Mie persorral imi este deosebit de greu s[ judec pe acest gigant. De aceea voi cere publicului cititor si-mi? Aceasta este cu atit mai natural, cu cit publicului nostru ii este cunoscutd doctrina lui Darwin de mult, iar cei care n-au avut posibilitatea s-o cunoascd dupd documentele secolului trecut ilu avut 1. Prima parte sI fie consacratir unora din problemele darwinisrnului.
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Despite periodic fluctuations, populations remain roughly the same size fact. Resources such as food are limited and are relatively stable over time fact. A struggle for survival ensues inference.
Individuals in a population vary significantly from one another fact. Much of this variation is heritable fact. Individuals less suited to the environment are less likely to survive and less likely to reproduce; individuals more suited to the environment are more likely to survive and more likely to reproduce and leave their heritable traits to future generations, which produces the process of natural selection fact.
This slowly effected process results in populations changing to adapt to their environments, and ultimately, these variations accumulate over time to form new species inference. Nature was widely believed to be unstable and capricious, with monstrous births from union between species, and spontaneous generation of life. After the turmoil of the English Civil War , the Royal Society wanted to show that science did not threaten religious and political stability.
John Ray developed an influential natural theology of rational order; in his taxonomy , species were static and fixed, their adaptation and complexity designed by God, and varieties showed minor differences caused by local conditions.
The biological classification introduced by Carl Linnaeus in also viewed species as fixed according to the divine plan. In , Georges Buffon suggested that some similar species, such as horses and asses, or lions, tigers, and leopards, might be varieties descended from a common ancestor.
Wernerians thought strata were deposits from shrinking seas , but James Hutton proposed a self-maintaining infinite cycle, anticipating uniformitarianism. Both envisaged that spontaneous generation produced simple forms of life that progressively developed greater complexity, adapting to the environment by inheriting changes in adults caused by use or disuse. This process was later called Lamarckism. Lamarck thought there was an inherent progressive tendency driving organisms continuously towards greater complexity, in parallel but separate lineages with no extinction.
Georges Cuvier strongly disputed such ideas, holding that unrelated, fixed species showed similarities that reflected a design for functional needs. All naturalists in the two English universities Oxford and Cambridge were Church of England clergymen, and science became a search for these laws.
Grant revealed his enthusiasm for the transmutation of species, but Darwin rejected it. Filled with zeal for science, he studied catastrophist geology with Adam Sedgwick. In December , he joined the Beagle expedition as a gentleman naturalist and geologist. Darwin discovered fossils resembling huge armadillos , and noted the geographical distribution of modern species in hope of finding their "centre of creation". At the zoo he had his first sight of an ape, and was profoundly impressed by how human the orangutan seemed.
In November , the anonymously published popular science book Vestiges of the Natural History of Creation , written by Scottish journalist Robert Chambers , widened public interest in the concept of transmutation of species. Vestiges used evidence from the fossil record and embryology to support the claim that living things had progressed from the simple to the more complex over time.
Darwin read it soon after publication, and scorned its amateurish geology and zoology,  but he carefully reviewed his own arguments after leading scientists, including Adam Sedgwick, attacked its morality and scientific errors. While few naturalists were willing to consider transmutation, Herbert Spencer became an active proponent of Lamarckism and progressive development in the s. Reminded of his lack of expertise in taxonomy , Darwin began an eight-year study of barnacles , becoming the leading expert on their classification.
Using his theory, he discovered homologies showing that slightly changed body parts served different functions to meet new conditions, and he found an intermediate stage in the evolution of distinct sexes. In , he completed the last part of his Beagle-related writing and began working full-time on evolution. He now realised that the branching pattern of evolutionary divergence was explained by natural selection working constantly to improve adaptation.
His thinking changed from the view that species formed in isolated populations only , as on islands, to an emphasis on speciation without isolation ; that is, he saw increasing specialisation within large stable populations as continuously exploiting new ecological niches. He conducted empirical research focusing on difficulties with his theory. He studied the developmental and anatomical differences between different breeds of many domestic animals, became actively involved in fancy pigeon breeding, and experimented with the help of his son Francis on ways that plant seeds and animals might disperse across oceans to colonise distant islands.
