And you cannot tell a priori how flexible human behaviour is. Our biology, let us say, gives us the modules. But then, how the modules turn out—how they are programmed if we like, differently in different environments—is another thing. By comparison, biology gives us the structures, whatever they may be, we need to learn language. We have them; no other animal has them to any remotely similar degree. But which language we then learn is not determined by biology, but by environment, as infants imitate the language of their mothers and their kin.
