DNA from a Fossil Canine Skull: Confirmation of an Ancient Domesticated Dog

Where did domesticated dogs come from?   That dogs are wolves has been known for some time but which wolves and when did domestication occur has been a more difficult question to answer.   Thousands of dog breeds and wolves have been genotyped to explore this question and that evidence suggests four and possibly more, separate wolf populations were part of independent domestication events.  Contributing to the story of the origins of domesticated dogs comes a report yesterday of DNA sequence data derived from a skull of a dog-like canid discovered in sediments in a cave in southern Siberia.  The skull was discovered in 1975 during excavations of this large cave.  The same cave has yielded over 71,000 semi-fossilized bones that were from hyenas, foxes, wolves, bears, goats, and a many other animals.  A previous analysis of this dog-like skull in 2011, found that the features of the skull strongly suggested that this skull was more similar to domestic dogs than to wolves (Ovodov et al. 2011 see references).  Now researchers have been able to extract DNA from teeth from this fossil skull and sequence a highly variable part of the mitochondrial genome in order to determine if this skull did belong to a domesticated dog or a wolf.  Here is the abstract of their current paper:

The origin of domestic dogs remains controversial, with genetic data indicating a separation between modern dogs and wolves in the Late Pleistocene. However, only a few dog-like fossils are found prior to the Last Glacial Maximum, and it is widely accepted that the dog domestication predates the beginning of agriculture about 10,000 years ago. In order to evaluate the genetic relationship of one of the oldest dogs, we have isolated ancient DNA from the recently described putative 33,000-year old Pleistocene dog from Altai and analysed 413 nucleotides of the mitochondrial control region. Our analyses reveal that the unique haplotype of the Altai dog is more closely related to modern dogs and prehistoric New World canids than it is to contemporary wolves. Further genetic analyses of ancient canids may reveal a more exact date and centre of domestication.  Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog:  Druzhkova AS, Thalmann O, Trifonov VA, Leonard JA, Vorobieva NV, et al. (2013) Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog. PLoS ONE 8(3): e57754. doi:10.1371/journal.pone.0057754.

Below is a relationship tree from this paper of modern and ancient wolves and dogs with this new “fossil” sample included.

What is notable here is the NWW and OWW refer to wolf populations and the light blue are domestic dogs.  The genetic data then point to multiple origins of domestic dogs among these wolves.  This very old dog sample is similar to one particular group of domestic dogs that is related to one distinct variety of wolves.

What can we conclude from this report?

Domestic dogs have been around a long time.  Most of the bones in this cave represent animals that would have been present before the last ice-age.  The geological context of the cave and its sediments suggests that it has barely been inhabited since the most recent ice-age and thus the thousands of individual animals that the bones represent found their way into the cave a very long time ago.

Foxes and Wolves have been in this area since the cave was accessible.  Radiocarbon dates on the wolf bones found in the cave were even older (>40 thousand years) than the dog bones. In addition there are bones of at least two species of foxes buried several feet under sediments in the cave.  The implication is that before the last ice age the same species of wolf and foxes were found in this area as are found in part of the world today.

Implications for Young Earth Creationism:

I was drawn to this article because I have just been doing comparisons of mitochondrial genomes and talking about how little difference there is between dogs and wolves compared to coyotes and other canines (see:  On Kinds and Common Ancestor).  From the tree above you can see that the coyote is quite different (the hash marks indicate that his line is much longer).  What we have with this cave is a time capsule filled with hundreds of organisms that were alive long ago.   Conventional geological estimations would put this cave as open for habitation for over 70,000 years.  The 4 to 5 feet of sediments with thousands of bones would seem to require many thousands of years to collect as there is no significant input of sediments from outside the cave and so what is found there is literally dust accumulation, a small amount so erosion from the cave roof and material from dead animals.   The origin of the cave and the accumulation of its contents in such a short time is a serious problem in itself for YECs.

Interestingly, the radiocarbon dates for the domestic dog are quite old. Young earth creationists have difficulty with radiocarbon dating but they still tend to accept it for recent times because of its obvious accuracy in dating objects of known age over the past 4000 years.  Dogs from Egypt from the earliest dynastic empires are only dates to 5000 or so years old. Still to old for YECs and yet not that old.  Here we have a dog dated to 33,000 years and wolves dates to more than 40,000 years.  If these dogs have the same origin as dogs from Egypt and were at one time a general canid on Noah’s ark why would they date to much older dates?  In addition, bones from other animals in this cave date to ages ranging from 50 thousand years (the limits of radiocarbon dating) down to just under 10,000 years that I am aware of.  In YEC chronology the ice age happened only hundreds of years after the global flood.  If all these animals wandered into this cave during the 300-400 years between the end of the flood and the ice-age, why are there such huge discrepancies in the dates?  One would expect that even if radiocarbon dating were bogus that the dates should at least be similar if all the animals lived around the same time.

More to the point of my recent discussion of baraminology (see Thoughts on Baraminology if you don’t know what that is) how do we come to have clearly identifiable species of canines that for YECs must represent extremely early descendants of the original canine kind on the ark?  They have all the features of our species today. Why are we not seeing the “evolution” of canines from a generalized canine ancestor pair to their present day condition? Rather we see fully formed and virtually genetically identical animals that are thousands of years old at a minimum.   If all of these canines evolved from a common stock from the Ark why are they so genetically distinct already? 

This is yet another example where YECs will have to propose incredible rates of genetic mutations and super powerful feats of natural selection to pull these animals apart into such distinct genetically isolated species units over such a short period of time.

References:

A 33,000-Year-Old Incipient Dog from the Altai Mountains of Siberia: Evidence of the Earliest Domestication Disrupted by the Last Glacial Maximum  Ovodov ND, Crockford SJ, Kuzmin YV, Higham TFG, Hodgins GWL, et al. (2011) A 33,000-Year-Old Incipient Dog from the Altai Mountains of Siberia: Evidence of the Earliest Domestication Disrupted by the Last Glacial Maximum. PLoS ONE 6(7): e22821. doi:10.1371/journal.pone.0022821

Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog:  Druzhkova AS, Thalmann O, Trifonov VA, Leonard JA, Vorobieva NV, et al. (2013) Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog. PLoS ONE 8(3): e57754. doi:10.1371/journal.pone.0057754.