Dogs became self-domesticated as they slowly evolved from wolves who joined humans in the hunt, according to the first study of dog genomes. And it shows that the first domesticated dogs came about 33,000 years ago and migrated to Europe, rather than descending from domesticated European wolves 10,000 years ago as had previously been thought.
     Scientists have long puzzled over how man's best friend came into existence but there is conflicting evidence on when and where wild wolves were first tamed. So in one of the largest studies of its kind Professor Peter Savolainen and colleagues sequenced the genomes of 58 members of the dog family including grey wolves, dogs from south-east and north-east Asia, from Nigeria, and a collection of breeds from the rest of the world.
     The DNA analysis found those from south-east Asia had a higher degree of genetic diversity, and were most closely related to grey wolves from which domestic dogs evolved.
Prof Savolainen, of the Royal Institute of Technology, Solna, Sweden, said this indicates "an ancient origin of domestic dogs in southern East Asia 33,000 years ago."
     Prof Savolainen said: "The mild population bottleneck in dogs suggests dog domestication may have been a long process that started from a group of wolves that became loosely associated and scavenged with humans, before experiencing waves of selection for phenotypes (mutations) that gradually favoured stronger bonding with humans, a process called self-domestication."
     The history of dogs may involve three major stages including loosely engaged pre-domesticated scavengers, domesticated non-breed dogs with close human-dog interactions, and breed formation following intense human selection for diverse sets of traits.
     The researchers said around 15,000 years ago, a subset of ancestors began migrating towards the Middle East and Africa, reaching Europe around 10,000 years ago. Although this dispersal is believed to have been associated with the movement of humans, the first movement of man's best friend out of south-east Asia may have been self-initiated. This may have been owing to environmental factors, such as the retreat of glaciers, which started about 19,000 years ago.
     Despite many efforts studying dog evolution, several basic aspects about the origin and evolution of the domestic dog are still in dispute including several different geographical regions as the proposed birthplace of domestic dogs, and estimations of the date of divergence between wolves and dogs of between 32,000 and 10,000 years ago. Prof Savolainen said: "Our study, for the first time, reveals the extraordinary journey the domestic dog has travelled on this planet during the past 33,000 years."
     Earlier studies have suggested wolves may have been domesticated by the first farmers about 10,000 years ago in the Middle East or Asia, possibly to guard livestock.
But the latest study has found it began much earlier, long before the development of agriculture.

Edited from The Telegraph (15 December 2015)