My professor once told us that we were thinking of Australopithecines, a recent hominid, all wrong.

While we thought of early human ancestors as less intelligent versions of ourselves, the correct analogy was to a modern Velociraptor: fast to the point of running animals to death, fiercely intelligent, and with unparalleled group coordination.

Arguably the last of the giant dinosaurs was the Moa, a bird with claws that could eviscerate a human with a single swipe, and our species wiped them out as a prey animal.

We are a terrifyingly effective species.

We are extremely good at throwing things with precision as well.

The combination of unusual tricep structure (also found in cats and the extinct great sloth), remarkably mobile shoulder structure (inherited from our primate ancestors) and grippy hands (thumbs!) gives us remarkable downward thrusting power useful for smashing, grabbing and throwing.

One of the earliest inventions, the spear-thrower, enhanced that ability even more, giving us the ability to kill big game from a distance with near impunity. (It works by increasing the lever arm. Think of a lacrosse stick.)

http://en.wikipedia.org/wiki/Spear-thrower