Ötzi's third
DNA study (August 2, 2010):
After
extracting DNA from a bone in Ötzi's pelvis, scientists have finally
produced a complete genome of the Iceman. This will allow scientists
to hunt for his modern-day relatives and study how certain diseases
such as cancer and diabetes have
mutated over the millennia.
This new study
(released August 2, 2010) provides the most information to date about
the iceman's DNA. Two earlier studies (see below) analyzed his
mitochondrial DNA (mtDNA) which provides information about his female
ancestors. The new study--with its complete genome--opens the door to
a wider population of matches. By the twentieth anniversary of the
Iceman's discovery (September 19, 2011), scientists are hopeful that a
few modern-day relatives might be found.
For more information:
Five
millennia on, Iceman of Bolzano gives up DNA secrets
What is mtDNA:
Mitochondria (structures within cells) are responsible for energy
production. These structures contain DNA that is passed from a mother to her children;
consequently, everyone inherits mitochondrial DNA (mtDNA) from his or her
mother. An analysis of a person's mtDNA can provide a view of the person's
female ancestry.
Why mtDNA is often preferred over
nuclear DNA: Unlike nuclear DNA (which contains genetic information from both
parents and which deteriorates rather rapidly after death), mtDNA lasts
much longer (mtDNA has been retrieved from ancient hair and bone samples,
for example). It is also easier to find since our cells contain many copies of this
DNA; therefore, it is perfect for use when trying to trace a person's
female ancestry.
The first study:
Researchers
were able to analyze a segment of
Ötzi’s mitochondrial DNA in this study.
They
determined that he belonged to the genetic group (called a haplogroup by
DNA researchers) known as K, a group to which about 8 percent of modern
Europeans belong. The K haplogroup has two lineages or sub-groups (called
subhaplogroups) identified as K-1 and K-2. Researchers in the early study
also determined that the Iceman belonged to the K-1 subhaplogroup.
This
finding suggested that many people (who share the K-1 subhaplogroup)
shared a common female ancestor with
Ötzi.
The second
study (2008):
The new study, according to biologist Franco Rollo of the University of
Camerino, Italy, provides "the
oldest complete human mitochondrial DNA sequence generated to date."
In this study, researchers
retrieved a complete version of Ötzi’s mitochondrial DNA.
Although they, too, found that
Ötzi belonged to the K-1 subhaplogroup, the analysis went further. The
K-1 subhaplogroup has three branches or clusters (K1a, K1b, and K1c--all
found in the modern European population). The
new study revealed that
Ötzi belonged to a previously unidentified cluster (now called K1ö,
for
Ötzi).
According to researchers Rollo,
as quoted on medicalnewstoday.com, "This doesn't simply mean that
Ötzi had some 'personal' mutations making him different from the
others but that, in the past, there was a group - a branch of the
phylogenetic tree - of men and women sharing the same mitochondrial DNA.
Apparently, this genetic group is no longer present. We don't know whether
it is extinct or it has become extremely rare." Another researcher, Martin
Richards, a professor of biology at the University of Leeds in northern
England, added, "Our research suggests that Ötzi's lineage may indeed have
become extinct."
What this
means: In short, the study found
that Ötzi
belongs to a branch of a mtDNA line that has not yet been identified in modern
Europeans.
Researchers are careful to
point out that, if a larger number of modern Europeans are genetically tested, especially
those who live in
the alpine areas where the Iceman once roamed, it is still possible that living
members of the K1ö
cluster can be found.
Trying
to add a bit of hope, researcher Rollo, in an email to Genomeweb.com,
said, “At the present state of knowledge
no one can claim to be the descendant of Ötzi but, who knows, perhaps in
a lonely Alpine valley....”
Stay
tuned for further developments.
Links to
further information
The
Iceman's mysterious genetic past
Mummy
mitochondrial genome sequence yields clues about human evolution
Surprising
Results Of Complete Mitochondrial Genome Of 5,000-Year-Old Mummy
