Dogs were domesticated between 20,000 and 40,000 years ago, scientists have said. Fresh research has narrowed down the timeline at which 'man's best friend' was first brought to heel. The latest discovery also contradicts a recent study that domestication happened separately in two different regions of the world.

Europe is perhaps the most important place to study for scientists seeking to understand the history and evolution of dogs. This is because most modern breeds appear to have mainly a European ancestry, and the oldest uncontested remains of modern dogs are found on the continent.

However, there has long been a debate between scientists about exactly when and where dogs were domesticated.

Indeed, while ancient mitochondrial DNA indicates that the centre of domestication was Europe, modern mitochondrial and genomic data suggests the phenomenon takes its roots from Asia and the Middle East. Researchers have tried to solve this puzzle for years, but they have so far reached conflicting results.

Last year, a study published in the journal Science suggested that humans domesticated dogs twice, on both sides of the 'Old World'. The scientists argued that two ancient and distinct populations of wolves may have been domesticated by men, in East Asia and Europe, at two different points in history.

But the question is far from being settled. The study now published in the journal Nature Communications contradicts these conclusions, showing a single origin of dog domestication.

Genomes of ancient dogs

The scientists sequenced the genomes of two dogs whose remains were discovered in Germany – one from the Early Neolithic (7,000 years old) and one from the End Neolithic (4,700 years old).

They compared them with a collection of 5,649 modern canids, including breed dogs, village dogs and wolves that had already had their genome sequenced, building an evolutionary tree to understand the relationship between ancient and modern dogs.

From these analyses, the scientists were able to reach a number of conclusions. First, they found that there was a genetic continuity between ancient and modern dogs, and no evidence that dogs in Europe were replaced by dogs from Asia during the Neolithic era, as had previously been discussed.

Their results also suggest that dogs were domesticated between 20,000 and 40,000 years ago. It is unlikely that domestication occurred separately twice in different places.

That being said, the genetic study of ancient and modern dog remains is just in its infancy and many more investigations will be needed to shed all the light on the issue of dog domestication.

"Genomic analysis of ancient samples is a relatively new field, we are just at the beginning. To settle the issue of when and where dogs were first domesticated, we would need older samples from other geographical regions," study first author Laura Botigué, from Stony Brook University (USA), told IBTimes UK.

"Most of the analyses that have been done up to now were based on modern samples but now almost everyone agrees that's not how we'll get a straight answer about the origins of domestication. We need older samples as well".

What is certain is that the debate will continue to find out more about the history of the relationship between men and their favourite pets, and that this research will likely continue to fascinate both scientists and members of the public.

"A lot of people can relate with this aspect of animal evolution as they have pets as well but most of all this kind of study is fascinating from an anthropological point of view to see how humans played a key role in the evolution of wolves into dogs as far back as 40,000 years ago, it's fascinating to learn more about this process,"Botigué said.