Natural Selection – The Theory

Charles Darwin

Natural selection is the cornerstone of Charles Darwin‘s theory, remaining a guiding influence on the twenty-first-century evolution industry. Even NASA defines life as functioning through Darwin’s theory of evolution –

“Life is a self-sustaining chemical; system, capable of Darwinian evolution.”

Its popularity blossomed with its ease of understanding. As J. Arvid Agren, evolution biologist at Harvard University, in The Gene’s Eye View of Evolution, notes –

“What attracted me to biology was a fascination with the logic of the theory of evolution by natural selection. No other theory explains so much with so little.”

Natural selection is an intuitively logical explanation describing how evolution drives biology. Nature, however, can defy logic. The story of Darwin formulating the theory on Galapagos while observing and recording facts about the island’s finches is logical but not necessarily scientific.

However, Darwin never said he developed the theory during his five-year voyage on the H.M.S. Beagle. Two years would elapse before beginning his work on a theory. As Darwin explained in his diary –

“In July [1837] opened first note Book on ‘Transmutation of Species’— Had been greatly struck from about month of previous March —on the character of S. American fossils—& species on Galapagos Archipelago. These facts origin (especially latter) of all my views.”

Even then, the concept of natural selection was still a year away. While reading An Essay on the Principle of Population, written by Thomas Robert Malthus, an English political economist, Darwin explains his connection with natural selection in his Autobiography

“In October 1838 … I happened to read for amusement Malthus On Population and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation ofThomas Robert Malthus the habits of animals and plants, it at once struck me that under these circumstances, favorable variations would tend to be preserved, and unfavorable ones to be destroyed. The result of this would be the formation of new species. Here, then, I had, at last, got a theory by which to work; but I was so anxious to avoid prejudice that I determined not for some time to write even the briefest sketch of it. In June 1842, I first allowed myself the satisfaction of writing a very brief abstract of my theory in pencil in thirty-five pages.”

Inspired by reading Malthus (pictured right) without leaving the British Isles again, Darwin completed a 230-page “brief abstract” six years later in 1842. Writing a letter to his wife, Emma –

“I have just finished my sketch of my species theory. If, as I believe, that my theory is true in time & be accepted by even one competent judge, it will be a considerable step in science.”

Popularity

Friedrich EngelsDarwin’s theory resonated throughout the political spectrum. From the socialists, Friedrich Engels (pictured left) wrote in 1883 –

“As Darwin discovered the law of evolution in organic nature, so [Karl] Marx discovered the law of evolution in human history.”

Weighing in on the impact of Darwin, in 1909, eminent American philosopher John Dewey (pictured right) reasoned –John Dewey

“The greatest dissolvent in contemporary thought of old questions, the greatest precipitant of new methods, new intentions, new problems, is the one affected by the scientific revolution that found its climax in The Origin of Species.” 

At the turn of the century, steel tycoon Andrew Carnegie (pictured left) commented on the validity of Darwin’s theory –

“There is no more possibility of defeating the operation of these laws (natural selection) than there is of thwarting the laws of nature which determine the humidity of the atmosphere or the revolution of the Earth upon its axis.”

In the words of America’s legendary late evolutionary biologist Stephen J. Gould (pictured right) of Harvard UniversityStephen Jay Gould

“The essence of Darwinism lies in a single phrase: natural selection is the creative force of evolutionary change.”

Julian Huxley, the grandson of Darwin’s Bulldog, in Evolution, the Modern Synthesis (1948), envisioned natural selection’s “creative force” as –

“Philosophically upside down, with Natural Selection instead of a Divine Artificer as the Deus ex machine.”

Scientist’s View

Natural selection continues as the central tenet of evolutionary biology, at least philosophically. Most scientific organizations endorse the teaching of evolution, even though no organization has developed a scientific consensus on the mechanisms of evolution in the past 50 years.

The popularity of natural selection among nineteenth-century scientists was mixed. In the subsequent editions of the Origin of Species, Darwin addresses the concerns of his contemporary naturalists. While Darwin was awarded the Royal Medal in 1853 for his scientific achievements, after the publication of the Origin of Species, the Society never again recognized any of Darwin’s works.

In taking a different approach, Niles Eldredge (pictured right) of Columbia University, a longtime collaborator with Gould and curator of the American Museum of Natural History, views the role of natural selection more cautiously than his one-time colleague Stephen Gould –

“In the literal sense of the word, no doubt, natural selection is a false term.”

Twenty-first-century critics of natural selection are not in short supply, even among the likes of Richard Dawkins

“Natural selection works because it is a cumulative one-way street to improvement. It needs some luck to get started, and the ‘billions of planets’ anthropic principle grant it that luck.”

Five Pillars of Natural Selection

The five pillars of natural selection driving evolution are variation, inheritance, selection, adaptation, and time. And, the essential evidence for natural selection, according to Darwin, is “slight successive changes” that give rise to “innumerable” transitional links between all life forms. As Darwin argued in the Origin of Species

“By the theory of natural selection, all living species have been connected with the parent-species of each genus, by differences not greater than we see between the natural and domestic varieties of the same species at the present day; and these parent-species, now generally extinct, have in their turn been similarly connected with more ancient forms; and so on backward, always converging to the common ancestor of each great class. So that the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great. But assuredly, if this theory be true, such have lived upon the earth.”

Therefore, “inconceivably great” evidence of transitional links beginning with a common ancestor is essential to validate his theory. Examining and analyzing natural selection from different perspectives gives insights into the theory’s history, its role in nature and evolution since Darwin introduced the term, and what modern critics of natural selection say.

While Darwin’s early work won awards from the Royal Society, later the society never awarded any of his later works on evolution for good reasons – Darwin’s theory of evolution emerged from a philosophy, not based on the principles of the scientific method.

 


Theory of Natural Selection Links

Study different aspects of Darwin’s theory of natural selection with the following links –

 


Refer to the Glossary for the definition of the terms.

 

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