The renowned Alpine Iceman, known as Ötzi, has painted an extraordinarily detailed picture of life some 5000 years ago, during the late Neolithic era. Researchers know Ötzi's age, his health, what he ate, and how he died. Now they have pinpointed his origins to a few valleys in southern Tyrol. Ötzi probably never strayed more than 60 kilometers from his birthplace and spent his entire life in the mountains of what's now Italy.
To link Ötzi to particular places, the researchers followed a number of clues. Wolfgang Müller of Australian National University in Canberra and an international team studied Ötzi's tooth enamel and thighbone. Dental enamel is fixed at the time the tooth is formed, so the three teeth the scientists examined contain the signature of trace elements in food ingested when Ötzi was about 3 to 5 years old, Müller explains. Bone, however, is remineralized with ingested substances every 10 to 20 years, giving a clue to the Iceman's whereabouts in adulthood. And tiny pieces of mica in Ötzi's intestine yielded data about the hours just before his death.
The isotopic signatures of tissue samples could then be matched to various soil and water samples from across the region. For example, ratios of the stable isotopes of oxygen in rainfall vary with altitude and geography. High-altitude inland areas, such as those north of where Ötzi was found, are depleted in the heavier oxygen isotope (18O), which drops out first as clouds travel from the Atlantic Ocean. More southern, Mediterranean-fed rainfall carries higher levels of 18O, and Ötzi's teeth matched these southern values, indicating that he lived in those valleys when his teeth formed. But his thighbone values lay between those and the values from the area where he was found, indicating that as an adult he spent time farther north at a higher altitude than his native valley.