This is Scientific American's 60-second Science, I'm Emily Schwing.Sometimes discoveries seem so simple."You know, basically, we found a bunch of holes in the ground."That's Eduard Reinhardt. He's an archaeologist and geologist at McMaster University in Ontario, Canada."But, you know, ultimately, very important holes in the ground."Reinhardt and colleagues believe they've found some of the first clear evidence of mining activity in a system of caves in Quintana Roo on the Yucatán Peninsula.The find dates back to between 10 and 12,000 years ago."So these are some of the very early people that have come and migrated to the Americas via the Bering Strait."But getting to what remains of these miners and the tools they left is a challenge."Like, as cave divers, you gotta be so careful you don't get lost."These cave systems in Mexico, which were once dry, are now completely filled with water, thanks to a warming climate and sea levels that rose over time.Winding passageways are narrow and dark. And the walls are made of unforgiving limestone, porous and with sharp edges.Reinhardt says the water that filled the caves has preserved everything."It's basically almost like somebody working at a factory: they turned the lights off, they went away and nobody ever came back."
