Wednesday, October 29, 2014

History of evolutionary thought,, Evolutionary thought, the conception that species change over time, has roots in antiquity, in the ideas of the ancient Greeks,Romans, and Chinese as well as in medieval Islamic science. With the beginnings of biological taxonomy in the late 17th century, Western biological thinking was influenced by two opposed ideas. French Macaron Pillow ,Creative Cushion - Matty's One was essentialism, the belief that every species has essential characteristics that are unalterable, a concept which had developed from medieval Aristotelian metaphysics, and that fit well with natural theology. The other one was the development of the new anti-Aristotelian approach to modern science: as theEnlightenment progressed, evolutionary cosmology and the mechanical philosophy spread from the physical sciences to natural history. French Macaron Pillow ,Creative Cushion - Matty's Naturalists began to focus on the variability of species; the emergence of paleontology with the concept of extinctionfurther undermined the static view of nature. In the early 19th century, Jean-Baptiste Lamarck proposed his theory of thetransmutation of species, the first fully formed theory of evolution. In 1858, Charles Darwin and Alfred Russel Wallace published a new evolutionary theory that was explained in detail in Darwin's On the Origin of Species (1859). SONY PCG-7122M battery Unlike Lamarck, Darwin proposed common descent and a branching tree of life, meaning that two very different species could share a common ancestor. The theory was based on the idea of natural selection, and it synthesized a broad range of evidence from animal husbandry, biogeography, geology, morphology, and embryology. SONY PCG-7121M battery The debate over Darwin's work led to the rapid acceptance of the general concept of evolution, but the specific mechanism he proposed, natural selection, was not widely accepted until it was revived by developments in biology that occurred during the 1920s through the 1940s. Before that time most biologists argued that other factors were responsible for evolution. SONY VAIO PCG-7192M battery Alternatives to natural selection suggested during "the eclipse of Darwinism" (circa 1880 to 1920) included inheritance of acquired characteristics (neo-Lamarckism), an innate drive for change (orthogenesis), and sudden large mutations (saltationism). The synthesis of natural selection with Mendelian genetics during the 1920s and 1930s founded the new discipline of population genetics. SONY VAIO PCG-7194M battery Throughout the 1930s and 1940s, population genetics became integrated with other biological fields, resulting in a widely applicable theory of evolution that encompassed much of biology—the modern evolutionary synthesis. Following the establishment of evolutionary biology, studies of mutation and variation in natural populations, combined withbiogeography and systematics, led to sophisticated mathematical and causal models of evolution.SONY VAIO PCG-7195M battery Paleontology and comparative anatomy allowed more detailed reconstructions of the history of life. After the rise of molecular genetics in the 1950s, the field of molecular evolution developed, based on protein sequences and immunological tests, and later incorporating RNA and DNA studies. The gene-centered view of evolution rose to prominence in the 1960s, followed by the neutral theory of molecular evolution, SONY VAIO PCG-7196M battery sparking debates over adaptationism, the units of selection, and the relative importance of genetic drift versus natural selection. In the late 20th century, DNA sequencing led to molecular phylogenetics and the reorganization of the tree of life into the three-domain system. In addition, the newly recognized factors of symbiogenesis and horizontal gene transfer introduced yet more complexity into evolutionary theory. SONY VAIO PCG-7191V battery Discoveries in evolutionary biology have made a significant impact not just within the traditional branches of biology, but also in other academic disciplines (e.g., anthropology and psychology) and on society at large. Proposals that one type of animal, even humans, could descend from other types of animals, are known to go back to the first pre-Socratic Greek philosophers. SONY VAIO PCG-7192V battery Anaximander of Miletus (c.610–546 BC) proposed that the first animals lived in water, during a wet phase of the Earth's past, and that the first land-dwelling ancestors of mankind must have been born in water, and only spent part of their life on land. He also argued that the first human of the form known today must have been the child of a different type of animal, because man needs prolonged nursing to live.[2] SONY VAIO PCG-71111M battery Empedocles (c. 490–430 BC), argued that what we call birth and death in animals are just the mingling and separations of elements which cause the countless "tribes of mortal things".[3] Specifically, the first animals and plants were like disjointed parts of the ones we see today, some of which survived by joining in different combinations, and then intermixing, and wherever "everything turned out as it would have if it were on purpose, there the creatures survived, being accidentally compounded in a suitable way".