When I was there about 35 years ago, the tour guide (a local historian) said only the remains of young boys were found in the "cenote," a spot where human sacrifices were made. According to the guide, the theory was that the leaders were secretly keeping the girls for themselves inside the temple, and then dressing the boys as girls and sacrificing them in front of the crowd.
Now, I'm reading that girls' remains have been found in the cenote, too. So, maybe some of the remains thought to be boys years ago were later found to be girls. But, if historians knew years ago that boys were sacrificed there, they shouldn't be surprised to find all the remains in the "chultun" were boys.
So sad... What a cold, bloodthirsty culture.
Quite.
When I was there a few months ago the tour guide showed us the place where the sacrifices were made. (It was at the end of field where they played the game with the vertical hoops on the walls), and he said that it is now believed that the AZTECS introduced the Maya to sacrifices.