Professor Randolph Nesse believes that conditions like heart disease, obesity and drug abuse can all be explained by the fact that the human body was not designed for the 21st Century. Nesse, professor of psychiatry at the University of Michigan, is one of the leading proponents of evolutionary or Darwinian medicine. Evolutionary medicine examines why some diseases still exist. According to Nesse, our bodies are designed to like things that are not good for us, from cigarettes to fatty foods. Similarly, we are not designed to follow advice encouraging us to change the way we live.