Evolution of the Dog

Genetic evidence indicates that your dog is a modified and first modification from wolf to dog took place in East Asia between 15,000 and 100,000 years ago. At some time in the distant past, three more genetic modifications took place, creating the groundwork for the variety of breeds we have today.

Until 1997, some scientists believed certain dogs were descended from jackals. In that year, an international team of scientists published the results of research into wolves, jackals, coyotes, and dogs. They studied genetic material called mitochondrial DNA.

Mitochondria are structures within cells, the DNA of which comes entirely from the mother. The line of descent is female to female. Over time, mutations are inevitable. The mutations produce diverging lines of mitochondrial DNA, but they remain constant, giving a unique signature to a line of descent.

The scientists learned that all dogs share their mitochondrial DNA with wolves. There is a direct line of descent. None shared its mitochondrial DNA with jackals or coyotes. Further investigation revealed that three out of four modern dogs share their mitochondrial DNA with a single female wolf’s ancestor. In other words, three quarters of all dogs today descend from one family of wolves. The remaining one in four shares its mitochondrial DNA with three other wolf ancestors. This means that there was probably one defining genetic event in which the wolf adapted to life in cohabitation with humans and became the “dog”.

Later on, but still in ancient times, other wolves mated with these “dogs” on three other occasions, leading to the three minor lines of descent.

Variety of wolves:
Today, when we think of wolves, we usually think of majestic North American timber-wolf packs or of the more independent European gray wolf. But there are many “breeds” of wolf that once existed or still exist today. In North America alone there were once more than 20 different wolf breeds. Some were massive – up to 135lb (60kg) in weight – and have been hunted to extinction within the last 100 years. In Asia, wolves were much smaller, with the Japanese wolf, or shamanu, about the size of a Springer spaniel.

The wolves that dogs evolved from have also evolved, but you can readily see the ancestry of the Asian pariah dogs in Asian and Indian wolves and the Nordic spitz breeds in the European and North American wolves. Evolution can occur surprisingly swiftly, and by 12,000 years ago, the ancestors of all modern breeds already existed.

The dog’s domestication
It seems reasonable to assume that primitive dogs, physically identical to wolves, formed a loose, scavenging association with ancient humans. However, this is only an assumption, since their fossils cannot be differentiated from wolf fossils. There are certainly wolf bones found with human fossils dating back ten of thousands of years, but were these wolves prey or primitive companions?

In parts of Asia, and even in Europe, archaeological sites predating the development of agriculture have yielded recognizable dog bones alongside human bones. Researches at the British Museum have confirmed that a jaw bone found in a cave in Iraq occupied by people 14000 years ago was that of an equally ancient domesticated dog, Israeli archaeologists discovered a 12,500-year-old human grave in which a dog pup was held in seemingly warm embrace by its female owner. In Spain, an even older burial site was excavated, revealing the skeleton of a girl. Around the girl, facing in four directions, were four dogs. Firm archaeological evidence reveals that humans and “proto-dogs” (primitive dogs) had formed a relationship well before our ancestors settled into permanent agricultural sites.

When our ancestors became agricultural and first settled into permanent villages, the wolf-dog came under new, unique pressures, and this is when is shape dramatically changed, leaving the first extensive fossil evidence of the modern dog: a smaller brain cavity, more compacted teeth, a smaller body. Within a short time, the shape of the dog evolved enormously. Archaeological evidence, as well as bas-relief carvings, shows that sight hounds ancestors of the modern Afghan, saluki, and greyhound, existed in Mesopotamia 6000-7000 years ago. More than 5000 years ago, guarding dogs ancestors of Rottweiler’s and bulldogs, existed in Tibet; small-eared, densely coated Nordic dogs, ancestors of the modern spitzes, existed in Siberia and northern Europe; while miniature dogs, ancestors of the pug, the Pekingese, and the Maltese, existed in China and Egypt.

Pottery and bas-reliefs show that herding dogs, not unlike the modern Canaan dog, were used in Israel around 4200 years ago. By 3200 years ago, short-legged herding dogs existed as far away Wales. Paintings and tapestries show that scent hounds, their bodies covered in short thin hair suited to warm weather, the ancestors of the modern basset hound and dachshund, were evident in Italy 1700 years ago. Water spaniels and retrievers made their appearance in Europe 1300 years ago, and terriers only 100 years later. Throughout the world, the dog’s relationship with us was varied and evolving – and getting ever closer.

Learning centers in the brain
Dogs have been bred for many utilitarian reasons: to guard, attack, herd, chase, fight, kill, follow scent trails, point, set, retrieve, pull carts and sleds, turn spits, and simply to comfort. They are capable of such varied tasks because their minds are flexible. They inherited from the wolf a selection of hardwired biological “learning centers” in their brains, related to abilities the wolf needed to survive and breed.

Through selective breeding, we have enhanced some of these learning centers and diminished others.

