At this point, it's only a matter of time.  Humans just take for granted that we are on top of the evolutionary ladder, while monkeys patiently observe and prepare.  Now they are mastering martial arts, so we can't even depend on ninjas to save mankind.

A part of you thinks, "Awwww, look at that cute monkey doing spin kicks" but another part of you thinks "Holy crap, that terrifying monkey is doing spin  kicks".  Monkeys are already stronger and more violent than us, the last thing they need to learn is a more efficient way to attack us.