Artificial Selection and Silver Foxes
In the 1950s, Dmitry Belyaev (Russian geneticist) and his team spent years breeding the silver fox (Vulpes vulpes) and selecting only those that showed the least fear of humans. After about ten generations of controlled breeding, the domesticated silver foxes no longer showed any fear of humans and often wagged their tails and licked their human caretakers to show affection. These silver foxes also started to have spotted coats, floppy ears, and curled tails.
As a result of domestication, the adrenaline levels of the domesticated foxes were significantly lower than normal. The presence of their multicolor coats is theorized by the scientists to be related to changes in melanin, which controls pigment production and shares a biochemical pathway with adrenaline. It could also be that it was a result of hormonal changes that occurred as the foxes became increasingly tame. The changes to the foxes’ coats as they became domesticated may have helped solve the biological riddle of how dogs evolved to have coats different from wolves.
The person interviewed in the video mentions that Darwin emphasized that evolution takes prolonged steps over many generations. This person in the video incorrectly mentions that Darwin was wrong because these foxes showed change in just two or three generations. This person should have noted that this change is due to artificial selection.
Darwin was well aware that rapid changes in appearance could appear in species, as he and other scientists of his day could see changes within a few generations with various breeds of dogs, and also artificial selection for various desired characteristics for flowering plants. This experiment does essentially the same thing. Early humans intuitively understood that more tame animals are more manageable so tended to select those animals for their usefulness. Natural selection, that is through nature and not man, generally works far more slowly, as those organisms best suited for a particular environment are more likely to survive and pass on their genes.
Watch the video and submit a note to the Discussion Forum:
1. What other evidence or examples of artificial selection is similar to the one described in this video?
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