Yes, given the headline I expected a coordinated attack that wiped out an entire group of gorillas, not a couple of skirmishes. Chimpanzees will attack humans, including eating human children. I don't see why small encounters that result in one or two deaths would be totally unexpected.
Did I mention natural behavior? Did the comment I responded to mention natural behavior? How is natural behavior relevant to the discussion between OP and I? What is the point that you are arguing and why are you taking it up with me? Further, how are you defining natural behavior? Can natural behavior change over time, in response to external stimulus?
Don't be sad. For grown ups its normal to live with objections. You'll learn.
> How is natural behavior relevant to the discussion
Original post: " Perhaps a particular chimp or gorilla was having a really bad day and just went out looking for a fight." that implies natural behavior.