Like a never-ending CSI episode, scientists have been scrutinizing the oldest mummy ever found with nearly all that forensic science has to offer. Over 12 years, they have learned what the man ate, his age, his health and they think they know more about how he died. Now they've answered another question — where he lived.
The latest series of tests on the mysterious, 5,200-year-old Iceman reveal the 46-year-old stuck close to home.
Hikers first found the mummified man frozen in a glacier in the Alps between Italy and Austria in 1991. Researchers have since nicknamed the specimen "Õtzi," after the Õtztal area where he was found.
To trace the ancient man's whereabouts, researchers led by Wolfgang Müller of the Australian National University in Canberra studied the different forms of elements in the Iceman's teeth, bones and intestines and compared them with types found in soil and water in the area.
They found the 5-foot-2-inch-tall man likely spent his entire life within 37 miles mostly south of the location where he was discovered. That would mean the Iceman lived most of his life in what is now Italy. His mummified remains are still in Italy — at a refrigerated museum designed just for him in the northern city of Bolzano.
Isotope for Every Age
The Iceman has revealed much about the Neolithic Copper Age of Europe. The frozen corpse was still clothed in goatskin leggings and a grass cloak, while a copper-headed ax and a quiver full of arrows were lying nearby. Now researchers say they can confidently link him with an ancient community that once settled in the region.
"I think it is important to know whether the Iceman was a chance wanderer in the Alps or whether he had migrated from farther away … or whether he was living in the local area during most of his life," said Müller. "We can now say that the latter was the case."
To reach that conclusion, Müller turned to chemistry.
Elements such as strontium, oxygen and argon occur in different forms, known as isotopes. Isotopes differ in the number of neutrons they carry in each atom. By comparing the ratio of one isotope found in the water or soil of a region to that found in the body tissue, researchers can locate the source of the Iceman's food or water and link him to that region.
Isotopes in Õtzi's teeth reveal where he spent his youth, since dental enamel is fixed at the time that the tooth is formed. Isotopes in his bones reflect where he spent most of his adult life, since bones are remineralized every 10 to 20 years. And isotopes taken from the mummy's intestine shed light on where he spent his final hours.
Müller and his colleagues also analyzed the chemical makeup of minerals that had been leached into Õtzi's water supplies to try and further narrow down his stomping grounds.
"It's a 'you are what you eat' type of thing," said Henry Fricke, a geologist at Colorado College in Colorado Springs who co-authored the recent analysis of the Iceman in today's issue of Science. "You incorporate elements from food and water and that's incorporated into your tooth enamel and bones."
Since the Alpine mountains around where the Iceman was found host minerals with a range of distinctive elements and isotopes, it was possible to link Õtzi with very specific locations.
Valley to Valley