Handedness
Physical anthropologists have pointed out that the human ability to throw weapons such as rocks and spears is quite notable. Chimpanzees have handedness, but their ability to throw is much less good. For protection, catching prey and for making tools, handedness is critical. Handedness may have been part of the mental make-up of Neanderthals, with asymmetric wear on their teeth as evidence. This would make sense, though it brings the question: "since its reason is not obvious, then why is it so widespread?". Even Darwin asked himself "Are monkeys right-handed??". In general, the answer appears to be yes.