A 46-year-old man entombed by a glacier about 5,200 years ago high in the mountains that border Austria and Italy probably spent his entire life within a 37-mile (60-kilometer) range south of where he came to his final rest, according to a new study.
Two German hikers found the "Iceman," also known as Ötzi, in the Ötzal Alps on September 19, 1991. He is heralded as the world's oldest and best preserved mummy. Since the Iceman discovery, scientists have labored to piece together his life history.
Who was he? How did he die? Where did he live?
Previous research suggests Ötzi was shot in the back by an arrow during a violent scuffle with at least two other people. The wound ultimately killed him, but not before he was able to scurry up the mountain in a futile attempt at escape.
While this theory has gained traction among the research community—it is supported by DNA analysis of the clothing, knives, bows, and arrows preserved in the ice with Ötzi—until now, the question of his origins and life-long travel patterns remained cloaked in mystery.
Wolfgang Müller, an Earth scientist with the Australian National University in Canberra, and colleagues compared the isotopic composition of a variety of elements, such as oxygen, strontium, and lead, found in the Iceman's teeth, bones, and stomach with isotopes in the soils and waters of the region to infer where he lived at various stages in his life.
"Single isotopic tracers have been used for quite a while in isolation. Their result is often equivocal. Only very recently—and our work is the first to utilize this array of methods—several isotopic tracers have been combined to get more precise information," said Müller.
The research, reported in the October 31 issue of the journal Science, restricts Ötzi's birth place to a few valleys on the Italian side of border with Austria and suggests he never strayed more than a few days' walk from home.
Thomas Loy of the School of Social Science at the University of Queensland in Australia, who performed the DNA analysis that suggested Ötzi died after a violent scuffle, said the data from Müller and colleagues were "compelling."
"Knowing where he more than likely grew up, and the limited travel he undertook as an adult, places him in a specific territory," said Loy. "And if the territory is known, then aspects of his life can be reconstructed."
The detective work of Müller and colleagues relied on two important factors: knowing when certain trace elements are locked into which part of the human body and knowing where such elements are found in the environment.
To determine origin, researchers look at teeth, which mineralize in the first few years of childhood and remain unchanged through life. Bones re-mineralize constantly and their composition indicates the mineralization of the last ten to 20 years of life.
"The outcome also really depends on the local geologic/hydrological variation, which in the case of the Iceman was particularly well suited," said Müller.
Given the variation in rock, soil, and water type, the researchers were able to divide Ötzi's potential range into four distinct areas. For example, the researchers looked at a particular oxygen isotope to determine if the water Ötzi drank came from the Austrian or Italian side of the Ötzal Alps.
"This is possible," said Müller, "because the Alps form a watershed in the area, so rain and snow north and south of the Alps is isotopically different in oxygen."
The result pins the Iceman's place of origin to a few valleys on the south side of the Alps but suggests that he migrated to a different area during adulthood. The data are also consistent with the idea that he spent a few months each summer high up in the mountains.
Shepherd or Hunter
According to the composition of Ötzi's bones, he spent anywhere from a maximum of two months to about one month each year above the timber line.
Müller said the evidence is consistent with his theory that Ötzi was a shepherd, going to the alpine regions for a few months each summer to graze livestock. Alternatively, Loy said the data is consistent with his theory that Ötzi was a specialist alpine hunter.
"The restricted area in which he apparently lived is consistent with a home base within a valley setting," said Loy. "Most commonly, hunting/village territories are defined by the topography with boundaries along ridges and passes."
Müller said the environment of Ötzi's home range was one where farming was practiced, suggesting that Ötzi too was a farmer. This is corroborated by the types of cereal grains found with Ötzi—farmed grains.
Regardless of whether Ötzi was a shepherd or specialist alpine hunter, the evidence that he spent his entire life in the region suggests to Müller that the alpine valleys of central Europe were permanently settled by the time the Stone Age came to a close.
Limestone soils dominate the landscape farther south, which are inconsistent with the isotopic signatures in Ötzi's teeth and bones, said Müller, meaning he did not spend time farther south, but rather stayed in the northern mountain valleys.
"He did not migrate there only during summer," said Müller. "That's why I think we can say the valleys were permanently inhabited. Plus, there are also a few settlements known."