Tag Archives: mitochondrial DNA

New twist in tale of dogs’ origins

The origin of dogs has inspired a lingering controversy in academia. Where and when did dogs first split off from wolves? One of the top dogs in this dispute, population genetics expert Peter Savolainen of Sweden’s KTH Royal Institute of Technology, isn’t about to roll over. He hopes his latest research will finally settle the matter.

Some researchers say canines first split off from wolves in the Middle East; others say it happened in Europe. But Savolainen has long held that dogs originated in South East Asia alone, and he says his team has compiled new evidence that confirms his earlier findings.

The study concludes that the split with wolves occurred about 33,000 years ago.

Savolainen’s earlier studies were based on analysis of mitochondrial DNA. But recently other researchers have used data from nuclear DNA to refute those findings, arguing that dogs originated in the Middle East, Central Asia or Europe.

But apparently, those researchers were thrown off the scent, according to Savolainen. The data they relied on did not include samples from South East Asia, he says. So if, as Savolainen says, dogs did indeed come from South East Asia, these studies would not have been able to detect it.

Photo by IStock

Photo by IStock

“Which is why we analysed the entire nuclear genome of a global sample collection from 46 dogs, which includes samples from southern China and South East Asia,” he says. “We then found out that dogs from South East Asia stand out from all other dog populations, because they have the highest genetic diversity and are genetically closest to the wolf.”

Savolainen says this provides strong evidence that the dog originated in South East Asia, which confirms his earlier studies of Mitochondrial DNA.

“We also found that the global dog population is based on two important events: the dog and wolf populations first began to split off about 33,000 years ago in South East Asia. The global spread of dogs followed about 18,000 years later.

He says one explanation for the split between dogs and wolves 33,000 years ago could be that the wolf population became divided and the south Chinese wolf developed into dogs. In that case, it is possible the global spread of dogs out of South East Asia is associated with domestication.

“The dog’s story thus appears to have begun 33,000 years ago, but the exact path to the fully-domesticated dogs that spread throughout the world 15,000 years ago is not yet clear,”

Savolainen, along with 14 other scientists, recently published the scientific article “Out of Southern East Asia: The Natural History of domestic dogs across the world.

Source:  AlphaGalileo media release

The migration of dogs in the Americas

A new study suggests that dogs may have first successfully migrated to the Americas only about 10,000 years ago, thousands of years after the first human migrants crossed a land bridge from Siberia to North America.

Photo by Angus McNab

Photo by Angus McNab

The study, which looked at the genetic characteristics of 84 individual dogs from more than a dozen sites in North and South America, is the largest analysis so far of ancient dogs in the Americas. The findings appear in the Journal of Human Evolution.

Unlike their wild wolf predecessors, ancient dogs learned to tolerate human company and generally benefitted from the association: they gained access to new food sources, enjoyed the safety of human encampments and, eventually, traveled the world with their two-legged masters. Dogs also were pressed into service as beasts of burden, and sometimes were served as food, particularly on special occasions.

Their 11,000- to 16,000-year association with humans makes dogs a promising subject for the study of ancient human behavior, including migratory behavior, said University of Illinois graduate student Kelsey Witt, who led the new analysis.

“Dogs are one of the earliest organisms to have migrated with humans to every continent, and I think that says a lot about the relationship dogs have had with humans,” Witt said. “They can be a powerful tool when you’re looking at how human populations have moved around over time.”

Human remains are not always available for study “because living populations who are very connected to their ancestors in some cases may be opposed to the destructive nature of genetic analysis,” Witt said. Analysis of ancient dog remains is often permitted when analysis of human remains is not, she said.

Previous studies of ancient dogs in the Americas focused on the dogs’ mitochondrial DNA, which is easier to obtain from ancient remains than nuclear DNA and, unlike nuclear DNA, is inherited only from the mother. This means mitochondrial DNA offers researchers “an unbroken line of inheritance back to the past,” Witt said.

The new study also focused on mitochondrial DNA, but included a much larger sample of dogs than had been analyzed before.

Source:  University of Illinois press release