Island mammoths postponed extinction

FAIRBANKS, Alaska, June 18 (UPI) -- A group of woolly mammoths on a Bering Sea island outlived the extinction of their mainland counterparts more than 11,000 years ago, U.S. researchers found.

St. Paul, an island 300 miles west of Alaska and part of the Bering Sea Pribilofs, was an upland connected to the mainland by a large, flat plain at the last glacial maximum, when the sea level was significantly below what it is now, said R. Dale Guthrie, a professor at the Institute of Arctic Biology at the University of Alaska-Fairbanks.

The mammoths at this location became stranded 13,000 years ago when the sea level rose after the last glacial maximum.

Radiocarbon-dated samples from the mainland go back 11,500 years -- at the end of the Pleistocene era -- compared to samples from St. Paul that, according to radiocarbon dating are about 7,900 years old, which is much later.

The mammoths survived for a longer period of time based on the availability of food, but due to inbreeding pressures the mammoths could not establish a permanent population on an island of only 36 square miles.