More than any other animal, human beings borrow against their future capabilities by depending on others in their early years. A big reason for this is that hunter-gatherers have always specialised in foods that need extraction and processing – roots that need to be dug and cooked, clams that need to be opened, nuts that need to be cracked, carcasses that need to be butchered – whereas chimpanzees eat things that simply need to be found and gathered, like fruit or termites.