Have you never wondered how some animal would completely take over if it was just a bit smarter? Example: A single fox can kill dozens of chicken. Imagine the chicken working together and attacking it, picking out the eyes etc. instead of literally not defending at all.

Or a herd of cow or whatever herd animal that could easily team up and trample/stomp/crush/… a predator but instead they all just run away and the slowest is dead.