JUANA SUMMERS, HOST:
When archaeologists study how ancient civilizations traveled, they can use evidence like wagons and stables and roads to understand how goods and people moved on land. But when they want to learn about how humans traveled on water, things get a little murkier. Well, a team of researchers in France has come up with a way to help answer some of those questions. They developed a computer model that estimates how easily Roman and Celtic travelers navigated rivers thousands of years ago. Professor Clara Filet studies European prehistory at the University of Bordeaux-Montaigne. She led the team who did this analysis, and she joins me now. Welcome.
CLARA FILET: Hello.
SUMMERS: Professor, first of all, why are rivers so important to understanding ancient people?
FILET: Nowadays, we underestimate the importance of rivers for our modern society because we don't use them that much anymore. But we have to keep in mind that before the development of planes and railways, rivers were the main highways of transport systems for ancient times. It was always more quicker. It was always more cheaper to take a certain amount of goods for trade, for example, to transport it using a boat on a river than to transport it using the roads and the wagons.
And also, we have a certain idea of the Roman Empire that comes from what we've always said in history and in archaeology - that a Roman road system was so efficient, so well designed. But we see more and more with archaeology, with history, that rivers were also very important, that it was very complementary with a road network.
SUMMERS: Paint us a picture about a river in modern-day France that was used by ancient people. If we transported to the river's banks, what might we see?
FILET: Let's take an example of the Rhone River, who is one of the main axes going from the Alps and going to the Mediterranean. And we know from ancient sources, both with archaeology and history, that it was a very used river axis - a lot of trade, a lot of boats, and villages and cities that were built along the river banks, and a trade that was very dynamic in this area.
SUMMERS: Tell us about the model that you created to figure all of this out.
FILET: The idea is - was that we know that people interacted a lot with each other using river navigation, for example. We just have indirect evidence because we don't have a lot of shipwrecks. We don't have a lot of remains of infrastructure. People working on ancient transport system needed to have a method to estimate how far upstream you can go on a river - until what point it was possible to navigate, and to estimate the section that could have been used at those times for river travel.
SUMMERS: How are you able to be confident that this model's reliable?
FILET: This model is a theoretical model. We use a certain number of numerical values and measures about those rivers and estimate navigability sections. And then we compare them to empirical data we have from the literature on some areas of the European rivers for which we have historical sources or archaeological sources to know which sections were navigable.
SUMMERS: And what about using it in other parts of the world to understand their past?
FILET: That was really the idea of the model. So we know that it can be used for areas with temporal climates, for which the rivers have not changed that much from those ancient periods to modern times. We only tested the model with European data - with European empirical data. So we know that it works in this area. But I would be very curious to see how people might take this model, try it on their own data, and what they can say about it and help us to improve the model.
SUMMERS: Professor Clara Filet. Her team's paper will be published in the October edition of the Journal of Archaeological Science. Professor, thank you.
FILET: Thank you very much.
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