Into the realm of the cave bear
Updated on 04 June 2009
Tom Clarke delves into deep caverns to uncover the mysteries of history and climate change hidden by Bear Cave in Poland.
With its crystal clear pools and spectacular stalagmites and stalactites the upper parts of Jaskinia Niedzwiedzia (Bear Cave) cave complex are regarded as the most beautiful in Poland.
Its lower reaches (there are 200 metres of tunnels and caverns in all) are more amazing still, but for conservation reasons remain closed to the public. Today the cave gets around 80 thousand visitors a year. Not bad for somewhere that was out of bounds for decades.
This whole area was once the home of the Soviet Union's uranium production. Until the late 1960s, there was an exclusion zone stretching 20 miles around the nearby town of Kletno. The mountain into which bear cave sinks was mined for the element that was then enriched before running the reactors and building the bombs of the cold war.
Kletno's uranium may have an even more sinister past. Until 1945 this whole area was part of Germany. The Nazis, racing the allies to exploit the newfound power of the atom, got their Uranium from here too.
At the end of the war the Americans seized Kletno's uranium and, so the story goes locally, some of it ended up in the "Little Boy" bomb dropped on Hiroshima. It killed 75,000 people in a flash.
In 1966 quarry workers blasting marble from the mountain discovered the Bear Cave. Long before the team from Durham University came here to study climate, it became a living laboratory.
The entrance of Jaskinia Niedzwiedzia today (Photo courtesy of Lisa Baldini)
The first explorations in the early 1970s found tens of thousands of bone fragments from extinct mammals that roamed the forests of central Europe. The cave floor was littered with the bones of wolves, cave lions, hyenas, bison and the highest concentration of cave bear remains in Europe. The earliest sediments date back 180,000 years.
Although the cave has been thoroughly excavated since the 1970s, even as we tried to make our way to the lower reaches of the cave we were pushing past pre-historic bones jutting out of the mud and rock crevices.
Dating these remains has recreated a detailed history of life in and around the cave long before man discovered it. Researchers from the University of Wroclaw, Jerzy Bieronski, Pawel Socha and Krzysztof Stefaniak who accompanied us on our visit, have been working to reconstruct a picture of Bear Cave's inhabitants as the climate has changed in the past.
Their analyses suggests that despite some serious cold periods in Europe's past, this area was never frozen over completely with evidence of tundra or woodland being present all the time - a fact that makes this area so crucial for the research on rainfall patterns now going on here. Because it never froze completely, water still made it down through the cave roof. 
Pristine environment of the lower cave (Photo courtesy of Lisa Baldini)
Much of the Polish team's research has centred on cave bears. This ancient relative of the brown bear stood ten feet high on its hind legs and could weigh half a tonne. They were once one of Europe's top predators and would certainly have been the subject of the scarier bed-time stories of our Neanderthal cousins who shared the forests with them.
One of the key mysteries is how so many of them got into the eponymous cave. All evidence suggests it was sealed until discovered by quarrymen in the 1960s and there is no trace of humans ever having entered the cave. If humans never made it in, it's a mystery how the cave bears made it.
Cave bear remains wedged in a limestone crevice (Photo courtesy of Lisa Baldini)
Recent radioactive carbon dating of cave bear bones by the Polish researchers has thrown up another mystery. The bears were thought to have gone extinct in Europe during the peak of the last glacial period around 27,000 years ago. However the remains of the bears in Bear Cave have now been found to date from well before then, at around 40,000 years old.
Why did cave bears from here die out so much earlier? Was it another change to the climate here that drove them to extinction? Or is there another reason why cave bears stopped coming here despite there being plenty of other animal remains around stretching right up to the present.
While their goals are completely unrelated, it's quite possible the climatic research being carried out by the Durham University team could complement that of their Polish colleagues in answering some of the continuing mysteries of Kletno's Bear Cave.
Stalagmite Cascade in the lower cave (Photo courtesy of Lisa Baldini)
