Fact that intelligence is very expensive in terms of energy consumption. Brain is already very expensive, highly intelligent species would need to dedicate more

Fact that intelligence is very expensive in terms of energy consumption. Brain is already very expensive, highly intelligent species would need to dedicate more energy. So unless evolution will evolve cheaper way of representing high intelligence (which might be possible, our brain chemical structures are artifacts of time we lived in the oceans), it is unlikely that a species would evolve substantially higher intelligence compared with humans. So to evolve superior intelligence: need a lot of food at regular intervals with strong evolutionary pressure for being smarter, instead of faster, tougher, bigger, or more violent. Generally unlikely to happen in nature.