Stress versus discrete negative emotions in the prediction of physical complaints: does predictive utility vary across ethnic groups?

Reports of stress and negative emotion are important predictors of health. However, whether discrete emotions or stress measures are more useful, whether they contribute independently to outcome, and whether they relate to health equally across ethnic groups remain unclear. In the current study, 207 US-born European American, US-born African American, Black English-speaking Caribbean, and Dominican men aged 40 years and older completed measures of somatic symptoms, trait emotions, and stress. Sadness and stress independently predicted symptom reports, even when examined concurrently, and with demographics controlled; trait anger did not predict symptoms. Moreover, the relations between trait emotions and symptoms varied across groups. Levels of sadness were associated with greater symptoms among US-born European American and Dominican men, but negatively associated among Black English-speaking Caribbean men, and the relations for anger also differed marginally across groups. The results underscore the importance of differentiating among discrete emotions and stress and considering ethnic interactions when examining reports of somatic symptomology. We suggest that the impact of psychological characteristics on health must be considered within cultural and ethnic contexts to be fully understood.

Genetic differentiation within and between species of the Drosophila willistoni group.

We describe allelic variation at 28 loci in six Caribbean populations of four sympatric species of Drosophila. Within any one species the allelic frequencies are very similar from population to population, although there is evidence of local as well as regional genetic differentiation. The genetic distance is greater between populations from different islands than between populations of the same island. When the allelic frequencies are compared between different species, a remarkable pattern appears. In any pair of species nearly half of the loci have essentially identical allelic frequencies, while nearly the other half of the loci have different alleles and in different frequencies. The loci with nearly identical allelic frequencies are different when different pairs of species are compared. The patterns of allelic variation within and between species are inconsistent with the hypothesis that the variation is adaptively neutral. Migration or mutation cannot explain the patterns of genetic variation, either. Balancing natural selection is the main process maintaining protein polymorphisms in natural populations.

Enzyme variability in the Drosophila willistoni group. IV. Genic variation in natural populations of Drosophila willistoni.

We describe allelic variation at 28 gene loci in natural populations of D. willistoni. Seventy samples were studied from localities extending from Mexico and Florida, through Central America, the West Indies, and tropical South America, down to South Brazil. At least several hundred, and often several thousand, genomes were sampled for each locus. We have discovered a great deal of genetic variation. On the average, 58% loci are polymorphic in a given population. (A locus is considered polymorphic when the frequency of the most common allele is no greater than 0.95). An individual fly is heterozygous, on the average, at 18.4% loci.-Concerning the pattern of the variation, the most remarkable finding is the similarity of the configuration of allelic frequencies from locality to locality throughout the distribution of the species. Our observations support the conclusion that balancing natural selection is the major factor responsible for the considerable genetic variation observed in D. willistoni.