If all the kings wise men, with all their combined trillions of neuronic brains working together can't make a brain, imo, mindless Mr. Natual Selection and his cohort, dead headed Ms Radom Mutation never did it.
This might be a reasonable assumption in say, oooh, a billion years or so, when you can begin to compare things without ignoring huge differences of several orders of magnitude in timescale.
If mankind could produce something as complicated as the human brain within a million years of now would you concede that RM/NS might do so given a billion? This is obviously a hypothetical question.
TTFN,
WK