Climate change killed the Neanderthals–or so a new study argues. They use an interesting proxy for reconstructing the climate.
To figure out the temperature, water supply, and windiness of Iberia from 20,000 to 40,000 years ago, the scientists looked at sediments on the ocean floor off Spain and Portugal. Because wind or water erode rocky minerals differently, the pebbles and fragments wash into the sea in different ratios, creating a steady track record of land conditions at the bottom of the ocean.
The scientists also focused on barite, a compound gathered by marine animals. The more barite in sediment, the more lively the oceans were at the time. “When we found big drops in marine productivity, we knew there were big changes in climatic condition in Iberia,” Jiménez-Espejo says.
The trouble with many climate proxies is that they can be influence by a multitude of factors. Ocean “liveliness” could be caused by any number of things other than wind.