By , his theory was much more sophisticated, with a mass of supporting evidence. Reasons suggested have included fear of religious persecution or social disgrace if his views were revealed, and concern about upsetting his clergymen naturalist friends or his pious wife Emma. His paper on Glen Roy had proved embarrassingly wrong, and he may have wanted to be sure he was correct. Darwin always finished one book before starting another.
While he was researching, he told many people about his interest in transmutation without causing outrage. He firmly intended to publish, but it was not until September that he could work on it full-time. His estimate that writing his "big book" would take five years proved optimistic.
Darwin was torn between the desire to set out a full and convincing account and the pressure to quickly produce a short paper. He met Lyell, and in correspondence with Joseph Dalton Hooker affirmed that he did not want to expose his ideas to review by an editor as would have been required to publish in an academic journal. He began a "sketch" account on 14 May , and by July had decided to produce a full technical treatise on species as his "big book" on Natural Selection.
His theory including the principle of divergence was complete by 5 September when he sent Asa Gray a brief but detailed abstract of his ideas. Darwin described natural selection as being analogous to the artificial selection practised by animal breeders, and emphasised competition between individuals; Wallace drew no comparison to selective breeding , and focused on ecological pressures that kept different varieties adapted to local conditions.
On 28 March Darwin wrote to Lyell asking about progress, and offering to give Murray assurances "that my Book is not more un-orthodox, than the subject makes inevitable.
The third edition came out in , with a number of sentences rewritten or added and an introductory appendix, An Historical Sketch of the Recent Progress of Opinion on the Origin of Species,  while the fourth in had further revisions.
The fifth edition, published on 10 February , incorporated more changes and for the first time included the phrase " survival of the fittest ", which had been coined by the philosopher Herbert Spencer in his Principles of Biology Darwin had told Murray of working men in Lancashire clubbing together to buy the fifth edition at 15 shillings and wanted it made more widely available; the price was halved to 7 s 6 d by printing in a smaller font.
It includes a glossary compiled by W. Book sales increased from 60 to per month. In a May letter, Darwin mentioned a print run of 2, copies, but it is not clear if this referred to the first printing only as there were four that year. Darwin corresponded with Royer about a second edition published in and a third in , but he had difficulty getting her to remove her notes and was troubled by these editions.
The existence of two rhea species with overlapping ranges influenced Darwin. These facts seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers.
He mentions his years of work on his theory, and the arrival of Wallace at the same conclusion, which led him to "publish this Abstract" of his incomplete work. He outlines his ideas, and sets out the essence of his theory: As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected.
From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form. Darwin discusses contemporary opinions on the origins of different breeds under cultivation to argue that many have been produced from common ancestors by selective breeding. However, for Darwin the small changes were most important in evolution. In this chapter Darwin expresses his erroneous belief that environmental change is necessary to generate variation.
He concludes that "a well-marked variety may be justly called an incipient species" and that "species are only strongly marked and permanent varieties". Darwin and Wallace made variation among individuals of the same species central to understanding the natural world.
Originea speciilor - Charles Darwin
Review-uri 1 In data de 27 decembrie , tanarul naturalist Charles Darwin parasea portul Plymouth la bordul corabiei Beagle. In urmatorii cinci ani, Darwin a cercetat plante si animale de pe cuprinsul lumii, adunand o serie de dovezi ce vor culmina intr-una dintre cele mai mari descoperiri din istoria omenirii: teoria evolutiei prin selectie naturala. In cartea Originea speciilor, aparuta dupa 28 de ani, in , Darwin prezinta descoperirea sa epocala, care avea sa schimbe pentru totdeauna felul in care oamenii se vad pe ei insisi si lumea in care traiesc. Aici, el demonstreaza intr-un mod convingator realitatea evolutiei, si anume faptul ca nu este posibil ca animalele si plantele existente sa fi aparut in mod separat, ci trebuie sa se fi transformat cu incetul din stramosi comuni. Cel mai important element din carte este acela ca explica in detaliu mecanismul care duce la o astfel de transformare: selectia naturala — ideea care a dat pentru prima data inteligibilitate stiintifica evolutiei ca fenomen. Fiind una dintre putinele opere stiintifice paradigmatice accesibile publicului larg, Originea speciilor nu numai ca a lansat stiinta biologiei moderne, ci totodata a influentat practic intreaga gandire literara, filosofica si religioasa.