Geoffrey Miller is an evolutionary psychologist, which means he studies how humans evolved and how different behaviours help us survive and reproduce. He looks at how natural selection, or the process of passing down helpful traits from parents to children, has shaped people's behaviour. For example, Miller has studied why people are attracted to different types of people, which is connected to the idea that our ancestors preferred those with traits that made them more likely to survive and pass on those traits (like being healthy). He has also studied why some people are more creative, which may link to how creativity and innovation helped humans in the past survive in their environment.