Complex systems are often characterized by distinct types of interactions between the same entities. These can be described as a multilayer network where each layer represents one type of interaction. These layers may be interdependent in complicated ways, revealing different kinds of structure in the network. In this work we present a generative model, and an efficient expectation-maximization algorithm, which allows us to perform inference tasks such as community detection and link prediction in this setting. Our model assumes overlapping communities that are common between the layers, while allowing these communities to affect each layer in a different way, including arbitrary mixtures of assortative, disassortative, or directed structure. It also gives us a mathematically principled way to define the interdependence between layers, by measuring how much information about one layer helps us predict links in another layer. In particular, this allows us to bundle layers together to compress redundant information and identify small groups of layers which suffice to predict the remaining layers accurately. We illustrate these findings by analyzing synthetic data and two real multilayer networks, one representing social support relationships among villagers in South India and the other representing shared genetic substring material between genes of the malaria parasite.

Religious rituals often entail significant investments of time, energy, and money, and can risk bodily harm. Instead of being evolutionarily inexplicable, such costly religious acts have been argued to be honest signals of commitment to the beliefs and values of the community, helping individuals establish good reputations and foster trusting, cooperative relationships. Most tests of this hypothesis have evaluated whether religious signalers are more prosocial; here I investigate whether signal receivers actually perceive religious signalers as such. I do this with data collected over 20 months of ethnographic fieldwork in two villages in South India, where Hindu and Christian residents engage in di↵erent modes of religious practice, including dramatic acts of firewalking and spirit possession as well as the more subtle but consistent act of worshipping at a church or temple each week. Each mode of religious practice is found to be informative of a distinct set of reputational qualities. Broadly speaking, in the long term, individuals who invest more in the religious life of the village are not only seen as more devout, but also as having a suite of prosocial, other-focused traits. In the short term, individuals who perform greater and costlier acts in the annual Hindu festival show a slight increase in the percent of villagers recognizing them as physically strong and hardworking. These results suggest that people are attending to the full suite of religious acts carried out by their peers, using these signals to discern multiple aspects of their character and intentions.

Food sharing has been a central focus of research in human behavioral ecology and anthropology more broadly. Studies of food sharing have typically focused either on the individual's motivations to share or the social formations and value systems that sharing produces. Here, we employ social network analysis to do both; investigating how strategic economic decisions, such as decisions about sharing, are embedded in and feed back onto social structure. This research is based on a questionnaire conducted with 110 Inuit households during twelve months of ethnographic fieldwork in Kangiqsujuaq, Nunavik, Canada. In Kangiqsujuaq, traditional Inuit resource harvesting and sharing practices co-exist with and depend upon opportunities and constraints in the cash economy. Food sharing in Kangiqsujuaq emerges as a complex social, political, and economic phenomenon that accomplishes different objectives for actors based on their social position. The network approach adopted in this research highlights the conjugate role of individual decisions and structural constraints in broader processes of social and cultural change. In the mixed economy of Kangiqsujuaq, food-sharing, social structure, and political influence are intimately connected. The results suggest that economic and political inequality in the settlement

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