Looks like animal min. just evolved to break its conspec avoidance code. That is, it learned to eat each other. Which always seems to be the first thing it does, for better or worse. That's probably also why it's having a hard time maintaining a high population: it's self limiting because as it gets too crowded they just eat each other.
You might want to try starting with a bot that already is cannibalistic, and see where it goes from there.