The oldest complete DNA sequence of a human mitochondria performed on the famous Tyrolean Iceman or Otzi revealed an unexpected fact for scientists: even though there are only 5,000 years of separation between him and the modern man, the genetic differences were significant between the two.

After performing a complete analysis on the mitochondrial genome of the well-preserved mummy, the scientists found that none of the descendants of his lineage are present in modern times. This is the reason why scientists had to name a new family tree: “Otzi’s branch.”

“This doesn’t simply mean that Otzi 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,” explained Franco Rollo of the University of Camerino, Italy. “Apparently, this genetic group is no longer present. We don’t know whether it is extinct or it has become extremely rare.”

Otzi is a well-preserved natural mummy discovered in 1991 in the Schnastal glacier in the Otztal Alps, near the border between Austria and Italy. Based on the place where he was found, as well as his physical appearance, Otzi was believed to have been either a hunter, or a shepherd. According to some scientists, he was less likely to have been involved in copper smelting due to a high degree of mobility in his lifestyle which does not characterize the Copper Age Europeans.

He is not only the oldest European mummy discovered, but he was also found not to belong to any of the K1 subclusters of the halogroup K. Halogroup K basically represents a mitochondrial lineage of the Western European genetic pool, and is divided into several subclusters. Otzi belongs to none of them.

The analysis of the mitochondrial DNA is of particular importance as changes usually occur only on a gradual matter from one generation to another, as Professor Martin Richards of the University of Leeds, and co-author of the study, explained. This makes it easier for scientists to establish the evolutionary link across human populations.

The fact that Ozti seems to belong to a lineage that is now possibly extinct has determined scientists to continue looking for clues in the area where the mummy was discovered.

What is most interesting is that this discovery comes two years after scientists declared Otzi to be part of the K1 subcluster. Almost 8 percent of Europeans belong to the K halogroup, which in turn is divided into two subclusters, K1 and K2. Furthermore, K1 has been divided in turn into three subgroups. Now, the possibility of a fourth K1 branch appeared.

However that may be, the discovery marks a breakthrough in mitochondrial DNA analysis of mummified samples, proving that they can indeed be fully sequenced. The findings appear in the journal Current Biology this week.