Upward selection pressure: Assuming that seal hunting comes with a nontrivial chance of failure because it's so complex, and greater intelligence produced a higher hunting success rate, wouldn't that be an upward selection pressure?
(of course even a good hunter would find it useful to be funny, charming, or occasionally devious, so this doesn't mean that Machiavellian Intelligence isn't also a root cause)
And defining the chimp-to-human scale may be tricky. You don't need to write poetry to pass along cooking instructions, but some kind of language is helpful to communicate the idea of "let these leaves dry for 2 days before you eat them". Physiologically speaking, our brains probably haven't changed much in millennia, and the "end goal" of natural selection probably wasn't the internet or jet engines, but we have those as nice side effects.