Galápagos: A Novel (1985)
“So I raise this question, although there is nobody around to answer it: Can it be doubted that three-kilogram brains were once nearly fatal defects in the evolution of the human race?
A second query: What source was there back then, save for our overelaborate nervous circuitry, for the evils we were seeing or hearing about simply everywhere?
My answer: There was no other source. This was a very innocent planet, except for those great big brains”
So it is our big brains that ruined an otherwise pleasant planet...Maybe we weren't ready for free will!