From Pleistocene wolves to starch-tolerant companions worldwide
Dogs descend from wolves domesticated at least 14,000 years ago—before agriculture—and perhaps over 25,000 years back. Canis familiaris now numbers up to one billion worldwide. Selective breeding produced roughly 450 breeds with wildly divergent bodies yet shared senses and social bonds.
The oldest widely accepted dog was buried about 14,223 years ago at Bonn-Oberkassel in Germany, alongside a man and a woman, all three dusted with red hematite and covered with heavy basalt slabs. It had pulled through canine distemper as a puppy, which is hard to imagine without devoted human nursing, and at an age when it could have done no useful work. Genetic dating puts the parting of dog and wolf lines somewhere 27,000 to 40,000 years back, and DNA shows every dog descends from an extinct wolf population unlike any living one. A 2021 review proposed domestication in Siberia about 23,000 years ago, after which dogs followed people into the Americas and across Eurasia.
The partnership probably began with wolves scavenging camp refuse, neither helping nor harming people. A 2018 study found 429 genes separating dogs from wolves, many tied to the neural crest, which can bring tameness, smaller jaws and floppy ears, suggesting that early selection targeted behaviour. Linnaeus named the dog Canis familiaris in 1758, setting it apart from the wolf because of its upturned tail. Whether the dingo counts as a dog is politically charged in Australia, since wild-dog status eases culling to protect livestock while separate-species status supports conservation.
Around 450 official breeds exist, more than for any other mammal, most founded from a handful of animals in the last 200 years once Victorian breeders took charge. Their skulls, bodies and limbs vary more than across the entire carnivore order, from the Great Dane at up to 79 kilograms to the Chihuahua at as little as half a kilogram. Yet every healthy dog has the same number of bones apart from the tail, which usually holds 26 vertebrae, and a jaw of about 42 teeth with carnassials for shearing meat.
Dogs out-smell and out-hear people but see far less sharply, perhaps eight times worse, in a two-colour world of yellows, blues and greys, struggling to tell red from green. One study suggests they sense Earth's magnetic field, preferring to relieve themselves lined up north to south when it is calm. There are an estimated 700 million to 1 billion dogs; roughly three quarters live in developing countries, mostly as street or feral animals, while 34 to 40% of American households keep one.
Source: Dog
