Ancient DNA Uncovers Late-surviving Alaskan Megafauna

Ancient DNA reveals late survival of mammoth
and horse in interior Alaska. 2009. J. Halle, et al., PNAS, published online before print December 17.

Extinct woolly mammoths and ancient American horses may have been grazing the North American steppe for several thousand years longer than previously thought. After plucking ancient DNA from frozen soil in central Alaska, a team of researchers uncovered "genetic fossils" of both species locked in permafrost samples dated to between 7,600 and 10,500 calendar years.

This new evidence suggests that at least one population of these now-extinct mammals endured longer in the continental interior, challenging the conventional view that these and other large species, or megafauna, disappeared from the Americas about 12,000 years ago.

Cores samples offer a clear picture of the local Alaskan fauna at the end of the last ice age. The oldest sediments, dated to about 11,000 years ago, contain remnant DNA of Arctic hare, bison, and moose; all three animals were also found in higher, more recent layers, as would be expected. But one core, deposited between 7,600 and 10,500 years ago, confirmed the presence of both mammoth and horse DNA.

"At this point, mammoths and horses were barely holding on. We may actually be working with the DNA of some of the last members of these species in North America," link