This informational text resource is intended to support reading in the content area. New evidence shows that polar bears split off from their closest ancestors, brown bears, less than 500,000 years ago. This is a very short time for a large mammal to evolve. In that time, polar bears have evolved many adaptations to their specialized lifestyle, including the ability to process the large amount of fat in their seal-based diet. This is shown by their unique DNA sequence of genes related to fat processing and heart development.