Irish scientists have discovered Siberian sled dogs have been helping humans survive for 9,500 years.
The work involving Trinity College Dublin will help unravel the mystery of where the domestic dog originates.
Sled dogs, such as huskies, Alsatians, Malamutes and the Greenland sled dog could just be man's most loyal and lasting friend.
Scientists at Trinity, the University of Copenhagen, University of Greenland and the Institute of Evolutionary Biology, Barcelona, have found the oldest dog genome and named it Zhokhov, after the Siberian island from where it originated.
Mikkel Sinding, from the Globe Institute and a Postdoctoral Fellow in Trinity's School of Genetics and Microbiology, said: "This emphasises that sledge dogs and Arctic people have worked and adapted together for more than 9,500 years."
Mr Sinding said the sled dogs "have adaptations that are probably linked to improved oxygen uptake, which makes sense in relation to sledding and gives the sledding tradition ancient roots".
"Based on that DNA we have sequenced the oldest complete dog genome to date and the results show an extremely early diversification of dogs into types as sledge dogs," he added.
Until now, it had been believed the 9,500-year-old Siberian dog was an ancient dog - one of the earliest domesticated canines.
But according to the new study, modern sled dogs such as the Siberian Husky share the major part of their genome with Zhokhov.
Mr Sinding said: "This means that modern sledge dogs and Zhokhov had the same common origin in Siberia more than 9,500 years ago. Until now, we have thought that sledge dogs were only 2,000-3,000 years old."
The modern sled dogs have more genetic overlap with other modern dog breeds than Zhokhov - but the studies do not show where or when this occurred.
Among modern sled dogs, the Greenland sled dog was highlighted as being closest to the original sled dog.