Tim Smith writes about the atlatl in the MDC Fresh Afield blog. This was the standard weapon used by Missouri hunters from the days of the mastodon until at least 1,000 BC when the bow and arrow first came into use. This new technology became the standard with time, but in truth, the atlatl still had some advantages.
Modern bows using advanced materials and technology have greatly increased the force of the arrow. Modern arrow heads have blades you could shave with, able to penetrate all the way through the deer's chest. Not so with the early bow and arrow.
An atlatl on the other hand can be thrown by one hand. It provides more force by extending the effective length of the hunter's arm. The heavier projectile, called the dart, traveling with greater velocity creates deeper penetration of the point.
You can find the history of the atlatl and its reintroduction to deer hunting in Missouri in the Missourian article and see an atlatl in action in a video from Missourian.
For the atlatl obsessed, see the resources at AtlatlNewsletter.html.