Actually, growing up around old-time JWs, who liked to speculate a lot, and read the old literature, I was exposed to the opposite idea. It is an early Bible Student teaching that the closer to Adam humans were, the nearer perfection, and hence more intelligent. In their early tracts against evolution, one of the key arguments Russell made was that humans are getting less intelligent over the centuries, therefore evolution can't be true. This betrayed a superficial understanding of evolution, but it also showed that Bible Students regarded ancient humans as superior to modern humans.
In particlar I remember the idea being floated that there were advanced civilisations before the flood of Noah, and part of the reason for the flood and the destruction of the Tower of Babel was to stall human progress which had advanced far too quickly because humans were still near perfection.