One of the biggest unanswered questions about human prehistory is where dogs underwent domestication.
An international group of geneticists and archaeologists, including from Durham University, have moved a step closer to uncovering this mystery.
The team has found that the ancestry of dogs can be traced to at least two populations of ancient wolves, an eastern source that contributed to all dogs and a separate more westerly source, that contributed to some dogs.
We already know that dogs originated from the gray wolf, with this domestication occurring during the Ice Age, at least 15,000 years ago. But until now, where this happened, and if it occurred in one single location or in multiple places, was still unknown.
The researchers, from 38 institutions in 16 different countries, turned to ancient wolf genomes to better understand where the first dogs evolved from wolves.
They analysed 72 ancient wolf genomes, spanning the last 100,000 years, from Europe, Siberia and North America. The remains included a full, perfectly preserved head from a Siberian wolf that lived 32,000 years ago.
By analysing the genomes, the researchers found that both early and modern dogs are more genetically similar to ancient wolves in Asia than those in Europe, suggesting a domestication somewhere in the east. However, they also found evidence that two separate populations of wolves contributed DNA to dogs.
Early dogs from north-eastern Europe, Siberia and the Americas appear to have a single, shared origin from the eastern source. But early dogs from the Middle East, Africa and southern Europe appear to have some ancestry from another source related to wolves in the Middle East, in addition to the eastern source.
One possible explanation for this dual ancestry is that wolves underwent domestication more than once, with the different populations then mixing together. Another possibility is that domestication happened only once, and that the dual ancestry is due to these early dogs then mixing with wild wolves.
It is not currently possible to determine which of these two scenarios occurred so a few more pieces of the puzzle are in place but there are more to be found.