In the mid-1800s, Charles Darwin published the origin of the species, which was a theory that plants and animals both evolved through what he coined as “natural selection.”
What this means is that each species has unique environmental challenges. And, the members of that species that are most able to adapt to and meet those challenges will be the ones most likely to survive and reproduce.
Now, although this theory was controversial at the time, it's become one of the best-substantiated theories in science today. The main idea behind evolution is that all life on earth is connected, related, and shares a common ancestor.
We’re all distant cousins here on Earth, and the diversity of life today is the product of what Darwin called natural selection. Which is often referred to as survival of the fittest. However, in this case, fittest refers not to physical fitness, but the ability to survive and reproduce in a changing and challenging world.
DNA & Mutations
Darwin didn't understand genetics back in his day. But, his observations proved true over time. So much so that over a century later, scientists found that the mechanism behind evolution is in the DNA.
DNA is a long sequence of similar units all strung together. The sequences of these units encode the instructions for turning genes on and off. Other parts of the DNA are genes that carry the instructions for making proteins to help build the organisms.
Genes encode different biological or behavioral traits, and these genes are passed down from parents to offspring. But, the genetic code or the DNA that's passed down from generation to generation can change. These random changes are called mutations.Mutations are essential to evolution. We can't evolve without change. If the mutation is unfavorable, then the animal with the mutation would most likely die.
But, if the mutationbenefits the animal, then that animal is very likely to reproduce and pass that favorable trait to its offspring. Eventually, that trait spreads through the population. While mutations are completely random, selection for them isn't. This process is called natural selection.
Recently, scientists discovered that dogs and cats share a common ancestor (along with bears and weasels), the Dormaalocyon. This creature was about a foot long, weighed about two pounds, and actually lived in trees. It is estimated that the Dormaalocyon lived roughly 55 to 66 million years ago. Which was right around the time dinosaurs became extinct.
Today's modern dogs evolved from a line of carnivorous or meat-eating mammals called canids,which are named for the shape of their teeth. And for millennia, several species evolved and became extinct. But, the first true dog,Leptocyon,appeared around 40 million years ago in North America.
Leptocyon’s descendant, Eucyon, lived when Eurasia was still attached to North America by the Bering Land Bridge. Populations of Eucyon evolved into the modern dog, genus canis. Although canines, including the first coyotes, continue to live in North America.
The first large wolves evolved in Eurasia and traveled back to North America and this included the now extinct Dire Wolf. The rise of human civilization marked the end of this era, and the first domestication of the gray wolf occurred somewhere in Europe or Asia anywhere from 15,000 to 30,000 years ago.
Most scientists today claim that the dog is a descendant of the gray wolf. However, some researchers at the University of Chicago believe that their genetic overlap is a result of breeding wolves and dogs together and that dogs and wolves evolved separately from a now extinct common ancestor.
The dogs we live with today have evolved slowly over millions of years. But, the rate of evolution has been sped up in the last few centuries, thanks to our human influence. This has changed many of the species on the planet, not the least of which is the dog.
The Relationship Between Man & Dog
The relationship between man and dog has forged some 30,000 years ago. The most widely held thought is that this early relationship was between man and wolf. However, there is some evidence that it may have actually been some form of wild dog that we domesticated, not the wolf.
It is not known why this relationship between man and dog was forged. But, it most likely had a lot to do with man's propensity for creating piles of garbage. It is very likely that wolves began rummaging around our trash heaps, and the friendliest and bravest wolves might have started to live with humans.
Early man probably welcomed these friendly few because wolves have traits that we would find useful. Even today, man uses the dog's superior sense of smell and vision to find food, and his speed to track and capture it.
Early dogs were also likely good alarm systems, warning early men if hostile strangers were approaching their camps. The wolves were likely just as happy with this new partnership because they were more likely to be guaranteed an easy meal and a safe home base. So this was likely a symbiotic and mutually beneficial living arrangement.
The merger between man and wolf would have happened in more regions than one. And, it's likely that man would have begun to put external pressure on their wolf companions by keeping the wolves who exhibited the traits that they liked, such as alarm barking or flushing prey. It is also likely that man culled the wolf population for those who exhibited unwanted behaviors such as aggression or lack of trainability.
