Some time ago I watched a TV wildlife programme in which a troop of chimpanzees saw off a leopard by throwing sticks and stones. These only went vaguely in the direction of the enemy: it was essentially an aggression-display. I was later told that no chimpanzee had ever been taught how to throw missiles attempting to hit a target, which is after all a very sophisticated concept.
This set me wondering whether, when our remote ancestors descended from the trees out onto the savanna, they had already acquired this skill, or whether it came later. Consider the advantages of being able to throw things accurately. If you can throw a stone the size of a cricket ball straight enough to hit a hyena at twenty paces, you are infinitely safer than if you cannot: even a large predator such as a lion my be deterred by a few well-thrown missiles. There are also huge advantages in the gathering of food: humans cannot run fast enough to catch even a rabbit, but accurate throwing greatly increases the chances of killing small game, not to mention making it much easier to bring down fruit and nuts from high trees. Also, a bipedal posture balanced on the hind legs does not bring many advantages to humans, but it greatly facilitates the throwing of stones.
From stones we can develop into spears, and, because suitable missiles are not always available, to the creation of some kind of bag to carry a supply around. This is a highly sophisticated concept, involving foresight and planning. I do not know whether this matter has been properly investigated, but it strikes me as being very important in the history of human cultural evolution.