By Imogen Foulkes
BBC News, Berne
The Schnidejoch glacier records human activity in the region
Melting alpine glaciers are revealing fascinating clues to Neolithic life in the high mountains.
And, as a conference of archaeologists and climatologists meeting in the Swiss capital Berne has been discussing, the finds are also providing key indicators to climate change.
Everyone knows the story of Oetzi the Ice Man, found in a glacier on the Austrian-Italian border in 1991. Oetzi was discovered at an altitude of over 3,000m.
He lived in about 3,300 BC, leading to speculation that the Alps may have had more human habitation than previously suspected.
Now, more dramatic findings from the 2,756m Schnidejoch glacier in Switzerland have confirmed the theory.
It all started at the end of the long hot summer of 2003, when a Swiss couple, hiking across a melting Schnidejoch, came across a piece of wood that aroused their curiosity.
They took it down with them, and gave it to canton Berne's archaeological department, where careful examination and carbon dating revealed the piece of wood to be an arrow quiver made of birch bark, dating from about 3000 BC.
"Finds in the Alps are very rare anyway," explains Albert Hafner, chief archaeologist with the canton of Berne. "But this is unique; we don't know of a quiver like this anywhere else in the world."
At first, the news of the find was kept quiet; historians feared treasure hunters on the Schnidejoch as the ice melted. But teams of archaeologists went up, and more and more artefacts were discovered.
The ice has protected the leather for thousands of years
"We now have the complete bow equipment, quiver and arrows," says Mr Hafner "And we have, surprisingly, a lot of organic material like leather, parts of shoes and a trouser leg, that we wouldn't normally find."
And the finds are not confined to 3000 BC. Some of the leather found, and a fragment of a wooden bowl, date from 4500 BC, older even than Oetzi, making them the oldest objects ever found in the Alps.
And from later periods, a Bronze Age pin has been discovered, as well as Roman coins and a fibula, and items dating from the early Middle Ages.
Key to climate change
What fascinates scientists about the age of the finds is that they correspond to times when climate specialists have already calculated the Earth was going through an especially warm period, caused by fluctuations in the orbital pattern of the Earth in relation to the Sun.
At these times, historians now speculate, the high mountain regions became accessible to humans.
Archaeologists needed time to investigate the area
For Martin Grosjean, a climatologist at Berne University, the Schnidejoch has become a mine of information on changes in the Earth's climate.
"The site is exactly at the point where the glacier responds most sensitively to short-term climate change and temperature variations," he explains. "So if we get more carbon datings from this site, we can get the most precise picture of short-term glacier fluctuations for the past six or 7,000 years."
The Roman coins found on the Schnidejoch are being seen as proof that the Romans used this route to cross the Alps from Italy to their territories in northern Europe. Interestingly, one of the Earth's chillier periods coincides with the decline of the Roman empire.
Proof that the Romans came this way
As the Earth cooled and the glaciers grew again, the Schnidejoch and other passes like it would have been blocked by ice. So did fluctuations in the Earth's climate contribute to the fall of the Roman empire?
"Well that may be stretching things a bit," laughs Martin Grosjean. "But what we do know is that the climate has fluctuated throughout history; in the past the driving force for the changes was the Earth's orbital pattern, now the driving force is green house gas emissions."
For Martin Grosjean, the leather items found on the Schnidejoch, dated at over 5,000 years old, are proof, if any more were needed, that the Earth is now warming up.
"The leather is the jewel among the finds," he says. "If leather is exposed to the weather, to sun, wind and rain, it disintegrates almost immediately.
Bit by bit, the Neolithic way of life is being revealed
"The fact that we still find these 5,000-year-old pieces of leather tells us they were protected by the ice all this time, and that the glaciers have never been smaller than in the year 2003 and the years following."
Scientists and archaeologists from all over the world attended the conference in Berne to hear about the Schnidejoch findings, and present research of their own.
Patterns have begun to emerge: researchers in Canada's Yukon region have found evidence of Neolithic farming and domesticated animals at high altitudes.
Again, they correspond with the calculations climatologists have made about the Earth's warmer periods.
In Norway, Atle Nesje has been analysing glaciers for the past 25 years. His calculations for the Norwegian icefields show a similar shrinkage and growth pattern to the alpine glaciers.
"Now these archaeological findings seem to fit quite nicely with our glacier reconstructions," he says. "This is very important in the debate about climate change in the past, the present, and also in the future."
A reconstruction of the shoes these mountain people used to wear
For historians however, the Schnidejoch is unexpected evidence that early man was far more at home in the high Alps than had been previously thought.
"In 1991, we were completely surprised by Oetzi," remembers Albert Hafner. "Up to then, we had always thought the Alps were not used, that people never went there.
"Now with Schnidejoch we know they were rather keen on mountaineering. It was a big challenge for them; look at the shoes, no Goretex for them. But we know they went up regularly."