Skip to comments.Polar bears' ancient roots pushed way back
Posted on 07/25/2012 6:22:06 PM PDT by SunkenCiv
...A new analysis of its DNA suggests that Ursus maritimus split from the brown bear between 4 million and 5 million years ago -- around the same time when, some scientists believe, the Arctic's thick sea ice first formed.
With such old origins, the creature must have weathered extreme shifts in climate, researchers report online July 23 in the Proceedings of the National Academy of Sciences. Simulations of how the DNA changed over time suggest that polar bear populations rose and fell with the temperature. After thriving during cooler times between 800,000 and 600,000 years ago, the bears seem to have suffered a genetic bottleneck and crashed after a warmer period that started about 420,000 years ago...
Lindqvist and colleagues had previously dated the emergence of the polar bear to no more than 150,000 years ago... But that research relied on a single fossil containing mitochondrial DNA, genetic material inherited from the mother. In April, the origin was pushed back to 600,000 years ago by Frank Hailer... His team examined more than 9,000 letters in nuclear DNA (derived from both parents) of modern bears.
The new study provides an even clearer picture, says Lindqvist, because it looks at the entire genetic blueprints of 23 modern polar bears... more than 2.5 billion letters in... nuclear DNA... more than 13 million points of comparison.
But the date in the new study was calibrated using the rate at which mutations appear in the DNA of primates, Hailer says...
Isolated brown bears living in Alaska's Admiralty, Baranof and Chichagof islands share between 5 and 10 percent of their DNA with polar bears, Lindqvist's team found. A previous study found that ancient brown bears in Ireland also shared much mitochondrial DNA with their comrades to the north.
(Excerpt) Read more at sciencenews.org ...
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
Just a tiny hint of global warming crap, expeditiously edited out by yours truly.
That damn bear is very nearly an aquatic mammal. It can weather anything.
Thanks,...new study is concerning for the Polar Bears....see the Globalwarminghoax keyword list .
share between 5 and 10 percent of their DNA with polar bears
THESE SUNSABITCHES ARE ALL GODDAM EFFING LIARS
how is it that brown and polar bears can interbreed and produce offspring? These GODDAM SUNSABITHCES claim humans and chimps are 98 percent identical yet there’s no such thing as a chimp human hybrid!
these lying mutha effas can kiss my ass.
Don’t hold back, tell us how you really feel. ;’)
Chimps (and gorillas, and orangutans, and gibbons) have 24 chromosome pairs, while humans have but 23, and the chromosomes won’t pair up right — there was a long period of experimentation into this in the USSR, during the Stalin “administration”.
There are two types of pandas, the Great Panda (which is the familiar one that looks like a giant stuffed toy) and the Lesser Panda, which may (or may not) be Asia’s closest living relative of the raccoon. The two panda types look similar but for size. The Great Panda is indeed a bear.
I’m not aware of any crossbreeding attempts using the Great Panda and one of the other bear species on Earth. That crossbreeding probably wouldn’t work, but it might be interesting to try. It would have to be artificial insemination one way or the other, because the Great Panda barely mates in the wild, much less in captivity.
Here's another one of my pet reprises:"For thirty years, nobody disputed this 'fact'. One group of scientists abandoned their experiments on human liver cells because they could only find twenty-three pairs of chromosomes in each cell. Another researcher invented a method of separating the chromosomes, but still he thought he saw twenty-four pairs. It was not until 1955, when an Indonesian named Joe-Hin Tjio travelled from Spain to Sweden to work with Albert Levan, that the truth dawned. Tjio and Levan, using better techniques, plainly saw twenty-three pairs. They even went back and counted twenty-three pairs in photographs in books where the caption stated that there were twenty-four pairs. There are none so blind as do not wish to see." (Matt Ridley, Genome: The Autobiography of a Species in 23 Chapters, p 23-24)The correct number of chromosomes could have been discerned, one would think, during the almost 35 years involved in the events above. The most daunting realization is that the double heliacal form of DNA was discerned in 1953, two years before this chromosome count was corrected.
I’m sure the Polar Bear population is happy to hear they are derived from the Brownie. Kissin’ cousins.
Ursa a lot more humor left fur us to find.
I’m confused why you are talking about pandas. Are you avoiding the facts or what?
I"m sure the complete scientific explanation runs out of words with which almost all of us are familiar, but what that means is you can NEVER have a human/chimp hybrid!
It also means something really, really, really, really big happened several million years ago.
WHO THE * CANCELED THE CORVAIR AND WHAT WAS HIS STUPIDAS REASON??
Must. Not. Make. Any. Comments. About. The. Wookie...
so this was supposed to be a response to post 6, not post 5.
Tell ya what, the crap these jackwads have been feeding us over the years is enough to make me point to global warming and tell them they are all no better than those jackasses.
I’m serious. Their bullshit is that deep.
If you got any pull you better start injecting the idea into their silly cackling, betwixt eachother, that they are a FUKING JOKE and need to get straight again before academic armageddon. environmental science is about to disappear. and good riddance.
don’t be an amateur!
That was a cross between a human and a yeti. Big difference.
In the early 1960s I recall my first experience ~ WITH A HIGH POWERED MICROSCOPE ~ they were still referring to "microscopic inclusions" inside the cells!
That was an innocent time ~ we were still just meat.
“Isolated brown bears living in Alaskas Admiralty, Baranof and Chichagof islands share between 5 and 10 percent of their DNA with polar bears”
The article goes on to say that polar bears and brown bears interbreed occasionally (much as coyotes and wolves occasionally do) and that this might be a “threat” to the polar bear in diluting what makes them unique.
In light of this I think what the journalist was ATTEMPTING to say is that these particular Brown bears are of 5 to 10% polar bear ancestry - much as some coyote populations are of 5 to 10% wolf ancestry.
So rather than being “SUNSABITCHES” that are “ALL GODDAM EFFING LIARS” - maybe the journalist was unclear in what they were attempting to say?
These are actually some Not-So-Great Auks, which are rare.
But grilling them for a while should take care of that.
That’s adorable. Of course, after the weight doubled, there weren’t any more games of that kind. ;’)