The health prospects of humanity are influenced by many things. There are extrinsic factors like poverty, violence, and infectious disease that can cause humans to die. There are also intrinsic factors, like the constraints of our biology (e.g. aging). The role these different factors play in causing disease and death in the world changes over time. The greater success we have with combating extrinsic risks, the greater the impact intrinsic risks have on our health prospects.