According to scientists, polar bears evolved from a well-known forest creature! By using fossil records and DNA analysis, researchers believe that two hundred thousand years ago, brown bears began searching for food across the frozen Atlantic ocean. About 7,000 years later, some of those bears split off from the group and traveled even farther north.
Although many of these adventurers died because they were unprepared for the frigid, glacier-ridden environment, others evolved to have a thicker and more camouflaged coat. Out with the omnivore diets and in with the ripping seals apart and devouring them. At first, the bears only ate animals that had washed ashore and died. Scientists believe that polar bears became their subspecies when they began to hunt and stalk seals. Even though polar and brown bears are very different from each other today.
How did the polar bear evolve?
Evolution is defined as the gradual changing of the same species to benefit their survival. There were two theories made on how this process happened.
Lamarck’s theory is the theory of acquired characteristics. Darwin’s theory is the theory of natural selection. Both scientists agree that evolution is caused by the need to survive. In this case, the Polar bear showcases this evolutional change in the color of the fur. This species, first of all from the common brown bear species thirty-five hundred thousand years ago.
Adopting many structural-functional and behavioral changes to survive their new Arctic environment makes them an outstanding example of how evolution can change organisms. It boosts their survival rates. In comparison, Lamarck and Darwin agree that evolution happens in or froze species to survive. Their theories differ significantly on some points.
- Charles Darwin’s idea of natural selection is based on species reliability on reproduction. He believed that if an organism obtains a trait that benefits survival and lives longer than the organisms, they haven’t got that trait. It means it will survive longer it all debridement spreading its survival trait with its offspring.
For example, white moss that lives in the woods would appear more so into the dark wood, making them an easy target for the prairies. So the Moss was driven to adapt to the new environment. Adopting a trait that makes them a darker color to camouflage up, the wood making them live longer and breed more, passing on their trade. Darwin dictates that the survival trait can only be inherited from their parents.
Some animals fit in one theory more than any other. The polar bear originated from the same species as brown bears. However, brown bears were introduced to a new environment. They were forced to adapt and change to survive. The Arctic is a harsh environment filled with barren white landscapes.
The polar bear’s ancestors, the brown bear, predominantly have woods around northern Africa and Europe. Its brown fur helped to camouflage with its brown forest environment. However, when these bears wandered into the icy tundra, the brown hair that once benefitted them made their apparent Brown thought in a bleak white environment.
It may sneak up on predators a challenging task when combined with the scarcity of food available challenge their survival. Therefore, when the brown bear was changed color to the third white, it could sneak up on its prey. But then they acquired camouflage. As a result of this one will trait, they could live longer and breed more than the brown bear in the Arctic environment.
Eventually, the newly evolved polar bear took over the brown bear population in the ice biome by surviving and passing on their trace. This evolutionary change justifies a clear example of Darwin’s theory of natural selection. While Darwin’s theory of natural selection is wildly acceptable assigned to the community. There is still a large amount of the world’s population that doesn’t believe in evolution, despite being a plethora of evidence suggesting otherwise.
Every supporting evolution is found in many different forms, such as fossils, DNA, and embryo similarities. Scientific research has found fossil and DNA evidence that proves evolution to change the polar bears has achieved. Studies on the similarities between brown bears and polar bears have revealed the existence of polar bears. This interbreeding scene suggests that the two species had contact with each other in part. Because of this, contacts would be due to the two species originated from the same group. But over a long time, the polar bear’s genes mutated from favorable polar bear’s native environments moving in the split away from the brown bears.
Scientists agree that the polar bear evolved from the brown bear. There’s been some debate on how long ago this happened. However, a recent discovery of a fossilized version of a polar bear’s jawbone has settled this argument. The fossil being confirmed is over 130,000 years old, making it the oldest polar bear fossil today. Organisms exhibit evolutionary changes that the human race can understand and interpret in fossils and DNA. The polar bear is an outstanding example of how a species can adapt to survive in a new environment. Their millions of other organisms showcase this just as well.
Polar bear adaptations & facts
Polar bear’s fur is not white. The fur is transparent. It consists of two layers of transparent hair, a soft thick undercoat, and a layer of hollow guard hairs. The layers only appear white because the air spaces in each hair scatter all visible wavelengths of light. Underneath this fur, polar bears have black skin. Sunlight can penetrate the bear’s transparent fur and reach its black skin, absorbing the sun’s heat and warms the bear’s body.
