Domestication pushed back | An archaeological dig in Siberia found a skull with characteristics of a dog from the last ice age
LINDELL BEACH, B.C. — A find deep in a Siberian mountain cave has pushed back the date for the domestication of dogs to 33,000 years ago.
It’s 19,000 years earlier than the previously accepted date of 14,000 years ago. Equally intriguing is that ancient dog remains of the same antiquity have also been found in a cave in Belgium.
The implications appear to be that dog domestication happened repeatedly at different times and in different geographic locations rather than happening as a single domestication event. The modern dog could therefore have multiple ancestors rather than a single common ancestor.
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“Both the Belgian find and the Siberian find are domesticated species based on morphological characteristics,” said Greg Hodgins, a Canadian research scientist with the University of Arizona’s Accelerator Mass Spectrometry Laboratory and co-author of the study, which was reported in the open access journal PLoS ONE.
“Essentially wolves have long, thin snouts and their teeth are not crowned, (but) domestication results in this shortening of the snout, widening of the jaws and crowning of the teeth.”
Hodgins said many artefacts were found in the cave between 1977 and 1991. The cave excavation was first done by Russian researcher Nikolai Ovodov in 1975, when the skull and both mandibles of a dog-like canid were found among the remains of foxes, cave hyenas, grey wolves, brown bears, ibex and hares deposited over thousands of years.
“(The excavation) was huge,” said Hodgins.
“Some 71,290 mammal bones (and bone fragments) came out of there. But the argument (being made) is that it was not fully a dog. It’s an incipient, on the way to becoming a dog. We go by the skull shape.”
Comparing this find to wolf skulls of the same time period showed the skull shape is between the two.
“This find pushes back the domestication event to before the last glacial period. It’s huge. That’s really one of the interesting things about it.”
The skull was extraordinarily well preserved. Hodgin’s lab used radiocarbon dating to set the date of the skull.
“The skull is about the size and shape of a modern male Samoyed dog except that it has much larger teeth,” said Susan Crockford, co-author of the study and researcher with Pacific Identifications Inc. of Victoria.
“We have no idea about the rest of the body. The large teeth are the characteristics that suggest that it was, at most, a wolf in the very early stages of domestication.”
At 33,000 years old, the Siberian skull predates a period of extreme cold known as the Last Glacial Maximum (LGM), which happened from 26,000 to 19,000 years ago. This was when the ice sheets of the last ice age reached their maximum extent before finally retreating.
They caused massive disruption of lifestyle patterns for humans and animals, forcing them to migrate or travel to find food, water and shelter. However, the Siberian cave where the skull was found was not occupied by humans before the LGM.
“There are lots of sites of similar age in the region, but the cave itself was not used for habitation,” said Crockford, who holds an adjunct faculty position in the University of Victoria’s anthropology and graduate studies departments.
“Animals (bears, hyenas, wolves) used it as a den and dragged their kills into it, and sometimes they died there, too.”
The concept of wolves and humans forming a bond leading to domestication so long ago might be more fanciful than accurate. Researchers agree wolves would have been drawn to human camps looking for remains of successful hunts, and there’s nothing to say that those Palaeolithic people didn’t eat wolves too, given the chance.
Wolves would most likely not have provided any guarding instinct, other than to guard their own food source.
“I don’t think that wolves or even dogs would have guarded or defended a human camp, not at the stage of domestication we’re talking about,” said Crockford.
She said it appears people had to become more mobile because the distribution and migration patterns of the animals they hunted changed and the conditions necessary for domestication were disrupted. As a result, it seems the incipient dogs reverted to the wild and they are not, apparently, an ancestor of the modern dog.
“In terms of human history, before the last glacial maximum, people were living with wolves and canid species in widely separated geographical areas in Euro-Asia, and have been living with them long enough that they were actually changing evolutionarily,” said Hodgins.
“Then climate change happened, human habitation patterns changed and those relationships with those particular lineages of animals apparently didn’t survive.”
The relationship between wolves, the earliest dogs, and humans is an enduring one shrouded in mystery. The discovery of the Siberian skull is starting to lift that veil of secrecy.
