“ We’ve found these prions in hundreds of strains and they are conferring all kinds of really interesting biology to the cells. ” — susan lindquist, page 14
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genome paints
a better portrait
of the iceman
dNa reveals Ötzi had lyme
disease, lactose intolerance
STORY ONE
By tina Hesman saey
By peering deeply into the DNA of the mummy known as Ötzi, geneticists have expanded the profile of the 5,300-year-old
Iceman: He had brown eyes, brown hair
and blood type O, was lactose intolerant
and his modern-day relatives live on
Corsica and Sardinia.
These vital statistics come from an
analysis of the Tyrolean man’s complete
genetic blueprint, reported online February 28 in Nature Communications . The
DNA analysis also reveals that the Iceman, found frozen and well-preserved in
the Italian Alps in 1991, carried genetic
risk factors for heart disease. And he was
infected with the bacterium that causes
Lyme disease, making him the oldest
known case of the disorder.
For the new study, researchers led by
Albert Zink, an anthropologist at the
European Academy of Bolzano in Italy,
removed a bit of Ötzi’s hip bone and
extracted DNA from the sample. The
mummy’s fresh-frozen state helped
preserve his DNA, making deciphering a complete genetic blueprint easier
than for most ancient samples, says Niels
Lynnerup, a forensic anthropologist at
the University of Copenhagen. “It is
much better DNA than you can get from
Researchers eduard egarter-Vigl (left) and albert Zink take a small piece of the
iceman’s hip bone in november 2010. dna extracted from the bone was used
to compile a complete genetic profile of the man, who lived in the southern alps
about 5,300 years ago.
one dry old bone,” he says.
Ötzi’s brown eyes and lactose intolerance are evidence that scientists are
right about the pace of evolution of
some human traits, says John Hawks,
an anthropologist at the University of
Wisconsin–Madison. Mutations that
gave rise to genes for blue eyes and the
ability to digest dairy products into
adulthood arose sometime within the
last 10,000 years but took many, many
generations to spread throughout
Europe. (Most evidence suggests the
lactose tolerance gene was widespread
in Europeans by the Middle Ages.)
People living in Ötzi’s time “had the
dairy animals, but what they didn’t
have was enough generations for the
gene to become common,” Hawks says.
The finding that the Iceman was lactose
intolerant supports that picture. “We
were right about this gene. It is new.”
Previous studies of Ötzi’s genetic past
examined DNA only from cells’ energy-
making factories, called mitochondria.
People inherit mitochondria from their
mothers, and mitochondrial DNA can be
used to trace a person’s maternal lineage.
Ötzi’s mitochondria carry some genetic
variants not seen in modern Europe-
ans, leading scientists to think that his
maternal line has died out.
