Your answer may be, it isn’t. In which case, have fun living in a cave, trying to figure out how to feed yourself and stay warm. Human beings have been using tools since we were nomadic tribes of hominids. We sharpened sticks into spears, carved flinty rocks into arrowheads, learned how to control fire and use it to keep us warm, cook our food, and change the chemical composition of materials to make pottery and other goods.