Why do humans look, think and act the way they do, and how did they get to be that way? These evolutionary questions shape our understanding of how our bodies and brains work and how we interact with one another and the environment. Research that focuses on them has many applications, from contributing to the work of doctors wanting to keep us healthy to informing those dealing with big issues like climate change. My work investigates the relationship between our ancestors and the environments of eastern and southern Africa. Our ancestors only started to live on the ground rather than in the trees a few million years ago, and so far we have not yet been able to explain how they managed to survive there without being eaten by predators like lions or hyenas. My work showed that one way of making a safe living on the ground would have been to live in areas that are rocky and rough, where there are lots of things to eat and opportunities to make stone tools and the larger animals can't get to you. I showed that scrambling across these landscapes might also have driven our ancestors to become upright and brainy.