Evolution doesn't work that way, it doesn't reach global maxima. For instance our eyes are inferior to those in octopuses in many ways, but they're good enough

Evolution doesn't work that way, it doesn't reach global maxima. For instance our eyes are inferior to those in octopuses in many ways, but they're good enough for us so we will probably never evolve better eyes (for a number of reasons, including lack of selective pressure and our eyes being on a separate evolutionary pathway that includes an optic nerve being in front of the macula). Likewise with the brain.