New genetics study reveals complex story

WASHINGTON: Much of the diversity of modern dog populations was present by the time the last Ice Age ended 11,000 years ago. A global study of ancient DNA found Thursday.

The paper, published in Science, showed how our dogs with their masters spread around the world, but also found fascinating periods when our shared history was decoupled.

A research team led by the Francis Crick Institute sequenced the genomes of 27 dogs, some of which lived nearly 11,000 years ago, in Europe, the Middle East and Siberia.

They found that by this point, long before any other animal was domesticated, there were at least five different types of dogs with different genetic ancestors.

Pontus Skoglund of Crick’s Ancient Genomics Laboratory, the chief author of the paper, said, “Some of the differences you see between dogs walking the street today date back to the Ice Age.

“At the end of this period, dogs were already common in the northern hemisphere.”

He added that this implies that diversity emerged much earlier, “a long time ago, during the Stone Age of the hunter-gatherer, the Paleolithic, long before agriculture”.

When and where dogs deviated from wolves for the first time is controversial – analyzes of genetic data show a window from around 25,000 to 40,000 years ago.

The new paper does not add to this angry debate, but does support the idea that, unlike other animals such as pigs, which appear to have been domesticated in multiple locations over time, there is a “single origin” from wolves to dogs .

The scientists found that all dogs likely share ancestry “from a single ancient, now-extinct wolf population,” with limited gene flow from wolves since domestication but significant gene flow from dog to wolf.

– – Convergent Evolution – –

By extracting and analyzing ancient DNA from skeletal material, the researchers were able to observe evolutionary changes as they occurred thousands of years ago.

For example, European dogs were very different about four or five thousand years ago and appeared to come from very different populations of dogs from the Middle East and Siberia. But over time, that diversity was lost.

“Although the European dogs we see today come in such an extraordinary variety of shapes and forms, genetically they are only derived from a very narrow subset of the diversity that previously existed,” said the newspaper’s lead author, Anders Bergstrom.

Evolutionary paths between our two species have at times followed similar paths.

For example, humans have more copies than chimpanzees of a gene that makes a digestive enzyme called salivary amylase, which helps us break down diets that are high in starch.

Likewise, the paper showed that early dogs carried additional copies of these genes when compared to wolves, and this trend only increased over time as their diet adapted to farm life.

This builds on previous research that found that sled dogs in the Arctic, like Inuits, developed similar metabolic pathways to enable them to process high-fat diets.

There were also periods when our history did not run parallel – for example, the loss of diversity that used to exist in dogs in early Europe was caused by the spread of individual invasive species, an event that was not reflected in human migrations.

The field of ancient DNA studies has revolutionized the study of our ancestors, and researchers are confident that dogs, our longest animal allies, can do the same.

“Understanding the history of dogs teaches us not only about their history, but also about our own history,” said Bergstrom.