and modern dog genomes reconstructs the passages of history of the -

emerges from the map of the complex genetic history of dogs, reconstructed by a study published in “Science” by Anders Bergström and colleagues from a large international collaboration, who analyzed 27 genomic sequences of dogs dating back as far as 11,000 years ago and coming from all over Eurasia. The result is part of a debate that has been going on for years about some crucial stages in the evolution of the dog, which mainly concern its origin and its relationship with humans. It is known in fact that the dogs have evolved from an ancestral population of wolves that have domesticated themselves following the human populations of hunter-gatherers of Eurasia of the Paleolithic and nourishing of their remains. However, the exact chronology and geographical location where the phylogenetic branch of the dogs emerged remain very uncertain due to the lack of remains of the epoch. One help comes from genetic data, which trace the event back to a time between 25,000-40,000 years ago, prior to the domestication of cattle, pigs and sheep, which took place in different geographical areas independently from different populations of wild animals. For dogs, on the other hand, genomic analyses tell a different story: separation from an extinct wolf population would have occurred only once. important. This hypothesis, which has so far remained speculative, is confirmed by the results of Bergström and colleagues: over the last 11,000 years, the phylogenetic branches of dogs and wolves have remained largely separate, only occasionally cross-breeding, and have spread all over the world. The data from the study also show another important fact: over the last 10,000 years, different groups of dogs have crossed frequently with each other and in different regions, both in Eurasia and in the Americas, according to patterns that reproduce the ancient genetic reshuffles of human populations. Hence the idea that the opportunities for encounters between human populations favored the encounters between the populations of dogs that were following them. There are important exceptions, however, where dogs do not seem to have followed their masters faithfully: in areas of present-day Iran, for example, indigenous dogs have at some point been replaced by others from the Middle East, although human populations have remained the same. Further evidence of convergent evolution between humans and dogs comes from changes in the genes coding for the enzyme amylase, contained in saliva, which is used to break down the molecules of starch, contained in cereals. These changes are evident in the genome of humans over the last 7000 years, i.e. since the beginning of agriculture, as well as in the genome of dogs indicating that dog feeding habits have also changed accordingly. “The dog is the oldest domestic animal and has a very old relationship with humans: understanding their history means understanding ours too,” Bergström concluded.