Humans, megafauna coexisted in Patagonia before extinction
Humans, megafauna coexisted in Patagonia before extinction
Cueva del Milodón, or Mylodon Cave, in Patagonia was named after the giant ground sloth whose
mummified skin and large deposits of dung were found in the cave. Credit: Alan Cooper.
During the last ice age, giant mammals roamed the wide-open steppes of what is now Patagonia. Around the time that humans were making their way down through North America and into South America, the climate began warming and large species of giant sloths and saber-toothed cats soon disappeared. Now, researchers looking at mitochondrial DNA from some of these megafaunal species are shedding light on the timing of the extinction and whether encroaching humans or changing climate — or both — were to blame for their disappearance.
Patagonia is an ideal place to study the Late Pleistocene megafaunal extinction, says Alan Cooper, a biologist at the Australian Center for Ancient DNA at the University of Adelaide and a co-author of a new study in Science Advances. “Patagonia has a number of volcanic caves and lake shore caves, many of which are stocked with megafaunal remains,” he says. “The cold temperatures also help preserve DNA and make for high-resolution data.”
Cooper and his colleagues used mitochondrial DNA extracted from radiocarbon-dated bones and teeth found in caves across Patagonia and Tierra del Fuego to map the genetic history of six megafaunal species, including the giant jaguar, large ground sloths and the one-ton short-faced bear. “The combination of radiocarbon dating and mitochondrial DNA allowed us to see the timing of the major changes in diversity of these populations,” Cooper says, and to “compare that timing with the arrival of humans in the area, as well as with the timing of warming.”
The team identified a narrow extinction phase starting about 12,300 years ago, while the earliest dates from archaeological sites place humans in the region starting about 14,600 years ago. “Clearly, we have a prolonged overlap between human presence in the area and the megafaunal extinction. These animals were coexisting with humans for some time before [the animals] started disappearing,” Cooper says.
More:
http://www.earthmagazine.org/article/humans-megafauna-coexisted-patagonia-extinction
Science:
http://www.democraticunderground.com/122849195
