Unless somebody spent hours and hours over a period of months and months and kept records while they were at it, they couldn't say whether a person in a nonliterate society is lefthanded or not.

When it comes to tasks, people cannot predict what hand they will use, and they may use one hand one time and the other hand another time. They may prefer the left hand for one task and the right for another, similar task.

For example, when I wore contact lenses, I washed them with my right hand and inserted them with my left. It was years before I even noticed that I was switching hands.

My husband, who I thought was the most right-handed guy in the world, demanded a left-handed mouse. One never knows, do one?