<P> In 2016, a study compared the mitochondrial DNA and whole - genome sequences of a worldwide panel of modern dogs, the mDNA sequences of 59 ancient European dog specimens dated 14,000 - 3,000 YBP, and the nuclear genome sequence of a dog specimen that was found in the Late Neolithic passage grave at Newgrange, Ireland and radiocarbon dated at 4,800 YBP . A genetic analysis of the Newgrange dog showed that it was male, did not possess genetic variants associated with modern coat length nor color, was not as able to process starch as efficiently as modern dogs but more efficiently than wolves, and showed ancestry from a population of wolves that could not be found in other dogs nor wolves today . As the taxonomic classification of the "proto - dog" Paleolithic dogs as being either dogs or wolves remains controversial, they were excluded from the study . The phylogenetic tree generated from mDNA sequences found a deep division between the Sarloos wolfdog and all other dogs, indicating that breed's recent deriving from the German Shepherd and captive gray wolves . The next largest division was between Eastern Asian dogs and Western Eurasian (Europe and the Middle East) dogs that had occurred between 14,000 - 6,400 YBP, with the Newgrange dog clustering with the Western Eurasian dogs . The northern breed Greenland dog and the Siberian husky were poorly supported in the tree, possibly indicating mixed ancestry . (See also Taimyr wolf admixture) </P> <P> The Newgrange and ancient European dog mDNA sequences could be largely assigned to mDNA haplogroups C and D but modern European dog sequences could be largely assigned to mDNA haplogroups A and B, indicating a turnover of dogs in the past from a place other than Europe . As this split dates older than the Newgrange dog this suggests that the replacement was only partial . The analysis showed that most modern European dogs had undergone a population bottleneck which can be an indicator of travel . The archaeological record shows dog remains dating over 15,000 YBP in Western Eurasia, over 12,500 YBP in Eastern Eurasia, but none older than 8,000 YBP in Central Asia . The study proposed that dogs may have been domesticated separately in both Eastern and Western Eurasia from two genetically distinct and now extinct wolf populations . East Eurasian dogs then made their way with migrating people to Western Europe between 14,000 - 6,400 YBP where they partially replaced the dogs of Europe . Two domestication events in Western Eurasia and Eastern Eurasia has recently been found for the domestic pig . </P> <P> The hypothesis is that two genetically different, and possibly now extinct, wolf populations were domesticated independently in eastern and western Eurasia to produce paleolithic dogs . The eastern Eurasian dogs then dispersed westward alongside humans, reaching western Europe 6,400--14,000 years ago where they partially replaced the western paleolithic dogs . A single domestication is thought to be due to chance, however dual domestication on different sides of the world is unlikely to have happened randomly and it suggests that external factors - an environmental driver - may have forced wolves to work together with humans for survival . It is possible that wolves took advantage of resources that humans had, or humans may have been introduced to wolves in an area in which they didn't previously live . </P> <P> The study used the radiocarbon age of the Newgrange dog to calibrate the mutation rate for dogs, which was similar to that calculated for the Late Pleistocene Taimyr wolf . Comparing the sequence of the Newgrange dog using this mutation rate with two modern wolves from Russia gave a divergence time between 20,000 - 60,000 YBP . However, these two modern wolves may not have been closely related to the population that gave rise to the dog, which may have diverged from their ancestor at a later time . </P>

When did we start keeping dogs as pets