The Fascinating Evolution of Polar Bears

If you're heading off on one of the excellent bear watching holidays to the Arctic, you may be interested to know a little history about the Polar Bear and its evolution.

Some time in the last 350,000 years, a crisis of food shortage drove some species of bears into the harsh environment of the Arctic. Research into the Polar Bear genome has presented new ancestry information and new archaeological findings have created a renewed interest in this magnificent creature.

Origins

Originally, a fossil of a bear bone found at Kew Bridge in London was dated to around 70,000 years ago. Since this discovery, a fossilised jawbone was found in the Arctic and dated to be over 100,000 years old, making the first evolution even earlier than scientists initially thought. These discoveries have proved to be an exciting development for both scientists and wildlife enthusiasts.

Evolution

In order to survive the harsh impact of the Arctic weather conditions, Brown Bears evolved in the following ways.

Insulation

The initial shock of the Arctic climate was simply not sustainable for many of the original migrators, and only those with thicker fur were able to survive and go on to breed. Over time, the magic of evolution provided them with fur consisting of two layers along with a thick layer of body fat. These adaptations allowed for incredible insulation, with metabolic rates remaining unchanged even when temperatures reach as low as -34ºF.

In fact, Polar Bears are so well insulated that they suffer more from overheating than they do from the freezing conditions. This has gone on to affect their ability to run long distances, as they are prone to overheat when they do so. Instead they choose a slow lumbering pace, providing ideal sighting opportunities for those on bear watching holidays.

Colour Change

Perhaps the most notable of changes was the lightening of the fur to the milky white coat so familiar today. Brown Bears originally had difficulty when it came to hunting in the Arctic, due to their bold, dark coats that alerted prey from miles away. Those that initially had lighter fur were far more successful in their hunting habits and therefore paved the way for this vital evolutionary adaptation.

The white coats help not only with hunting but also to stay hidden from predators (mainly including territorial threats from their own kind), and they're known to dig shelter pits in snow banks in freezing weather and become invisible as snow drifts over them. Unfortunately, bad weather isn’t ideal for sightings on bear watching holidays, but once weather conditions improve chances increase dramatically.

Marine Abilities

The Polar Bear is the only bear considered a marine mammal, due to its incredible swimming abilities. Whilst originally good swimmers, they evolved to be able to swim long distances in order to travel from one ice floe to the next. They have also been spotted diving for food with extreme speed and precision, and have the unique ability to swim underneath thin ice. The rare sighting of a Polar Bear diving for kelp has been a huge source of excitement for scientists and tourists on bear watching holidays. It provides further evolutionary evidence of how far Polar Bears have come since the times of their darker coloured ancestors.

Marissa Ellis-Snow is a freelance nature writer. If you’re looking for bear watching holidays, Naturetrek specialises in expert-led natural history and wildlife tours worldwide. Naturetrek brings over 25 years of experience to polar expeditions and tours to other spectacular regions on Earth.

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