Can Evolution Go Backwards?

In Cyril Kornbluth's 1950's short story The Marching Morons, John Barlow accidentally goes into suspended animation, to be revived centuries later in the year 7-B-936. He awakes in a very different world where the average IQ is 45 and the few intelligent humans remaining are struggling to deal with the morons. The human race has regressed. Is devolution possible? Can evolution go backwards? The answer is no, it can't go backwards, because evolution is change without direction. - Cyril Kornbluth, The Marching Morons, Galaxy April 1951