I seem to recall, bottlenose dolphins have been known to attack and kill spinner dolphins for "fun" (i.e. they don't eat the dolphin afterwards). Cats play with

I seem to recall, bottlenose dolphins have been known to attack and kill spinner dolphins for "fun" (i.e. they don't eat the dolphin afterwards). Cats play with mice before finally killing them. That's, in my mind, as close to an "experiment" as you get in nature. Don't assume humans are the worst animals out there: while we have our horrible streaks, if we gave our mental capacity over to other animals (say, chimpanzees), the world would be no prettier. At least we've mostly eliminated the murder of our rivals' children so that we can impregnate the mother, unlike our closest genetic relative.