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Ötzi the Iceman @ Mummy Tombs

His DNA

A number of DNA studies have been done on Ötzi over the years. At first, scientists wanted to study his mtDNA and sequence his genome. In recent years, they have used this information to determine if the Iceman has any living relatives.

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. 

Two early studies of Ötzi's mtDNA were done. The first used a small part of Ötzi's mtDNA; as a result of it, many people came to believe they were his descendants. But a second study (October 2008) that analyzed his complete mtDNA sequence suggested that he had no living maternal descendants...as far as we now know. But the complete genome (study three) could help locate some descendants. Finally, the fourth study has located 19 living male relatives.

In chronological order, here are the results of four important studies of Ötzi's DNA:

mtDNA/Genome studies:

Study 1: Researchers analyzed a segment of Ötzi’s mitochondrial DNA and 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 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. 

Study 2: Researchers retrieved a complete version of Ötzi’s mitochondrial DNA (mtDNA). This is "the oldest complete human mitochondrial DNA sequence generated to date." 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 second 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 meant: In short, the second study found that Ötzi belongs to a branch of a mtDNA line that has not yet been identified in modern Europeans. Researchers were 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....” Still, many scientists believe that Ötzi's maternal line has probably died out.

Study 3: After extracting DNA from a bone in Ötzi's pelvis, scientists finally produced a complete genome of the Iceman. This allowed them to expand their hunt for his modern-day relatives and study how certain diseases such as cancer and diabetes have mutated over the millennia. This study (released August 2, 2010) provided the most information to date about the iceman's DNA and opened the door to a wider population of matches. At first, his genome seemed to suggest that the Iceman was more closely related to the present-day people of Sardinia.

But additional research by teams of scientists compared the Iceman's genome to the genome of many different groups of people: present-day Europeans as well as the skeletal remains from ancient skeletons of hunter-gatherers from Sweden and Spain and of farmers from Sweden and Bulgaria. The researchers concluded, according to livescience.com, that, "of modern people, Sardinians are Otzi's closest relatives. But among the prehistoric quartet, Ötzi most closely resembled the farmers found in Bulgaria and Sweden."

Study 4: Because Ötzi's maternal ancestors are thought to have become extinct, scientists were interested in finding possible male relatives. In this study, researchers tried to match a specific Y-chromosome mutation called G-L91, found in Ötzi's genome, to the DNA records of 3,700 Austrian men who had donated blood. This mutation is passed from father to child.

Out of this group, researchers found 19 who were the genetic relatives of Ötzi. This means that these men and the Iceman had the same male ancestor. But researchers did not tell the 19 men of their connection to Ötzi, as they continued to do further research on other populations from nearby countries. They suspect that they will find other men with the same rare mutation.

Stay tuned for further developments.

 

Links to further information

The Iceman's mysterious genetic past  

Surprising Results Of Complete Mitochondrial Genome Of 5,000-Year-Old Mummy