warren barbour began to think the tiny faces would yield an answer. arbour: during my dissertation research, i occasionally would run across figurines that had fingerprints, and they sort of added a humanity to my work, and i started looking for them, and they sort of brought me closer to the manufacturer of the print. i started wondering who he was, and i figured i would never be able to find that. and i started wondering whether or not i could find something else out about them. keach: barbour's curiosity led him to the modern science of fingerprints where he discovered that with a large enough sample he might be able to discern the gender of the person who made the print. males have wider ridges. females have narrower ones. through trial and error, he devised a technique to make permanent molds of the fingerprints. from these he began to construct a sample. finally, an intriguing discovery -- direct evidence that one set of workers was being replaced by another. barbour: it appears that the early handmade figurines were made by females. after the es

warren barbour has studied these compounds since 1962. this is the central patio of the apartment compound, called sequala, which is a typical apartment compound at teotihuacan. it's about half a football field on the side. it contains a central patio, a temple on the east side, and four apartments. to get the picture of this, you have to see elaborate paintings on the lower sections of the walls... the upper walls painted like wallpaper in reds and whites and greens. the pillars would go up to roofs with wood and covered porticoes, where children would be sitting and playing a game like parchesi. you would see dogs walking around, food being cooked, baskets in corners, stacks of grain. this would have been the center of life in the compound. and you have to remember that this would be repeated 2,000 times in other apartment compounds throughout teotihuacan. keach: in many ways, teotihuacan was a dramatic step forward in the evolution of ever more complex societies. it was the beginning of a cosmopolitan, urban way of life. the city's fam