Hammer 1.0 was a rock. Hammer 2.0 was a rock attached to a piece of wood, and the caveman that came up with that one must have been pretty pleased; he was the first ergonomicist.
Today we have tons of tools featuring a handle of one material and a head made of another, but there's an ecological problem with this design: The two things can wear out at different rates. In my lifetime I've thrown away scores of toothbrushes because the bristles were spent, but I've never thrown one away because the handle wore out.