[4] Sony VAIO VGN-FW31Z battery Other philosophers who became more influential in the Middle Ages, including Plato, Aristotle, and members of the stoic school of philosophy, believed that the species of all things, not only living things, were fixed by divine design. Plato (c. 428–348 BC) was called by biologist Ernst Mayr "the great antihero of evolutionism",[5] because he promoted belief inessentialism, which is also referred to as the Theory of Forms. Sony VGN-NR11Z Battery This theory holds that each natural type of object in the observed world is an imperfect manifestation of the ideal, form or "species" which defines that type. In his Timaeus for example, Plato has a character tell a story that the Demiurge created the cosmos and everything in it because, being good, and hence, "... free from jealousy, He desired that all things should be as like Himself as they could be". SONY VAIO PCG-21211M battery The creator created all conceivable forms of life, since "... without them the universe will be incomplete, for it will not contain every kind of animal which it ought to contain, if it is to be perfect". This "plenitude principle"—the idea that all potential forms of life are essential to a perfect creation—greatly influenced Christian thought.[6] SONY VAIO PCG-21212M battery However some historians of science have questioned how much influence Plato's essentialism had on natural philosophy by stating that many philosophers after Plato believed that species might be capable of transformation and that the idea that biologic species were fixed and possessed unchangeable essential characteristics did not become important until the beginning of biologic taxonomy in the 17th and 18th centuries.[7] SONY VAIO PCG-21212V battery Aristotle (384–322 BC), the most influential of the Greek philosophers in Europe in the Middle Ages, was a student of Plato and is also the earliest natural historian whose work has been preserved in any real detail. His writings on biology resulted from his research into natural history on and around the isle of Lesbos, and have survived in the form of four books, usually known by theirLatin names, Sony VGN-NR11S Battery De anima (on the essence of life), Historia animalium (inquiries about animals), De generatione animalium(reproduction), and De partibus animalium (anatomy). Aristotle's works contain some remarkably astute observations and interpretations—along with sundry myths and mistakes—reflecting the uneven state of knowledge during his time.[8] However, forCharles Singer, SONY VAIO PCG-21213V battery "Nothing is more remarkable than [Aristotle's] efforts to [exhibit] the relationships of living things as a scala naturæ."[8] This scala naturæ, described in Historia animalium, classified organisms in relation to a hierarchical "Ladder of Life" or "Chain of Being", placing them according to their complexity of structure and function, with organisms that showed greater vitality and ability to move described as "higher organisms".[6] SONY VAIO PCG-21214V battery Aristotle believed that features of living organisms showed clearly that they must have had what he called a final cause, that is to say that they had been designed for a purpose.[9] He explicitly rejected the view of Empedocles that living creatures might have originated by chance.[10] Other Greek philosophers, such as Zeno of Citium (334–262 BC) the founder of the Stoic school of philosophy, Sony VAIO PCG-31111M battery agreed with Aristotle and other earlier philosophers that nature showed clear evidence of being designed for a purpose; this view is known as teleology.[11] The Roman stoic philosopher Cicero wrote that Zeno was known to have held the view, central to Stoic physics, that nature is primarily "directed and secure for the world...the structure best fitted for survival."[12] Sony VAIO PCG-31311M battery Epicurus (341–270 BC) anticipated the idea of natural selection. Lucretius explicated these ideas in his De rerum natura. In the Epicurean system, it was assumed that many species had been spontaneously generated from "Gaia" in the past, but that only the most functional forms survived to have off-spring. The Epicureans do not seem to have anticipated the full theory of evolution as we now know it and seem to have postulated a separate abiogenetic Sony VAIO PCG-8152M battery events for each species rather than postulating a single abiogenetic event coupled with the differentiation of species over time from a single (or small number of) originating parent organism(s). Ancient Chinese thinkers such as Zhuangzi (Chuang Tzu), a Taoist philosopher who lived around the 4th century BC, expressed ideas on changing biologic species. According to Joseph Needham, Sony VAIO PCG-8131M battery Taoism explicitly denies the fixity of biological species and Taoist philosophers speculated that species had developed differing attributes in response to differing environments.