Dog History: How and Why Dogs were Domesticated

Recent Scientific Findings about our First Domesticate Partner

Variation on a Dog
Variation on a Dog. Michael Blann / Getty Images

The history of dog domestication is that of an ancient partnership between dogs (Canis lupus familiaris) and humans. That partnership was likely originally based on a human need for help with herding and hunting, for an early alarm system, and for a source of food in addition to the companionship many of us today know and love. In return, dogs received companionship, protection, shelter, and a reliable food source. But when this partnership first occurred is still under some debate.

Dog history has been studied recently using mitochondrial DNA (mtDNA), which suggests that wolves and dogs split into different species around 100,000 years ago. Although mtDNA analysis has shed some light on the domestication event(s) which may have occurred between 40,000 and 20,000 years ago, researchers are not agreed on the results. Some analyses suggest that the original domestication location of dog domestication was in East Asia; others that the middle east was the original location of domestication; and still others that a later domestication took place in Europe.

What the genetic data has shown to date is that the history of dogs is as intricate as that of the people they lived alongside, lending support to the long depth of the partnership, but complicating origin theories.

Two Domestications?

In 2016, a research team led by bioarchaeologist Greger Larson (Frantz et al. cited below) published mtDNA evidence for two places of origin for domestic dogs: one in Eastern Eurasia and one in Western Eurasia. According to that analysis, ancient Asian dogs originated from a domestication event from Asian wolves at least 12,500 years ago; while European Paleolithic dogs originated from an independent domestication event from European wolves at least 15,000 years ago. Then, says the report, at sometime before the Neolithic period (at least 6,400 years ago), Asian dogs were transported by humans to Europe where they displaced European Paleolithic dogs.

That would explain why earlier DNA studies reported that all modern dogs were descended from one domestication event, and also the existence of evidence of two domestication event from two different far-flung locations. There were two populations of dogs in the Paleolithic, goes the hypothesis, but one of them—the European Paleolithic dog—is now extinct. A lot of questions remain: there are no ancient American dogs included in most of the data, and Frantz et al. suggest that the two progenitor species were descended from the same initial wolf population and both are now extinct.

However, other scholars (Botigué and colleagues, cited below) have investigated and found evidence to support migration event(s) across the central Asia steppe region, but not for a complete replacement. They were unable to rule out Europe as the original domestication location.

The Data: Early Domesticated Dogs

The earliest confirmed domestic dog anywhere so far is from a burial site in Germany called Bonn-Oberkassel, which has joint human and dog interments dated to 14,000 years ago. The earliest confirmed domesticated dog in China was found in the early Neolithic (7000–5800 BCE) Jiahu site in Henan Province.

Evidence for co-existence of dogs and humans, but not necessarily domestication, comes from Upper Paleolithic sites in Europe. These hold evidence for dog interaction with humans and include Goyet Cave in Belgium, Chauvet cave in France, and Predmosti in the Czech Republic. European Mesolithic sites like Skateholm (5250–3700 BC) in Sweden have dog burials, proving the value of the furry beasts to hunter-gatherer settlements.

Danger Cave in Utah is currently the earliest case of dog burial in the Americas, at about 11,000 years ago, likely a descendant of Asian dogs. Continued interbreeding with wolves, a characteristic found throughout the life history of dogs everywhere, has apparently resulted in the hybrid black wolf found in the Americas. Black fur coloration is a dog characteristic, not originally found in wolves.

Dogs as Persons

Some studies of dog burials dated to the Late Mesolithic-Early Neolithic Kitoi period in the Cis-Baikal region of Siberia suggests that in some cases, dogs were awarded "person-hood" and treated equally to fellow humans. A dog burial at the Shamanaka site was a male, middle-aged dog which had suffered injuries to its spine, injuries from which it recovered. The burial, radiocarbon dated to ~6,200 years ago (cal BP), was interred in a formal cemetery, and in a similar manner to the humans within that cemetery. The dog may well have lived as a family member.

A wolf burial at the Lokomotiv-Raisovet cemetery (~7,300 cal BP) was also an older adult male. The wolf's diet (from stable isotope analysis) was made up of deer, not grain, and although its teeth were worn, there is no direct evidence that this wolf was part of the community. Nevertheless, it too was buried in a formal cemetery.

These burials are exceptions, but not that rare: there are others, but there is also is evidence that fisher-hunters in Baikal consumed dogs and wolves, as their burned and fragmented bones appear in refuse pits. Archaeologist Robert Losey and associates, who conducted this study, suggest that these are indications that Kitoi hunter-gatherers considered that at least these individual dogs were "persons".

Modern Breeds and Ancient Origins

Evidence for the appearance of breed variation is found in several European Upper Paleolithic sites. Medium-sized dogs (with wither heights between 45–60 cm) have been identified in Natufian sites in the Near East (Tell Mureybet in Syria, Hayonim Terrace and Ein Mallaha in Israel, and Pelagawra Cave in Iraq) dated to ~15,500-11,000 cal BP). Medium to large dogs (wither heights above 60 cm) have been identified in Germany (Kniegrotte), Russia (Eliseevichi I), and Ukraine (Mezin), ~17,000-13,000 cal BP). Small dogs (wither heights under 45 cm) have been identified in Germany (Oberkassel, Teufelsbrucke, and Oelknitz), Switzerland (Hauterive-Champreveyres), France (Saint-Thibaud-de-Couz, Pont d'Ambon) and Spain (Erralia) between ~15,000-12,300 cal BP. See the investigations by archaeologist Maud Pionnier-Capitan and associates for more information.

However, a recent study of pieces of DNA called SNPs (single-nucleotide polymorphism) which have been identified as markers for modern dog breeds and published in 2012 (Larson et al) comes to some surprising conclusions: that despite the clear evidence for marked size differentiation in very early dogs (e.g., small, medium and large dogs found at Svaerdborg), this has nothing to do with current dog breeds. The oldest modern dog breeds are no more than 500 years old, and most date only from ~150 years ago.

Theories of Modern Breed Origination

Scholars now agree that most of the dog breeds we see today are recent developments. However, the astounding variation in dogs is a relic of their ancient and varied domestication processes. Breeds vary in size from the one pound (.5 kilogram) "teacup poodles" to giant mastiffs weighing over 200 lbs (90 kg). In addition, breeds have different limb, body, and skull proportions, and they also vary in abilities, with some breeds developed with special skills such as herding, retrieving, scent detection, and guiding.

That may be because domestication occurred while humans were all hunter-gatherers at the time, leading extensively migrant lifeways. Dogs spread with them, and thus so for a while dog and human populations developed in geographic isolation for a time. Eventually, however, human population growth and trade networks meant people reconnected, and that, say scholars, led to the genetic admixture in the dog population. When dog breeds began to be actively developed about 500 years ago, they were created out of a fairly homogenous gene pool, from dogs with mixed genetic heritages which had been developed in widely disparate locations.

Since the creation of kennel clubs, breeding has been selective: but even that was disrupted by World Wars I and II, when breeding populations all over the world were decimated or went extinct. Dog breeders have since reestablished such breeds using a handful of individuals or combining similar breeds.

Sources:

Thanks to researchers Bonnie Shirley and Jeremiah Degenhardt for fruitful discussions about dogs and dog history. The scholarly work on dog domestication is quite voluminous; below are listed a few of the most recent studies.