Skip to comments.True causes for extinction of cave bear revealed
Posted on 08/24/2010 6:46:14 AM PDT by decimon
The cave bear started to become extinct in Europe 24,000 years ago, but until now the cause was unknown. An international team of scientists has analysed mitochondrial DNA sequences from 17 new fossil samples, and compared these with the modern brown bear. The results show that the decline of the cave bear started 50,000 years ago, and was caused more by human expansion than by climate change.
"The decline in the genetic diversity of the cave bear (Ursus spelaeus) began around 50,000 years ago, much earlier than previously suggested, at a time when no major climate change was taking place, but which does coincide with the start of human expansion", Aurora Grandal-D'Anglade, co-author of the study and a researcher at the University Institute of Geology of the University of Coruña, tells SINC.
According to the research study, published in the journal Molecular Biology and Evolution, radiocarbon dating of the fossil remains shows that the cave bear ceased to be abundant in Central Europe around 35,000 years ago.
"This can be attributed to increasing human expansion and the resulting competition between humans and bears for land and shelter", explains the scientist, who links this with the scarce fossil representation of the bear's prey in the abundant fossil record of this species.
In order to reach their conclusions, the team of scientists, led by the Max Planck Institute for Evolutionary Anthropology (Germany) studied mitochondrial DNA sequences from bear fossils in European deposits (Siberia, Ukraine, Central Europe and the Iberian Peninsula, specifically Galicia), and carried out a Bayesian analysis (of statistical probability).
The scientists also made comparisons with the modern brown bear (Ursus arctos) and with fossil samples of this species of bear, and managed to show why one became extinct and the other did not. In order to demonstrate this, the study analysed 59 cave bear DNA sequences and 40 from the brown bear, from between 60,000 and 24,000 years ago for the cave bear and from 80,000 years ago up to the present day for the brown bear.
Decline of the caves, extinction of the bears
The impoverishment of ecosystems during the last glacial maximum was "the 'coup de grace' for this species, which was already in rapid decline", the author explains.
The present day brown bear did not suffer the same fate and has survived until today for one simple reason brown bears did not depend so heavily on the cave habitat, which was becoming degraded, and this is why they did not follow the same pattern as the cave bears.
"Brown bears rely on less specific shelters for hibernation. In fact, their fossil remains are not very numerous in cave deposits", the Galician researcher says.
The definitive extinction of the cave bear "broadly" coincides with the last cooling of the climate during the Pleistocene (between 25,000 and 18,000 years ago), which may have led to a reduction in shelter and the vegetation that the animals fed on.
The cave bear inhabited Europe during the Late Pleistocene and became definitively extinct around 24,000 years ago, although it held out for a few thousand years longer in some areas, such as the north west of the Iberian Peninsula, than in other places. This ursid was a large animal, weighing 500 kg on average, and was largely a herbivore. The bear hibernated in the depths of limestone caves, where the remains of individuals that died during hibernation slowly accumulated over time.
Stiller, Mathias; Baryshnikov, Gennady; Bocherens, Herve; Grandal D'Anglade, Aurora; Hilpert, Brigitte; Muenzel, Susanne C.; Pinhasi, Ron; Rabeder, Gernot; Rosendahl, Wilfried; Trinkaus, Erik; Hofreiter, Michael; Knapp, Michael. "Withering Away-25,000 Years of Genetic Decline Preceded Cave Bear Extinction" Molecular Biology and Evolution 27(5): 975-978, mayo de 2010. doi:10.1093/molbev/msq083
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Ball bearing ping.
Obviously ... Bush’s fault.
What the...! They had "climate change" 50,000 years ago?
I thought Daryl Hannah and her clan were responsible.
Largely a herbivore? In all my reading they seemed to have been omnivores with an occsional human for antipasto.
They studied some fossils to learn about genetic diversity. From these genetic studies, they have decided that:
1) Human expansion diminished the bear population
2) Competition over cave habitat was a critical factor.
Genes can tell us this?
You can call it science if you want, but I call it supposition.
since they are clocking the extinction as to some 18-24k yrs ago I’m going out on a limb and saying the Flood took care of these bears while the human population was down to a mere handful of people.
There weren’t enough humans around to affect their population. Probably a change in fauna due to climate change.
Whut...you don't believe in Jungle Girl?
Amazing that we can assess mDNA from these specimens.
Their conclusion is not surprising. Climate change finished off many species that humans had started in decline, IMO.
As human beings displace large predators they create breaks in the breeding ranges. That in turn leads to genetic isolation and each small group of predators begin to exhibit variations in their MtDNA.
It turns out that it's quite easy to figure out when the bears disappeared simply by counting the remains in caves AND by checking their MtDNA to see if they were part of a genetically isolated population.
