LOL, word salad.
>>3
The fact that there's no immediate payoff for slightly larger brains means that the only way a species is going to develop brains as big as ours is by getting lucky with a sexual selection feedback loop. It happened for us, and we got lucky in that once you get over the initial hump, high intelligence does turn out to be advantageous. We could just as easily have ended up like the peacock.
This. And like someone else around here said, after that "initial hump", there's no point in being the SECOND most intelligent species on the planet. The inferior species would just end up as slaves or else annihilated. Also, you can't develop much of a language underwater.