The discovery of the oldest ever dog DNA suggests they have been our best friends for nearly 16,000 years -- 5,000 years earlier than had previously been thought, new research said Wednesday.

Despite being ubiquitous in the homes, backyards and hearts of people across the world, surprisingly little is known about where dogs come from.

“It’s just an interesting mystery,” Swedish geneticist Pontus Skoglund of the UK’s Francis Crick Institute told reporters.

Dogs are most likely a mix of two types of grey wolves, he said. However exactly when dogs diverged from wolves has been difficult to trace, partly because their ancient bones are tricky to tell apart.

That is why scientists behind two new studies published in the journal Nature sequenced the genomes from archaeological remains, shedding light on the elusive origins of our furry friends.

The first study revealed that the world’s oldest canine DNA was discovered in a piece of a skull in Pinarbasi in what is now Turkey.

The female puppy, which was perhaps “a few months old”, probably looked like a small wolf when it lived roughly 15,800 years ago, according to study co-author Laurent Frantz of the Ludwig Maximilian University of Munich.

Before Wednesday, the oldest-known dog DNA was from 10,900 years ago.