Bears are able to live and sometimes thrive from the North Pole to the tropical rainforests around the equator and although they are largely confined to the forests nowadays, in the not too distant past they dominated grassy plains as well. And in overcoming the challenges of each new habitat they migrated into presented, they have evolved to drastically change diets. Bears evolved from small carnivorous animals and yet have become omnivorous, insect eaters, or have a diet occupied entirely of plant foods. So how have bears been able to evolve to eat almost any food in a very small amount of time.