This article reports an association between the variation of dopamine D4 receptor (DRD4) allele frequencies around the globe and population migration patterns in prehistoric times. After compiling existing data on DRD4 allele frequencies of 2,320 individuals from 39 populations and on the migration pattern of these groups, we found that, compared to sedentary populations, migratory populations showed a higher proportion of long alleles for DRD4. The correlation between macro-migration (long-distance group migration) and the proportion of long alleles of DRD4 was .85 ( p Ͻ .001), and that between micro-migration (sedentary vs. nomadic settlement) and the proportion of long alleles was .52 ( p ϭ .001). We discussed the adaptive value of long alleles of DRD4-a genetic trait that has been linked in some studies to the personality trait of novelty-seeking and to hyperactivity-in migratory societies and the possibility of natural selection for a migration gene.

We discuss and test competing explanations for polygyny based on household economics, malecentered kin groups, warfare, and environmental characteristics. Data consist of codes for 142 societies from the Standard Cross-Cultural Sample, including new codes for polygyny and environmental characteristics. An explanatory model is testedfor the worldwide sample using regression analysis, and then replicated with regional samples. We obtain conuergent results with two different measures of p o & . n y , cultural rulesfor men's marriages and the percentage of women married polygynousIy. We conclude that the best predictors of polygyny are fraternal interest groups, warfarefor capture of women, absence of constraints on expansion into new lands, and environmental quality and homogeneity.

Boas argued that anthropologists should make historical comparisons within well-defined regional contexts. A century later, we have many improvements in the statistical methodologies for comparative research, yet most of our regional constructs remain without a valid empirical basis. We present a new method for developing and testing regions. The method takes into account older anthropological concerns with relationships between culture history and the environment, embodied in the culture-area concept, as well as contemporary concerns with historical linkages of societies into world systems. We develop nine new regions based on social structural data and test them using data on 35 I societies. We compare the new regions with Murdock's regional constructs and find that our regional classification is a strong improvement over Murdock's. In so doiig we obtain evidence for the cross-cultural importance of gender and descent systems, for the importance of constraint relationships upon sociocultural systems, for the historical importance of two precapitalist world systems, and for strikingly different geographical alignments of cultural systems in the Old World and the Americas.

A model of causes and consequences of sexual division of labor in agriculture is tested using a sample of Afncan societies. Crop type and the presence or absence of slavery are shown to be effective predictors of the degree of female contribution to agricultural subsirtence, and the degree of polygyny u shown to be affected by female agricultural contribution and the form of residence. Autocorrelation effects are found and are shown to be a consequence of Bantu societies having higher female participation in agriculture than would otherwise be expected. His publications on the theory of social structure range from Mexican and North American Indian comparative and cade studies to previous cross-cultural studies on the division of labor, and to more general mathematical models and methods. He is currently publishing a network theory of role. status. and social structure using various case studies.MALCOLM M. DOW meived his B.A.

Female agricultural contributions decline with agricultural intens