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 Democrats Clinton, Kaine Offer 'Very Different Vision' Than Trump

    In a jab at Trump, Clinton says her team wants to 'build bridges, not walls'; Obama Hails Kaine's record; Trump calls Kaine a 'job-killer'

    Turkey Wants Pakistan to Close Down institutions, Businesses Linked to Gulen

    Thousands of Pakistani students are enrolled in Gulen's commercial network of around two dozen institutions operating in Pakistan for over two decades

    AU Passport A Work in Progress

    Who will get the passport and what the benefits are still need to be worked out

    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.
    In State of Emergency, Turkey’s Erdogan Focuses on Spiritual Movementi
    X
    July 22, 2016 11:49 AM
    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 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 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 Poor Residents in Cleveland Not Feeling High Hopes of Republican Convention

    With the Republican Party's National Convention underway in Cleveland, Ohio, delegates and visitors are gathered in the host city's downtown - waiting to hear from the party's presidential candidate, Donald Trump. But a few kilometers from the convention's venue, Cleveland's poorest residents are not convinced Trump or his policies will make a difference in their lives. VOA's Ramon Taylor spoke with some of these residents as well as some of the Republican delegates and filed this report.
    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 With Yosemite as Backdrop, Obama Praises National Parks

    Last month, President Barack Obama and his family visited some of the most beautiful national parks in the U.S. Using the majestic backdrop of a towering waterfall in California's Yosemite National Park, Obama praised the national park system which celebrates its 100th anniversary this year. He talked about the importance of America’s “national treasures” and the need to protect them from climate change and other threats. VOA’s Julie Taboh reports.
    Video

    Video Counter-Islamic State Coalition Plots Next Steps

    As momentum shifts against Islamic State in Iraq, discussions are taking place about the next steps for driving the terrorist group from its final strongholds. Secretary of State John Kerry is hosting a counter-IS meeting at the State Department, a day after defense ministers from more than 30 countries reviewed and agreed upon a course of action. VOA Pentagon correspondent Carla Babb reports.
    Video

    Video Russia's Participation at Brazil Olympic Games Still In Question

    The International Olympic Committee has delayed a decision on whether to ban all Russian teams from competing in next month's Olympic Games in Brazil over allegations of an elaborate doping scheme. The World Anti-Doping Agency recently released an independent report alleging widespread doping by Russian athletes at the 2014 Winter Olympics in Sochi. So far, only Russian track and field athletes have been barred from the Summer Games in Brazil. VOA's Zlatica Hoke 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.
    Video

    Video Millennials Could Determine Who Wins Race to White House

    With only four months to go until Americans elect a new president, one group of voters is getting a lot more attention these days: those ages 18 to 35, a generation known as millennials. It’s a demographic that some analysts say could have the power to decide the 2016 election. But a lot depends on whether they actually turn out to vote. VOA’s Alexa Lamanna reports.

    Special Report

    Adrift The Invisible African Diaspora