@jimm619
I'm wondering if some outside force, like the Poul Andersen story about a force field crossing path with Earth the effect being a distinct lowering of intelligence of any kind of organic brain.
So we grew up as a race, 20,000 years of such a field, then the field left Earth, meandering through the galaxy, and THEN we got REALLY smart.
Brain Wave by Poul Anderson.
Sigh.
Seems like now we are in the extreme dumb down stage of that field.