Slow thawing of a cold case


Iceman: After uncovering many facts, researchers continue to study a mummy to find the cause of death of a man who lived more than 5000 years ago.

October 31, 2003|By Michael Stroh | Michael Stroh,SUN STAFF

A pair of German climbers were the first to spot the shriveled tea-colored corpse, peeking from the Alpine ice 10,500 feet above sea level. They didn't think much of it at first. In the Alps, after all, it's not unheard of for glaciers to occasionally disgorge the dead.

But it soon became obvious the body, pried from the pass with a jackhammer, was no unlucky modern mountaineer. Radiocarbon dating revealed the 5-foot-2 man drew his last breath 5,200 years ago, making him older than Egyptian royal mummies. The press called him the Iceman. Scientists nicknamed him Otzi, after the region just south of the Italian-Austrian border where he turned up.

Since his discovery in September 1991, Otzi has been providing scientists with an unprecedented glimpse into daily life in prehistoric Europe.

"In my eyes, Otzi is the greatest archaeological discovery of the last century," says James Dickson, a University of Glasgow botanist who has studied the mummy.

The mummy has also proved to be the coldest of cold cases. But creative forensic work over the past 12 years has slowly been prying loose his secrets, addressing questions about Otzi's age, diet and - most intriguingly - what killed him. Now an international team of scientists appears to have solved one more long-standing riddle: Where was Otzi from?

Windows into life

Geochemist Wolfgang Muller of the Australian National University in Canberra compared samples from Otzi's teeth, bones and intestines to soil and water samples collected from the mountainous region where he was found. As he describes in today's issue of Science, each type of biological sample offered researchers a window into a different period of Otzi's life.

Tooth enamel, for example, forms in childhood and remains essentially unchanged until death. So anything Otzi ate or drank between ages 3 and 5 would leave behind chemical clues in his teeth.

"It's sort of become a cliche, but this really shows that you are what you eat," says Henry Fricke, a geochemist at Colorado College in Colorado Springs who analyzed a small test tube of Otzi's tooth samples.

Slivers from Otzi's thighbone, on the other hand, provide a record of Otzi's adulthood, since the minerals in them regenerate every 10 to 20 years. Finally, Muller and his team found specks of the mineral mica in Otzi's intestines that helped pinpoint his whereabouts in the months before his death.

The scientists were lucky that the soil and water in the region turned out to be chemically diverse. Rainwater north of the rocky pass where Otzi was found contains different forms of oxygen than rainwater to the south. By looking for common chemical signatures in the environmental and biological samples, the scientists were able to map out the Iceman's movements during his life.

What the samples showed is that Otzi most likely spent his childhood south of his final resting place, possibly in a village called Feldthurns in the Eisack Valley. As an adult, he made his way west and lived in the Etsch Valley. In all, the evidence shows, Otzi never strayed more than 40 miles from his childhood home.

"It's really a door into early history," says Horst Seidler, an anthropologist at the University of Vienna who heads the committee that coordinates Otzi research. Muller's study, he says, was "ingenious."

Studying Otzi, he notes, is not easy. Since 1998 Otzi has resided in a custom-built, climate-controlled vault in the South Tyrol Museum of Archaeology in Bolzano, Italy, about 35 miles southeast from where Otzi was discovered. Although Austria first claimed the Neolithic mountain man, he is now owned by Italy.

It took Muller two years to obtain permission to enter the vault - housed in a former Bank of Italy building - and obtain small samples from Otzi. Researchers don scrubs and surgical masks to enter the vault, which is kept at a constant 21.2 degrees Fahrenheit and 98 percent humidity. To prevent the refrigerated air from sucking moisture from the 30-pound corpse, Otzi is kept encrusted in a thin layer of protective ice, which gives his turkey-brown skin a reflective sheen.

Muller's study is only the latest tantalizing discovery about Otzi made over the years. Bone studies showed that he was probably 46 years old. Pollen grains of the hop hornbeam tree dredged from his gut signaled that Otzi probably died in late spring, since that is when the tree blooms.

Blackened, tattoo-like marks on his lower spine, right knee and ankle have led some researchers to suggest that Otzi may have been treated with acupuncture, since the marks are close to traditional Chinese acupuncture points. But some of the most exciting insights have come from the extensive clothes and equipment found with him in the ice. These, scientists say, offer a unique window into the world in which he lived.

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