Europeans have done the same with human remains in Western and Northern Europe and demonstrated the existence of the Ice Age human refugia near the French/Spanish border. They tracked the Sa'ami North, then East around the residual Scandinavian Ice Lobe and then South just checking "remains".
A couple of things you have to recall about the last Ice Age is that it was immediately followed by the Younger Dryas. This is a climate anomaly ~ the current proposal (with much evidence) is that a comet hit the residual ice lobe in North America (in Canada). This broke it up and plugged the St. Lawrence. That reduced the incidence of freshwater reaching the North Atlantic, the Atlantic Conveyor stopped, and Europe froze again. Otherwise, this event occurred entirely within the time of the current INTERGLACIAL which is rapidly coming to an end having "peaked" with several spikes in the last thousand years. That BTW is typical of ALL the preceeding 20+ Ice Ages.
Within the range of the previous Ice Age there were several Interstadials ~ which are warm periods of LESS THAN 10,000 years ~ that affected North America, or Asia, or Europe, or South America, at different times in different areas.
Our brand of humanity managed to penetrate Central Asia during an Interstadial there about 50,000 years ago. An interstadial that affected Europe and Asia North of the Himalayas about 35,000 years ago allowed our brand of people to move into Europe and near China. 15,000 years ago the current Interglacial began and our brand of people moved on into the Chinese Plains, Siberia, etc, and into most of Europe, West Asia, Middle East, etc.
So, what about these bears? Well, there was a PEAK in the glaciation at about 20,000 years ago. That put a crimp in everybody's trick! Before all that modern human radiation into East Asia and Europe it got really cold, lots of ice and snow came, and it happened everywhere in the latitudes affected by the great glaciers.
So, whatever human beings were up to 35,000 years ago, that was interrupted by what happened 20,000 years ago, and then 15000 years ago everything changed again. About 11,000 years ago that doggone comet hit and it was back to square one for another 1500 years, particularly in North America and Europe.
Humanity barely hung on during that period ~ the European Brown Bear didn't have a chance.
Great read on your post, lots of info. Thanks
That is the PEAK GLACIATION period ~ where even more ice was being created and shorelines were receeding out into the surf by probably 100 ft beyond the earlier Glacial shoreline (worldwide).
The real deal in floods comes with the FIRST MELTDOWN which occurred in Antarctica about 14,500 years ago. If that happened fast, you could have had a gigantic lake form there. With a precipitate collapse of the surrounding Ice wall, the tsunamis could have been a mile high. They would have reached virtually every landmass on Earth ~ check the globe to see how much Southern shoreline is exposed to gigantic Antarctic tsunamis ~ rather sobering. Central Africans, Central and Western Europeans, Central Siberians and people living in the Himalayan Plateau, the New Guinea highlands, Northern Australia, and other places out of the line of this sort of world flood would survive. Fur shur the floodwaters would reach as high as the mountains.
Afterwards the meltdown of the North American ice sheet, and the much smaller Siberian glaciers would have raised sea levels another 100 or so feet.
Eventually that would result in the breakdown of the barrier between the Mediterranean and Black Lakes in near historical times.
You can look up various tables regarding sea levels at the end of the last Ice Age to see that there are different meltdown zones. The two biggest have to be Antarctica and North America. The other meltdowns are of a far lesser scale and impact. That of Antarctica was a world ender. The North American meltdown was far more orderly but destroyed much useful human habitat (alluvial areas near oceans).
The rise of human civilization coincides with a relatively peaceful period in terms of rate of ocean level change. We've had time to adjust and to figure out how to grow our own food and raise our own game.
This is going to end real soon when the ice comes back, the ocean levels drop rapidly, and our alluvial plains rapidly wash away into the ocean depths.
We must presume this bear had been previously edumacated! The next bear will eat the cat.
Thanks decimon!...started to become extinct in Europe 24,000 years ago... international team of scientists has analysed mitochondrial DNA sequences from 17 new fossil samples... show that the decline of the cave bear started 50,000 years ago, and was caused more by human expansion than by climate change.That must be some damned detailed mtDNA. What a ridiculous mess.
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The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization
by Richard Firestone,
Allen West, and
What was that middle thing?
And here I thought that stuff like that was encoded into the RNA, so we could encapsulate it, swallow a pill, and not have to show up for lecture classes...labs still required.
What was that cat figuring on doing if it caught that bear?
I didn’t even use that finger. ;’)
Sooner or ladder it will happen.
You ROCK, seigneur!
Southern tier - forested hilly land — I had a close encounter with a black bear - about 300 pounder a few days ago — the moment I saw him and he caught a whiff of us—he thankfully ran the other way. (chuckle)
He was about 50 feet away...down a hill.
