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 bulldoze 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 fossil 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 discovered 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 consistent 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 sooner to overheat when they do so. Instead they choose a slow lumbering pace, providing ideal sight opportunities for those on bear watching holidays.
Color Change
Perhaps the most intolerable 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 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 is not 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 colored ancestors.