When you consider the environment at this time, trees would be few and far between, making wood a scant resource. Adding an antler foreshaft means that if your shaft breaks, it would be at the join...So perhaps it was a strategy to try and ensure retrieval and reuse of valuable wood. As a bonus, it also leads to a far superior projectile - the density of antler at the front means it flaps about less, has a better flight path so is more accurate. Also, better penetration of the target. It occured to me that carrying both a bow and atlatl would be a wise move...if your bow breaks, a replacement could be tricky=no food+death, but you still have the thrower... Adopting a composite projectile means you can adapt your strategy as needs be. One final thing, on the point I found, I always thought the triangular base looked odd compared to other definite tangs...Seeing the foreshaft in the video, with a slot cut at the tip, you can see how it fits. Clever stuff, and deep respect for those hardy ice age hunters...
