Researchers looked at 180 of the 186 societies in the SCCS for changes over time in lineage systems. The goal was to estimate the frequency of transitions away from and to matriliny cross-culturally, as well as explore the potential causes of these patterns / transitions. The study focused on two overarching research questions: 1. How common are transitions away from matriliny and how often do ‘reverse transitions’ to matriliny occur? 2. What causes transitions to or from matriliny? Overall, the study found that transitions away from matriliny have been quite common within the time frames covered by the ethnographic samples available, while transitions from another system to matrility have been rare. In answering the second question, the researchers report the highest correlation is between subsistence transitions (towards pastoralism, intensive agriculture, or a market economy) and lineage transitions (away from matriliny) as well as between higher levels of social complexity (measured by stratification, slavery, and population size) and lineage transitions (away from matriliny).

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.

Using t-test, generalized linear models (GLMs) and Bayesian regression models in a sample of 1188 pre-industrial societies, this study explores the research question: Why have foraging, horticulture, and pastoralism persisted into the 20th and 21st century? The authors test the marginal hypothesis and the oasis hypothesis of agricultural intensification. The first hypothesis suggests that foragers persisted because foragers predominantly inhabited marginal habitats that were typically unsuitable for agricultural purposes. The second hypothesis suggests that intensive agriculture emerged in regions characterized by limited biodiversity and a dependable water supply not reliant on local rainfall. In addition, the authors test whether specific kinds of biodiversity (elephants, malaria, and tsetse flies) correlate with agricultural intensification in African societies. The results support the marginal and oasis hypotheses, but only marginally support the African hypothesis, since only tsetse fly has a significant negative correlation to agricultural intensification.