Tag Archives: genetics

The Lords of Beringia

I am continually gob-smacked by the obsessive public interest in Atlantis.  Why, oh why, does a mere mention of this fabled continent quicken the heartbeat of so many?  Google, as I just did, “continent of Atlantis,”  and you will turn up a whopping  1,020,000 hits.  And a depressing number are devoted to bizarre lunatic-fringe theories concerning the location of the sunken continent  (my current favorite puts Atlantis somewhere off the coast of the Indonesia).

By contrast,  try mentioning Beringia to your friends and kids.  How many of them have heard of it?   It’s a real, honest-to-goodness sunken land–a huge chunk of northern real estate that once connected Alaska to Siberia and that now lies at the bottom of the Bering Sea.  It drowned,  as many of you undoubtedly know,  when huge ice sheets melted at the end of the last Ice Age and topped up sea levels by some 330 feet. Read more…

Another Step Closer to Waking the Dead

This has been quite a week for ancient DNA stories.  First, the feature article in Archaeology magazine about the possibility of Neanderthal cloning.  And yesterday,  a research paper in Nature reporting the success of an international team in reconstructing the ancient genome of a 4000-year-old man from northwestern Greenland.

The latter project clearly takes us one step closer towards the ability to clone a Neanderthal,  the subject of my last two posts.   But today,  I’d to focus on the new research from Greenland and what I think is important about it.

The team, led by Eske Willerslev,  a very, very  media-savvy researcher at the University of Copenhagen (whose work I have posted on before), obtained its ancient DNA from a tuft of human hair  excavated by an archaeological team in 1986 from a site in northwestern Greenland.  Willerslev and his colleagues make a strong claim that they have ruled out modern contamination.

The archaeologist who excavated the hair has gone on record stating in the 87 pages of supplementary material posted by  Nature that none of the ethnic Greenlanders on his team touched the sample.   He also affirms that no one who was likely of Asian descent handled the hair later during its storage in the museum.

So the team does indeed seem to be working with an uncontaminated ancient sample.  And Willerslev–an expert on ancient DNA–and his Ph.D. student Morten Rasmussen report that the team has reconstructed 80 percent of the nuclear genome.  Based on this,  the team has learned a number of things.

Number one,  the hair belonged to a man who descended from northern-eastern Siberians who migrated to the New World as early as 6400 years ago.  Number two,  the individual in question had blood type A+, brown eyes,  dark skin,  a predisposition to baldness, a genetic adaptation to polar cold,  and other identifiable traits.

Archaeologists already knew, however,  from decades of painstaking study of artifacts that the early Greenlanders descended from northern Asian migrants.   No surprises there.  What is new,  and I think very exciting,  are all the  details of appearance and physiology that have come to light about this particular  individual– gleaned from just a few hairs.

Archaeology has never been very good at getting down to the level of the individual, particularly in that vast expanse of time we call prehistory.   Excavations of  house floors,  middens,  and shell mounds supply a lot of information on families,  communities and populations.   But they rarely say much if anything about individuals.  And in places like North America,  archaeologists try very hard now to avoid digging human remains–a major source of information about individuals–out of respect for Native American beliefs.

So this new ability to glean a lot of information about an individual from a human hair is bound to come in extremely handy,  and I applaud the Danish team for their success.   But its clear to me that such techniques are yet another worrying step along the road to cloning an ancient human or an ancient hominin.

The Danish led team is trying to calm our fears.  “The genome we’ve reconstructed is no Frankstein’s monster,”  team member Rasmussen told EurekAlert!.  “It’s more like we’ve got the blueprints for a house, but we don’t know how to build it.”

For how long,  I wonder.  How long.

Reconstruction/drawing of Inuk by Nuka Godfredtsen.

Why We Should Worry about Neanderthal Clones

Should we clone Neanderthals?  That’s the provocative question that science writer and editor Zach Zorich poses in the forthcoming issue of Archaeology,  hitting the news stand on February 15th.  I received an advance copy late last week and read Zorich’s article this weekend. I’ve been thinking about this question ever since, and already I have arrived at my own  answer.  No.  No.  NO.

First of all,  I should point out that this is not a pie-in-the-sky question.  Zorich interviewed an impressive A-list of researchers–including geneticists who are sequencing the Neanderthal genome and leading paleoanthropologists who study ancient hominins–and some clearly believe that a cloned Neanderthal awaits us somewhere down the line.

