Dogs may be man's best friend, but science understands very little about their origin. The central question of where domesticated dogs came from "might not be as important as the origin of the universe," says James Gorman at the New York Times, but it "almost seems harder to answer." And a new study has only left evolutionary experts with even more questions. Here, a brief look at the great canine mystery:

What do we know?
The consensus is that dogs likely descended from wolves and were the first animals that humans domesticated. The first canine pets probably appeared in Asia or Africa (or both) sometime between 15,000 to 100,000 years ago. But exactly when, where, or how the animals became domesticated has been nearly impossible to pinpoint.

The confusion arises from "significant amounts of cross-breeding" in which dogs engaged over time, says lead author Dr. Greger Larson, an evolutionary biologist at Durham University in London. Modern dogs' genetic makeup is so cloudy and complex that biologists can only trace the origins of most breeds back 150 years or so. The 15,000 years before that are, according to Larson, a "big blurred mess." 

But weren't dogs bred by humans?
Yes. A few dog varieties were selectively bred by man to tackle certain jobs such as sniffing out game. In theory, this should make it easier to map where they came from, but our four-legged friends also traveled with us all over the world and often bred on their own. The result: Lots of dead ends on the genetic map; many older canine varieties have disappeared altogether. That said, biologists refer to up to fourteen breeds, including Akitas, Afghan hounds, Chinese Shar-Peis, Basenjis, and Salukis as "ancient dog breeds" because they can be traced back further, at least a few thousand years.

What were the new study's objectives?
Researchers sequenced genetic material from 1,375 dogs representing 35 breeds — including six ancient varieties — and 19 wolves to see if they could get a better idea of where domesticated dogs originated.

What did they find?
Experts thought the DNA of ancient breeds would trace back geographically to areas of the world where the oldest fossils and other archaeological remains of domestic dogs were found. They were wrong. After sequencing the genetic makeup of these ancient breeds, experts were "no closer to the first domestic dogs," says BBC News. Again, the culprit was cross-breeding.

Now what?
Humans have long buried their best friends, says Larson, and fossils dating back 15,000 years can have their DNA extracted and analyzed. "We're not a million miles away" from unraveling the mystery of dogs' origins, says Larson. "We're close."

Sources: BBC News, LiveScience, New York Times