Mankind in ancient times was way smarter than we are today, not dumber! The proof is on the planet.

Average Human Intellect - today; Average Human Intellect - 1,000 years ago; Average Human Intellect - 2,000 years ago; Average Human Intellect - 3,000 years ago; Average Human Intellect - 4,000 years ago; Average Human Intellect - 5,000 years ago; Average Human Intellect - 6,000 years ago