My research focuses on understanding how and why environments influence the phenotypes upon which selection acts. For this work I primarily use longitudinally collected observational data, including measures of behavior, genomics, physiology, and life history traits. Empirically, I test hypotheses on developmental plasticity, life history theory, and natural selection using data from long-term studies of wild animals and human cohorts. Much of my empirical work uses data from the Mara Hyena Project (MHP), but I also use data from wild birds and human cohorts. A common through-line in my research is the application of causal inference methods and systematic approaches to study design for observational data. For these methodological and quantitative endeavors, I have developed rich and ongoing interdisciplinary collaborations with epidemiologists, biostatisticians, and computer scientists. I provide additional details on active projects on my research page.