Hostname: page-component-5d59c44645-lfgmx Total loading time: 0 Render date: 2024-02-29T15:00:49.266Z Has data issue: false hasContentIssue false

NATURAL HISTORY OF ASHKENAZI INTELLIGENCE

Published online by Cambridge University Press:  17 June 2005

GREGORY COCHRAN
Affiliation:
Department of Anthropology, University of Utah, Salt Lake City, USA
JASON HARDY
Affiliation:
Department of Anthropology, University of Utah, Salt Lake City, USA
HENRY HARPENDING
Affiliation:
Department of Anthropology, University of Utah, Salt Lake City, USA

Abstract

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.

Type
Regular Articles
Copyright
2005 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)