It is thought that polar bears have evolved from the brown bear. Thousands of years ago, somewhere around the Ice Age, a population of brown bears became dependent on the abundance of seals in the icy waters of the north.
They learned to live almost entirely on seals and became entirely carnivorous. Due to the habitat in which their natural prey lived, it became necessary for the bears to be come efficient swimmers. Over time they developed larger feet which made them much more capable in the water. The feet is also thought to disperse their weight more evenly, enabling them to walk on thin ice without falling through. The claws also grew larger, enabling them to grip their prey with ease.
Reduced temperatures ensured that the coats of the bears would become thicker. Their color also changed from brown to white. This was obviously to aid in camouflage and improve their chances whilst hunting.
Their overall size of the bears increased over time so that the polar bears of today are much larger than their brown bear ancestors. This is attributed to the fact that the prey of the polar bear is large and an immensely powerful animal is needed to subdue this prey.
The skin of the polar bear is black and the hairs near the skin hollow, which helps it warm up.
The changes, over time, have served to produce a formidable predator; one which has no natural predators itself, except for man.
