Since more recent genetic studies suggest that the date of domestication occurred far earlier, a different theory has gained the support of many scientists. But, Hare notes, the physical changes that appeared in dogs over time, including splotchy coats, curly tails, and floppy ears, follow a pattern of a process known as self-domestication.
Friendliness somehow drives these physical changes, which can begin to appear as visible byproducts of this selection in only a few generations. The selection of social foxes also had the unintended consequence of making them look increasingly adorable—like dogs. But some would have been friendlier, which may have given them access to human hunter-gatherer foodstuffs.. We did not domesticate dogs. Dogs domesticated themselves.
A study last year provided some possible genetic support for this theory. Evolutionary biologist Bridgette von Holdt , of Princeton University, and colleagues suggest that hypersocial behavior may have linked our two species and zero in on a few genes that may drive that behavior. Interestingly, in humans genetic variation in the same stretch of DNA causes Williams-Beuren syndrome, a condition characterized by exceptionally trusting and friendly behaviors.
Mice also become more social if changes occur to these genes, previous studies have discovered. The results suggest that random variations to these genes, with others yet unknown, may have played a role in causing some dogs to first cozy up with humans. The physical differences between a basset hound and wolf are obvious, but dogs have also changed in ways that are more than skin or fur deep.
One recent study shows how by bonding with us and learning to work together with humans, dogs may have actually become worse at working together as a species. Their pack lifestyle and mentality appear to be reduced and is far less prevalent even in wild dogs than it is in wolves. But at the first sign of trouble, dogs do something different.
They look back to their human companion for help. This work hints that dogs may have lost some of their physical problem-solving abilities in favor of more social strategies, ones that rely on the unique sort of cooperation domesticated dogs have with humans. While a Russian Blue cat might not look too different from a Maine coon, a Chihuahua certainly looks very different from a Great Dane. It's not just about the different dog breeds classified by the American Kennel Club, but also about how far dogs go back.
Dogs were domesticated by humans over 19, years ago. Their relationship with their humans back then wasn't quite the same as it is now, but it shows just how far back the human and dog bond goes. Because of this bond and humans' attachment to dogs, the practice of breeding dogs grew increasingly popular. Humans realized just how much of a useful companion a dog could be, so dogs began to be bred for specific purposes. This is when we started getting dogs for herding, dogs for hunting, dogs for sporting, and more.
Dogs began to be bred for specific purposes that relied on their appearance, agility, size, form, and more. The vast physical differences are largely driven by relatively few loci regions in the genome.
These loci have a large phenotypic effect, leading to strong differentiation among breeds. This is particularly interesting for evolutionary biologists, and pinpointing such regions in the genome has for example recovered the genetic basis of size variation among dog breeds. We now also have an understanding of the mutations that control traits such as coat characteristics and ear floppiness.
So if breeds are that similar to one another in their genomes, how are the vast differences maintained? The obvious answer is the mating pattern we impose on our dogs — we keep breeds separate by preventing interbreeding between them. The fact humans keep them apart is crucial here. In both these cases there would be complete reproductive isolation between the two groups, whether they be humans and chimps, lions and tigers, or Labradors and poodles.
Yet two entirely different dogs will produce perfectly fertile offspring, and many modern breeds in fact originated in this way. Of course in some cases other factors might make mating very tricky.
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