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Man set foot in Ice-Age Tibet

The hand of the earliest Tibetan? 20,000 years-old and 16,000 years older than any known record of humans on the plateau
The hand of the earliest Tibetan? 20,000 years-old and 16,000 years older than any known record of humans on the plateau  


By Nick Easen
CNN Hong Kong

LHASA, China -- Fossilized hand and footprints have revealed that mankind lived on the Tibetan plateau at the height of the Ice Age -- 16,000 years earlier than anyone previously thought.

The 19 fossilized signs of life have also cast doubt on the theory that the plateau was fully covered by a glacier one kilometer thick at that time.

The 20,000 year-old prints, 85 kilometers (53 miles) from Lhasa, predates any archaeological evidence on the plateau and suggests that man may have migrated to the "roof of the world" extremely early on.

At the arid and frigid site, 4,200 meters above sea level, scientists found the marks of at least six individuals, of which two were children, including a well-structured stove.

"The findings mean that human settlement here is 16,000 years earlier than scientists thought, but also human beings had the ability to adapt to such cold environment," Hong Kong University's Professor David Zhang told CNN.

Since the height of the last Ice Age was between 24,000 and 18,000 years ago, the evidence, which shocked Zhang, shows that early man could adapt to this extreme environment.

The findings, published in both the journal Nature and an American geophysical journal, are also a nail in the coffin for the ice-covered plateau hypothesis.

The theory indicates that the 4,000-meter high Tibetan plateau was completely covered in ice, thicker than the present Greenland ice sheet, even during the last Ice Age.

Yet the findings clearly indicate that the plateau was partially ice-free, and that man was able to survive there, albeit around hot springs where the climate was more equitable.

Until this discovery, the oldest known settlements were from the Late Neolithic Age, around 4,000 years ago, which led scientists to believe that Tibetans migrated onto the high-plateau around this time.

Archaeological findings of prehistoric remnants are rare in Tibet because of its political sensitivity and poor physical conditions.

Stumbled on the marks

Fossilized footprints at a hotspring, perhaps the Tibetan plateau was more habitable that scientists first thought
Fossilized footprints at a hotspring, perhaps the Tibetan plateau was more habitable that scientists first thought  

Professor Zhang stumbled on the marks in marble-like rocks, while he investigated the hot springs in 1986, and returned to collect a sample in 1995.

It was not until 1999 when he involved dating specialist Professor S.H. Li that they were able to calculate the age of the hand and footprints.

The Ice-Age hot spring that probably attracted early Tibetan settlers also preserved their hand and footprints for future posterity.

The soft mineral mud prints dried in to a durable limestone deposit called travertine, which allowed Zhang and Li to date the prints using a technique called thermo-luminescence dating.

The process involves using quartz as a mineral clock since tiny grains of the mineral were trapped in the deposit when the mud solidified 20,000 years ago.

Heated quartz emits light in proportion to the time that has passed since it was last warmed up or exposed to light.

The next step for Zhang and his colleagues is to further investigate past environmental changes on the Tibetan plateau, as well as the current physical environment.

"It is the roof of the world with the deepest gorges and highest mountains. It is worth protecting and it may later tell us something more," Zhang told local media.



 
 
 
 







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