perhaps (and i don't know) the added nutrition from eating cooked food had greater benefit at time T for individuals with slightly better brains via natural var

perhaps (and i don't know) the added nutrition from eating cooked food had greater benefit at time T for individuals with slightly better brains via natural variation a la genetics/mutation...and if so they'd slightly be more active and slightly be more reproductive, correlating advent of cooked food with improving brains, but not as causally as suggested?