Polar Bear Inspects A Car, Alaska, United States

Constantine John Phipps was the first to describe the polar bear as a distinct species. He chose the scientific name Ursus maritimus, the Latin for 'maritime bear', due to the animal's native habitat. The Inuit refer to the animal as nanook (transliterated as nanuuq in the Inupiaq language). The Yupik also refer to the bear as nanuuk in Siberian Yupik. The bear is umka in the Chukchi language. In Russian, it is usually called бе́лый медве́дь (bélyj medvédj, the white bear), though an older word still in use is ошку́й (Oshkúj, which comes from the Komi oski, "bear"). In French, the polar bear is referred to as ours blanc ("white bear") or ours polaire ("polar bear"). In the Norwegian-administered Svalbard archipelago, the polar bear is referred to as Isbjørn ("ice bear").
The polar bear was previously considered to be in its own genus, Thalarctos. However, evidence of hybrids between polar bears and brown bears, and of the recent evolutionary divergence of the two species, does not support the establishment of this separate genus, and the accepted scientific name is now therefore Ursus maritimus, as Phipps originally proposed.
The bear family, Ursidae, is believed to have split off from other carnivorans about 38 million years ago. The Ursinae subfamily originated approximately 4.2 million years ago. According to both fossil and DNA evidence, the polar bear diverged from the brown bear, Ursus arctos, roughly 150,000 years ago. The oldest known polar bear fossil is a 130,000 to 110,000-year-old jaw bone, found on Prince Charles Foreland in 2004. Fossils show that between ten to twenty thousand years ago, the polar bear's molar teeth changed significantly from those of the brown bear. Polar bears are thought to have diverged from a population of brown bears that became isolated during a period of glaciation in the Pleistocene.