Evolution doesn't distinguish between physical and mental challenges and organs aren't the unit of evolution. They don't survive or reproduce in isolation.
Species can and do evolve different adaptations to the same evolutionary pressures. Bret isn't convincing.
Have we actually had much in the way of mental challenges on an evolutionary timescale? It would appear to be a reasonably recent phenomenon. I think I heard Jordan Peterson comment that a couple of hundred years ago, most people were piss poor working in fields, so a high IQ didn't actually gain you very much.
Species can and do evolve different adaptations to the same evolutionary pressures. Bret isn't convincing.