PANAMA CITY, Panama, Dec. 1 -- The Smithsonian Tropical Research Institute issued the following news: * * * Digging deep into the oldest and largest monument in the Maya area of Mexico Recent discoveries in an archaeological site in Mexico sheds new light into the beginning of the Maya civilization, and how they perceived the passage of time. By Vanessa Crooks A large mound that looked like a natural hill in the state of Tabasco, in southwestern Mexico, turned out to be the largest prehispa more PR