In graduate school, I earned beer money by modeling for life drawing classes in various art departments. (Don’t judge, grad school doesn’t pay well and beer isn’t free.) In the long hours standing around, I would survey the room and count how many of the aspiring artists were left-handed. Later in my career, I did the same thing — counting lefties, not standing around naked — in the biology classes I taught.
Funny thing, in any given class, around 10 per cent of the students were lefties. It turns out this is true for all human populations, not only middle-America university classes. Globally, about 90 per cent of people are righties. But why?