Genomics researcher Anders Bergstrom and colleagues recently sequenced the genomes of 27 dogs from archeological sites scattered across Europe and Asia, between 4,000 and 11,000 years old. These genomes, along with those of modern dogs and wolves, show how dogs moved around the world with humans after their domestication.
All dogs in the study originated from the same common ancestor, but this initial dog population split into at least five branches as it expanded in different directions. As groups of people separate, migrate, and meet other groups, they lead their dogs. Dogs̵
“Understanding the history of dogs teaches us not only their history, but also our history,” Bergström of the Francis Creek Institute said in a statement.
We still don’t know who released the dogs
We still don’t know exactly when and where the first domestication of dogs took place; it already had a rather complicated history 11,000 years ago. But it seems to have happened only once. Ancient genomes suggest that all dogs have a common ancestor that they do not share with modern wolves. According to Bergstrom and his colleagues, this probably means that all dogs come from a group of wolves and that group has already disappeared.
Modern gray wolves do not appear to be very closely related to any of the ancient or modern dogs in the study. This suggests that since domestication has separated them, wolves have not contributed much DNA to canine bloodlines.
The oldest dog in the study lived with Mesolithic hunter-gatherers about 10,900 years ago in present-day Sweden. His DNA suggests that most of his ancestors are from the eastern branch of the dog family tree – the branch that gave rise to Siberian dogs, native North American dogs and even singing dogs from New Guinea and the Australian dingo.
But some of the dog’s ancestors also came from a branch that followed humans in the Levant and Southwest Asia. These pieces of DNA were probably taken as souvenirs when the dog’s ancestors met dogs from another population. In other words, 11,000 years ago, dogs had time to become a species, divide into separate populations as they moved away, and then meet again and exchange DNA.
You have dogs, you will travel
Bergstrom and his colleagues wanted to know how the history of the dog population ranks with that of humans. They compared their data from ancient dogs with what ancient people’s DNA tells us about how groups of people have migrated and interacted over the past 12,000 years. Not surprisingly, the timing of divisions, mergers, and movements mostly coincided. This suggests that as groups of people migrate, they take their dogs with them and the dogs become almost the same things that people did when they met new neighbors.
Ancient human DNA tells us that early farmers in present-day Turkey moved north and west to Europe about 8,000 years ago and it took only a few centuries to completely replace the populations of hunter-gatherers that were already there.
“It’s not clear how these movements came about – either because of illness, or because of violence, or because of some prejudiced marriage process – but what genetics shows unequivocally is that these changes have happened, and much more so. more dramatically than any archaeologist expected, ”Reich said in 2018.
And DNA from ancient European dogs tells us that many similar things have happened between the dogs of Neolithic newcomers and those (like the aforementioned 11,000-year-old Swedish dog) who have already been there. In general, dogs found at archeological sites in Northern and Western Europe have a more eastern origin and less Levantine origin than dogs found in the south and east – and vice versa.
Some dogs were on a very long occasion
The stories of dogs and humans coincide, at least in a broad sense. But Bergstrom and his colleagues found a few points where the history of dogs seemed “separate” from ours. These differences are probably the result of disease, trade, preferences for certain types of dogs or people who move to a new place without taking the dogs (which sounds awful, fair). These “separate” population stories can tell us about how dogs fit into ancient human societies.
Several thousand years after the Neolithic conquest of Europe, another group of people moved west from Central Asia. They probably brought in dogs like the 3,800-year-old animal recovered from an archeological site in the Russian steppes.
But while steppe herders added their DNA to the mix that makes up modern European populations, their dogs didn’t seem to mix much with native dogs. In China, meanwhile, the opposite has happened. Steppe pastoralists have expanded to the east, but modern humans in East Asia do not carry much of their DNA. However, modern East Asian dogs get a lot from their ancestors from dogs such as the 3,800-year-old dog Srubnaya.
“Maybe sometimes there is an element of chance in these processes, so if we can repeat the tape of human history many times, the result for dogs may not always be the same,” Bergstrom told Ars.
Old dogs and new genomes
Part of the reason why the earliest years of domestication of dogs are so fuzzy (I’m not sorry) is that the DNA of ancient dogs was quite scarce. Until a recent study, scientists had published only six prehistoric genomes of dogs and wolves. In case you maintain a result, we have sequenced more Neanderthal genomes than prehistoric canine genomes – so far, ie.
“Ancient DNA is still a young field, and for most animals, not much research has been done on whole genomes,” Bergstrom told Ars. International efforts by archaeologists and museum curators were needed to add him and his colleagues to 27 ancient canine genomes. Collaborators have found the remains of ancient dogs in museum and university collections and in lists of materials excavated at archeological sites.
According to Bergstrom, older canine genomes, along with more archaeological evidence of how dogs fit into ancient cultures and economies, could help us understand the origins of dogs and parts of our common history that seem to disagree.
Maybe one day we will even learn the answer to the most pressing question of all: “What is a good dog?”
Science, 2020 DOI: 10.1126 / science.aba9572 (For DOI).