By investigating the isotope compositions of minerals found in Oztis tooth enamel, bones and intestine, and comparing them to those of environmental sources like water and rocks, the researchers were able to identify particular areas near where tzi died as places he probably frequented. Oxygen isotopes, for example, hint at where tzi got his drinking water. Levels of these isotopes in his tooth enamel, which is fixed during childhood, suggest that tzi spent his early years in lower elevations south of where his body turned up. Levels in his bones, which remineralize throughout life, indicate that the Iceman ventured into higher altitudes during later years.
Strontium isotopes in teeth and bones narrowed the geographical possibilities even further, pointing to areas of distinct rock composition. And data from argon isotopes from very small rocks in tzis intestine--presumably ingested with food or water--fine-tuned the picture. Geochemist Wolfgang Mller of the Australian National University in Canberra, the lead author on the study, says he and his colleagues were able to select one locality in the area with the closest isotopic matches between tzi and the environment as a possible site of tzis childhood. Called Feldthurns, this site in the Eisack Valley has produced archaeological finds typical of the Copper Age, the period during which tzi lived. The argon data suggest that he subsequently spent time in the Etsch Valley, before heading to the tzal region where he died. But other nearby sites are geochemically consistent with data from tzi, too, Mller points out. "I would talk of probabilities and likelihoods," he says, "you cant say for certain."
Part of the mystery surrounding tzis life comes from the fact that he seems to have been far from home when he died. Discovered high up in the snowy mountains, dressed against the cold and possibly bearing injuries related to a fight, the Icemans corpse raises tantalizing questions about just what tzi was doing there. But Mller says that the location at which tzi was found is compatible with the travels of a shepherd of the time, noting that the data indicate that tzi spent one or two months a year at high altitudes. --Chris Jozefowicz