Jack Dykinga / Grinding stones in Mayan Ruins, Oxkintok, one of the oldest cities in the Yucatan with hieroglyphic inscriptions showing some of the earliest dates known in the Yucatan.

Jack Dykinga / Mayan Ruins at Oxkintok, one of the oldest cities in the Yucatan with hieroglyphic inscriptions showing some of the earliest dates known in the Yucatan. Mexico

Luiz Claudio Marigo / Rupestrian inscriptions made by pre-Colombian men, dated 10,000 years ago, in Sete Cidades National Park, municipality of Piracuruca, Piaua State, Northeastern Brazil. March 2009

Luiz Claudio Marigo / Rupestrian inscriptions made by pre-Colombian men, dated 10,000 years ago, in Sete Cidades National Park, municipality of Piracuruca, Piaua­ State, Northeastern Brazil. March 2009

Daniel Gomez / The Temple of the Inscriptions. Tomb of Pakal. Palenque archaeological site,

Staffan Widstrand / Ancient stone carvings, Luxor temple, Egypt.