Many of the most abundant organisms on earth—including humans—are so successful because they cooperate with one another. Although cooperative species tend to be found in harsh environments characterized by drought and unpredictable rainfall, it remains unclear why. Nearly all previous work has established global patterns between social behavior and environment by comparing different species in different habitats. Yet, determining why environmental harshness favors cooperation requires within-species studies across different habitat types rather than just among-species correlations across the globe. By combining field experiments and long-term observations, studies of brain morphology and gene expression, and theoretical modelling, the researchers will establish the largest within-species study of cooperation ever attempted in social wasps that span a range of more than 4000 km across Sub-Saharan Africa. From arid deserts to lush rainforests, Africa’s most widespread wasp Belonogaster juncea is ideally suited to study the links between the environment and cooperation. Using populations in Cameroon, Kenya, and South Africa, the researchers will work at a continental scale to help transform the field of social evolution. Results will be of interest to biologists and social scientists studying cooperation broadly; AI deployment will benefit researchers tracking individuals in complex environments; and our international team (USA, UK, Cameroon, Kenya, South Africa, Taiwan) will pr