others have but do not express on first blush

8) Races exists. There are rough clusters of humans that have branched off from each other via population bottlenecks. Roughly, the Bantu peoples of Congo and those of South Africa can be genetically shown to have more affinity with each other on average than to a Swede or a Korean. But, as Steve Sailer would say, they are fuzzy sets. African mt-DNA lineages for instance are found in all branches, because they are the most diverse, and Eurasian (and New World populations) are the result of founder effect from base populations in Africa that emigrated ~80,000 years ago. In their turn, the various Eurasian branches of humanity separated from each other, so that Europeans and Northeast Asians parted ways as genetically relatively isolated populations (from each other) by ~40,000 years ago. This does not imply gene flow did not occur, but geographic boundaries such as the Sahara, the central Asian massifs and various forms of agriculture dictated by climate created sharp clines in some regions that delineate boundaries between geographic races [1]

9) The tripartite separation between Europeans, Africans and East Asians and analysis of a variety of traits seems to map well on the genetic relatedness, Europeans and East Asians, though different, tend to cluster with each other, while Africans tend to express different phenotypes

10) The picture is incomplete, many groups are not willing to give blood because of historical distrust of scientists (Australian Aborigines and Native Americans), while detailed analysis of behavior and standardized testing are far from rigorous for most of the world outside of Europe, the United States and Eastern Asia (African Americans, about 20% European, are used as a proxy for West African in my mind)

11) There are certain physiological traits that can not be disputed-black Africans have the highest twinning rates & fasted physical development (early puberty), while East Asians show results at the other extreme

All these facts, and more that I can't think of at this moment, hint to me that there might very well be differences on average that are non-trivial and might have public policy and social implications. There are counter-examples, the rise and fall of the Sephardic Jewry, the low IQs of Koreans in Japan, the small closing of the black-white IQ gap, etc. But none of these are compelling enough for me to reject the hypothesis that human biodiversity is factually probably correct-and just as those who accept that "race does not exist" can explain away the points I have made above, I believe I can formulate plausible explanations within an HBD paradigm for these "anomalous results." The key is that I think my explanations are less strained than those who reject the idea of race.

Finally, let me add this, we know that human populations do start out from small groups and expand, and hint at population bottlenecks and rapid growth. Iceland and Ireland are two examples. What are the chances that historically separated populations will have all the exact same aptitudes?. To me the answer is that it is unlikely, that by chance and genetic drift various human populations will develop their own frequencies of various alleles that code for phenotypes. They will have their own response to environments and adapt both culturally and biologically. ‘tis nature as work. Man is a social animal, but biology is still the bedrock of our nature.

[1] You walk from Brittany across Europe and cross the Bosporus and go through the Middle East and into South Asia. The cline would be slow and gentle, as white Europeans merge into olive Middle Easterners who somewhere in the mountains of the Hindu Kush start to become brown South Asians. This whole western stretch of Eurasia has traditionally been the home of the "Caucasoid" race-but once in India, there is a relatively sharp demarcation between the Tibeto-Burman peoples of the highlands around the subcontinent's northern and eastern fringe and the brown Indians of the lowlands. Why is this? I suspect that different forms of agriculture and lifestyle issues (the rather precipitous rise in elevation that creates vastly different microclimates over a short distance) played a part in preventing too much intermarriage, though the mixed phenotypes in Nepal and to a lesser extent Assam and Bengal illustrate that it did happen. Similarly, the Bantu people spread no further than the central region of modern South Africa because the western Cape was not conducive to their tropical agriculture with its Mediterranean climate. This coincidence of geography preserved the Khoisan peoples so that they lasted until the Dutch appeared on the scene to execute the inevitable genocide

From Jason Malloy:

It is especially important to note that for both racial groups the head
size X IQ correlation exists within-families as well as between-families,
indicating an intrinsic, or functional, relationship, as explained in
Chapter 6. Equally important is the fact that within each sex, whites and
blacks share precisely one and the same regression line for the regression
of head size on IQ. When blacks and whites are perfectly matched for
true-score IQ (i.e., IQ corrected for measurement error), either at the
black mean or at the white mean, the overall average W-B difference in head
circumference is virtually nil.

Taken together, these findings suggest that head size and IQ are similarly
related to IQ for both blacks and whites. Although matching blacks and
whites for IQ virtually eliminates the average difference in head size,
matching the groups on head size does not equalize their IQs. This is what
we in fact should expect if brain size is only one of a number of brain
factors involved in IQ.

[source Jensen's G FACTOR]

Posted by razib at 01:04 AM