Human history is that of dogs. The largest ever research into the ancient genome of animals showed that where humans went, so did their four-legged friends ̵1; to one point. The study also identified large regional changes in human ancestry that left little mark on the dog population, as well as the time when the dog was changed, but not the owner.
Analysis of more than two dozen Eurasian dogs also revealed that these animals were domesticated and became popular around the world before 11,000 years ago. But it does not make any claims as to when or where wolf domestication took place, a problem that has upset researchers and has at times caused heated debate.
“Dogs are a unique marker for human history,” said Pontus Skoglund, a population geneticist at the Francis Crick Institute in London who co-led the study. Sciencefirst. “Sometimes human DNA might not show up parts of prehistoric times that we could see with the dog genome.”
Until a few years ago, the genetic history of dogs was mainly told through the DNA of modern dogs. But this gave a messy picture, because much of the genetic diversity of early dogs was likely lost when modern breeds were established. The first studies of the ancient dog genome have hinted at past changes in the canine population. But with only six ancient dog or wolf genomes available to date, such conclusions are preliminary.
To expand the DNA of ancient dogs, Skoglund’s lab joined groups led by Greger Larson, an evolutionary geneticist at the University of Oxford, UK and archaeologist Ron Pinhasi at the University of Vienna, leader. Together, the teams have decoded 27 genomes of ancient dogs. Models come from Europe, the Middle East and Siberia, and are between 11,000 and 100 years old.
By modeling relationships in and between ancient and modern dog groups, researchers have determined that a 10,900 year old dog from Russia is distinct from European, Middle Eastern, and Siberian dogs. or later ancient America, as well as being characterized by a line of dogs by modern New Guinea singing dogs (a reference to the Australian dingo dog). “It was 11,000 years ago, there were at least five different groups of dogs around the world, so the breed’s origins were essentially earlier,” Skoglund said.
With so many genomes, researchers can track ancient dog populations as they moved and mingled, and compare these changes to changes in human populations. Sometimes the dog travels parallels the human. When Middle Eastern peasants began expanding into Europe 10,000 years ago, they brought dogs and animals – like their owners – mixed with the local population. Ancient Middle Eastern dogs that lived about 7,000 years ago were associated with modern dogs in sub-Saharan Africa, possibly related to human movements ‘back to Africa’ around the time there.
But the history of humans and dogs has not always been the same. An adult influx from the steppes of Russia and Ukraine 5,000 years ago led to a permanent change in the genetic makeup of Europeans, but not European dogs. The study also revealed that European dog ancestors have become less diverse over the past 4,000 years, a period when the thorough sampling of ancient human DNA was less controversial.
Angela Perri, an archaeologist at Durham University, UK, said the cause of this disconnection is a mystery. “Was it an introduction of something like an epidemic? Favorite culture? Get rid of the old to get the new one? She wondered. “These may be cultural questions that DNA cannot answer.”
“Dogs can start exploiting humans because they are a useful resource to keep them alive,” said Elinor Karlsson, an evolutionary geneticist at the University of Massachusetts School of Medicine in Worcester. Dogs can move freely, follow people or move between groups when it suits their preferences.
Evolutionary biologist Robert Wayne at the University of California, Los Angeles, sees the large-scale analysis of the ancient dog genome as a big step forward. Efforts to clearly identify the source of domestic dogs will need to take the same approach, he added. “It only requires complete sampling of wolves and dogs throughout dog domestication history.”
“Without the large numbers of older dog and wolf genomes,” it was difficult to know that early world conquest, “Skoglund said.