A well-preserved 33,000-year-old dog skull recovered from a cave in the mountains of southern Siberia is more closely related to modern dogs than to wolves.
This finding, from an international team led by a Russian researcher, backs up a study from last year that identified the specimen as one of the oldest fossils of domesticated dogs.
The skull was first discovered in 1975 in a cave in the Altai Mountains, a range situated in East-Central Asia where China, Russia, Mongolia and Kazakhstan meet.
The initial study of the specimen showed that “Altai dog”—named after the mountains where it was found—had a snout that resembled domesticated Greenland dogs from 1,000 years ago, but had large teeth similar to wild European wolves from 31,000 years ago.
To clarify the new specimen’s place on the canine family tree, Anna Druzhkova, from the Siberian Branch of the Russian Academy of Sciences, and her colleagues used mitochondrial DNA extracted from a fossil tooth and jaw bone.
Mitochondrial DNA is the genetic material found in the mitochondria—the powerhouses of all cells. This DNA is separate from that contained in the nucleus and, unlike the nuclear DNA, is inherited only from the mother.
Researchers compared the mitochondrial DNA of “Altai dog” to currently living species of dogs, wolves and coyotes. They also cross-referenced it to extinct species of canids—the family of animals that includes domesticated dogs, foxes, wolves, jackals and coyotes.
By analyzing the DNA in several ways, the researchers found that “Altai dog” is more closely related to domesticated dogs than to wolves, making it one of human’s earliest best friends.
The results were published Mar. 6 in the open-access journal PLoS One.
This specimen is the second-oldest domesticated dog fossil found, to date. The oldest, the Goyet dog, is from 36,000 years ago.
The exact date that dogs split off from their wolf ancestors and started spending more time with humans is unknown. Some scientists estimate this occurred in the Late Pleistocene—some 100,000 years ago. The fossils that are most clearly domesticated dogs, however, are only from around 14,000 years ago—well before the start of agriculture, but several thousand years after “Altai dog.”
It’s unlikely that dogs were rapidly domesticated from wolves.
“The wolves were not deliberately domesticated, the process of making a wolf into a dog was a natural process,” Dr. Susan Crockford of Pacific Identifications, Canada, one of the authors of the study from last year, told the BBC.
Wild wolves were likely attracted to people by the scraps of food left behind. Over time, the early dogs became more integrated into the human society.
In addition to clarifying the canine family tree, the analysis of the new fossil may shed some light on where domesticated dogs first started hanging around humans.
“These results suggest a more ancient history of the dog outside the Middle East or East Asia, previously thought to be the centers where dogs originated,” said Ms. Druzhkova.
Like domestication, which was gradual process, further details of the murky history of dogs awaits the discovery of more ancient dog-like remains.
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Reference: Druzhkova, A., Thalmann, O., Trifonov, V., Leonard, J., Vorobieva, N., Ovodov, N., Graphodatsky, A., & Wayne, R. (2013). Ancient DNA Analysis Affirms the Canid from Altai as a Primitive Dog PLoS ONE, 8 (3) DOI: 10.1371/journal.pone.0057754
Photos:
- Altai dog skull: 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
- Altai Mountains map: 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
