Anthropology: The Iceman defrosted

Marta Paterlini reports on an exhibition marking 20 years since Ötzi, one of the world's oldest natural mummies, was discovered under the Alpine ice.

Ötzi²⁰: Life, Science, Fiction, Reality

South Tyrol Museum of Archaeology, Bolzano, Italy. Until 15 January 2012.

As dead celebrities go, Ötzi the Iceman must be one of the most closely studied — he has been measured, X-rayed and dated. But the 5,300-year-old mummified corpse, found part-buried in ice on the Tisenjoch Pass in the Alps spanning the Italian–Austrian border in 1991, still holds surprises. Many of his secrets are revealed in Ötzi²⁰, a major exhibition that opened this week at the South Tyrol Museum of Archaeology in Bolzano, Italy, to mark the 20th anniversary of his discovery.

Wounded by an arrowhead in his left shoulder, Ötzi is thought to have frozen to death while fleeing attackers. Much of the analysis so far has concentrated on the belongings found with him, but this has shifted. “So far the attention has been on Ötzi's clothes and tools. Now, the physical body becomes the focus,” explains museum director Angelika Fleckinger.

Central to the exhibition is a new reconstruction of his body by twin brothers Alfons and Adrie Kennis, Dutch palaeontological artists who previously put a face to Neanderthal man. The artists reconstructed Ötzi's body by comparing his bone measurements, such as femur length, to those of men today. They sculpted muscles from modelling clay, attaching them to an appropriately sized skeleton. Using a polyurethane mould, they crafted a silicone torso, adding legs in resin and plastic. The model is finished with five thin layers of silicone 'skin', each painted individually.

Ötzi the Iceman has been 'reincarnated' by palaeontological artists Alfons and Adrie Kennis using forensic findings as well as artistic inspiration. Credit: SOUTH TYROL MUS. OF ARCHAEOLOGY/H. ENGLE-21LUX

The skull was made using accurate three-dimensional computerized tomography scans of Ötzi's head as a guide. Ultrasound measurements of skull morphology and average skin and flesh thickness were used as the basis for modelling his facial tissues — a technique used in forensic medicine to reveal injuries. Together with traces of some mummified characteristics, “all these data gave us an estimate of his portrait, complete with wrinkles, hair and eyelashes,” explains Adrie Kennis.

“What I found peculiar was the small nasal cavities,” says Adrie. This trait, along with his fine bones, means that Ötzi would have looked fragile, he adds. The artists also think that he would have appeared older than someone in their mid-forties today, because his features would have been ravaged by greater exposure to the harsher, hotter climate of the time.

The reconstruction team had many discussions about the precise moment at which to depict him. “We agreed to stage it a day before his death, when he is wandering up to the mountains, a spark of stress on his face,” Adrie explains. Ötzi would have been uncomfortable — he was wounded and on his own, perhaps being followed. This sombre picture contrasts with his smiling face in the museum's earlier model.

Even more striking is the colour of Ötzi's eyes: not blue, as in the previous portrayal, but brown. This derives from the first analysis of the mummy's DNA, extracted from a sample of pelvis bone.

When the mummy was defrosted in November 2010 for the first time since its discovery, researchers found that the stomach was filled with matter (previous analyses had been limited to the intestine). Using histological, morphological, DNA and botanical analysis, they aim to determine which bacteria Ötzi was carrying at the time of his death — information they hope will improve their conservation strategy and hint at his dietary habits.

Aside from his recent thaw, Ötzi is usually kept at −6 °C and 98% air humidity, and is misted with water once a month. The droplets freeze on the surface of the body, preserving it in a thin shell of ice. The crystals on his skin are visualized in an installation by British artist Marilène Oliver, also on display in the exhibition. In Ötzi: Frozen, Scanned and Plotted (2007), Oliver converted a computerized tomography scan of the frozen body into an image by drilling some 50,000 holes into 80 acrylic sheets that were then stacked into a translucent three-dimensional block. The result is a ghostly impression of Ötzi's form.

Ötzi²⁰ embraces the full spectrum of the Iceman's discovery, his life and the media circus and scientific sleuthing that has followed. With plans to update exhibits throughout the year, the show provides a focus for the new scientific findings that are contributing to the emerging picture of Ötzi.