The physical and behavioral traits that man began to select for would have varied with each population, the climate they lived in, and the type of hunting they preferred. With this, the wolf became domesticated. And, in all likelihood, eventually became the dog that we live with today.
While the behavior of those early wolves changed. The man couldn’t change which behaviors the dogs came programmed with. We had to work with the behaviors that were already innate to the wolf (example: wolves can chase and they could bark, heard, and carry things in their mouths). But, the man didn't teach the wolf to do these things. These behaviors were already innately programmed into the wolf.
However, man could select to make those traits stronger or weaker. An example would be allowing the dogs that were best at carrying to breed and cull the dogs that weren't good at carrying and strengthen that trait.
But, what man couldn't do, was teach the wolves to do something outside of their innate programming like building houses for example. This is because wolves do not carry the genetics for it. To summarize, man could strengthen and weaken certain behaviors. But, the dogs were still wolves. Albeit, with carefully selected behavior traits.
The man was also able to selectively breed their dogs for appearance. They could breed only for thick double coats. Or, they could select for a particular size of a dog or a particular color. But, they could only work with the colors and the recessive genes at the early dogs were already genetically programmed for (i.e. pink or green dogs were not possible because those colors were not already genetically there).
All of these changes in behavior and outward appearance influenced by man can happen in a very short period of time. An example of this is a Russian study on foxes titled Early Canid Domestication or the “Farm- Fox Experiment” where researchers selectively bred foxes for “tameness” over a 40 year period. The researchers in this study simply selected the friendliest foxes and bred them to other friendly foxes. As such, each generation became more friendly.
By the eighth to 10th generation, the researchers began to notice physical changes in the foxes even though they were only selecting for friendliness. The foxes had begun losing pigmentation, some developed star-shaped white spots on their face, floppy ears started to develop, and even rolled tails. After 15 to 20 generations, they began to see shorter tails/legs, changes to the shape of their skull, and underbites/overbites.
The foxes also began to reach sexual maturity much earlier than their wild counterparts and further puzzled the researchers when they began cycling twice a year like dogs. Interestingly, even though these foxes began cycling twice a year like dogs, they could not reproduce when they were bred in a heat that was outside of the usual time that foxes would become fertile in the wild.
Even though those changes and traits happen quickly through domestication, what did not change is the fact that they were still foxes. They sought out human companionship and acted very much like dogs. But, genetically, they were still foxes- not dogs. Their physiology was the same, their metabolic pathways were the same, their nutritional requirements were the same... They were still foxes.
Through the centuries, man has selected dogs for particular traits. But, those traits also need to be genetically present, or we cannot select for them. Through selective breeding, we have the ability to make spotted dogs or dogs with floppy ears because those traits are already in the genes.
However, we cannot make pink dogs or dogs with five legs because there's no pink or five-legged gene. We can't breed dogs that can drive cars, but we can breed dogs to exaggerate their existing behaviors or traits that they're genetically programmed for, such as flushing or retrieving. Meaning, we can only work with the genes that we have.
Nutrition & The Dogs Origin
It is important to remember this because when we discuss nutrition, we have to remember that genetically, the dog is still a wolf. Man cannot selectively breed dogs to become herbivores (like cows) or omnivores (like pigs). This is because dogs don't have the same digestive tract and metabolic pathways as those other animals.
Dogs have virtually the same digestive tract and metabolic pathways that their ancestors had 30,000 years ago and the same one the wolf's ancestors had millions of years ago.
And, because dogs completely lack the ability to breed with other animals, the dogs' physiology and anatomy will fundamentally remain the same for another several million years. We just can't change genetics to that degree, we can only manipulate existing genes and traits.
To that point, biologist Robert Wayne examined the DNA of seven breeds of dogs and 26 gray wolf populations from different locations around the world. He found that the genotype, or genetic identity, was identical with only one or two restriction sites.
Meaning that the modern dog’s entire DNA sequence differs from the wolf by only about 0.2%. Now, in comparison, the dog differs from the coyote by about 4%. Which, incidentally, is about the same percentage that separates man from chimpanzees.
Despite their appearance and diversity, dogs are still essentially wolves when you look under the hood. The expression of some of their genes and enzymes might have changed a bit, but it's probably a mistake to think that the dog or the dog's diet should be significantly different than the wolf.