The title says it all. The article fails to expand on it, although I'm sure the scholar has lots of evidence to back up his theory. I'd take it one step further and suggest that the regular Mayans got sick of the "ripping beating hearts out" sacrifices...

The decline of the Maya civilization began some 1,100 year ago when millions of Indians working on the contruction of tall pyramidal temples and palaces learned that their kings weren't gods, Spanish anthropologist Andres Ciudad told EFE. The collapse of this culture with its brilliant mathematicians, astronomers and engineers, came when monarchs stopped being immortal in the eyes of their subjects, said Ciudad, who is deputy dean of the Faculty of Geography and History at Madrid's Universidad Complutense. The inhabitants of Mayan lands, which extended through much of what is now Guatemala, El Salvador, Belize, Honduras and Mexico, at some point understood there was no sense in working themselves to death building pharaonic edifices and temples destined for the burial of kings who had no "heavenly privileges."

Source: MercoPress