STATE COLLEGE, Pa., March 1 (UPI) -- U.S. and Swedish scientists say they have sequenced the genome of the polar bear -- the oldest mammalian genome to be sequenced so far.
The researchers from Pennsylvania State University, the University of Buffalo, the University of Oslo in Sweden and other institutions said very few polar bear fossils have been found.
"Because polar bears live on the ice, their dead remains fall to the bottom of the ocean or get scavenged, "said University of Oslo Professor Oystein Wiig. "They don't get deposited in the sediments like other mammals."
The 110,000-to-130,000-year-old polar bear fossilized jawbone and tooth was discovered during 2004 by an Icelandic geologist in Norway.
"Our results confirm that the polar bear is an evolutionarily young species that split off from brown bears some 150,000 years ago and evolved extremely rapidly during the late Pleistocene," said Charlotte Lindqvist, an assistant research professor at the University of Buffalo.
"This is, by far, the oldest mammal mitochondrial genome to be sequenced," Penn State Professor Stephen Schuster said. "It's about twice the age of the oldest mammoth genome that has, to date, been sequenced."
The study that included researchers from the U.S. Geological Survey, the University of Iceland and the Norwegian Polar Institute appears in the Proceedings of the National Academy of Sciences.