As anyone with gnomes in there garden knows, gnomes are not smart creatures and yet the gnomes who fought in the Gnomish Great War were as intelligent as you or I. This is because when lawns were invented gnomes learned that they could live in these green paradises if they acted stupid and harmless. Over the next two thousand years gnomes adapted to be as stupid as they had originally  pretended. For all you science lovers gnomes change much faster then we do.