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Ancient iceman has no modern kin

The 5,000-year-old mummy Öetzi, found in a glacier in the European alps 17 years ago and believed to be an ancestor of modern Europeans, actually belonged to a different genetic family and may have no living descendants, researchers report today in Current Biology. The researchers sequenced linkurl:mitochondrial DNA;http://www.the-scientist.com/article/display/19318/(mtDNA) extracted from Öetzi's intestines, offering the oldest complete mtDNA sequence of modern humans. "We sort of ass

By | October 30, 2008

The 5,000-year-old mummy Öetzi, found in a glacier in the European alps 17 years ago and believed to be an ancestor of modern Europeans, actually belonged to a different genetic family and may have no living descendants, researchers report today in Current Biology. The researchers sequenced linkurl:mitochondrial DNA;http://www.the-scientist.com/article/display/19318/(mtDNA) extracted from Öetzi's intestines, offering the oldest complete mtDNA sequence of modern humans. "We sort of assume when we look at populations today we see representations of [ancient populations] as well," linkurl:Joanna Mountain;http://www.stanford.edu/group/mountainlab/people/joanna_mountain.html an anthropological geneticist at Stanford University who was not involved in the study, told The Scientist. The current study, she said, "counters that thinking." "Sequences from linkurl:mummies;http://www.the-scientist.com/news/display/36437/ and fossils can inspire us to consider a whole new history or path for human history" by revealing populations that we don't commonly think about, she added. Franco Rollo, an anthropological geneticist at the University of Camerino in Italy and first author of the study, began studying the now-famous iceman only a few days after Öetzi was pulled from an Alpine glacier in 1991. Since then, Rollo and other researchers have studied Öetzi extensively, from the fabric of the clothes he wore to the linkurl:last meal;http://www.pnas.org/content/99/20/12594.abstract?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=otzi+iceman&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT he ate. In their latest study Rollo and colleagues sequenced mtDNA obtained from Öetzi's intestines. An organism's DNA starts to degrade immediately after death, so studying ancient samples can be tricky, linkurl:Martin Richards,;http://www.fbs.leeds.ac.uk/staff/profile.php?tag=Richards an archeogeneticist at the University of Leeds and study coauthor explained to The Scientist. Compared to chromosomal DNA, mtDNA is a smaller molecule that occurs in higher concentration in cells. Because mtDNA is passed along the maternal line, forgoing recombination, and has a high mutation rate, it provides a good model for studying human evolution, Richards said. Preliminary sequencing studies of roughly 400 base-pairs of mtDNA acquired from bone conducted in 1994 led researchers to believe modern day Europeans who share a common ancestral DNA sequence, called the K1 linkurl:lineage,;http://www.the-scientist.com/article/display/14663/ were descendants of Öetzi. With the DNA samples from Öetzi's intestines, Rollo's group used PCR amplification and linkurl:pyrosequencing technology;http://www.the-scientist.com/article/display/53235/ to reassemble and sequence Öetzi's entire 16,569 base-pair mtDNA genome. The researchers then compared Öetzi's mtDNA genome to a database of 115 modern people in the K1 lineage. Although Öetzi shared a mutation with modern people in the K1 lineage, three additional mutations suggested Öetzi's mtDNA belonged to a different sublineage group than modern Europeans. The results "show the iceman belongs to a cluster found in Europe [the K1 lineage], but he belongs to a branch that appears to have diverged from the others ... some 20,000 years ago ... and seems to have become very rare," if not extinct, Richards said. The study raises the questions about Öetzi's clade, Mountain said. "Was the clade rare at the time [Öetzi lived] ... or did entire populations [like Öetzi] go extinct that were once common?" "Öetzi is the evidence of an evolutionary process that makes some mitochondrial lines surviv[e] through the millennia while other are lost," Rollo told The Scientist by Email. "One wonders what we could find if we were able to study more ancient H. sapiens remains." Because of issues of rapid degradation and contamination in studying ancient DNA, Richards explained, scientists are "stuck with trying to work out modern genetic sequences and inferring back [in time]," limiting understanding of human evolution to only the lineages that survived not those who went extinct. Rollo's team now plans to attempt the sequencing of Öetzi's Y chromosome DNA, which is less abundant than mtDNA, but offers a counterpart to mtDNA, in that it is passed only through the paternal line. "It will be also very interesting to see whether the descendents of Öetzi indeed are all extinct," Rollo said. "[As far as we know], no one can claim to be the descendent of Öetzi but, who knows, perhaps in a lonely Alpine valley..."
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Comments

