Race differences in behaviour: A review and evolutionary analysis

Quantitative trait loci associated with brain weight in the BXD/Ty recombinant inbred mouse strains

Adult C57BL/6J (B6) male mice had 37% heavier brains than did DBA/2J (D2) mice, while their body weights did not differ. The BXD recombinant inbred (RI) series of 20 strains, derived from a cross between B6 and D2 inbred strains, was used as the initial screen to determine significant associations between male brain weight and brain:body weight ratio, with allelic variation at 360 known marker gene loci. For brain weight, this yielded five candidate chromosome regions, each reflecting a possible quantitative trait locus (QTL) site affecting brain weight. The second step was to test as many of these five as possible using standard (non-RI) inbred strain data for brain weight previously reported in the literature. For this purpose, only strains possessing the same alleles as the B6 or D2 strains were used. Sufficient data to test two of the five candidate QTL were available. Of these, one was strongly supported as a site affecting brain weight--the D7rp2 region of chromosome 7. For the brain to body weight ratio, four chromosome regions emerged as significantly associated in the BXD series, but none were amenable to testing due to a lack of allelic information for the standard inbred strains. However, two of these regions showed highly significant associations (p less than 0.001, single test) that merit consideration as QTL sites for future testing. These two are the Hba region on chromosome 11 and the D17Tu7 region on chromosome 17. The genetic correlation between brain and body weight was low (r = 0.28), indicating that these two traits are largely genetically independent in the BXD RI series.

A Response to “Differences in Motor Proficiency According to Gender and Race” by Carol E. Plimpton and Celia Regimbal

Problems which prevented an accurate understanding of apparent differences in children's motor development are discussed.

Twinning and the r/K reproductive strategy: a critique of Rushton's theory

The theory of r selection, favoring population growth, as opposed to K selection, favoring more efficient utilization of resources, has in recent years been applied by Rushton to contrast human ethnic groups in terms of their r/K reproductive strategies, suggesting the existence of a continuum from r groups, producing many offspring but providing little parental care, to K groups, producing few offspring but providing much parental care. Rushton's theory, which is largely based on ethnic differences in twinning rates, is here critically examined. It is pointed out that twinning rate differences are not necessarily genetic in origin since various environmental factors clearly play a role, and also that twinning, as a mode of reproduction, is not necessarily an r strategy, considering the high prenatal and perinatal selection to which it has been, and still is, associated. Moreover, Rushton misinterprets a number of relevant aspects related to the biology of twinning. The claim that ethnic differences in twinning rates provide evidence for an r/K typology in human populations with respect to reproductive strategies does not appear to be warranted.

Testosterone and gonadotropin levels and r/K reproductive strategies

It is proposed that different levels of testosterone are the physiological basis in males of the racial differences in sexual drive which form the core of the different r/K reproduction strategies documented by J. P. Rushton. There is direct evidence for higher testosterone levels in Negroids than in Caucasoids and indirect evidence from the incidence of cancer of the prostate. Prostatic cancer is a function of testosterone levels and shows increasing incidence from Mongoloids to Caucasoids to Negroids. It is further proposed that in females the hormonal basis of differential r/K behaviour lies in the level of gonadotropin.

Race and brain weight: a note on J.P. Rushton's conclusions

Rushton's (1988) reinterpretation of recent research on brain weight one-sidedly emphasizes the findings of heavier brain weight in whites than in blacks and neglects to comment on a larger difference found between men and women. Rushton explicitly used brain size as indicator of intelligence. His implicit conclusion that women are less intelligent than men is not supported by empirical research.

Scientific racism: reflections on peer review, science and ideology

The scholars who use Social Science & Medicine in their research and teaching, who publish their work in it, participate in its peer review of manuscripts, and attend its conferences belong to various nationalities, disciplines, and cultural traditions. Our common enterprise originated in and depends upon liberal democratic social institutions, and assumes their values. With all our differences and disagreements, we are committed to scientific research in a common effort to improve human health and welfare. Our professional careers are a large part of our personal lives, so that our science, our lives, and our values are a single fabric. The present lecture is a meditation on this situation based upon my own heritage, personal experience, and career in anthropology, and on the recent publication in Social Science & Medicine of an essay that attributed the epidemiology of AIDS to racial variation.