© UnknownOld days: “Olmec: Colossal Masterworks of Ancient Mexico” at the de Young Museum showcases a range of objects, such as this group of standing figures and celts dated from 900–400 BC.
The headline items in the de Young Museum's new special exhibit, "Olmec: Colossal Masterworks of Ancient Mexico" are indeed colossal, similar to the iconic - if much more contemporary - Easter Island heads.

The unique show, organized by many and led by the de Young's Kathleen Berrin and Virginia M. Fields of the Los Angeles County Museum of Art, represents the only chance for visitors to see 140 ancient objects outside their homes in 25 Mexican and U.S. museums. In addition to the huge heads, the exhibition also features many small, fascinating works of art.

The Olmec ("people of the rubber country") created a pre-Columbian civilization in south-central Mexico, now the states of Veracruz and Tabasco. Thriving some 3,500 years ago, the Olmec pre-dated other Mesoamerican civilizations, such as the Zapotecs, Teotihuacans, Aztecs and Mayans.

Unlike many other ancient civilizations, the Olmec disappeared without a trace, leaving uncertainty behind them. Their contemporaries were the golden age of Greece and the Zhou dynasty of China, both known in great detail today, unlike the Olmec.

Even the name, Olmec, is in the Nahuatl dialect of the Aztecs - nothing of their own language is known.

The huge, mysterious stone heads, some weighing 24 tons, come from the time before the Bronze Age arrived in Central America. They could not have been shaped using metal tools - they had to be created using stone on stone, making them even more impressive.

What are they? Scholars are uncertain, but guesses range from gods to kings to players of a Mesoamerican game similar to racquetball, but often involving ritual human sacrifice.

One theory combines others by saying the heads are of kings dressed as ballplayers, complete with helmets.

Among many small, complex objects that vie for attention with the colossal heads is a miniature scene labeled "Offering 4." Somewhat reminiscent of Stonehenge, the ceremonial scene shows six slender surfboard-like serpentine celts - prehistoric stones - forming a wall, with a human figure in front.

Two jadeite and 13 serpentine male figurines stand facing him, their heads shaved, as customary in Olmec culture. The figurines and celts are embedded in a matrix of reddish-brown sand and covered with a layer of white sand. Some of the heads are elongated, marking those figures' royal status. As several Mesoamerican cultures, the Olmec is believed to have practiced artificial cranial deformation.