I base this on the glorious and well-known (though not universally accepted) fact that stupid people have more children than smart people:
Demographic studies have indicated that in humans, fertility rate and intelligence tend to be inversely correlated, that is to say, the more intelligent, as measured by IQ tests, exhibit a lower total fertility rate than the less intelligent.We're getting stupider at a pretty good clip:
Retherford and Sewell examined the association between the measured intelligence and fertility of over 9,000 high school graduates in Wisconsin in 1957, and confirmed the inverse relationship between IQ and fertility ..., they calculated a dysgenic decline of .57 IQ points per generation.So that's 20 to 30 IQ points per millennium, making a person of average intelligence, one-thousand years from now, borderline imbecilic.
And probably plenty fertile.
The intelligence range of humans will probably be quite compressed as well. That has the added benefit of compressing inequality since nobody will be smart enough to "get ahead" and humans will eventually become one big happy tribe wallowing in the muck in a new Garden of Eden, where ignorance and stupidity is bliss.
Hopefully, no one will then be stupid enough to eat the fruit of knowledge and bring the numerous problems associated with intelligence upon humanity again.