When chopping onions the other day, i accidentally chopped my left thumb too. Aware that this is a very common phenomenon, i contemplated on it.
The positioning of our thumb on our palm can be explained scientifically using evolution as one theory. Of course, for us to grasp things, our fingers have to be opposable, and the thumb plays a major role in this act.
If the thumb was placed someplace else i don't know, perhaps, we would have evolved a different mechanism which enabled us to grasp.
Coming back to my contemplation, i wondered if there were another finger in place of the thumb, say, the little finger (which is not significant when compared to the thumb); then even if that finger was hurt, the injury wouldn't incapacitate the hand to a great extent. Maybe, if they were a little finger instead of the thumb, then the same would be used to a great level.