Societies are exploring what sustainable development means for development choices. Increasingly, we recognise that human population health is not just an input to socioeconomic development, but is an essential outcome, and, over time, a marker of sustainability. There has been recent attention to how stocks of social and human capital precondition gains in population health. However, recognition of how environmental change can limit health and survival has been slower. Over many millennia, disease and longevity profiles in populations have reflected changes in environmental conditions and, often, excedances of carrying capacity. Today, population growth and the aggregated pressures of consumption and emissions are beginning to impair various global environmental systems. The research tasks in detecting, attributing, and projecting the resultant health effects are complex. Have recent health gains, in part, depended on depleting natural environmental capital? Population health sciences have a crucial contribution to make to the sustainability project.