April 29, 2017 - In 1825, Benjamin Gompertz observed that, to a reasonable approximation, mortality rates after maturity in the British population increased exponentially with age. This unexpected yet simple relationship has since been seen in many multi-cellular organisms. Biologists have sought to explain the phenomenon as a result of natural selection: very crudely, natural selection doesn't oppose the body carrying a collection of genes dying so long as the genes have already been passed on to the next generation. However, while these qualitative arguments lead one to expect that mortality rates increase with age, they don’t predict the particular form of the connection between age and mortality. Evans will discuss ongoing work that has as its ultimate goal the development of a quantitative framework that more fully explains how observed patterns of mortality result from natural selection. Steven Evans represents Class III.