Charles Darwin

Evolution
 

Charles Darwin

Related interest:
Origin of Species
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Tree of Life
 

Pictures of Charles DarwinCharles Robert Darwin (12 February 1809 to 19 April 1882) was a British naturalist who ranks among the most famous (and to some infamous) scientists in history. Remarkably, long before genetics and the copying mechanism of genetic material through DNA were understood, Charles Darwin’s concept of natural and sexual selection (or evolution) was mostly correct. Evolution endures as the organizing principle of all biological science.

Darwin’s interest in natural history arose as he studied medicine and theology at university. Darwin's five-year voyage on the Beagle and provided the empirical evidence for developing his theory of natural selection by 1838. Knowing that others had been severely punished for such "heretical" ideas, he only confided in his closest friends and continued his research. By 1858, however, knowing that Alfred Russel Wallace had developed a similar theory, he was finally forced to publish his controversial theory.

Darwin’s 1859 book On the Origin of Species by Means of Natural Selection, or The Preservation of Favoured Races in the Struggle for Life (usually shorteded to The Origin of Species) explicated how evolution by common descent explained the diversity he observed in nature.

Darwin believed that his theory had guided life and its diversity across geological time, and beautifully described the result as the Tree of Life:


Darwins first evolutionary tree "The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species . . . The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was small, budding twigs; and this connexion of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups . . . From the first growth of the tree, many a limb and branch has decayed and dropped off, and these lost branches of various sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known to us only from having been found in a fossil state . . . As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all a feebler branch, so by generation I believe it has been with the Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications" (Charles Darwin, 1859).

and:

From the first dawn of life, all organic beings are found to resemble each other in descending degrees, so they can be classed in groups under groups.

both from: Charles Darwin, Origin of Species, Chapter 13


Darwin's tangled bank quote is particularly notable because the environmental context of natural selection is emphasized (“widely-different checks act on the same species in different districts”). Chance is thus, not a factor.Tangled Bank

"In the case of every species, many different checks, acting at different periods of life, and during different seasons or years, probably come into play; some one check or some few being generally the most potent, but all concur in determining the average number or even the existence of the species. In some cases it can be shown that widely-different checks act on the same species in different districts. When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this! Every one has heard that when an American forest is cut down, a very different vegetation springs up; but it has been observed that ancient Indian ruins in the Southern United States, which must formerly have been cleared of trees, now display the same beautiful diversity and proportion of kinds as in the surrounding virgin forest. What a struggle must have gone on during long centuries between the several kinds of trees, each annually scattering its seeds by the thousand; what war between insect and insect - between insects, snails, and other animals with birds and beasts of prey - all striving to increase, all feeding on each other, or on the trees, their seeds and seedlings, or on the other plants which first clothed the ground and thus checked the growth of the trees! Throw up a handful of feathers, and all must fall to the ground according to definite laws; but how simple is the problem where each shall fall compared to that of the action and reaction of the innumerable plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on the old Indian ruins!"

Water-colour portrait of Charles Darwin painted by George Richmond in the late 1830sHere are a few more excerpts from Origin of Species, and other quotes of Charles Darwin:

"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science."

"In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment."

"Nothing before had ever made me thoroughly realise, though I had read various scientific books, that science consists in grouping facts so that general laws or conclusions may be drawn from them."

"But when on shore, & wandering in the sublime forests, surrounded by views more gorgeous than even Claude ever imagined, I enjoy a delight which none but those who have experienced it can understand - If it is to be done, it must be by studying Humboldt"

"I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection"

"I have no great quickness of apprehension or wit which is so remarkable in some clever men, for instance Huxley"

"We will now discuss in a little more detail the Struggle for Existence."

"The expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient"

" As for a future life, every man must judge for himself between conflicting vague probabilities."

" Believing as I do that man in the distant future will be a far more perfect creature than he now is, it is an intolerable thought that he and all other sentient beings are doomed to complete annihilation after such long-continued slow progress"

"doing what little one can to increase the general stock of knowledge is as respectable an object of life, as one can in any likelihood pursue"

"we can allow satellites, planets, suns, universe, nay whole systems of universe[s,] to be governed by laws, but the smallest insect, we wish to be created at once by special act"

"I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars"

"I am a strong advocate for free thought on all subjects, yet it appears to me (whether rightly or wrongly) that direct arguments against christianity & theism produce hardly any effect on the public; & freedom of thought is best promoted by the gradual illumination of men's minds, which follow[s] from the advance of science. It has, therefore, been always my object to avoid writing on religion, & I have confined myself to science. I may, however, have been unduly biassed by the pain which it would give some members of my family, if I aided in any way direct attacks on religion"

"Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science"

Phacops Trilobite  Schizochroal  Eye"To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real"

"Man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system- with all these exalted powers- Man still bears in his bodily frame the indelible stamp of his lowly origin."

 


 
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