So it’s not too early to begin thinking and debating about the ethics of cloning one of our hominin kin.  While some researchers champion the idea out of pure scientific curiosity and the desire to learn more about an extinct hominin,  I think it’s a terrible idea.  I simply don’t trust my fellow Homo sapiens sapiens to treat another hominin with kindness and respect.  Our track record with other primates, for example,  is appalling–using chimpanzees for circus shows and laboratory experimentation, hunting gorillas for meat,  and killing orangutan mothers  in order to sell their babies as pets.

And here’s something else that worries me about a Neanderthal clone.  In the 1920s, the Soviet leader  Josef  Stalin ordered the researcher who perfected the technique of artificial insemination,  Ilya Ivanov,  to create a “living war machine. ”  Ivanov’s brief, as American writer Charles Siebert reports  in his remarkable book, The Wachula Woods Accord,  was to artificially inseminate chimpanzees with human sperm to create a new hybrid.

Stalin dreamed of a large,  invincible Red Army and a vast slave workforce to carry out his Five Year Plans.  He thought a chimp-human hybrid would serve admirably. According to Russian newspapers,  Stalin told Ivanov “I want a new invincible human being insensitive to pain,  resistant and indifferent about the quality of food they eat.”

Ivanov failed miserably to produce such chimp-human hybrid, though he certainly tried.   In 1930s,  the biologist fell from political grace and was exiled to Kazakhstan in one of the many purges of the time.

All this strikes me as an important cautionary tale.   What if one of the world’s dictators  got it into his head to clone Neanderthals as slave laborers or a new kind of soldier, one physically stronger than modern humans?   It sounds far fetched,  I know.  But I don’t think we can blithely ignore the lessons of history.

Mammoth DNA in Ancient Dirt

What can a pinch of dirt from the  Alaska permafrost tell us about the extinction of mammoths and prehistoric horses?  An awful lot,  says an international team of researchers headed by James Haile,  a geneticist at the University of Copenhagen.  By sequencing ancient mitochondrial DNA from soil samples and dating the soil,  Haile and his colleagues concluded that both mammoths and ancient horse species were still grazing Alaskan meadows some 7600 to 10,500 years ago–at least 2500 later than other research suggests.   Their findings have just appeared in an online paper in the Proceedings of the National Academy of Science

Haile and several of his colleagues have a long-standing interest in the subject of ancient DNA,  and whether this fragile molecule  can really survive degradation over thousands of years in geological layers.   Remember,  we are not talking about ancient DNA encased in animal teeth or bone:  Haile and his colleagues are searching for ancient molecules from urine and faeces in the soil.

Here’s what Haile’s team did in this new study.  They collected permafrost core samples from the tundra near Stevens Village, and dated the layers in the core by two methods:  C14 dating and optically simulated luminescence.  Then the team sequenced the ancient mitochondrial DNA in the layers.  In the stratum dated between 7600 and 10,500 years ago, they discerned the ancient DNA of woolly mammoth,  prehistoric horse, moose,  and snowshoe hare.   In upper layers dated to more recent times, they found moose,  hare, and the like, but no trace of woolly mammoth or prehistoric horse.

Team member Eske Willerslev, an ancient DNA expert at the University of Copenhagen, sees this as the beginning of a whole new era in our studies of the ancient megafauna and their mysterious demise.  “With ancient DNA analysis,”  Willerslev said in a prepared statement, “we are completely independent of skeletons, bones, teeth, and other macrofossil evidence from extinct animals.  This greatly increases the possibility of finding evidence of the existence of a species through time.”  Indeed,  the team has coined a new term for this:  they now talk of identifying “ghost ranges” for the  animals.

All this sounds extremely interesting and exciting.   And if  Haile, Willerslev and their colleagues have it right,  researchers will definitely need to rethink their theories about the demise of the mammoths and other large megafauna. The team’s new proposed extinction dates would not mesh in any way with the arrival of human hunters in the Americas or with a proposed comet strike.

But I confess I am skeptical.  The validity of dirt DNA, for example,  still seems to be a hotly contested issue among ancient DNA experts.   Researchers are still debating, for example,  the authenticity of ancient human DNA extracted from fecal material found Paisley Cave in Oregon, evidence that was used to advance the case of Pre-Clovis humans in the New World.

Big claims require big evidence.   Haile and his colleagues have now put out the idea that researchers can abandon the quest for skeletal evidence and simply take soil samples to pinpoint the demise of the mammoths. Let’s see other research teams duplicate his findings.