Archaeology, traditionally, has been a science of smallness and span. It has used shovels and brushes and human eyes -- tools that require intricacy and precision and, to some extent, luck -- to discover, plot by plot, the sweep of human history.
Archaeology's future, however, may rest not only in the earth's soil, but also in its sky. In a paper published last week in the Proceedings of the National Academy of Sciences, the Harvard archeologist Jason Ur and the MIT computer scientist Bjoern Menze describe a new land-analysis technique that makes use of satellite imagery to study wide swaths of soil -- in their example, the soil of ancient Mesopotamia (the stretch of land that today comprises Iraq, northeast Syria, southeast Turkey, and southwest Iran). The method that Menze and Ur (yep, Ur!) have developed focuses on the analysis of anthrosol, a type of soil that forms as a result of long-term human activity -- and that, being generally richer in organic matter than its counterparts, often has a different color than the soils that surround it.
From the ground, those distinctions don't look like much. From the sky, however, they reveal patterns that can, in turn, suggest the locations of -- and, even more intriguingly, the pattern of networks among -- the world's earliest civilizations. (In addition to color variations, mounding, the raised soil that is the legacy of early civilizations' mud-and-brick homes, can suggest the existence of centuries'-old settlements.) By combining the earthly and the bird's-eye, Menze and Ur have so far created "the largest archaeological record for a landscape in Mesopotamia." That record currently maps about 14,000 different sites -- spanning, in all, about 8,000 years of human history.
Their work is a significant development for several reasons. First, while it's a commonly held belief that Mesopotamia is the birthplace of the world's earliest cultures -- "the cradle of civilization," and all that -- the size and distribution of human settlements within those cultures have long remained a mystery. The team's broad record of settlements can offer valuable insights into how ur-cultures interacted with each other. But the work of aerial archaeology could have wider-reaching ramifications, too -- among them the suggestion that the most ancient of human mysteries could find their answers in the most cutting-edge of human technologies.