This carving deep in the cave we were exploring is the Mayan god of fertility. Couples having trouble conceiving had a ceremony conducted by the priests here. If the god blessed the couple with a baby, they were expected to sacrifice the baby to the god with the promise of many more offspring in the future.
I am a first born with a birthday yesterday. If my parents were Mayans back then I would have been the one sacrificed and never had the chance to celebrate more the 50 years on the planet.