Polar bears are excellent swimmers. They’ve evolved to have a narrow skull and a long flexible neck that help streamline their bodies in the water. It provides the reach and flexibility they need to bring their noses up for air. Their front paws are large up to 12 inches wide flat and act like paddles. The bears swim and even hunt marine animals while underwater.
Additionally, the bears have a two to four-inch fat layer that helps keep them buoyant and warm as they swim. Polar bears are the largest land carnivore. They may grow up to eight feet tall and weigh over one thousand seven hundred and sixty pounds. Far outweighing the next largest land predator, the Kodiak brown bear, by several hundreds of pounds. This hefty size allows polar bears to hunt large, powerful animals like walruses and beluga whales. Despite their enormous size, polar bears have no natural predators apart from humans.
Polar bears only live in the arctic. This region includes areas of Russia, Greenland, Norway, and the United States. However, up to 80 percent of the world’s polar bears live in Canada. Polar bears may traverse islands and coastlines. But most of the time, the bears live directly on sea ice that can be found between landmasses. However, as climate change is causing sea ice to recede, polar bears are beginning to make their way further inland to find food. They are not endangered for now. Between 22,000 and 31,000 polar bears are in the wild, but their populations may be at risk in the future.
Climate change and rising ocean temperatures are causing sea ice in the polar bears hunting grounds to melt more rapidly and for longer periods. This may play a role in a projected 30 percent population decrease by 2050. Life on top of the world comes with many challenges but translucent fur, strong swimming capabilities, and considerable body size. Polar bears have become well adapted to life in the wintry north.
Why polar bears don’t hibernate?
Polar bears live in the Arctic Circle, which might cause you to assume it’s the long days that keep these fuzzy areas from enjoying a long winter’s nap. But science believes otherwise. Hibernation is a strange business. It’s not the same as sleeping. Science is still figuring out how to properly define hibernation, as all animals do it a little differently.
Hibernation is a way to conserve energy during the year when food for some animals grows scarce. Bears, groundhogs, and chipmunks jump to mind first, but some fish, reptiles, birds, and bats also experience it in some way. During hibernation, breathing and heart rate slow, metabolism plummets, and body temperature follows that trend too.
It’s sort of like a natural state of suspended animation! Hibernating animals go through physiological changes, whereas sleeping animals maintain normal physiology but change their mental state. It’s tough to wake up a hibernating animal, and doing so takes so much energy it wouldn’t go back under again. Seriously, the arctic ground squirrel’s body temperature gets so low, the neurons of its brain are incapable of firing.
Bears aren’t “true hibernators” because they don’t shut down like that. But they don’t need food or water all winter, which is a mark of hibernation. And they don’t like poop or pee. Not even once. Polar bears don’t hibernate, but the females can go 240 days without food. They commonly lose around 1.7 pounds per day (0.77 kg) and birth cubs during this time. They escape the harsh winter by “denning” or building a hollow in the snow. Meanwhile, the males hunt or stalk seals and prey in what’s called “walking hibernation,” meaning their body temperature remains normal. But their metabolic rate slows down.
A study in Genome Biology and Evolution compared the genetic code of hibernating brown and black bears to non-hibernating polar bears to determine how they can do that without curling up to sleep. Within the DNA, researchers discovered polar bears have genes that ramp up nitric oxide production. Nitric oxide tells the polar bear’s body to stop breaking down fat into energy and instead convert it directly to heat in a process called adaptive or non-shivering thermogenesis. Polar bears have a thermostat to keep them warm and help conserve energy in response to their current diet or environment.
For the record, panda bears, sun bears, sloth bears of Asia, and spectacled bears of South America also do not hibernate mainly, like with the polar bear. It is because there’s no season lack of food.
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F. Hailer, Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.
V. Kumar, The evolutionary history of bears is characterized by gene flow across species.
Population genomics reveals recent speciation and rapid evolutionary adaptation in polar bears.
W. Miller, Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change.
G. A. Feldhamer, “Polar bear, Ursus maritimus” in Wild Mammals of North America: Biology, Management, and Conservation.
A. M. Lister, Behavioural leads in evolution: Evidence from the fossil record.