Charles Darwin evidence | Charles Darwin's Theory of Evolution by natural selection

Charles Darwin evidence

Pigeons Prove a Point – DNA Evidence Supports Darwin's Theory

Pigeon SkullsIf you’ve read “On the Origin of Species”, you’ll know that Darwin had a thing for pigeons. The astonishing variety of breeds provided a perfect model organism for him to present his ideas on variation. Darwin (as well as most naturalists at the time) suspected that all breeds of domestic fancy pigeons were descendants of the rock dove (Columba livia). The degree of variation present between these breeds is so marked that Darwin suggests an ornithologist would believe them to be separate species: “Altogether at least a score of pigeons might be chosen, which if shown to an ornithologist, and he were told that they were wild birds, would certainly, I think, be ranked by him as well-defined species.”

Darwin’s studies on pigeons serve to illustrate the extent to which animals can be shaped by selection for a particular trait. Under domestic conditions we humans act as the selective pressure.Who wouldn't like one of these? est individuals. The offspring produced are likely to be large like their parents, as will the neighbouring plants with which they may breed, compounding the effect over generations.

An individual species can be shaped into countless forms, depending on the desired traits. All dogs, for example, are descended from grey wolves. Under domestication they performed different tasks and were selectively bred to improve their ability to perform those tasks. Greyhounds were bred for speed, Collies were bred for shepherding and Chihuahuas were bred primarily as a companion animal for mentally deficient socialites.

White English Trumpeter

Darwin believed that this observed variation would occur in nature as well, though the selective pressures would be very different. This subtle variation is well preserved in the evolutionary history of polar bears(Ursus maritimus), which are descended from brown bears(Ursus arctos). These bears likely evolved from populations of brown bears that became isolated by glaciation. The resultant morphological changes were “selected” by the environment in which the bears now had to live. The most obvious of these changes is the white coat, which would prove to be an obvious advantage to a predator trying to disguise itself in arctic conditions.

Back to the topic at hand; why have I been cooing (I know, I’m sorry) over pigeons? Well, as useful as the pigeon experiments were in showing how one ancestral form can give rise to countless new varieties, it did require its proponents to take something of a leap of faith when it came to the assumption that all breeds of fancy pigeon were descendants of the rock pigeon. Because Darwin didn’t have access to today’s technologies (not that he’d know what to do with them if he did), there has been very little genetic evidence to back up his assumptions. Until now…

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