Darwin And Dogs
Observing Darwin's postulate's with man's best friend
From the Shih-tzu to the Siberian Husky: Physical and psychological diversity in dogs
Around 145,000 years ago, there was a genetic split between the wolf, and the animal that was to become the dog. This rift is defining in both canine and human history, for, many scientists agree that dogs were an integral part of the evolution of homo sapiens sapiens. The genetic split from wolves to dogs was relatively fast, compared to our genetic development. This is due to the fact that, in addition to natural selection, human domestication played a role in canine evolution.
There is a lot of scientific debate concerning how to classify dogs. Should they be their own species? Or a sub-species of wolves? Does the term species even apply to them? For now, most agree that the best classification we can give them is that of Canis Lupus Familiaris, a direct acknowledgement of their ancestors, Canis Lupus.
Dogs are among the most physically diverse species in the planet, ranging incredibly in size, temperament, and physicality. There is a myriad of different dog breeds, demonstrating, to an extent, Darwin's first postulate: the variation of individual organisms within one species. But, this myriad of dog-breeds was greatly influenced by humans and our selective breeding, thus causing an interruption or acceleration to a natural process. But this doesn't mean Darwin's ideas can't be observed within dogs, on the contrary, they are evident in canine behaviour.
A Siberian Husky is more physically similar to the Grey Wolf than it is to the Shih-tzu, yet it behaves more like the small, flat-nosed dog than it does like its ancestor. Both the Husky and Shih-tzu engage in similar mating habits and socialise in much the same way, and, most importantly, both of them will seek human companionship and establish eye-contact with us as a way to communicate. The establishment of eye-contact between dog and human is a major point in our relationship with dogs. Unlike wolves, dogs use their gaze to point and communicate with us. So, despite the obvious physical differences between the Husky and Shih-tzu (differences which were inflated by us), both of them are without a doubt, dogs.
Toto is a shih-tzu, although physically he is much smaller than other dogs his breed. He also has a peculiar temperament.
Photo by me.
Chaplin used to be up for adoption in Huaperros, a local animal shelter. Last summer he was adopted by a family. He appears to be a brown lab, but is physically smaller than most brown labs.
Photo by me.
Copine is a Siberian Husky. But she is taller and larger than most females her breed.
Photo by me.
Photo by me.
Photo by me.
Dog Breeds, Traits and Heredity: Darwin's second postulate in the dog gene pool
Dog breeds are an interesting topic. The dog breed classification system is mostly designed by humans and has been tailored to fit our needs. Through selective breeding, we "designed" our ideal dogs for various activities, from the calm, herding sheep-dogs, to the easily stimulated beagle, ideal for tracking. The way we've tailored dogs demonstrates Darwin's second postulate: the idea of genetic inheritance. This concept governs dog breeding. In order for a dog to be considered part of a breed, he must be born from parents both of the same breed, if he isn't he is considered a mix. The physical traits of the breed, as well as some temperamental traits, are passed down through inheritance. That's why all Golden Retrievers look more or less the same, there is variation within them, but for the most part they are fairly large dogs with long fur ranging from golden-brown to light yellow.
We can better visualise this concept with mixed breed dogs. Let's look at Jupiter (pictured below), a dog who used to be up for adoption in Huaperros. Jupiter has no determined breed, but just by looking at him (his powerful jaw, wide chest and firm shoulders) we can assume that he probably has a pit-bull parent.
The Wolf-Dog Split Through Artificial Selection: Darwin's third and fourth postulates
A key idea is that humans greatly influenced canine evolution, therefore it is often difficult to differentiate our process from the natural one. Nonetheless, Darwin himself recognized that artificial selection parallels natural selection, and even used dog breeding to visualise his concepts. Thus, we can observe his last two ideas in the wolf-dog split.
Darwin's fourth postulate focuses on the idea of natural selection. Organisms with certain traits will survive more, or be able to breed more, than those without them. Early dog domestication is said to have paralleled the beginning of human agricultural society. This meant that the earliest proto-dogs were probably wolves who were comfortable enough with approaching human settlements in order to scavenge food. Crowded environments meant that these proto-dogs had to be less aggressive and territorial than their wolf counterparts. Thus, they had to posses certain genes that allowed for submissiveness and calmness. Recording of the dog genome has allowed scientists to observe what causes such variance between dog breeds, and what gene sequences are steady throughout all breeds. The common genes include those that code for the nervous system, essentially genes that code for temperament and sociability. This means that sometime during the proto-dog domestication period, the proto-dogs who were able to socialize the most and essentially adapt to a human-dominated environment, were those that were allowed to live with humans. Humans, of course, played a role into this selection, but this process, Darwin argues, occurs in nature without human intervention. The wolf-dog split is yet another case of a species adapting to the specifications of its environment.
Darwin's this postulate is deeply tied to the idea of selection. Not all organisms of a species survive long enough to breed, and who survives depends on who has certain traits. This essentially occurred in the proto-dog domestication process. The friendliest or more sociable of these creatures were allowed to live with humans and mate, those that were too aggressive were not allowed near human settlement and most likely returned to wolf packs.
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