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

    Video Migrants Continue to Risk Lives Crossing US Border From Mexico

    In remote areas of the Sonoran Desert, which straddles the US-Mexico, thousands of migrants face arid desolation

    Video Recycling is Lifeline for Lebanon’s Last Glassblowers

    It's an ancient craft that stretches back millennia - but despite Lebanon’s trash crisis providing a lifeline, remaining glass blowers face an uncertain future

    Meet the Alleged Killer of Cambodia’s Kem Ley

    What little is known about former soldier, troublesome Buddhist monk and indebted gambler, raises more questions than answers

    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.
    London’s Financial Crown at Risk as Rivals Eye Brexit Opportunitiesi
    X
    VOA News
    July 25, 2016 5:09 PM
    By most measures, London rivals New York as the only true global financial center. But Britain’s vote to leave the European Union – so-called ‘Brexit’ – means the city could lose its right to sell services tariff-free across the bloc, risking its position as Europe’s financial headquarters. Already some banks have said they may shift operations to the mainland. Henry Ridgwell reports from London.
    Video

    Video London’s Financial Crown at Risk as Rivals Eye Brexit Opportunities

    By most measures, London rivals New York as the only true global financial center. But Britain’s vote to leave the European Union – so-called ‘Brexit’ – means the city could lose its right to sell services tariff-free across the bloc, risking its position as Europe’s financial headquarters. Already some banks have said they may shift operations to the mainland. Henry Ridgwell reports from London.
    Video

    Video Recycling Lifeline for Lebanon’s Last Glassblowers

    In a small Lebanese coastal town, one family is preserving a craft that stretches back millennia. The art of glass blowing was developed by Phoenicians in the region, and the Khalifehs say they are the only ones keeping the skill alive in Lebanon. But despite teaming up with an eco-entrepreneur and receiving an unexpected boost from the country’s recent trash crisis the future remains uncertain. John Owens reports from Sarafand.
    Video

    Video Migrants Continue to Risk Lives Crossing US Border from Mexico

    In his speech Thursday before the Republican National Convention, the party’s presidential candidate, Donald Trump, reiterated his proposal to build a wall along the U.S.-Mexico border if elected. Polls show a large percentage of Americans support better control of the nation's southwestern border, but as VOA’s Greg Flakus reports from the border town of Nogales in the Mexican state of Sonora, the situation faced by people trying to cross the border is already daunting.
    Video

    Video In State of Emergency, Turkey’s Erdogan Focuses on Spiritual Movement

    The state of emergency that Turkish President Recep Tayyip Erdogan has declared is giving him even more power to expand a purge that has seen an estimated 60,000 people either arrested or suspended from their jobs. VOA Europe correspondent Luis Ramirez reports from Istanbul.
    Video

    Video Calm the Waters: US Doubles Down Diplomatic Efforts in ASEAN Meetings

    The United States is redoubling diplomatic efforts and looking to upcoming regional meetings to calm the waters after an international tribunal invalidated the legal basis of Beijing's extensive claims in the South China Sea. VOA State Department correspondent Nike Ching has the story.
    Video

    Video Four Brother Goats Arrive in Brooklyn on a Mission

    While it's unusual to see farm animals in cities, it's become familiar for residents of Brooklyn, New York, to see a little herd of goats. Unlike gas-powered mowing equipment, goats remove invasive weeds quietly and without adding more pollution to the air. As Faiza Elmasry tells us, this is a pilot program and if it proves to be successful, the goat gardener program will be extended to other areas of New York. Faith Lapidus narrates.
    Video

    Video Scientists in Poland Race to Save Honeybees

    Honeybees are in danger worldwide. Causes of what's known as colony collapse disorder range from pesticides and loss of habitat to infections. But scientists in Poland say they are on track to finding a cure for one of the diseases. VOA’s George Putic reports.
    Video

    Video Wall Already Runs Along Parts of US-Mexico Border

    The Republican Party’s presidential nominee, Donald Trump, gained the support of many voters by saying he would build a wall to keep undocumented immigrants and drugs from coming across the border from Mexico. Critics have called his idea impractical and offensive to Mexico, while supporters say such a bold approach is needed to control the border. VOA’s Greg Flakus has more from the border town of Nogales, Arizona.
    Video

    Video New HIV Tests Emphasize Rapid Results

    As the global fight against AIDS intensifies, activists have placed increasing importance on getting people to know their HIV status. Some companies are developing new HIV testing methods designed to be quick, easy and accurate. Thuso Khumalo looks at the latest methods, presented at the International AIDS conference in Durban, South Africa.
    Video

    Video African Youth with HIV Urge More Support

    HIV, the virus that causes AIDS, is the top killer of teens in sub-Saharan Africa. But many youths say their experience with the virus is unique and needs to be addressed differently than the adult epidemic. VOA South African Correspondent Anita Powell reports.
    Video

    Video Pop-Up Art Comes to Your Living Room, Backyard and Elsewhere

    Around the world, independent artists and musicians wrestle with a common problem: where to exhibit or perform? Traditional spaces such as museums and galleries are reserved for bigger names, and renting a space is not feasible for many. Enter ArtsUp, which connects artists with venue owners. Whether it’s a living room, restaurant, office or even a boat, pop-up events are bringing music and art to unexpected places. Tina Trinh has more.
    Video

    Video Scotland’s Booming Whisky Industry Fears Brexit Hangover

    After Britain’s vote to leave the European Union, Scotland’s government wants to break away from the United Kingdom – fearing the nation’s exports are at risk. Among the biggest of these is whisky. Henry Ridgwell reports on a time of turmoil for those involved in the ancient art of distilling Scotland’s most famous product.

    Special Report

    Adrift The Invisible African Diaspora