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When were dogs domesticated? A new DNA study comes closer to unraveling the mystery.
A young gray wolf along the Columbia River in British Columbia, Canada. Image source: wisen007/Getty Images
Where did our ancestors first domesticate dogs? When was it domesticated? is one of the most puzzling unanswered questions in human history.
We know that modern dog breeds originated from gray wolves (Canis lupus) and were domesticated during the last Ice Age (at least 15,000 years ago).
But exactly, and whether it's in one place or multiple places, remains uncertain.
In a new study published in the journal Nature, researchers used ancient wolf DNA to delve further into dog evolution and found that their ancestry can be traced back to two different wolf groups. "With this project, we have significantly increased the number of ancient wolf genomes sequenced, allowing us to Includes the period in which dogs originated, with detailed descriptions of wolf ancestors.”
They found that dogs' ancestors descended from at least two separate wolf packs - one from the east that gave rise to all dogs, and one from the west.
Image credit: Bergström et al., 2022, DOI: 10.1038/s41586-022-04824-9
The sampling locations of ancient wolves and an ancient cave were analyzed on base maps from Natural Earth (naturalearthdata.com).
Two distinct ancient wolf groups
Gray wolves have existed throughout much of the Northern Hemisphere for the past hundreds of thousands of years. An international team of geneticists and archaeologists has sequenced the genomes of 72 ancient wolves excavated from Europe, Siberia, and North America.
They also used data from the genomes of 68 modern wolves, 169 modern and 33 ancient dogs, so the total data set spans the past 100,000 years.
By analyzing these genomes, the team found that early dogs in Siberia, the Americas, East Asia and Europe appeared to have a common origin from a wolf species in eastern Eurasia.
However, early dogs from the Middle East, , Africa and southern Europe appear to have (with the exception of the eastern Eurasian species) derived half of their ancestry from distinct populations related to modern southwestern Eurasian wolves.
So either wolves were domesticated more than once and the different populations subsequently mixed together, or they were domesticated only once (in the eastern Eurasian species) and these early dogs then mixed with wild wolves.
"Dogor," an 18,000-year-old wolf puppy from Yakutia, was included in the study. Image credit: Sergey Fedorov
Tracking natural selection
Because the 72 ancient wolf genomes studied spanned approximately 30,000 generations, it was also possible to look back and construct a timeline of how wolf DNA changed over time.
"This is the first time scientists have directly tracked natural selection in large animals over a 100,000-year time frame," said senior author Dr. Pontus Skoglund, group leader of the Ancient Genomics Laboratory at the Francis Crick Institute. See evolution happening in real time instead of trying to recreate it from today's DNA". The
research team found several cases of mutations spreading throughout the wolf species, which is possible because the species is highly connected over great distances.
This connection may be why wolves survived the Ice Age while many other large carnivores disappeared.
is a mutation in one gene in particular that was extremely rare in every wolf for about 10,000 years (30,000 to 40,000 years ago) and is still present in all wolves and dogs today.
These mutations affect a gene called IFT88 on chromosome 25, which is involved in the development of skills and jaw bones.
As part of the study, a genome with 12x coverage was sequenced from a 32,000-year-old wolf skull from Yakutia.Source: Love Dalén
The rapid spread of these mutations through populations may have been driven by changes in the types of prey available during the Ice Age, which gave wolves an advantage due to their head shape. But the gene may also have other, unknown functions in wolves.
The team is continuing the search for ancient wolf ancestors, dogs' closest relatives, hoping to more accurately reveal where domestication most likely occurred. It is now focusing on genomes from other places not included in this study, including regions further south.
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