Tuesday, June 04, 2002

Questions and Answers on Race Send this entry to: Del.icio.us Spurl Ma.gnolia Digg Newsvine Reddit

Questions and Answers on Race I've gotten a lot of questions about the pieces of "race theory" that fall through the gaps. Pretty much everyone accepts that the Bell Curve's data on the predictive validity of IQ has borne up under intense scrutiny, and they grant that IQ is as useful a predictor for blacks and Hispanics as it is for whites. Most people also accept that Rushton's compiled data is accurate and consider his explanation to be the most plausible to date, but there are many points that fall through the gaps of this theory. I'm going to list in question and answer format some of the most common questions I've received and what I know about the possible answers. This is the first installment in an ongoing series. 1. I am not convinced that culture isn't responsible for current disparities in IQ among races. What do you think of Jared Diamond's Guns, Germs and Steel?

Diamond is just about the most coherent advocate of the environmentalist position. Recall that my position is that genes and environment are both contributors to phenotype, while Diamond will cede only that group differences are due to environmental differences. But one of the tenets of the theory of evolution is that different environments will exert different selection pressures. Equatorial regions have generally resulted in darker skin tone (with the exception of Southeast Asia), but there are other modifications that are more than skin deep (e.g. malarial resistance). In a nutshell, Diamond allows that environments for the groups differed but denies that major genetic differences could arise as a result of this difference. There are excellent book reviews by Steve Sailer and Rushton which cover Diamond thoroughly.

2. The American Indians (Amerinds) are genetically of Asian descent and have only had 10-20 kiloyears or so of genetic isolation. So why aren't they at least of equal IQ performance with whites, assuming they exhibit reduced performance because of disadvantage?

I don't have all the answers here, and as far as I know there have not been large scale IQ tests of Native Americans. There has been a lot of genetic evidence that indicates that Amerinds at some time in their past experienced a bottleneck or founder effect. What that means is that at sometime in the past (either in the migrating "founder" band or due to starvation) population levels dropped substantially and genetic diversity was choked off. It may be that individuals not representative of the North Asian population (e.g. with lower IQs) were members of the founders. This is speculation. The issue of Amerind origins (number of migrations, etc.) still hasn't been resolved to everyone's satisfaction. It is however agreed that Amerinds exhibit evidence of a bottleneck/founder effect. Here's a reference on this which has a bunch of pointers to literature.

3. Shouldn't there be "Asian genes" in Hispanic and Amerind populations?

Asian genes do exist in these populations, as you'll see from the lecture notes I linked. However the genetics are distinct enough that you can tell the difference between Hispanics, Amerinds and Asians if you were given two vials of blood. The differences are important enough that Hispanics and Amerinds are suboptimal blood donorsfor each other.

4. Southeast Asians

I don't know much about genetic studies on Southeast Asians, but they are genetically distinguishable from Northeast Asians. The genetic evidence shows that Southeast Asians are closer to Africans than the Northeast Asians are. Northeast Asians exhibit much less genetic diversity on the Y chromosome as certain alleles are not extant or of very different frequency in Northeast vs. Southeast Asian populations. It's not as severe as the Native American bottleneck/founder effect. If you have full text access to Nature Genetics, here's the link to the article. You might also want to check out Cavalli Sforza's massive population genetics book. I'll get it out of the library (eventually...) and take another look at it with specific attention to the Northeast/Southeast Asian distinction. I'm sure there will be relevant information in there.

5. Why might Ashkenazi Jews exhibit a high IQ not replicated by Sephardic Jews?

There are genetic differences between Ashkenazi Jews and Sephardic Jews, but the extent of these differences has not been totally hashed out (to my knowledge). Genetic evidence (Science 1999 October 15; 286: 451-453) to date indicates that:

The data suggest that present-day Ashkenazim descend from a relatively small number of ancestors, perhaps 10,000 to 20,000 in Poland and neighboring states at the beginning of the 16th century and even fewer 1000 years ago. The data are consistent with historical investigations that suggest that the wealthier classes of this population expanded rapidly despite many losses in subsequent pogroms.

I don't know why Ashkenazis would have higher IQs than the Sephardim if both communities practiced the selective marriage (essentially eugenic) practices that their genetic life history (via mtDNA) seems to indicate they did. I'm not aware of representative studies of the Sephardim mean IQ. However, to reiterate: if you've read my blog or the WSJ statement you know the IQ results are not meaningless - they are excellent predictors for the tested group.

