Chemistry Reference
In-Depth Information
Chemists use an instrument called a mass spectrometer to mea-
sure the relative abundance of isotopes. There are different kinds of
mass spectrometers, but the basic idea is to measure the mass of a
substance by applying a force. The response to this force depends on
the object's mass—think of Newton's second law, where accelera-
tion equals force divided by mass. In the case of mass spectroscopy,
the substances to be measured are first ionized—they are made into
charged particles called ions by stripping electrons. A magnetic field
deflects the motion of an ion, and the deflection depends on the ion's
mass, most of which is due to the protons and neutrons in the nucleus.
The technique separates different isotopes and measures their abun-
dance in a given sample.
In 2003, Wolfgang Müller, a researcher then at the Australian Na-
tional University in Canberra, and his colleagues performed isotope
measurements of Ötzi's teeth and bones, then compared these values
with surrounding soils, rocks, and streams. In order for these technique
to succeed in pinpointing locations, there must be some variability—a
uniform environment would give no clues—and fortunately there is
variation in the complex alpine forests and valleys of the Ötzal Alps.
Müller and his colleagues found that the Iceman probably spent his
childhood in the Eisack Valley, located 25-30 miles (40-48 km) from
the site he was found, as shown on the map opposite. As an adult, he
spent considerable time in the Etsch Valley, about 12 miles (19.2 km)
south of where he died. Based on this evidence, Ötzi did not stray too
far from home. Müller and his colleagues published their findings in a
paper, “Origin and Migration of the Alpine Iceman,” in a 2003 issue of
Science.
Other clues shed light on Ötzi's culture. As Klaus Oeggl, a research-
er at Innsbruck University in Austria, and his colleagues noted in a 2007
issue of
Quaternary Science Reviews,
“The investigations of the Tyrolean
Iceman 'Ötzi' and his artefacts, discovered at a remote location high in
the Eastern Alps, have contributed greatly to the knowledge of the life-
style of Neolithic humankind.” The Iceman was well clothed to survive
in the harsh alpine environment, and the blade of his copper axe was
extremely pure and well made. He was not in the best of health, for he
suffered from arthritis, as evidenced by the condition of his joints, and
the remains of parasitic whipworm eggs found in his intestine indicate
he would have been experiencing digestion trouble.
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