Dopamine receptor D4 (DRD4) exhibits the largest number of polymorphisms of any dopamine receptor yet identified, and variation in DRD4 has been linked to variation in traits such as novelty-seeking and attention deficit/hyperactivity disorder. DRD4 also exhibits large variation between populations. Here, the authors test the hypothesis that natural selection acting on DRD4 may account for variation in between-population migratory patterns, using genetic and historical data from 39 populations.

Genetic, linguistic, and geographic data can be used to explain the distribution of cultural units ("semes") and to understand the evolutionary mechanisms of culture. Three broad models of cultural transmission attempt to explain why cultures share semes: (1) Cultural diffusion, emphasizing horizontal transmission. (2) Local adaptation, where trail-and-error learning leads to the independent adoption of semes by different peoples living in similar environments. (3) Demic diffusion, which emphasizes vertical and frequency-dependent transmission. Authors test the explanatory power of each model using cultural, genetic, linguistic and geographic data from 36 African cultures.

The ability of adults to digest lactose is common only in populations of European and circum-Mediterranean origin, a distribution thought to be a result of genetic adaptation to drinking milk from domestic livestock. Two additional hypotheses have been proposed to explain the distribution of high lactose digestion capacity: (1) supplemental calcium in high-latitude populations prone to vitamin D deficiency and (2) maintenance of water and electrolytes in the body in highly arid environments. However, these hypotheses are confounded by the shared ancestry of populations whose lactose digestion capability has been tested. Therefore, the authors test all three hypotheses using a phylogenetic comparative method for 62 cultures.

While not mechanically related, the transmission of genes and the transmission of languages are both mediated by culture. For example, in societies where marriage outside the language group is common, matrilocal residence practices may result in the preferential conservation of the mother’s language(s), as well as the development of distinct mtDNA haplogroups throughout a region. In this study, the authors use single nucleotide polymorphism (SNP) data from 130 culturally distinct populations to assess the correlation between genetic distance and linguistic distance, while controlling for various cultural and geographic factors (in other words: when populations are more genetically dissimilar, do they also tend to be further apart linguistically?). Results suggest that while the often-referenced idea of sex-based transmission of language is not universally predictable, linguistic distance almost always tends to correlate positively to both spatial and mitochondrial genetic variation.

By testing relationships between musical, geographic, genetic, and linguistic distance among nine indigenous groups in Taiwan, the researchers aim to quantitatively evaluate a developing theory of coevolution between these traits. An especially strong correlation between musical variability and genetic distance suggests that music may possess worldwide time depth, diversity, and universality equal to or greater than that of language, and could thus serve as a complementary marker for reconstruction of long-term population shifts.

This article investigates peer relations in infancy, both in primates and in preindustrial human societies. Data from these populations shows a strong tendency toward a multi-age composition of play groups rather than solely peer-aged play groups for infants. Patterns in child care across societies of different subsistence types are empirically examined.

The researcher looks for empirical evidence of natural selection as an explanation for worldwide variation in novelty-seeking behavior. Examining the relationship between variability in frequency of the DRD4 exon III 7-repeat allele variant (a variant theorized to stifle dopamine reception and thus encourage compensatory novelty-seeking behavior) and migratory distance from prehistoric humans' origin point in East Africa yields a positive correlation. After controlling for various biogeographic indicators, the researcher theorizes that presence of the DRD4 exon III 7-repeat variant provided an exploratory urge and evolutionary advantage to hunter-gatherers and pastoralists who migrated into unfamiliar environments.

Using qualitative ethnographic data on the development of hunting skills, MacDonald evaluates several previous models of life history theory and the role of learning. Alternative theories and predictions are identified. Although the sample is ad-hoc and no hypotheses are statistically tested, MacDonald descriptively analyzes cross-cultural similarities and differences to gain insight into human evolution, hunting, and learning.

This article explores the possible relationship between the cultural evolution of language, music, and genetic variation beyond the level of language families. Due to their linguistic diversity, the authors use a sample of 14 Northeast Asian societies with matching information on their music, genetics, and linguistic patterns. The variables measuring language are lexicon, phonology, and grammar. Then, the authors compare each variable's relationship to music and genetic variation. The results only show a significant correlation between grammar and genetic variation.

Authors use genealogical data to investigate pair bond stability and reproductive skew across a sample of 80 small-scale societies. Results suggest that male reproductive skew and pair-bond stability are independent sources of cross-cultural variation in human mating patterns.