But... but... we all know that the earliest people were gentle vegetarians, living in harmony with all animals and plants. That’s what the Liberals say about our paleolithic ancestors and earliest Americans. It is we evil modern (white) humans that have destroyed the planet! I’m so confused!
It’s a good thing you didn’t have a bag of donuts or that bear would still be chasing you.
Erm...which finger was that?....
I’m not holding my breath.
That dates all the way back to the early days of “Worm Runners Digest”, when people were training flat worms, then feeding them to untrained worms and noting how much of the learned information was passed on relative to the non-fed untrained worms.
Yup bunch of slack in those arguments. Hell I wish I could earn a living just making up a bunch of hokey b.s.
What FUN that would be!
How can they possibly come to any conclusion? How about they just state what they find and don’t try to have “THE ANSWER”.
Also, one has to suspect that a hibernating bear would be a tempting package of protein for a hungry human with a spear....
a bag of donuts
I suspect the humans ate the game up in winter and the bears starved to death in the Spring.
The coming Ice Age will prove the value of the greasy, tender, overweight Leftwingtards ~ and don’t you forget that.
The reporter indicates that as there were fewer bears there were fewer different sorts of mtDNA ~ yet, the thesis here is that human presence was depriving the Cavebears of food ~ that is, range.
Think about that a moment. We have human beings, and as they spread out into more and more isolated groups way-back-when there's less breeding with the ol'gals "down home" and those local mtDNA strands can go ahead and be mutated (randomly) and show up in all the locals in just a few generations.
We use this information to track and trace human expansion ~ but it takes "isolation" from all the other humans for this trick to work.
With these Cavebears the guy is telling us that they got isolated by humans as their numbers dwindled but the researchers found FEWER different mtDNA strands.
That information is contradictory. In fact, it indicates that one sort of Cavebear came to dominate the whole species, which would mean little, if any, isolation of one group of Cavebears from the other Cavebears.
In that case I would suspect that the Cavebears all died off fairly rapidly from DISEASE ~ maybe something like West Nile Virus.
We saw that happen with the crows in the Eastern United States. That one virus wiped out the vast flocks that used to fly around. Now we have crows coming back who are immune to the virus, but there still aren't many, and I just bet there are many fewer mtDNA lines among the crows in North America these days than there were before that plague.
Thanks for your post. When I saw the time frames, I suspected the last glacial cycle had a hand in doing them in.
The human population 50K ya had begun to recover from the great Toba Megavolcano around 74K years ago. I imagine the cave bear population was also reduced by Toba, but humans resurged more so than the cave bears not being limited to cave habitat.
If I recall correctly, the comet was around 13,000 years ago, the younger Dryas around 11,000 ya. Actually, the comet may have caused a surge of fresh water thus changing the North Atlantic Deep Water circulation and bringing on the cold. Actually concentrated salt when ice freezes in the north is what keeps it going. In fact, a big danger if the Arctic ice melts in the summer is that fresh water will be increased in the North Atlantic, slowing NADW and causing severe winters in Britain and Europe.
Lots of cold, regrowth of glaciers, etc in Europe.
The last big glaciation ended with the Bolling Interstadial, which is a period of warm weather starting about 14000 years ago, and ending about 12,800 years ago.
My preference is to use the major sea-level rises as the touchstone for estimating aggregate global climate however.
If you think of the Bolling Interstadial as being the beginning of the current Interglacial, and with interglacials being typically about 10,000 years long, we are already 4000 years into the next glacial period BUT where's the ice?
If you think of the Bolling Interstadial as a brief interruption of the last period of glaciation, and not as the beginning of the current warm period, then we are about 700 years away from the beginning of the next major glaciation.
If the comet interrupted the current warm period, we are overdue. if the comet simply returned things to normal by interrupting an anamolous warm spell, we have time to waste.
A third view is it doesn't matter because we have gained control of the heating and cooling of the Earth by generating our own clouds, carbon dioxide load and we have nukes if need be.
Given the choice between returning to the world climate of 12 million years ago or letting a couple of miles of ice grind over the United States and Europe, I'll take the warmth any time.
So, tens of thousands of years of a flood to create this process?
I doubt it.
Besides, wasn’t it 40 days/nights?
We conclude that neither the effects of climate change nor human hunting alone can be responsible for the decline of the cave bear and suggest that a complex of factors including human competition for cave sites lead (sic) to the cave bear's extinction.If scientists just blindly collect data and never make a guess at its meaning, then they aren't scientists. How does one generate hypotheses without speculation?
It's often the laymen--including the lesser science reporters--who misuse the possibilities they suggest in the scientific literature.
Generally, they are thought to have been herbivores--based on teeth, mandible, and skull morphology, as well as isotope work (generally low 15N)--although some researchers think that some populations (Romania?) might have become omnivorous when stressed. That is still debated, however.
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