These results are more than just pretty pictures of ancient sites. They have the potential to challenge our understanding of the collapse of ancient civilisations. For example, they show that many areas which were once thought to be rainforest, actually used to be cleared, and sustained significant populations. They also show that many of the great ceremonial centres which are now engulfed in foliage, were once surrounded by large cities, with populations of hundred of thousands – or even millions – of people.
In often-fragile ecosystems, reliant on a stable climate, it is now much easier to see how environmental change might have contributed to the collapse of these ancient civilisations. As a result, many ideas about the collapse of ancient societies, such as those promoted by Jared Diamond – who emphasises social, political and economic factors – may require some significant rethinking.
There are, of course, several problems with this technology. One is cost: the Cambodia survey was generously funded by the European Research Council, but access to both the equipment and the planes would be limited for most archaeologists. Some of the landscapes may be too remote to even reach by light aircraft or helicopter, or local authorities may ban such flights.
Francisco Goncalves, Author provided
Placing Lidar technology onto drones may solve this issue in the future, but at present there have been only limited examples of their use in tropical zones. Given the scale of some of these sites, and the minimum height required (around 800m) a plane will remain the preferred method for now.
There is also the problem of ground-truthing. While these Lidar images are amazing, they do require careful interpretation and validation. Some may well show ancient features, but others may be quite modern in origin. So the archaeologist with their machete may not be entirely redundant – in fact, with this new technology at hand, they may be even more important than before.