ABSTRACT
So far we have considered the relationship between evolution and typical human behavioral responses, such as how we develop, socialize and use our emotions and cognitive abilities to help us understand the world. Given that one in four people living in the West today will experience some form of a mental health issue, however, it is necessary for evolutionary psychologists to consider the field of abnormal psychology. In this chapter we consider why as a species we are so vulnerable to “mental illnesses” and other problems of abnormal behavior, such as
164 E V O L U T I O N A N D A B N O R M A L P S Y C H O L O G Y
autism, within a framework of evolution by natural selection . In order to do this, we need to understand why it is that due to constraints on the process, evolution does not lead to perfection. As will be seen, genes that have positive effects can also have negative ones (either in themselves or when combined with other genes). We also need to consider the notion that in some cases mental health problems today may be based on adaptations to the past. In order to achieve this, we will introduce the emerging field of Darwinian medicine, and in particular the work of evolutionary psychiatrist Randolph Nesse.
