Leveraging diverse ancestry and environmental variables to understand the evolution and architecture of complex traits - PROJECT SUMMARY This grant proposes to investigate three critical areas of human genetics: the role of natural selection in shaping the genetic architecture of complex traits, gene-environment interactions, and demographic history inference. First, we will model recessive selection on complex traits by leveraging X chromosome data to better understand the strength of selection across different traits and diseases. Second, we will explore gene- environment interactions using innovative statistical models, focusing on how genetic risk evolves with age and environmental exposure. Third, we will develop novel methods based on ancestral recombination graphs to refine our understanding of human demographic history, including migration patterns and ancient admixture events. This research will generate new insights into genetic variation, improve the predictive accuracy of polygenic risk scores, and clarify population histories, with broad applications across diverse genetic datasets.