Avatar of: Michael Pollock

Michael Pollock

Posts: 5

October 30, 2008

I'm not sure that the differences between the Ice-man's mtDNA and that of modern Europeans necessarily means that he wasn't ancestral to them. Presumably his mtDNA would be characteristic of the population to which he belonged, but because he is male, he could have had dozens of offspring, none of whom would share his mtDNA.
Avatar of: richard novick

richard novick

Posts: 3

October 30, 2008

As Helicobacter pylori has been shown to be an excellent tracer of human lineages (see D. Falush et al., Science 299, 1582 (2003);T. Wirth et al., Proc Natl Acad Sci U S A 101, 4746 (2004)) and as the Iceman would almost certainly have been infected, it might be very interesting to obtain Helicobacter sequences from his gastric mucosa and compare them with Helicobacter sequences specific for different ethnicities. \n
Avatar of: anonymous poster

anonymous poster

Posts: 1

October 30, 2008

True, Mr. Pollack, and how absolutely simple. The scientific thinking and writing in the article is shameful.
Avatar of: Fred Sagan

Fred Sagan

Posts: 2

October 30, 2008

Michael Pollock (below) highlights an error in the interpretation of the results of this research.\n\nSurely it merely indicates that Oetzi's mother has few, if any, surviving female descendents.\n\nMore extensive research to sequence Oetzi's Y chromosome would be necessary to arrive at the conclusion expressed in the article.
Avatar of: john toeppen

john toeppen

Posts: 52

October 30, 2008

Gee, this sort of makes you wonder if the Ice Man?s genetic traits were de-selected. He made great tools, probably had a good sense of direction, general intelligence, and was involved in commerce and trade. Perhaps these traits are not desired by our species in general. Michael is certainly correct to first order, but did the ice man?s maternal siblings and relatives all die for similar reasons? Maybe even meeting their ends violently as did Oetzl himself, with an arrow in his side? Was it genocide? Is this the price of deviation? Do only the moose hunters or those running with the herd survive in a intolerant human cultures? Or is Weird Science a real possibility? I can?t help but wonder?.
Avatar of: Fred Sagan

Fred Sagan

Posts: 2

October 30, 2008

On reviewing and considering my previous post, I realize that, I too, am guilty of hasty and sloppy thinking.\n\nIf Oetzi's mother's offspring or those of any of her female lineage were all males that branch of her mtDNA lineage would end.\n\nSimilarly if Oetzi's offspring or those of any of his male lineage were all daughters that branch of his Y chromosome lineage would end.\n\nBearing this in mind, plus the tendency for gender bias to be extreme in some families and also what must have been a short and hazardous existence with limited opportunities to successfully raise a large family, it is of little surprise that ancient mtDNA has any significant representation in the modern population.\n\nSimilarly, if it is determined that his Y chromosome DNA is now rare it would not be remarkable.
Avatar of: tian xia

tian xia

Posts: 34

October 31, 2008

Iceman can still be the ancestor, only because he has a good wife with all the current mitochondrial mutations.
Avatar of: John Collins

John Collins

Posts: 37

October 31, 2008

It seems to me that some of the resent blogs are drawing hasty conclusions about the scientific conclusions of this paper. It seems reasonable to assume that Oetzi's mother's mitochondrial DNA was not carrying three mutations unique to her. Rather these specific changes would be spread amongst many relatives having come down a lineage for several generations previously, with potentially many hundreds or even thousand of progeny. It would seem this whole group has been genetically isolated and not contributed in a major way to modern day Europeans. A possibility is that they all died out and this maternal germ-line was lost.
Avatar of: anonymous poster

anonymous poster

Posts: 107

November 1, 2008

The authors of the paper deserve some blame for the confusion, for using the misleading term "descendants of Oetzi". (If they were repeatedly misquoted, I apologize.) Surely it is totally irrelevant if Oetzi himself left any descendants. What is interesting is the implication that there was a human maternal lineage that diverged from contemporary lineages 20,000 years ago, survived for at least 15,000 years, and then apparently died out. Y chromosome DNA may indicate if Oetzi's paternal lineage follwed a similar course, which might suggest that an entire reproductively isolated population died out.
Avatar of: Robert Birdwell

Robert Birdwell

Posts: 10

November 1, 2008

It seems to me that this is another example of a conclusion borne of that lethal combination of ignorance wedded to arrogance. \n\nThis rash conclusion may appear satisfactory, in a confident, dogmatic, sort of way, at the level of the author's current knowledge, but I'm quite certain that in a few months, or years, this conclusion will be the butt of jokes.
Avatar of: anonymous poster

anonymous poster

Posts: 2

November 3, 2008

Do we not remember that most lineages go extinct in the natural world? Why then are we surprised about these data? We would have beat the odds to actually find an ancestor.
Avatar of: Chris Squires

Chris Squires

Posts: 1

November 4, 2008

Perhaps this person's mother came from a small and distant tribe, and few female relatives survived. The skillful workmanship, ability to plan, artistic or scientific indications (tattoos? -- possibly used in primitive medicines, possibly indicating trigger points or acupuncture points for future reference? Or "just" art?) could be CULTURALLY inherited.\n\nMany modern people think nothing of combining art, food, science and clothing from many different cultures and places with which they have no genetic link. Many modern populations will also live and die in isolation, leaving no heirs, genetic or otherwise.\n\nHave they only looked for relatives in modern European people, or have they looked at other parts of the world? I agree that it is more likely that they WON'T find modern-day relatives, because the great majority of genetic lines will have died off. Basic population genetics.

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