Chimpanzees sharpening their spears; now that's interesting. Mostly young, and/or female chimps doing this and hunting bushbabies; curioser and curioser. Definitely food for thought on human origins.

We seem to exhibit both the male-dominated aggressive social structure of chimpanzees and also the gift-and-sex social practices of bonobos. This would make sense since we split off from the line before chimps and bonobos specialized. The hunting behavior seems more an innovation in response to need than a revolution on social structure, but it could alter future chimp evolution. 

The particular population observed to do this is in an area lacking colobus monkeys, a favorite prey. At a minimum it is a reminder that animals can innovate; more specifically it will be looked at closely by anthropologists. An old argument, (among those that accept we are evolved), is who were the innovators in early hominids. This will not settle that, but it will add a few data points to our knowledge of pre-civilized behavior.

This is an excellent example of what we call intelligence. An ant colony is pretty smart, but can't change its behavior. Mammals and birds, however, can find new ways to make a living. In this case, the troop males catch green monkeys but don't share them, so the "outs", females and juveniles, have taken to hunting the primate called bushbabies.

There is circumstantial evidence of stone-tool-making by chimps, but this is happening as we watch, like the troop that learned to wash grain in the river and to use sticks to extract insects. Equally interesting is the hunting chimps have been observed hanging around in caves, socializing and sleeping. Since chimps are considered tree-dwellers, this is pretty intriguing.

These are our closest cousins, culturally, and next-of-kin genetically, among our family, the primates. Here's hoping for a bright future for them.