[13] Taoism regards humans, nature and the heavens as existing in a state of "constant transformation" known as theTao, in contrast with the more static view of nature typical of Western thought. Sony VAIO PCG-5P1M battery Titus Lucretius Carus (d. 50 BC), the Roman philosopher and atomist, wrote the poem On the Nature of Things (De rerum natura), which provides the best surviving explanation of the ideas of the Greek Epicurean philosophers. It describes the development of the cosmos, the Earth, living things, and human society through purely naturalistic mechanisms, without any reference to supernatural involvement. SONY VAIO PCG-81212M battery On the Nature of things would influence the cosmological and evolutionary speculations of philosophers and scientists during and after the Renaissance.[15][16] This view was in strong contrast with the views of Roman philosophers of the stoic school such as Marcus Tullius Cicero, Seneca, and Pliny the Elder who had a strongly teleological view of the natural world that influenced Christian theology.[11] Sony Vaio VGN-CR13/R Battery Cicero reports that the peripatetic and stoic view of nature as an agency concerned most basically with producing life "best fitted for survival" was taken for granted among the Hellenistic elite. In line with earlier Greek thought, the 4th-century bishop and theologian, Augustine of Hippo, wrote that the creation story in Genesis should not be read too literally. SONY PCG-8113M battery In his book De Genesi ad litteram ("On The Literal Interpretation of Genesis"), he stated that in some cases new creatures may have come about through the "decomposition" of earlier forms of life.[17] For Augustine, "plant, fowl and animal life are not perfect ... but created in a state of potentiality", unlike what he considered the theologically perfect forms of angels, the firmament and the human soul.[18] SONY PCG-8112M battery Augustine's idea 'that forms of life had been transformed "slowly over time"' prompted Father Giuseppe Tanzella-Nitti, Professor of Theology at the Pontifical Santa Croce University in Rome, to claim that Augustine had suggested a form of evolution.[19][20] Henry Fairfield Osborn wrote in From the Greeks to Darwin (1894):If the orthodoxy of Augustine had remained the teaching of the Church, Sony VAIO PCG-7148L battery the final establishment of Evolution would have come far earlier than it did, certainly during the eighteenth instead of the nineteenth century, and the bitter controversy over this truth of Nature would never have arisen. ...Plainly as the direct or instantaneous Creation of animals and plants appeared to be taught in Genesis, Augustine read this in the light of primary causation and the gradual development from the imperfect to the perfect of Aristotle. Sony VAIO PCG-7151L battery This most influential teacher thus handed down to his followers opinions which closely conform to the progressive views of those theologians of the present day who have accepted the Evolution theory.[21] In A History of the Warfare of Science with Theology in Christendom (1896), Andrew Dickson White wrote about Augustine's attempts to preserve the ancient evolutionary approach to the creation as follows. Sony VAIO PCG-7152L battery For ages a widely accepted doctrine of spontaneous generation had been that water, filth, and carrion had received power from the Creator to generate worms, insects, and a multitude of the smaller animals; and this doctrine had been especially welcomed by St. Augustine and many of the fathers, since it relieved the Almighty of making, Adam of naming, and Noah of living in the ark with these innumerable despised species. Sony VAIO PCG-7153L battery In Augustine's great treatise, De Cenesi contra Manichæos, on Genesis he says: "To suppose that God formed man from the dust with bodily hands is very childish. ...God neither formed man with bodily hands nor did he breathe upon him with throat and lips." Augustine suggests in other work his theory of the later development of insects out of carrion, and the adoption of the old emanation or evolution theory, Sony VAIO PCG-7154L battery showing that "certain very small animals may not have been created on the fifth and sixth days, but may have originated later from putrefying matter." In his great treatise De Trinitate (on the Trinity) he develops at length the view that in the creation of living beings there was something like a growth—that God is the ultimate author, but works through secondary causes; Sony VAIO PCG-7161L battery and finally argues that certain substances are endowed by God with the power of producing certain classes of plants and animals. Although Greek and Roman evolutionary ideas died out in Europe after the fall of the Roman Empire, they were not lost to Islamic philosophers and scientists. In the Islamic Golden Age of the 8th to the 13th centuries, philosophers explored ideas about natural history. Sony VAIO PCG-7162L battery These ideas included transmutation from non-living to living: "from mineral to plant, from plant to animal, and from animal to man".