Bears have evolved over millions of years from small, weasel-like ancestors. Modern bears like brown bears, black bears, polar bears, and pandas can be found across the northern hemisphere. Bears range in size from the massive Kodiak bear, which can weigh over 1 ton, to smaller black bears. Despite their size, many bears are excellent swimmers, climbers, and have a good sense of smell and vision. The giant panda is one of the most unique bears due to its primarily herbivorous diet.