Ceibal Excavation (3 of 3) (image) University of Arizona Caption Researches are challenging the two prevailing theories on how the ancient Maya civilization began. Credit Photo by Takeshi Inomata, University of Arizona Usage Restrictions This visual may only be used in conjunction with reporting/posting of this news release. Image/video credit must be included exactly as indicated. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.