Paleogenomics: Siberia's Ice Age "Puppies" Were Actually Extinct Wolves

In the vast, frozen expanse of Siberia, the ground holds secrets. For millennia, the permafrost has acted as a natural deep-freeze, preserving remnants of a long-lost world. Recently, this icy vault has yielded some of its most captivating treasures: remarkably well-preserved "puppies" from the Ice Age. These discoveries sparked a wave of excitement and speculation. Could these be the earliest ancestors of our beloved canine companions? The answer, unlocked by the revolutionary field of paleogenomics, was far more complex and intriguing than anyone had imagined.

A Glimpse into a Lost World

The story begins with a series of extraordinary finds. In 2011 and 2015, near the Siberian settlement of Tumat, mammoth ivory hunters stumbled upon the mummified remains of what appeared to be puppies. These were not mere skeletons; the permafrost had preserved their fur, teeth, and internal organs with incredible fidelity. One particularly famous specimen, discovered in 2018 and nicknamed "Dogor"—a Yakutian word for "friend"—was an 18,000-year-old male with intact whiskers and eyelashes.

The proximity of some of these finds to what appeared to be human-processed woolly mammoth bones fueled speculation that these could be among the earliest domesticated dogs. The timing was tantalizing. Scientists believe the genetic split between dogs and wolves occurred between 20,000 and 40,000 years ago, with the first definitive evidence of domesticated dogs appearing around 15,000 years ago. The Siberian "puppies" seemed to fit perfectly into this critical window of canid evolution.

The Power of Paleogenomics

To unravel the true identity of these ancient canines, scientists turned to paleogenomics—the study of ancient DNA. This cutting-edge field allows researchers to extract and sequence genetic material from long-dead organisms, offering a direct window into the past. By comparing the genomes of the Siberian specimens with those of modern wolves and dogs, scientists could determine their place in the canid family tree.

The initial results were puzzling. The DNA from Dogor, for example, couldn't be definitively identified as either dog or wolf. This ambiguity only deepened the mystery. Was Dogor a common ancestor to both, a so-called "missing link" in the story of dog domestication?

The Verdict: An Extinct Wolf Lineage

Further, more comprehensive genomic analyses of Dogor and the Tumat "puppies" finally delivered a verdict. These were not dogs, nor were they the direct ancestors of modern dog breeds. Instead, they belonged to a distinct, now-extinct population of Pleistocene wolves.

A 2022 study published in Nature analyzed the genomes of 72 ancient wolves from across Europe, Siberia, and North America, spanning the last 100,000 years. This extensive dataset revealed that while all modern dogs are more closely related to ancient wolves from eastern Eurasia than from Europe, none of the sequenced ancient wolf genomes, including Dogor's, were a direct match for the ancestors of dogs. This suggests that the wolf population that gave rise to our four-legged friends is still out there, waiting to be discovered in the vast genetic landscape of the past.

A Complex Family Tree

The findings from these Siberian wolves have added new layers to our understanding of dog domestication. It's now believed that dogs may have a dual ancestry, with two separate wolf populations contributing to their genetic makeup. Early dogs from northeastern Europe, Siberia, and the Americas seem to have a single origin from an eastern Eurasian wolf population. However, early dogs from the Near East and Africa appear to have up to half their ancestry from a different wolf population related to modern southwest Eurasian wolves.

This could mean that wolves were domesticated on more than one occasion, or that early dogs interbred with local wolf populations as they spread across the globe with their human companions.

Life and Death in the Ice Age

Beyond their evolutionary significance, the Siberian wolf cubs offer an unprecedented glimpse into life during the Pleistocene. Analysis of the stomach contents of the two Tumat cubs, who were determined to be female siblings from the same litter, revealed their last meal. Incredibly, they had dined on woolly rhinoceros. This was a surprising discovery, suggesting that these ancient wolves, even as cubs, were part of a pack capable of taking down such formidable prey.

The cubs, estimated to be only a few months old, were still nursing, as evidenced by chemical analysis of their teeth. They were found without any visible injuries, leading researchers to believe they were in their den when it collapsed, perhaps in a landslide, trapping them for millennia.

A Frozen Frontier of Discovery

The Siberian permafrost continues to be a treasure trove for scientists. As the climate changes and the permafrost thaws, more of these incredible time capsules are being revealed. Each new discovery, from a 57,000-year-old wolf pup named Zhùr found in the Yukon to the ongoing analysis of the Siberian specimens, adds another piece to the puzzle of our planet's past.