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.

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.

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 'obstetrical dilemma' postulates that human females evolved a pelvis shape that was a compromise between the needs of bipedal locomotion and the need for a wider pelvic opening. The implication is that the female pelvis should be similar across the world. Researchers examine the size and shape of the birth canal of female individuals in the Goldman and Human Origin datasets. Contrary to the 'obstetrical dilemma,' the findings reveal that there is indeed significant geographical variation in size and shape of the female birth canal. Neutral evolutionary processes, particularly genetic drift, were suggested to be influential in female canal shape whereas the predicted effects of climate on canal diversity were only minimal.

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.

Researchers used population samples from the ALFRED database and the Human Genome Diversity Project (HGDP), in conjunction with 68 populations from the Ethnographic Atlas, in an attempt to identify specific genes involved in human adaptation to environmental stimuli as a result of migration. Specifically, researchers looked at the allele frequencies for four different genes typically associated with varying subsistence forms. These four included the APOE apolipoprotein E gene (lipid transport and regulation of cholesterol), LCT lactase gene (enzyme that decomposes lactose), CCR5 chemokine receptor gene (deletion mutation that decreases immunodeficiency virus propagation), and the ADH1B alcohol dehydrogenase gene (important enzyme for alcohol metabolism). The allele frequencies were then analyzed to distinguish any possible correlation to economic-culture types using a two-sided Spearman Test. Researchers also ran a similar test to analyze allele frequencies and pathogen load, however the majority of the findings were not statistically significant. The findings suggest that there is a definite relationship between the allele frequencies and type of economy of a population.

The authors test the relationship between ethnolinguistic area and various environmental variables in a cross-cultural sample of hunter-gatherer, pastoral, and agricultural subsistence groups in order to evaluate various hypotheses surrounding the geographic and ecological origins of cultural diversity. They propose that societies which adopted agriculture at the beginning of the Holocene were less directly affected by climate which, combined with the effect of increasing political and cultural complexity, allowed coordination and homogenization of ethnolinguistic groups over a broader swathe of territory.

Through phylogenetic comparison, Holden and Mace explore the relationship between descent and cattle among a sample of 68 Bantu/Bantoid-speaking populations in Africa. The authors posit that when matrilineal cultures adopt cattle, they become patrilineal. Possible theories are offered to explain trends and variation in the data.

This paper examines the enormous variation in linguistic diversity among Pacific Islands by testing its relationship with various environmental variables put forth in several common theories of language richness. The researchers identify variables relating to land area and island isolation as accounting for about half of variation in linguistic diversity, suggesting that the other half is a result of complex social factors.

The authors explore the relationship between differences in technology adoption across cultures in snapshots from 1000 BCE, 0 CE, 1500 CE, and 2002 CE. While acknowledging various flaws inherent in the ambitious scope of their dataset, a significant relationship is nonetheless revealed between technology adoption in 1500 CE and technology and income in 2002 CE after controlling for various geographic and demographic factors. The authors suggest that this persistence may occur because technology adoption is heavily dependent on stock of prior technology.