Here is an example of why those interested in the history of economics  
such as Robert Dimand should take Rushton, or by extension, human  
biology and genetics, seriously. Ashkenazi Jews are a high IQ,  
economically successful group, that has also suffered from  
discrimination and persecution over the years. There are also certain  
genetic diseases which have a high incidence among this group. A group  
at the University of Utah has put forth a hypothesis that links these  
facts to natural selection for intelligence among this group.  
  
Albert Himoe  
  
Read the the paper here  
<http://homepage.mac.com/harpend/.Public/AshkenaziIQ.jbiosocsci.pdf> :   
  
This paper elaborates the hypothesis that the unique demography and  
sociology of Ashkenazim in medieval Europe selected for intelligence.  
Ashkenazi literacy, economic specialization, and closure to inward gene  
flow led to a social environment in which there was high fitness payoff  
to intelligence, specifically verbal and mathematical intelligence but  
not spatial ability. As with any regime of strong directional selection  
on a quantitative trait, genetic variants that were otherwise fitness  
reducing rose in frequency. In particular we propose that the well-known  
clusters of Ashkenazi genetic diseases, the sphingolipid cluster and the  
DNA repair cluster in particular, increase intelligence in  
heterozygotes.  
  
Other Ashkenazi disorders are known to increase intelligence. Although  
these disorders have been attributed to a bottleneck in Ashkenazi  
history and consequent genetic drift, there is no evidence of any  
bottleneck. Gene frequencies at a large number of autosomal loci show  
that if there was a bottleneck then subsequent gene flow from Europeans  
must have been very large, obliterating the effects of any bottleneck.  
The clustering of the disorders in only a few pathways and the presence  
at elevated frequency of more than one deleterious allele at many of  
them could not have been produced by drift. Instead these are signatures  
of strong and recent natural selection.