Are Americans Hyperactive Neanderthals?

United States of Cavemania

During my recent journey across America (well, Indiana, Texas, and a few short stops) I read some journal articles for my class on genetic politics. I have already read three texts for that class, so it was an interesting change of pace.

Behavioral genetics and evolutionary psychology, two scientific disciplines with related but separate views on Human Nature, are controversial. And by “controversial” I mean “detested by the Left.” While BG and EP have different assumptions and often draw different conclusions, the Leftist belief of omni cultura ex cultura denies any genetic link to behaviors. When feminists attacked Harvard President Larry Summers for saying the sexes may think differently and apologized for it, we saw a once-great American university bow to Leftist pressure to bury genetic research.

This genetic politics post focuses on one surprising hypothesis generated by Behavioral Genetics (if not Evolutionary Psychology): that Americans may be more “Neanderthal” than other peoples. Specifically, an odd mutation linked to a form of ADD is prevalent among both whites and american indians. No “missing links” between this mutation and the standard genetic sequences are known. Either every single one has died out in the human population — or this mutation did not come from a human population.

Notes from a journal article and a commentary are extracted below.

In Our Genes,” by Henry Harpeding and Gregory Cochran, PNAS, 8 January 2002,

Evidence of positive selection acting at the human dopamine receptor D4 gene locus,” by Yuan-Cun Ding et al, PNAS, 8 January 2002,

“Associations have been reported of the seven-repeat (7R) allele of the human dopamine receptor D4 (DRD4) gene with both attention-deficit/hyperactivity disorder and the personality treat of novelty seeking.” (Ding et al 309)

“calculations of the allele age based on the relatively high worldwide population frequency of the DRD4 4R and 7R alleles suggest that these alleles are ancient (>300,000 years old. refs. 25 and 26; see Methods). On the other hand, calculations of the allele age based on the observed intraallelic variability (refs. 26 and 26, see Methods) suggest that the 7R allele is 5-10 fold “younger” (30,000-50,000 years old). Such a large discrepancies between allele ages calculated by these two methods usually are taken as evidnece that selection has increased the frequency of the allele to higher levels than expected by random genetic drift (26).” (Ding et al 313)

“It is difficult ot imagine what type of bottleneck could produce such results, i.e., strong worldwide LD for a single allele (DRD47R), yet little LD for the remaining alleles. A model that is consistent with the observed results is the “weak Garden of Eden” hypothesis (24), in which the DRD4 allele would be hypothesized to be ancient and present in indigenous populations, whereas the 7R allele was spread by expansion out of (and into) Africa.” (Ding et al 313)

“Given the highly unlikely recombination/mutation events required to generate the 7R allele from the 4R allele, a possibility worth considering is that importation of this allele from a closely related hominid lineage. What lineage that may be can only be speculated, but Neanderthal populations were present at the approximate time the 7R allele originated. Under this model, the coalescence time for the 4R and 7R alleles then would be ancient, with the importation occurring only recently, as measured by LD. Obviously, additional experimental work may clarify these speculations.” (Ding et al 313-314)

“It is possible also to speculate, however, that the very traits that may be selected for in individuals possessing a DRD4 7R allele may predispose behaviors that are deemed inappropriate in the typical classroom setting and hence diagnosed as ADHD.” (Ding et al 314)

“The D4 dopamine receptor (DRD4) locus may be a model system for understanding the relationship between genetic variation and human cultural diversity.” (Harpending and Cochran 10)

“[Ding et al] showed that the allele associated with ADHD has increased a lot in frequency within the last few thousand to tens of thousands of years.” (Harpending and Cochran 10)

“This curious pattern, an allele that has been in the population for a very long time at a very low frequency, suggests that some kind of balancing selection has been maintaining 7R, but preventing it from becoming common until recently. An alternative is that 7R was incorporated form another hominid species during the expansion of modern humans.” (Harpending and Cochran 10)

“It is entirely possible that some psychological traits are adaptive yet, because they are irritating or undesirable, are called mental illness.” (Harpending and Cochran 10)

“Even if 40 or 50 thousand years were too short a time for the evolutionary development of a truly new and highly complex mental adaption, which is by no means certain, it is certainly long enough for some groups to lose such an adaption, for some groups to develop a highly exaggerated version of an adaption, or for changes int eh triggers or timing of that adaption to evolve.” (Harpending and Cochran 10-11)

“These selective forces must not be the same in all populations, because the 7R allele is quite common in some populations (South American Indians), exists at intermediate frequencies in others (Europeans and Africans), and is rare or non-existant in yet others (East Asia, !Kung Bushmen) (2).” (Harpending and Cochran 11)

“Because the prominent phonotypica effects of 7R are in males, we need to ask what is the niche in human socities for males who are energetic, impulsive (i.e. unpredictable) and noncompliant?)” (Harpending and Cochran 11)

“Boserupt (16) calls these ‘female farming systems,’ a euphemism for societies where men live off women. Freed from domestic responsibility, men can occupty their time decorating themselves and planning the next raid.” (Harpending and Cochran 11-12)

“There is an unsettling parallel with the dad males of the working class in contemporary industrial societies and the cad males of the underclass (17).” (Harpending and Cochran 12)

“One study found that a simple of difficult infants survived a drought at a higher rate than easy infants (18).” (Harpending and Cochran 12)

“It is probably no accident that two of the best known ethnographies of the twentieth century are titled ‘The Harmless People’ about the !Kung who have few or no 7R alleles, and “The Fierce People,” about the Yanomamo with a high frequency of 7R.” (Harpending and Cochran 12)

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