News / Science & Technology

Polar Bear Fossil Traces Origin to Brown Bears

A scientific analysis of a rare polar bear fossil indicates that the large, white-coated mammals evolved in the relatively recent past from common brown bears.  The discovery suggests polar bears' ancestors migrated toward the North Pole in response to global warming thousands of years ago, and adapted quickly to their new Arctic habitat.

Scientists analyzing the rare fossil, found in Norway's northern Svalbard islands in 2004, conclude that polar bears appear to have evolved from brown bears 150,000 years ago  - a mere blink of an eye on the earth's geological  timeline.  
 
The genetic evidence comes from an unusually well-preserved polar bear jawbone with a canine tooth still attached to it - a rare find because most polar bear carcasses are consumed by scavengers or sink to the sea bottom.  The DNA mapped from the jawbone is the earliest mammalian genome ever sequenced.

Researchers have long suspected that the arctic-dwelling animals evolved from brown bears because of their present-day genetic similarities.  But scientists could not confirm an evolutionary timeline.   Estimates of the origins of polar bears have ranged all the way from 150,000 years ago to one million years ago.   But a comparison of the DNA in the polar bear fossil and in a group of modern brown bears living on a group of islands off the Alaskan coast showed the two genomes more closely related than they are today.

The researchers were able to estimate that the polar bears' ancestors branched off from the brown bear population when they headed north and adapted to the Arctic habitat, becoming a separate species about 150,000 years ago.

Charlotte Lindqvist, an evolutionary biologist at the University of Buffalo in New York, led the research.  Lindqvist says the fossil appears to be that of an adult male approximately the same size as modern polar bears.

"We found that it probably had a diet similar to polar bears today.  And from the stratus [sic] [stratum or layers of rock or sediment] from where the fossil was found, we can see that it lived in an environment probably similar as today," she said.  "So, this means that very rapidly polar bears probably adapted to a habitat very similar to what we see today," she added.

Lindqvist and colleagues theorize that one reason for the migration of brown bears to the Arctic may have been to escape the interglacial warming of the late Pleistocene period.

It's possible that Svalbard, where the fossil was found, served as a refuge for bears attempting to survive rising temperatures during this climate change, according to co-researcher Stephan Schuster of the University of Pennsylvania Center for Comparative Genomics.

"It is questionable how they would survive this, and I think the most logical scenario would be that they were following the cold weather," said Schuster.  "And Svalbard would have been this kind of environment, where the polar bears could have gone and survived this warming period," he said.
 
Even today, notes the University of Buffalo's Charlotte Lindqvist, brown bears have been spotted wandering into areas considered to be polar bear habitats in the Canadian Arctic, suggesting that current warming trends may once again be impacting brown bear populations.

Lindqvist and her research team plan further genetic analysis of the polar bear fossil, which should yield clues about the migration routes taken by brown bears to the Arctic and the bears' rapid adaptation to the polar environment.
 
Additional studies could also tell researchers at what point during its evolution the polar bear developed its white coat, which Lindqvist says is actually colorless but looks white against the snowy landscape.

"By recovering more of the genome, we may be able to answer more questions about their evolution and their origin and how they adapted to their current habitats.  And perhaps something about how they may be able to adapt to future changes," said Lindqvist.

An international team of researchers described the polar bear fossil in the Proceedings of the National Academy of Sciences.

You May Like

Lebanese Media Unite to Support Palestinians in Gaza

Joint newscast billed as Arab world’s first unified news bulletin in support of Hamas-controlled Gaza Strip More

Photogallery Australian PM Alleges ‘Coverup’ at MH17 Crash Site

Meanwhile, Russia's ambassador to Malaysia denies plane's black boxes were opened before they were handed over to Malaysian officials More

Despite Advances in AIDS Treatment, Stigma Lingers

Leading immunologist tells VOA that stigma is often what prevents those infected with disease from seeking treatment More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Nature of Space Exploration Enters New Agei
X
Elizabeth Lee
July 20, 2014 2:36 AM
Forty-five years ago this month, the first humans walked on the moon. It was during an era of the space race between the United States and the Soviet Union. World politics have changed since then and -- as Elizabeth Lee reports -- so has the nature of space exploration.
Video

Video Nature of Space Exploration Enters New Age

Forty-five years ago this month, the first humans walked on the moon. It was during an era of the space race between the United States and the Soviet Union. World politics have changed since then and -- as Elizabeth Lee reports -- so has the nature of space exploration.
Video

Video Chicago’s Argonne Lab Developing Battery of the Future

In 2012, the U.S. Department of Energy’s Office of Science awarded a $120 million grant to a new technology center focused on battery development - headquartered at Argonne National Laboratory in suburban Chicago, Illinois. As VOA’s Kane Farabaugh reports, there scientists are making the next technological breakthroughs in energy storage.
Video

Video In NW Pakistan, Army Offensive Causes Massive Number of Displaced

Pakistan’s army offensive in North Waziristan has resulted in the large-scale displacement of the local population. VOA's Ayaz Gul reports from northwest Pakistan where authorities say around 80 percent of the estimated 1 million internally displaced persons [IDPs] have settled in Bannu district, while much of the remaining 20 percent are scattered in nearby cities.
Video

Video Kurdish Peshmerga Force Secures Kirkuk, Its Oil

The Kurdistan regional government has sent its Peshmerga troops into the adjacent province of Kirkuk to drive out insurgents, and to secure the area's rich oil fields. By doing this, the regional government has added a fourth province to the three it officially controls. The oil also provides revenue that could make an independent Kurdistan economically strong. VOA’s Jeffrey Young went out with the Peshmerga and filed this report.
Video

Video Malaysia Reeling: Second Air Disaster in Four Months

Malaysia is reeling from the second air disaster in four months involving the country’s flag carrier. Flight 340 vanished in March and despite an extensive search, no debris has been found. And on Thursday, Flight 17, likely hit by a surface-to-air missile, came apart over eastern Ukraine. The two incidents together have left more than 500 people dead. VOA Correspondent Steve Herman reports from Kuala Lumpur.
Video

Video Diplomatic Crisis Grows Over MH17 Plane Crash

The Malaysia Airlines crash in eastern Ukraine is drawing reaction from leaders around the world. With suspicions growing that a surface-to-air missile shot down the aircraft, there are increasing tensions in the international community over who is to blame. Henry Ridgwell reports for VOA from London.
Video

Video Undocumented Immigrants Face Perilous Journey to US, No Guarantees

Every day, hundreds of undocumented immigrants from Central America attempt the arduous journey through Mexico and turn themselves over to U.S. border patrol -- with the hope that they will not be turned away. But the dangers they face along the way are many, and as Ramon Taylor reports from the Rio Grande Valley in Texas, their fate rests on more than just the reception they get at the US border.
Video

Video Scientists Create Blackest Material Ever

Of all the black things in the universe only the infamous "black holes" are so black that not even a tiny amount of light can bounce back. But scientists have managed to create material almost as black, and it has enormous potential use. VOA’s George Putic has more.
Video

Video Fog Collector Transforming Maasai Water Harvesting in Kenya

The Maasai people of Kenya are known for their cattle-herding, nomadic lifestyle. But it's an existence that depends on access to adequate water for their herds and flocks. Lenny Ruvaga reports for VOA, on a "fog collector."

AppleAndroid