Pigeons helped Darwin understand variation within a single species, said Lisa Thompson, exhibit developer for the Natural History Museum of Utah. "No other single species of bird shows as much diversity within that species as domesticated pigeons do," Thompson said.
Darwin studied the way pigeon breeders would choose certain desirable traits and mate pigeons with those traits — so future generations would develop those traits.
He saw that breeders were doing to pigeons what natural selection did to all species, said Donney Nicholson, a curation officer with the Natural History Museum in London, which is loaning the fantail pigeon specimen to the Utah museum.
"Darwin asked: If [a pigeon] can change by artificial means, can the environment do the same thing over a longer period of time?" Nicholson said.
Variation, Darwin found, is the key to natural selection. "Natural selection can't work unless there are individuals that have slightly different traits that convey some kind of adaptive advantage, and allows them to survive better than … other members of their species," Thompson said. "If all the members of a population had the exact same traits, if there were no variation, there would be nothing for natural selection to act upon, and there would be no change. Nothing would evolve. Everything would stay the same."
The "Pigeons" exhibit shows not only Darwin's specimen, but first editions of "On the Origin of Species" and "The Variation of Animals and Plants Under Domestication," an 1868 volume that included much of his research corroborating his earlier work.
Both books are on loan from the University of Utah's Marriott Library, which owns first-edition copies of all of Darwin's books, said Luise Poulton, managing curator of the Marriott Library's rare-books department.
The library acquired some of the Darwin books, Poulton said, at the request of Michael Shapiro, associate professor of biology at the University of Utah, who is leading research on pigeon genetics that follows in Darwin's footsteps.
The "Pigeons" exhibit is paired with a touring exhibit also opening Saturday, "Birds of Paradise: An Amazing Avian Evolution," created by National Geographic and The Cornell Lab of Ornithology. That exhibit includes examples of many tropical bird species from New Guinea, which demonstrate a type of evolution called "sexual selection" — variations that allow males to attract females.
"It's a type of evolution that puzzled Charles Darwin at first," Thompson said, noting that Darwin once wrote a letter to a colleague saying that "the sight of a peacock tail makes me sick."
"He couldn't explain through natural selection why in the world a peacock would have a tail like that," Thompson said. "It doesn't help you evade predators. It's obviously cumbersome and expensive to grow. But the advantage it does convey is that having the most attractive tail does get you the most mates."