Evolution Before Our Eyes: How Macaques Learned To Fish
Scientists in Indonesia recently published a paper documenting their field observations of long-tailed macaques going fishing. Even better, they don't just reach into the water to grab their own fish—they watch other macaques at work and learn from their techniques. One researcher theorized that "perhaps a couple of generations back, one primate caught a fish and it was subsequently copied." The scientists suspect that the macaques fish when no other food is available, though they stress that not enough data exists to say for certain.
If the macaques learn to fish and then, over time, macaques with adaptations that make fishing easier or more successful survive at a higher rate than other macaques so that the adaptation becomes more prevalent or more pronounced, that would be evolution. Otherwise, it's just one really smart macaque and a bunch of other monkeys playing copy cat.
there could also end up being some sexual selection going on if females refuse to mate as regularly with macaque males that spend too much time fishing rather than helping out around the tree.
(I once participated in an extended argument about whether sexual selection was best described as a type of natural selection or a process all its own. Teach the controversy I say! Yeah, I have many friends just as geeky as I am.)