Finding new buildings and even cities is all very well and good - a new Machu Picchu or Chichen Itzas would be the crowning achievement of any archaeologists’ career. But, it goes without saying, most buildings and land modifications are rarely so dramatic. What is really important is who was in these buildings and how many. The more buildings, roads, wells, agricultural terraces and residential complexes are found, the higher the number of people that lived there.
Population estimates of the Americas at the time of European contact have been steadily increasing over the past decades as archaeologists have slowly found new sites and dug over existing ones. That has gradually overturned the image of the Americas as a vast unexplored, unpopulated wilderness. But Lidar surveys are now beginning to dramatically change our view, says Fisher.
“Widespread Lidar surveys will reveal a Mesoamerican landscape that was more densely settled, and an environment that was more pervasively modified, then previously thought,” said Fisher. Instead of a wilderness, here were two continents with vast populations, grand urban centres and widespread agriculture. But, perhaps more importantly, in revealing what life was like before the Conquistadors arrived in the 1500s, it also reveals the devastation that they wrought when they came into contact with native populations.
“Before, a 40% die off seemed implausibly high,” said Fisher, “now 80% seems more likely.”
You may expect that dramatic findings and conclusions like this would mean the case for Lidar has been made. But not everyone is convinced by the laser revolution. Archaeologists like Rosemary Joyce, a professor of Mesoamerican archaeology at the University of California, Berkeley, and Russell Sheptak, a visiting scholar there, believe that the some of the proponent’s claims do not stack up.
“What I specifically reject,” says Joyce, “is the claim that Lidar is both faster and cheaper than other archaeological methods, if we are interested in understanding sites, not just discovering them.”
To really understand a site, you need boots on the ground, they say.
These are arguments that the Lidar community are familiar with, and have some sympathy with. Both the Chases and Fisher teams admit that cruising over the tree-tops in a plane does not totally supplant the need to get up close and personal with a site. Without their 29 years of experience at Caracol, the Chases admit they would not have been able to recognize what they were seeing through Lidar as quickly as they did. Instead, it is a tool that allows them to quickly zoom in on potential features of interest. It also allows sites to be mapped quickly, allowing them to be preserved from looters and development.
However, they take issue with arguments based on cost. Although they admit that Lidar can be expensive at face value – usually around $350 per square kilometer - they maintain it is still cheaper than traditional digs. For example, the Chases calculate the cost of Lidar per square kilometer is vanishingly small in comparison with the cost of travel, living on site, hiring workers, provisioning the dig and the thousand other misfortunes that an expedition to the jungle can encounter. Fisher, however, puts it more bluntly: “I don’t know how people can say it’s not cost-effective,” he says. “It saved us 10 years of research, for the cost of one season of excavation.”
Over the next few years, as with all developments in computing, Fisher expects to see that cost continue to fall and its use to sky rocket. “Ten years from now, this is going to be like radiocarbon dating,” says Fisher, referring to a standard technique now used by all archaeologists to date finds. “Lidar is going to be folded into your research program, a really basic thing you do to understand the questions you want to answer.”