Caption: The decline of the cave bear began 50,000 years ago due to human expansion.
Credit: RockCreek
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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.
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References:
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
Credit: RockCreek
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Ball bearing ping.
Obviously ... Bush’s fault.
What the...! They had "climate change" 50,000 years ago?
sarc/
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.
It was the domestication of the house cat.
We must presume this bear had been previously edumacated! The next bear will eat the cat.
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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
Simon Warwick-Smith
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