Friends stick with each other and in the case of man's friend - the domesticated dog - this has been going around for 33,000 years. In the most comprehensive DNA study to date, international researchers were able to trace the ancestry of present-day canines to species domesticated by humans in Southeast Asia many years ago.

The roots and evolutionary changes involving the domesticated dog (Canis lupus familiaris) have long been controversial and remain unsolved. Disputes always seem to arise when discussions about the date, place and frequency of animal domestication are initiated.

In the new study, 58 canids were obtained from all around the world. Among the species collected include 11 primitive dogs from Southeast Asia, 12 gray wolves from Eurasia, four village dogs from Nigeria, 12 aboriginal dogs from Northeast Asia and 19 different dogs from across the Americas and Old World (Africa, Europe and Asia).

Analysis showed that dogs started to migrate out of East Asia and headed to Africa and Middle East 15,000 years ago. The canines reached Europe after 5,000 years.

What drove the move? The species itself.

"For some reason, dogs stayed around East Asia for a long time before their migration out of Asia," said senior author Ya-Ping Zhang from the Chinese Academy of Sciences Kunming Institute of Zoology. The team hypothesized that the cold weather may be a big factor that prevented the dogs from leaving Asia.

The researchers also found that the study dogs from Southeast Asia exhibited increased genetic diversity, suggesting the origin of the species. The said dogs were found to have a close relationship with gray wolves.

DNA study continues to be a choice modality for dog research because fossil quality of dogs in East Asia is poor. Due to the warm and humid weather, Zhang said the region is not conducive for fossil preservation.

Another discovery is that ancient dogs travel back and forth, just like humans. As per DNA analysis, the team found that the dogs that moved out of Southeast Asia went back to the continent, but it targeted northern China on its return. In the said region, the dogs interbred with the locals before it migrated to the Americas.

The 33,000-year-old dogs, which skulls were traced back in a cave in Altai Mountains in Siberia and in Belgium, were the most intriguing part of the research.

"This study opens many potential avenues for future," the authors wrote. For example, American colonization history and the rate of wolf-dog mixture in the Middle East and Africa is not yet clearly established. Obtaining samples from other parts of the world and employing genomic analysis will help experts have a better picture of worldwide dog migration.

The study was published in the journal Cell Research on Tuesday, December 15.

Photo: Jack Pease | Flickr

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Tags: Dogs DNA Canine