Taking advantage of this broad diversity, this project is dedicated to building and testing anthropological models to explain observed patterns of genetic and linguistic variation at the levels at which they originate. Until now, most studies of genetic and linguistic evolution and differentiation have focused on large-scale regional or continental patterns, characterized from a phylogenetic perspective. Yet all such patterns arise from processes that begin at the community level. In collaboration with Indonesian researchers and public health teams, our research team has been collecting genetic linguistic, demographic, environmental, medical and ethnographic data from villages throughout the archipelago.

A combination of inferential and predictive approaches are being be used to investigate the multi-scale processes by which larger patterns such as human sociality, language patterning and disease susceptibility emerge. Thus, we are developing our own genetic and linguistic models appropriate for the spatiotemporal scales under study, creating software to implement the models, and working with developers to improve their own highly regarded software packages.

We tested our approach of examining linguistic and genetic variation by beginning with the contact zone eastern Indonesian island of Sumba, where Neolithic Austronesian farming communities settled and began interacting with aboriginal foraging societies ~3,500 years ago.Using historical linguistics, we reconstructed the phylogeny of the languages of Sumba based on a 200-word Swadesh list sampled from 29 localities. Thus reconstruction supports the hypothesis that Sumbanese languages derive from a single ancestral Austronesian language. However, the proportion of cognates (words with a common origin) traceable to Proto-Austronesian varies among language sub-groups distributed across the island. When we combine these results with genetic data, we found a positive correlation between the percentage of Y chromosome lineages that derive from Austronesian (as opposed to aboriginal) ancestors and the retention of Proto-Austronesian cognates.We also found a striking correlation between the percentage of Proto-Austronesian cognates and geographic distance from the site where many Sumbanese believe that their ancestors arrived on the island. Thus, indeed, language-gene-geography correlations can be established on a fine scale. Consequently, historical patterns of social interaction between expanding farmers and resident hunter-gatherers largely explain community-level language evolution on Sumba.

A second project begins in noting that many studies have argued that reproductive skew biased towards dominant or high-ranking men is very common in human communities. Indeed, demographic statistics collected over short time scales support these claims. If this pattern persists, then reproductive skew should produce a genetic signal. As an illustration of a modeling project examining communities on a regional scale, our research group posed the question: Are these differences are heritable and potentially subject to cultural selection? However, using our community genetics based sampling strategy and some new inferential techniques, we found that only 5 of 41 Indonesian communities showed any statistically significant departure from neutrality. Thus, male dominance seldom translates into increased fertility over deep timescales, and reproductive skew rarely has evolutionary significance.

The discovery that neutral processes explain most haplotype distributions in these communities parallels earlier results from the development of neutral theory in genetics and ecology. In anthropology, the availability of community-level data enables us to distinguish both genetic and cultural selection from neutral demographic processes. This first test of the neutral theory in anthropology suggests that, as in genetics and ecology, the appropriate null model is neutrality.

These two test cases show us that the temporal scales of this research puts us in the transition zones between sociolinguistics and historical linguistics and between quantitative genetics and population genetics. Thus, our success will in large part be depended on our ability to understand the nature of these transitions. As we move to investigate another portion of the archipelago or pose additional questions on the nature of the comparative histories of communities, we will appreciate more deeply both how generally applicable are our methods and how richly varied are the peoples of Indonesia.