obregon: but mexican artist a scholar miguel carruas and ththpologistlfso casoshar srling's view. stling pugh: it was at that time that alfonso caso announced that he considered the olmec the mother culture of mesoamerica and at that time, that just put the olmec on the map, because he was the outstanding mexican anthropologist. obregon: in fact, the origins of olmec art turned out to be far older than even covarrubias, caso and stirling imagined. radiocarbon dating at san lorenzand other olmec sis hapushed back the ginning of olmec culture by more than a milleium, to circa 1,200 b.c. newsreel announc: now we're off for the second phase of our exploration. obregon: stirling beganigging at san lorenzo in 1946, with the archaeologist philip drucker. stirling pugh: and sure enough, ere was a big head, a beautifully carved big head, much finer [and] more ndsome thanhe ones at la venta. obregon: stirling proposed that these enigmatic sculptures wereortraits of prominent individuals in olmec society. mostf the vast site of san lorenzo remains to be explored. new speaker: we now know tha