What does all this mean? It means that there are still many things we don't know about the genetics of race. Population genetic based life histories are really hot right now, and I anticipate that we'll know a lot more in 10 years once we can sample the genetics of large populations more cheaply. There are obstacles to this process, but if they're overcome we will have a good shot at reconstructing the small scale dynamics of the human diaspora. As an ancilliary benefit we'll have an (improved) map of human genetics to follow Cavalli-Sforza's masterwork. As for intelligence, IQ is an excellent predictor for those tested - of whatever race - that correlates with what most would perceive as intelligence. I don't know how to rationalize the (important) cases above, but Rushton has done the best job to date with Asians, Europeans & Africans in his book "Race, Evolution, & Behavior". I think that Rushton is on to something, but his theory is incomplete if it can't account for the cases discussed above. It seems to me that the major issue is the question of Hispanic and Amerind genetics, which may be explainable in terms of the founder effect. Since such work is fraught with controversy, the normal process of rational discourse has been derailed and it may be a while before people publicly follow in Rushton's footsteps. However, as I've said before, the gold standard for intelligence research is an understanding of the molecular genetics of intelligence. This is the sort of research being pursued by groundbreakers like Plomin, Thompson, and Tsien. Once we understand which genes contribute to high intelligence, we can inspect the (representative) genotypes of populations and ask whether such genes are present or not. We may not be able to come up with evolution-based rationalizations for why these genes are present, but the molecular genetic evidence will be indisputable. It's my prediction that we will find that genes which contribute to high intelligence are most prevalent in the following populations: Europeans, Russians (Eurasians), Koreans, Chinese, Japanese, Ashkenazi Jews, Indian Brahmins, and (some) Middle Eastern groups (particularly the Iranians). This prediction is eminently verifiable/falsifiable, and I wouldn't be surprised to see subpopulations in groups I hadn't thought of exhibiting genetic predispositions to high intelligence. (Alaskan Natives strike me as a particularly likely case...) One other note: official pronouncements on genetics must by necessity include an ink cloud, so take any studies that "disprove race" on genetic grounds with a massive grain of salt. For example, don't be surprised to hear Orwellian doubletalk like this one:

"What we didn't see was any variation that really defined what might be considered to be an ethnic group," Vovis said. "What we did see, however, was that different versions of a gene may be present at higher frequencies in one group of a geographical origin over another."

posted by godlesscapitalist | 6/04/2002 09:01:00 PM | |

Principles of Population Genetics
Genetics of Populations
Molecular Evolution
Quantitative Genetics
Evolutionary Quantitative Genetics
Evolutionary Genetics
Molecular Markers, Natural History, and Evolution
The Genetics of Human Populations
Genetics and Analysis of Quantitative Traits
Epistasis and Evolutionary Process
Evolutionary Human Genetics
Mathematical Models in Biology
Evolutionary Genetics: Case Studies and Concepts
Narrow Roads of Gene Land 1
Narrow Roads of Gene Land 2
Narrow Roads of Gene Land 3
Statistical Methods in Molecular Evolution
The History and Geography of Human Genes
Population Genetics and Microevolutionary Theory
Population Genetics, Molecular Evolution, and the Neutral Theory
Genetical Theory of Natural Selection
Evolution and the Genetics of Populations
Genetics and Origins of Species
Tempo and Mode in Evolution
Causes of Evolution
The Great Human Diasporas
Bones, Stones and Molecules
Natural Selection and Social Theory
Journey of Man
Mapping Human History
The Seven Daughters of Eve
Evolution for Everyone
Why Sex Matters
Mother Nature
Grooming, Gossip, and the Evolution of Language
R.A. Fisher, the Life of a Scientist
Sewall Wright and Evolutionary Biology
Origins of Theoretical Population Genetics
A Reason for Everything
The Ancestor's Tale
Dragon Bone Hill
Endless Forms Most Beautiful
The Selfish Gene
Adaptation and Natural Selection
Nature via Nurture
The Symbolic Species
The Imitation Factor
The Red Queen
Out of Thin Air
Evolutionary Dynamics
The Origin of Species
The Descent of Man
Age of Abundance
The Darwin Wars
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Of Moths and Men
The Language Instinct
How We Decide
Predictably Irrational
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Fooled By Randomness
Descartes' Baby
Religion Explained
In Gods We Trust
Darwin's Cathedral
A Theory of Religion
The Meme Machine
Synaptic Self
The Mating Mind
A Separate Creation
The Number Sense
The 10,000 Year Explosion
The Math Gene
Explaining Culture
Origin and Evolution of Cultures
Dawn of Human Culture
The Origins of Virtue
Prehistory of the Mind
The Nurture Assumption
The Moral Animal
Born That Way
No Two Alike
Survival of the Prettiest
The Blank Slate
The g Factor
The Origin Of The Mind
Unto Others
Defenders of the Truth
The Cultural Origins of Human Cognition
Before the Dawn
Behavioral Genetics in the Postgenomic Era
The Essential Difference
Geography of Thought
The Classical World
The Fall of the Roman Empire
The Fall of Rome
History of Rome
How Rome Fell
The Making of a Christian Aristoracy
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Keepers of the Keys of Heaven
A History of the Byzantine State and Society
Europe After Rome
The Germanization of Early Medieval Christianity
The Barbarian Conversion
A History of Christianity
God's War
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The Sacred Chain
Divided by the Faith
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Pursuit of Glory
Albion's Seed
From Plato to Nato
China: A New History
China in World History
Genghis Khan and the Making of the Modern World
Children of the Revolution
When Baghdad Ruled the Muslim World
The Great Arab Conquests
After Tamerlane
A History of Iran
The Horse, the Wheel, and Language
A World History
Guns, Germs, and Steel
The Human Web
Plagues and Peoples
A Concise Economic History of the World
Power and Plenty
A Splendid Exchange
Contours of the World Economy 1-2030 AD
Knowledge and the Wealth of Nations
A Farewell to Alms
The Ascent of Money
The Great Divergence
Clash of Extremes
War and Peace and War
Historical Dynamics
The Age of Lincoln
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What Hath God Wrought
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