Category Archives: Ancient DNA

The Archaeologist and the Wolf

There’s been a lot of talk around our dinner table lately about a fascinating new book entitled The Philosopher and the Wolf.    Half autobiography, half philosophical meditation, the book explores the intense relationship that University of Miami philosopher Mark Rowlands had with a wolf that he naively adopted as a cub.  As Rowlands recounts it, Brenin the wolf was a superb companion, but as a true pack animal he could not tolerate solitude.

Indeed,  Rowlands could not leave his wolf alone anywhere.  When once he left Brenin in his jeep during a ferry trip,  the frustrated animal began to literally eat his way through the vehicle,   shredding seats and seat belts and gnawing away the roof.  There wasn’t much left of the interior when Brenin was done. So Rowlands learned to take his  wolf with him everywhere,  even into the classroom.

I thought of this anecdote today as I was read an intriguing  news article about the work of archaeologist Jeff Blick.   Blick, who teaches at Georgia College & State University, is an expert on prehistoric dogs.  He has spent much of the past two decades analyzing the skeletons of 112 dogs that he and his colleagues excavated from the Weyanoke site in Virginia.  It is, by all reports,  the largest collection of prehistoric dog skeletons in North America.

Blick, who much prefers cats to dogs in his private life, has learned an awful lot about these 1000-year-old canines.  The dogs were about the size of a modern Shetland sheep dog,  and while some were sacrificed,  at least one was buried at the feet of its owner.   They dined on fish, turkey, and turtle meat,  and they may well have been barkless.  Many of the early Europeans in the Americas commented on the fact that the native dogs didn’t let out barks;  instead they tended to howl like their wolf ancestors.   (And for those of you who have never heard what a wolf sounds like,  please click here.)

Blick is interested in the question of where and how dogs were first domesticated. Some research suggests that eastern Asians were the first to domesticate wolves and that their faithful pets followed them on a long cold trek across Beringia to the New World.  Other research points to an origin in northern Africa.  Blick himself now hypotheses that people in North America and other parts of the world independently domesticated dogs and he is now trying to gather ancient canine DNA to test the idea.

All this of course begs the biggest question of all in my mind.  Why did humans first tame wolves and turn them into dogs?  I’m beginning to think that wolves themselves had at least a small say in the matter.  They didn’t want to be alone.

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.