RENEE MONTAGNE, HOST:
No one knows when humans first started using maps. One contender for the world's oldest map was found in Turkey in an ancient city that dates back 9,000 years. Some archaeologists say the map shows an erupting volcano looming over what looks like a schematic plan of the city. Others aren't so sure it's even a map at all. NPR's Nell Greenfieldboyce reports that a study of volcanic rocks provides a new clue.
NELL GREENFIELDBOYCE, BYLINE: The prehistoric settlement in central Turkey is known as Catalhoyuk. Thousands of people once lived there in mud-brick houses that were crammed together like honeycombs. It was a huge town for a time when people were first transitioning from hunter-gatherer to agricultural societies. The British archaeologist who was excavating the site in the early 1960s made a dramatic find - a mural.
He said it showed a bird's eye view of the settlement's houses plus a distinctive volcano with two peaks, just like the one that lies about 80 miles away. This mural has often been called the world's oldest known map.
AXEL SCHMITT: In volcano textbooks or textbooks about cartography and mapping, they would always in their introduction mention this mural and that it's potentially, you know, the oldest map, and the oldest depiction of a volcanic eruption.
GREENFIELDBOYCE: Axel Schmitt is a geologist at the University of California, Los Angeles. He studies volcanoes, and he was doing fieldwork in Turkey when he first learned of this mural. He also learned there was a controversy - that this may not be a map at all. The image of the so-called erupting volcano, which is covered with dots, looks a lot like paintings of leopard skins seen elsewhere at the site.
Plus, the so-called map of the city could be just a repeating abstract pattern, like the ones painted on other walls. Schmitt says, how could we ever really know?
SCHMITT: You know, these people that lived in Catalhoyuk 9,000 years ago, they are - you know, they're fascinatingly strange to us. There's always a danger in taking our views and knowledge and trying to impose it onto, you know, a culture that is that different from ours.
GREENFIELDBOYCE: But he knew at least one thing could be tested scientifically. If this was supposedly an image of the twin-peaked volcano erupting, it would be good to know if the volcano actually had erupted while people were living at the site. To find out, his team collected samples of pumice from the volcano's summit and flanks.
They used two different dating techniques to determine when those rocks formed in an explosive volcanic eruption. And lo and behold, they found that there was an eruption about 9,000 years ago.
SCHMITT: There was an eruption, you know, at the time people lived in Catalhoyuk. I think that is without doubt.
GREENFIELDBOYCE: The uncertainty in all the measurements means they don't know whether the person who painted the mural was alive when it happened, but stories of a dramatic eruption could have been passed down for generations.
SCHMITT: You know, volcanic eruptions are very impressive events. Maybe there was some idea that the mountain was a volcano that's part of the lore of the people of Catalhoyuk.
GREENFIELDBOYCE: The results are reported in a scientific journal called PLOS ONE and they have impressed Keith Clarke. He's a cartographer at the University of California, Santa Barbara who has a special interest in the world's earliest maps.
KEITH CLARKE: I can't say with 100 percent certainty but I would believe that the evidence is now in the favor of it actually being a map.
GREENFIELDBOYCE: This mural is from a period thousands of years before other accepted maps, but Clarke thinks ancient humans weren't as primitive as we think and that maps probably go back even farther. Nell Greenfieldboyce, NPR News.