Dog evolution

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The video “Dogs and More Dogs” presents one of the most perplexing questions in evolutionary biology: how did the diversity of dogs evolve from a relatively homogeneous population of wolves. Anthropological data suggests that dogs came into existence some fifteen thousand years ago. In terms of the history of earth and the majority of the organisms that inhibit it, dogs are still very young. It is thus very remarkable that one species (wolves), which must have looked somewhat alike, could have given rise to the huge differences we see between the Chihuahua and the Golden Retriever.
The narrator of the video proposed two hypotheses to explain this evolutionary diversification. The “adoption hypothesis” suggests that our human ancestors thousands of years ago came across an irresistible wolf pup, fell in love with it, and brought it home to raise as a pet. Through constant battles with the predatory instincts of wolves, our ancestors were able to artificially select for the tamest animal and eventually domesticate the wolves, which became the dogs.
On the other hand, the “leftover hypothesis” proposes that the domestication of wolves came about as a by-product of city development. When human settled down in villages, waste dumps would have inevitably appeared. This provided a new ecological niche for the wolves: scavengers in human waste. Tamer wolves that were not afraid of humans would be at an advantage in getting food from the dump. Animals that could take advantage of this resource would not need to hunt in the wild and thus have a better chance at survival. Over generations, natural selections would favor tameness and facilitate its spread through the scavenger wolf population. This then gave rise to dogs.
Whether dogs arose ...

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... Their results suggest that a few SNPs of dominant effect (2 to 6 in general) may account for large amounts of morphological differences in dog breeds (70%). This suggest that the evolution of dogs from wolves may be the result of a few very significant point mutations that swept across the population because they produced the traits desirable to humans.
In summary, while the video provides two possible and seemingly logical models for the evolution of dogs, it fails to account for the genetic basis of selection and other possible mechanisms of evolution. Further genomic studies are needed to better elucidate how dogs evolved.

Works Cited

Boyko, A. R., Quignon, P., Li, L., Schoenebeck, J. J., Degenhardt, J. D., Lohmueller, K. E., ... & Ostrander, E. A. (2010). A simple genetic architecture underlies morphological variation in dogs. PLoS biology, 8(8), e1000451.
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