The study ‘Origins and Genetic legacy of Prehistoric dogs’, published by the journal Science, reports on the work by the research team that sequenced the ancient DNA of 27 dogs, some of which lived until nearly 11,000 years ago in Europe, the Near East and Siberia. According to the data gathered, at that point in history, just after the Ice Age and before any other animal was domesticated, there were at least five different types of dogs with distinct genetic ancestries.

This finding shows that the diversity seen nowadays among dogs in different parts of the world originated when all humans were still hunters and gatherers. According to Pontus Skoglund, group leader of the Crick Ancient Genomics laboratory, “some of the variation that can be seen among the dogs walking down the streets today originated in the Ice Age. By the end of this period dogs were already widespread across the northern hemisphere”.

The study of ancient genomics involves extracting DNA from skeletal material and analysing it. It provides a window into the past allowing researchers to uncover evolutionary changes that occurred many thousands of years ago.

The research team has shown that these early dog lineages mixed and moved over the last 10,000 years to give rise to the dogs we know today. For example, early European dogs were initially diverse and appeared to come from two very different populations, one related to the dogs of the Near East and the other to Siberian dogs. However, at some point that diversity was lost because it is no longer present in European dogs.

As Anders Bergström, post-doctoral researcher at the Crick Ancient Genomics laboratory, pointed out, “if we look back more than four or five thousand years ago, we can see that Europe was a very diverse place when it came to dogs. Although the European dogs we see today come in such an extraordinary array of shapes and forms, genetically they derive from a very narrow subset of the diversity that used to exist”.

Parallel evolution

The researchers also compared the evolution in dog history with changes in human evolution, lifestyles and migrations. In many cases comparable changes took place, as humans would have taken their dogs with them as they migrated across the world.

But there are also cases in which human and dog histories do not relate to each other. For example, the loss of diversity that existed in dogs in early Europe was caused by the spread of a single dog ancestry that replaced other populations. This dramatic event is not reflected in human populations, and it remains to be determined what caused this change in European dog ancestry.

Greger Larson, Director of the Palaeogenomics and Bio-Archaeology Research Network at the University of Oxford, says: “Dogs are our oldest and closest animal partner. Using DNA from ancient dogs is showing us just how far back our shared history goes and will ultimately help us understand when and where this deep relationship began.”

Ron Pinhasi, leader of the group at the University of Vienna, says: "Just as ancient DNA has revolutionised the study of our own ancestors, it’s now starting to do the same for dogs and other domesticated animals. Studying our animal companions adds another layer to our understanding of human history.”

While this study provides major new insights into the early history of dog populations and their relationships with humans and each other, many questions still remain. In particular, research teams are still trying to uncover where and in which human cultural context dogs were first domesticated.

Contribution of the UPV/EHU

Aritza Villaluenga is an assistant lecturer in the Department of Geography, Prehistory and Archaeology at the UPV/EHU and a member of the Consolidated Research Group in Prehistory (IT-1223-19) on the Álava campus of the UPV/EHU.

Villaluenga has contributed towards the research by identifying canid remains from the Upper Palaeolithic found at archaeological sites in Gipuzkoa. A total of 32 exemplars, of which only one turned out to be a dog, while the rest could be wolves (Canis lupus) or dholes (Cuon alpinus). “This study has analysed the origin of the domestication of the dog (Canis familiaris),” he said. “This subject has been hotly debated and it is the first time that it has been considered on a global scale, including animals found in archaeological contexts 10,000 years ago in Asia, Africa, the Americas and Europe.”

The only animal that has been able to be included in the study comes from the Marizulo cave (Urnieta). The cave was excavated by J. M. Barandiaran between 1962 and 1967 and that excavation revealed a burial site in which the skeleton of a young man together with the skeleton of a dog and a lamb were found. This animal has been included in the current study revealing an age of 5,390±34 years BP (AMS C14 dating), in other words between 6,173 and 6,287 years before the present.

Genetically, this dog was of the type of dogs in the Neolithic, which had replaced the early dogs of the Palaeolithic and which, in turn, would end up being replaced by Bronze Age dogs, predecessors of current European dogs, including the Euskal Artzain Txakurra (Basque Sheep Dog).