Polar bears evolution surprise

2012-04-20 15:03
Polar bears evolved earlier than previously thought. (AP)

Polar bears evolved earlier than previously thought. (AP)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

London - Polar bears evolved as a separate species far earlier than previously thought, according to a new genetic study, which adds to worries about their ability to adapt in a rapidly warming world.

Research published on Thursday found the Arctic's top predators split off from brown bears, their closest relatives, around 600 000 years ago - five times earlier than scientists had generally assumed.

The finding suggests polar bears took a long time to adapt to their icy world and may therefore struggle to adjust as the Arctic gets warmer and the sea ice melts, depriving them of vital hunting platforms.

Despite being a very different species in terms of body size, skin and coat colour, fur type, tooth structure, and behaviour, previous research had indicated that polar and brown bears diverged only recently in evolutionary terms.

That assumption was based on studying mitochondrial lineage - a small part of the genome, or DNA, that is passed exclusively from mothers to offspring.

Climate


But after studying a lot more DNA from inside the cell nucleus, using samples from 19 polar and 18 brown bears, Frank Hailer of Germany's Biodiversity and Climate Research Centre and colleagues reached a very different conclusion.

They found both polar and brown bears were much older, as species, according to a paper published in the journal Science.

"Previous studies suggested that polar bears would have had to be evolving very rapidly, since they were so young," Hailer said in a telephone interview.

"Our study provides a lot more time for polar bears to adapt... It makes more sense from an evolutionary standpoint that polar bears would be older."

His team's calculations put the moment when the two types of bears diverged in the Pleistocene period, when the climate record shows that global temperatures reached a long-term low.

That could be coincidental but it suggests that the planet's cooling may have triggered the split.

While the latest research implies that past polar bear adaptation was probably a slow process, it also means the animals have been through warming phases before.

"If they go extinct in this phase of warming, we're going to have to ask ourselves what our role in that process was," Hailer said.

"In previous warm phases between the ice ages polar bears were able to survive. The main difference this time is that humans are impacting polar bears as well."

Genetic studies are an important tool in researching the evolutionary history of polar bears, since the animals typically live and die on sea ice. As a result, their bodies sink to the sea floor, where they get ground up by glaciers or remain undiscovered, making fossils scarce.
Read more on:    science  |  animals  |  archaeology
NEXT ON NEWS24X
SHARE:

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
16 comments
Add your comment
Comment 0 characters remaining
 

Inside News24

 
/News
Traffic & Train Alerts
Traffic
Cape Town 05:39 AM
Road name: MetroRail

Due to extensive vandalism and criminal activity there are NO trains between Nyanga/Chris Hani (Khayelitsha) and Nyanga/Kapteinsklip - all stations on these sections are CLOSED

Montague Gardens 18:07 PM
Road name: Montague Drive

ROADWORKS - lane closures both directions for BRT lane construction - expect delays

Jobs in Cape Town [change area]

Property [change area]

Travel - Look, Book, Go!

Magical Massinga

Spend 5 nights at the gorgeous Massinga Beach Lodge in Mozambique and only pay for 4 from R13 220 per person sharing. Includes return flights, accommodation, transfers and romantic turndown. Book now!

Kalahari.com - shop online today

Up to 60% off - clearance sale!

Save up to 60% on appliances, books, electronics, toys, movies and more. Offer valid while stocks last. Shop now!

Deal of the Week!

Get bestselling John Green novels now just R99 each! Hurry and get yours while stocks last. Shop here.

Mind blowing deals on beauty & fragrances

Save up to 30% off beauty and fragrances. Offer valid while stocks last. Shop now!

Up to 50% off hair care products!

Save up to 50% on professional hair care products at kalahari.com. Offer valid while stocks last. Shop now!

30% off academic books

Score a mind blowing 30% off academic books! Offer valid while stocks last. Shop now!

OLX Free Classifieds [change area]

Samsung Galaxy s4

Mobile, Cell Phones in South Africa, Western Cape, Cape Town. Date October 24

Best bargain in big bay

Real Estate, Houses - Apartments for Sale in South Africa, Western Cape, Cape Town. Date October 25

VW Golf 6, 1.6 Trendline (Excellent condition)

Vehicles, Cars in South Africa, Western Cape, Cape Town. Date October 25

Horoscopes
Aquarius
Aquarius

Social media is pulling you in and you have the desire to find out everything you know about your friends and you have the urge to...read more

There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.








Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.