| Arguing for evolution '11 |
| 1 | Copyright 2011 by Sehoya Cotner and Randy Moore Arguing for evolution : an encyclopedia for understanding science Introduction: Evolution as a Predictive Science "What insect could suck it?" These were the words Charles Darwin used when, in 1862, he was confronted with the Madagascan orchid, Angraecum sesquipedale. A specimen had been sent to Darwin by James Bateman, a British naturalist and botanical illustrator who was helping Darwin with his forthcoming manuscript, On the Various Contrivances by which British and Foreign Orchids are Fertilised by Insects (1862). |
| 2 | The orchid amazed Darwin, largely because it possessed "a whip-like green nectary of astonishing length." Because the flower's nectar sat at the base of a foot-long spur, Darwin could not imagine what creature might be able to pollinate it. Yet based on his decades of observation, including his experiences on his famous voyage aboard HMS Beagle (1831-1836), Darwin was able to make a logical prediction: "In Madagascar there must be moths with proboscises capable of extension to a length of between ten and eleven inches!" Nobody had ever reported on such a creature; moreover, the same group of orchids had been used earlier by the Duke of Argyll to cite the existence of a creator. |
| 3 | Yet five years later, Darwin's correspondent—and co-discoverer of natural selection, Alfred Russel Wallace— refuted the Duke's claim, saying "that such a moth exists in Madagascar may be safely predicted; and naturalists who visit that island should search for it with as much confidence as astronomers searched for the planet Neptune, and they will be equally successful!" Sure enough, in 1903—21 years after Darwin's death —scientists reported the existence of a moth in Madagascar with a proboscis long enough to reach the unusual orchid's nectar. |
| 4 | The aptly named Xanthopan morgani praedicta is rare and nocturnal, thus explaining why it took decades to confirm its existence. Science, a process by which we interpret the natural world, involves making observations and testing predictions. Charles Darwin, best known for his contributions to evolutionary biology, made several predictions, such as the existence of the unusual orchid-pollinating moth in Madagascar. |
| 5 | For decades, this prediction was neither supported nor falsified. However, Darwin's claim was logical and theoretically possible to confirm, as are all scientific predictions. Although some of Darwin's predictions (e.g., his claims about inheritance) turned out to be wrong, his most famous prediction—namely, that evolution is driven by natural selection—was remarkably insightful. Darwin wasn't the first person to propose that evolution occurs, but he knew that such a claim "would be unsatisfactory until it could be shown how the innumerable species inhabiting this world have been modified so as to acquire that perfection of structure and coadaptation that most justly excites our admiration" (italics added). |
| 6 | Darwin described his 1859 masterpiece, On the Origin of Species, as "one long argument" detailing this mechanism with numerous specific examples and an outline for future discoveries. Darwin understood the value of testing predictions to the scientific process: "as modern geology has almost banished such views as the excavation of a great valley by a single diluvial wave, so will natural selection, if it be a true principle, banish the belief of the continued creation of new organic beings, or of any great and sudden modification in their structure." Darwin's proposed mechanism (i.e., natural selection—the principle "by which each slight variation, if useful, is preserved") has been repeatedly confirmed by evidence gathered from paleontology, biogeography, biochemistry, medicine, comparative anatomy, embryology, molecular biology, behavioral ecology, anthropology, and other scientific disciplines. |
| 7 | As American paleontologist Niles Eldredge noted, "Nothing that we have learned since Darwin has contravened Darwin's basic description of how natural selection works." In Arguing for Evolution, we discuss natural selection and associated predictions regarding evolution. To model evolution as "science in action," we have organized each chapter around a series of confirmed predictions arising from basic tenets of evolution, and loosely arranged by discipline (geology, paleontology, molecular biology, etc.). |
| 8 | Coverage Libraries, museums, hospitals, universities, and other institutions throughout the world are filled with books, journals, monographs, videos, and other materials that document the evidence for evolution. We cannot possibly include all of this evidence in a one-volume book such as Arguing for Evolution, but we have presented the basic lines of evidence for Darwin's great idea. Although Arguing for Evolution covers general information and iconic topics about evolution (e.g., Galapagos, Darwin's finches), we have also included numerous fresh examples that illustrate these basic principles. |
| 9 | Furthermore, we have dedicated entire chapters to topics that are often absent (or included parenthetically) in other treatments of evolution, such as coevolution, behavior, biogeography, and the age of Earth. For example, whereas many books simply declare Earth's age to be ~4.5 billion years, we discuss how scientists first came to know that Earth is old, and then how they determined that it is ~4.5 billion years old. |
| 10 | These arguments provide excellent examples of how to use an understanding of evolution to illustrate "science in action." They are also important for countering the claims of evolution's most vocal, persistent, and well-funded critics—the young-Earth creationists—who, as their name suggests, base their rejection of evolution, geology, physics, and other sciences on an age of Earth that they derive from their particular religious beliefs. |
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