朝活ミニテスト 第12回

Seeing Beneath the Jungle

For much of the twentieth century, many archaeologists believed that the ancient Maya of Central America lived mainly in scattered settlements separated by dense forest. According to this view, the great sites with their famous pyramids were largely ceremonial centers surrounded by small farming villages, rather than true cities. Mapping the region on foot, however, was slow and difficult, so researchers could examine only small areas at a time, and much of what lay beneath the thick jungle remained unknown.

That picture changed dramatically with the use of lidar, a technology that fires huge numbers of laser pulses from an aircraft to create detailed maps of the ground beneath the trees. Surveys in Guatemala and elsewhere revealed tens of thousands of previously unknown structures, including houses, raised roads, farm terraces, and defensive walls. The findings suggest that Maya cities were far larger and more interconnected than once thought. Some researchers have used the data to argue that the region once supported millions of people. Others, however, urge caution, pointing out that population estimates depend on assumptions about how many structures were occupied at the same time.

Lidar has also changed how archaeology is done. Because researchers can identify promising sites before visiting them, they can plan excavations more efficiently and make better use of their limited budgets. The maps may also help authorities protect sites threatened by looting and illegal land clearing. However, experts stress that ground investigation remains essential. Laser images can reveal the shape of a structure, but they cannot show when it was built, how it was used, or whether anyone actually lived in it. For that, archaeologists must still pick up their tools and dig.