One of the factors that differentiate a dog’s learning capabilities from ours is the influence of culture. In humans, behavior spreads from person to person; this is the basis of our religious beliefs, our fashion sense, even our food preferences. Not so in the dog. Other than in puppyhood, dogs are relatively poor learners from the “culture” of other dogs. In that sense there are limited cultural influences on their behavior. Your dog’s ability to think and to communicate with you is based on the array of abilities it inherited from the wolf.

Among others, I believe dogs have learning centers for the following abilities:
·         The value of relationships, both dominance and kinship: “I’ll let my pup do that to me, but I won’t let anyone else”

·         The need and ability to mate: “I know who is who and which end is which.”

·         Knowledge of motion and forces; understanding mechanics: “that branch is going to fall on me.”
·         A capacity to map large territories mentally: “I can find my way home.”

·         Choosing where to live, both for safety and for productivity: “under that table looks perfect for me.”

·         The intuition to patrol, investigate, and make territory: “I need to check out what passed this way yesterday.”

·         An understanding of danger and how to be cautious: “Is it safe to walk that narrow path?”
·         An ability to know what should and should not be eaten:”I’ll chase the small one but not the big one.”

Efficiency of “Wiring”:
All dogs inherit hardwired modules for these specific types of behavior, but in some breeds, modules for certain behaviors are more efficiently wired than for others. That is why Yorkshire terriers are picky eaters, while Labradors eat anything, and why dachshunds bark when they are looked at, but beagles do not seem to notice even a dominant stare. When you try to understand what your dog is telling you, remember: its abilities to learn and communicate are those of the wolf. Your canine friend is not just a human in disguise.

Breed evolution
The greatest genetic diversity among dogs exists in East Asia, and this is the strongest evidence for their geographical origins. Genetic research, studying what scientists call Microsatellites is snippets of DNA with known locations on the chromosome. Microsatellite DNA sequences are shared among closely related individuals. Geneticists studied 85 dog breeds and observed that they all fit into one of four different clusters of related breeds. Of these four clusters, three have relatively recent origins, evolving within the last 200-300 years. This indicates to us that most breeds of dog are, in face, modern. The dogs in these three categories appear to have been bred for use by humans in guarding, hunting, and herding.

Pet dogs are “domesticated” in the sense that they have successfully acclimatized to life on our terms. But what makes them so willing to do so?

An answer to this question comes from fascinating studies of another canine – the fox. In Britain over the last 20 years, the fox has successfully acclimatized to living in a densely populated human environment, and its “flight distance” – how likely it is so flee when being approached by something unfamiliar – has diminished.

In a selective – breeding program, within just ten generations, Russian biologist Dimitri Belyaev “domesticated” the red fox. He produced individuals that sought out human companionship, barked more, and often had drooping lop ears. In effect, he perpetuated the club in the fox. He produced individuals that were lifelong juveniles. That is exactly what we did with dogs, and it is what we treasure in their personalities. Dogs are forever youthful, always curious, and reliably responsive to their human “parents.”

“Intelligence” and “train-ability”
I hear it every day: “Isn’t she the most intelligent dog you’re ever seen?”, or “this it the most intelligent dog I’ve ever had.” I read about it as well. I doubt there is breed standard anywhere in the world that does not use the word “intelligent” in its description of that breed. But what does its corollary “dumb” mean?
I am going to avoid using the word “intelligent,” but it is still useful to try to understand what people mean when they use it. In essence, there are four different types of intelligence that we should think about when considering what our dogs are doing. These are skills and abilities that help a dog adapt to its environment, or alter its environment to make it better to live in.

Learning ability:
Generally speaking, dogs with good learning ability need only a few exposures to a situation in order to form stable responses. A perfect example is knowing exactly which cupboard their toys are kept in and coming running when it is opened.

Slightly different is the skill of problem-solving; the faster a dog solves a problem, with the fewest false starts, the better its problem – solving capacity. For example, if you place a food reward on the far side of a barrier and attach it to a sting running under the barrier and to the side where the dog is, how long does it take the dog to understand that if it pulls on the string, it gets the reward? Generally speaking and certainly compared to primates, dogs are not that good at mental problem – solving, but some are better than others, sheep – herding breeds such as the Border collie have been selectively bred for their problem – solving capabilities.

Communication intelligence:
Sometimes called obedience intelligence or working intelligence, communication intelligence is what helps the dog work with humans. A dog may have good problem – solving and learning abilities, but it also needs efficient communication skills to understand what we want it to do. It needs a willingness to take directions and not to be distracted. Dogs with longer attention spans and persistence are more capable of concentrating on a task. While learning ability and problem – solving help the dog act for itself, communication intelligence helps the dog interact with us.

Instinctive intelligence:
These are the forms of intelligence that are hardwired into the brain’s various learning centers. Through selective breeding, we enhanced some dogs’ inherited aptitudes and diminished others. Terriers are persistent diggers; toy dogs bark territorially; hounds howl to communicate; and retrievers retrieve.