Very 1950s, echoes of Midwich Cuckoos and even EE Doc Smith. The earth emerges from a field which has supressed intelligence for millions of years. Not only does human IQ jump to the 500s, but apes start talking and farm animals get too smart to be kept on the farm. On other worlds intelligence developed to a "just copes" level. On earth it developed to the same level, but with the field removed it leaps beyond anything else around. The "new humans" escape into space, leaving the earth to the (ex) morons, to find new challenges.
***Imported from old blog***