“What a piece of work is man,” not in the negative sense of Shakespeare through Hamlet, but in truth.
The mind of man truly is a piece of work. How was it that someone looked at a rock that had been chipped against another rock, maybe by rolling water or wind, and that someone decided he could bang two rocks together and make the same tool? Eventually, that man, and his counterpart in different areas of the world, looked for stones that were more easily chipped and which gave a sharper edge or point. Others decided that taking out part of a stone tool made a place for gripping by hand. Still others decided that fixing a sharp stone to a piece of wood produced a superior hunting tool than did a sharp stick or a better axe.
Of all those inventions, how was it that someone decided to make a spear thrower? How did an ancient human know that a curved stick placed against the butt end of a spear would give greater range and accuracy? To go from throwing a stick to using an aid in the throwing represents a process of thinking equal to discovery of math.