That is the conclusion of a study reported in Science News.
"The discovery of this jawbone confirms that the polar bear was already a distinct species at least 110 kya, and as such any findings from genetic research based on this specimen could contribute to answering key questions on the evolutionary history of this species." source p. 5054
Analysis of the mitochondrial DNA show that polar bears split from Alaskan bears 150,000 years ago.
“Within this clade, we estimated the mean age of the split between the ABC bears and the polar bears to be 152 ky, and the mean age for all polar bears as 134 ky, near the beginning of the Eemian interglacial period and completely in line with the stratigraphically determined age of the Poolepynten subfossil.” Charlotte Lindqvist et al, “Complete mitochondrial genome of a Pleistocene
jawbone unveils the origin of polar bear, Proc. Natl. Acad. Science, USA, 107(2010):11, p. 5054
The picture below shows the temperature (black curve) from a Greenland Ice core back to 100,000 years ago. Notice the warmth.
This next picture shows the temperature of the Vostok core from Antarctica. Notice that the world was warmer than at present about 100,000 years ago in that core as well. That means that the polar bears survived the warm periods. The hysteria about their future is misplaced.
This, of course, means that polar bears lived through the last interglacial period when it was warmer than it is today. And we are supposed to worry about us killing the polar bears. What a laugh. The bears can take care of themselves.