The one thing I remember from Anthropology 101: There were only two groups of people in early human evolutionary history - those that were attracted to sharp pointy objects and fire, and those that weren't. The ones that were attracted to these things and henced used them had relatively easier lives and hence more offspring (ie. more knife nuts!)the ones that weren't attracted to these tools had fewer children; they went the way of the Neanderthal. And thus, as my professor was apt to say, we are all offspring of these knife/fire-loving people and we are genectically predispositoned to liking knives and fire (the modern equivalent of which is a nice flashlight).