http://www.independent.co.uk/multimedia/archive/00025/monkeys1_25894b.jpg

There's no stone tip. The end of the spear probably isn't even fire hardened. Then again it is straight and long making it easy to be accurate a long distance from your reach. It would even fly fairly straight if it was thrown. Not only our distant ansestors but people today could be found using a tool like this.

http://open.salon.com/even-monkeys-know-which-rock-will-break-the-toughest-nut

The article that goes with this pictures explains that the Capuchin monkey selects from a collection of stone tools.

http://www.stripes.com/blogs/the-rumor-doctor/the-rumor-doctor-1.104348

There have been many stories about monkeys on the battlefield. I'll believe that article sbout the trained use of weapons. However, monkeys in the wild are very dangerous.

Hey everybody believed our dog loved me. No one told them that mom had to wipe me down with a pork chop first.