The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is often considered a symbol of the pristine Arctic. An analysis of newly sequenced polar bear genomes is providing important clues about the species’ evolution, suggesting that climate change and genetic exchange with brown bears helped create the polar bear as we know it today. The international study, led by researchers at Penn State and the University at Buffalo, found evidence that the size of the polar bear population fluctuated with key climatic events over the past 1 million years, growing during periods of cooling and shrinking in warmer times.