News24

Polar bears evolution surprise

2012-04-20 15:03

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.

Comments
  • CharlesDumbwin - 2012-04-20 15:33

    Let me guess, this took 'billions of years' so no one can prove it?

      wesleywt - 2012-04-20 15:36

      Hey dumb dumb... you really make my day with your special kind of stupid. Did you not read the article. They did again prove evolution.

      wesleywt - 2012-04-20 15:36

      Hey dumb dumb... you really make my day with your special kind of stupid. Did you not read the article. They did again prove evolution.

      mbossenger - 2012-04-20 15:49

      Did you read the article? Or did you just do the usual knee jerk reaction you seem to have to all evolution related articles?

      mbossenger - 2012-04-20 15:49

      Did you read the article? Or did you just do the usual knee jerk reaction you seem to have to all evolution related articles?

      Patrick - 2012-04-20 16:06

      @Wesleywt & Mbossenger - "around 600 000 years ago" mankind has no record from back then, ergo there is no actual rock solid proof merely assumptions based of scientific method that we call science and not guess work because it's done by men in coats.

      Patrick - 2012-04-20 16:06

      @Wesleywt & Mbossenger - "around 600 000 years ago" mankind has no record from back then, ergo there is no actual rock solid proof merely assumptions based of scientific method that we call science and not guess work because it's done by men in coats.

      Glyn - 2012-04-20 20:30

      Dumb!

      Glyn - 2012-04-20 20:30

      Dumb!

      mbossenger - 2012-04-20 20:56

      Patrick - so you claim all forensic science is also invalid as there was nobody to observe what happened?

      mbossenger - 2012-04-20 20:56

      Patrick - so you claim all forensic science is also invalid as there was nobody to observe what happened?

      Patrick - 2012-04-20 23:37

      @Mbossenger - "all forensic science is also invalid as there was nobody to observe what happened" not at all and that's not what i'm saying, I am, however saying that you can't say something is 600 000 years old as there hasn't been anything of similar known age to compare it to. We have no point of reference on this matter. If it's within mankind's written and documented record then i will agree that you can accurately determine the age of something but 600 000 years is an estimated guess in the dark. You can compare it to how something we know ages and make a knowledgeable guess on the matter but if you can't say with 100% certainty that something is 600 000 years old, there are simply too many unknown variables.

      Patrick - 2012-04-20 23:37

      @Mbossenger - "all forensic science is also invalid as there was nobody to observe what happened" not at all and that's not what i'm saying, I am, however saying that you can't say something is 600 000 years old as there hasn't been anything of similar known age to compare it to. We have no point of reference on this matter. If it's within mankind's written and documented record then i will agree that you can accurately determine the age of something but 600 000 years is an estimated guess in the dark. You can compare it to how something we know ages and make a knowledgeable guess on the matter but if you can't say with 100% certainty that something is 600 000 years old, there are simply too many unknown variables.

      wesleywt - 2012-04-21 11:17

      @ Patrick. As a geneticist I can confirm you don't have a clue what you are taking about.

      wesleywt - 2012-04-21 11:17

      @ Patrick. As a geneticist I can confirm you don't have a clue what you are taking about.

      mbossenger - 2012-04-21 14:38

      Patrick - you are seriously claiming the only way of dating something is from human records?

      mbossenger - 2012-04-21 14:38

      Patrick - you are seriously claiming the only way of dating something is from human records?

  • mbossenger - 2012-04-20 15:56

    "Polar bears evolved as a separate species far earlier than previously thought" - *creationsit hat on* but but but there has never been any examples of a new species being formed!!!! Macro evolution has never been observed!!!! *creationist hat off*

  • Felix - 2012-04-20 15:58

    I wonder if N24 has a small department of about three people who troll all day to encourage comments on their site? What do you think Charles?

      zaatheist - 2012-04-20 19:55

      CharlesDumbwin is a poe. Remember before the last election there was a rabid ANC supporting troll commenting on News24? Turned out to be a bunch of university students seeing how far they could push ridiculousness. DumbWin (geddit) is their new creation.

      zaatheist - 2012-04-20 19:55

      CharlesDumbwin is a poe. Remember before the last election there was a rabid ANC supporting troll commenting on News24? Turned out to be a bunch of university students seeing how far they could push ridiculousness. DumbWin (geddit) is their new creation.

  • Glyn - 2012-04-20 20:31

    Interesting.

  • SaintBruce - 2012-04-20 23:36

    far earlier than previously thought, - five times earlier than scientists had generally assumed. That assumption was based... "Previous studies suggested... That could be coincidental While the latest research implies that past polar bear adaptation was probably a slow process making fossils scarce. Ok,Ok - just look at these phrases and tell me with a high degree of certainty that they point to: 1) Proving Evolution [Wesleywt] 2) factual based on a very small sample ( 18 and 19 sets of data) 3) using assumptions, maybe's, could have's, coincidentaly, and phrases such as five times greater than scientists had generally assumed. This is hardly scientific in presentation nor substance and really detracts from the Evolutionists cause. It is such a pity that such vague phrases are used when coupled with the word "science" that deals in absolutes, laws and empirical data. The whole "making fossils scarce" is a convenient way out of a sticky dilemma and couches this whole idea in a lot of supposition. Now, if you were a Supernatural God and you designed DNA and RNA to work in a certain way to propagate life, it would be expected that the genetic system will be common to all forms of living things. If it works ,use it. In truth, we just don't know enough about how life works to be absolute in such claims as - proof of evolution. That's still a theory and any facts ascribed to it do not constitute a body of truth.

  • Jan - 2012-04-24 16:39

    Biodiversity and Climate Research Centre?

  • gideon.bakkes - 2012-06-21 00:40

    Hi all of you! Remember we are now in the Post-Modern era, so my "truth" is just as good as your "truth"! After all, all this research is interesting - it says the polar bear survives previous warm periods. Evolution or no evolution, it is now on us to ensure the survival of the polar bear!

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