Where did dogs come from? What was the original ancestor of the dog? When did the first domestication take place? Why did humankind domesticate the dog? What purpose did this domestication serve? How did dogs become one of the most popular animal companions of humankind?
The aforementioned questions are hardly new. A considerable number of studies have been conducted and published to explore the hypotheses and theories that could provide a concrete and clearer explanation concerning the origins of the domestic dog and the reason behind their domestication. However, the scientific community remains divided. This article provides a concise review of some literatures.
Ancestral origins of the domestic dog
Several studies provide distinctive conclusions regarding the ancestral origins of the domestic dog. However, there are more recent studies concluding that dogs did not directly emerge from modern wolves. Instead, dogs and wolves diverged from ancient wolf-like or canid species.
Adam H. Freedman et al studied dog and wolf genomes from broad regions in Eurasia thought to be centres of dog domestication. Their analysis revealed that dogs and wolves evolved from a common ancestor between 9,000 and 34,000 years ago.
The team of Freedman et al generated genome sequences from several canid species including three grey wolves each from China, Croatia, and Israel; the basenji dog breed that originated in central Africa and the dingo dog breed that originated from Australia; and a golden jackal that served as an outside group representing earlier divergence. The genomic analysis of this diverse group of canid species revealed that dogs and wolves diverged from a wolf-like or canid species that went extinct. Furthermore, the analysis also suggested that dog breeds are closely related to each other while the three wolves from China, Croatia, and Israel share closer genetic similarities than dogs.
It is worth mentioning that the analysis also suggested that the observed genetic overlap between modern dogs and wolves was a result of more recent interbreeding that transpired after dog domestication. In other words, the analysis revealed that dogs did not directly descend from a single group of wolves.
The study of Natia Kopaliani et al supports the conclusion of Freedman et al regarding the recent interbreeding between dogs and wolves. By examining maternal-inherited or mitochondrial DNA and microsatellite markers of 57 livestock guard dogs, 9 mongrel dogs, and 102 grey wolves in Georgia, the researchers found out that the interbreeding or hybridization between wolves and dogs has been a common occurrence in areas where dogs are used to guard large livestock. Furthermore, they also found out that about a third of the sampled dogs shared relatively recent maternal ancestry with local wolves and not with the wolves in the Far East, where some researchers believe dogs were first domesticated.
Although Freedman et al placed the first domestication of dog somewhere between 9,000 and 34,000 years, the study of Pontus Skoglund et al suggested that the close relationship between humans and dogs might go back 27,000 to 40,000 years ago. Nonetheless, their study still supports Freedman et al.
Skoglund et al performed a genomic analysis of an ancient Taimyr wolf bone fragment randomly found during an expedition to the Taimyr Peninsula in Siberia. They did not readily realize that the bone fragment came from a wolf. Regardless, they could also mistaken it as something that could belong to a modern wolf because wolf population is common in the area. However, a genomic analysis and a radiocarbon date revealed that the bone came from an ancient wolf-like or canid species that inhabited the Taimyr Peninsula.
Further results of the genomic analysis of Skoglund et al revealed that modern-day Siberian Huskies and Greenland sled dogs share an unusually large number of genes with the ancient Taimyr wolf. In addition, the study concluded that the ancient Taimyr wolf represents the most recent ancestors of modern wolves and dogs—thereby supporting the conclusion of Freedman et al that these two species diverged from one common ancestor while rejecting other conclusions from other studies suggesting that dogs directly emerged from modern wolves.
Reasons for the domestication of dogs
The studies of Freedman et al and Skoglund et al placed the emergence of the domestication of dog within a timeline that predates the rise of agriculture. Thus, these studies contradict that popular stories that early farmers adopted a number of docile wolves to assist in livestock and agriculture. In other words, dogs were domesticated probably during the time when humans still lived as hunters and gatherers.
Nevertheless, the historical relationship between humans and dogs are unique. When thinking of domestication, it is easy to gather the fact that humans domesticated animals including cows, sheep, and goats to promote and support food production through livestock and agriculture. In other words, the domestication of wild species was usually associated with the development of agriculture. The domestication of dogs is different. The study of Freedman et al suggested that the ancient canid species followed early hunter-gatherers as part of its natural instinct to exploit the carcasses left after human hunting and consumption. Note that large carnivores are naturally drawn toward these leftovers.
As these hunter-gatherers moved and migrated, so did the ancient canid species. The canids following the migratory patterns of these early human groups gave up their territoriality and were less likely to reproduce with resident territorial canids. Furthermore, these canids tracked human groups to a large degree and for a long period.
It is important to note that this emerging relationship between the ancient canid species and hunter-gatherers transpired simultaneous across Europe and Asia. A study by Nikolai D. Ovodov et al had been living long enough with humans across separated geographical regions in Eurasia. Throughout their emerging relationship with the hunter-gatherers, these canids were actually changing evolutionarily. Remember that the study of Freedman et al revealed that modern dogs did not directly descend from a single group of wolves.
These canids or ancient-wolf like and dog-like species eventually became domesticated. Possibly, the hunter-gatherers domesticated these animals for protection, companionship, and perhaps, for assisting with hunting. Nevertheless, the conclusions in the studies of Ovodov et al, as well as in the studies of Freedman et al and Skoglund et al suggested that dog is the oldest domesticated animal. The domestication of dogs was probably a gradual and evolving occurrence simply because the emerging and developing encounter between the ancient hunter-gatherers and the wolf-like or canid species dog ancestors was a product of the instinctive behaviour of the latter.
Further details of the study of Freedman et al are in the article “Genome sequencing highlights the dynamic early history of dogs” published in 2014 in the journal PLoS Genetics. Details of the study of Kopaliani et al are in the article “Gene flow between wolf and shepherd dog population in Georgia” published in 2014 in the Journal of Heredity. Details of the study of Skoglund et al are in the article “Ancient wolf genome reveals an early divergence of domestic dog ancestors and admixture into high-latitude Breeds” published in 2015 in the journal Current Biology.
Further details of the study of Ovodov et al are in the article “A 33,000-Year-Old Incipient Dog from the Altai Mountains of Siberia: Evidence of the Earliest Domestication Disrupted by the Last Glacial Maximum” published in 2011 in the journal PLoS Genetics.