A fan of pigeon breeding, Darwin used evidence from the human domestication of animals to support his theory of natural selection. For thousands of years humans have selectively bred animals and plants, favoring the tastiest, most colorful, woolliest, smartest, heartiest, or fastest running. Darwin called animal husbandry and agriculture "artificial selection" because of how well humans can mimic natural selection. As a result of artificial selection, new varieties and new species are created. Dogs in all their splendid variety are the product of artificial selection from an ancestral wolf species.
Humans do not necessarily select for the same traits that natural selection would favor. Survival can be enhanced by human intervention, so traits that would potentially be detrimental to the success of an organism in the wild are able to thrive. For example, seedless watermelons are unable to reproduce and some fancy dog breeds need frequent medical attention for their cute, yet health-threatening traits like too short legs and too short snouts.
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