[24] In the medieval Islamic world, the scholar al-Jahiz wrote his Book of Animals in the 9th century. Conway Zirkle, writing about the history of natural selection in 1941, said that an excerpt from this work was the only relevant passage he had found from an Arabian scholar. Sony VAIO PCG-7171L battery He provided a quotation describing the struggle for existence, citing a Spanish translation of this work: "The rat goes out for its food, and is clever in getting it, for it eats all animals inferior to it in strength", and in turn, it "has to avoid snakes and birds and serpents of prey, who look for it in order to devour it" and are stronger than the rat. Sony VAIO PCG-7172L battery Mosquitos "know instinctively that blood is the thing which makes them live" and when they see an animal, "they know that the skin has been fashioned to serve them as food". In turn, flies hunt the mosquito "which is the food that they like best", and predators eat the flies. "All animals, in short, can not exist without food, neither can the hunting animal escape being hunted in his turn. Sony VAIO PCG-7173L battery Every weak animal devours those weaker than itself. Strong animals cannot escape being devoured by other animals stronger than they. And in this respect, men do not differ from animals, some with respect to others, although they do not arrive at the same extremes. In short, God has disposed some human beings as a cause of life for others, and likewise, he has disposed the latter as a cause of the death of the former."[25] Sony VAIO PCG-7174L battery Al-Jahiz also wrote descriptions of food chains.[26] Some of Ibn Khaldun's thoughts, according to some commentators, anticipate the biological theory of evolution.[27] In 1377 Ibn Khaldun wrote the Muqaddimah in which he asserted that humans developed from "the world of the monkeys", in a process by which "species become more numerous"[27] Sony VAIO PCG-7181L battery In chapter 1 he writes: "This world with all the created things in it has a certain order and solid construction. It shows nexuses between causes and things caused, combinations of some parts of creation with others, and transformations of some existent things into others, in a pattern that is both remarkable and endless."[28] The Muqaddimah also states in Chapter 6: Sony VAIO PCG-7182L battery We explained there that the whole of existence in (all) its simple and composite worlds is arranged in a natural order of ascent and descent, so that everything constitutes an uninterrupted continuum. The essences at the end of each particular stage of the worlds are by nature prepared to be transformed into the essence adjacent to them, either above or below them. Sony VAIO PCG-7183L battery This is the case with the simple material elements; it is the case with palms and vines, (which constitute) the last stage of plants, in their relation to snails and shellfish, (which constitute) the (lowest) stage of animals. It is also the case with monkeys, creatures combining in themselves cleverness and perception, in their relation to man, the being who has the ability to think and to reflect. Sony VAIO PCG-7184L battery The preparedness (for transformation) that exists on either side, at each stage of the worlds, is meant when (we speak about) their connection. During the Early Middle Ages, Greek classical learning was all but lost to the West. However, contact with the Islamic world, where Greek manuscripts were preserved and expanded, soon led to a massive spate of Latin translations in the 12th century. Sony VAIO PCG-7185L battery Europeans were re-introduced to the works of Plato and Aristotle, as well as to Islamic thought. Christian thinkers of the scholastic school, in particular Abelard and Thomas Aquinas, combined Aristotelian classification with Plato's ideas of the goodness of God, and of all potential life forms being present in a perfect creation, to organize all inanimate, Sony VAIO PCG-381L battery animate, and spiritual beings into a huge interconnected system: the scala naturæ, or great chain of being.[6][30] Within this system, everything that existed could be placed in order, from "lowest" to "highest", with Hell at the bottom and God at the top—below God, an angelic hierarchy marked by the orbits of the planets, mankind in an intermediate position, and worms the lowest of the animals. Sony VAIO PCG-382L battery As the universe was ultimately perfect, the great chain was also perfect. There were no empty links in the chain, and no link was represented by more than one species. Therefore no species could ever move from one position to another. Thus, in this Christianized version of Plato's perfect universe, species could never change, but remained forever fixed, in accordance with the text of Genesis. Sony VAIO PCG-383L battery For humans to forget their position was seen as sinful, whether they behaved like lower animals or aspired to a higher station than was given them by their Creator.[6] Creatures on adjacent steps were expected to closely resemble each other, an idea expressed in the saying: natura non facit saltum("nature does not make leaps").[6] Sony VAIO PCG-384L battery This basic concept of the great chain of being greatly influenced the thinking of Western civilization for centuries (and still has an influence today). It formed a part of the argument from design presented by natural theology. As a classification system, it became the major organizing principle and foundation of the emerging science of biology in the 17th and 18th centuries. Sony VAIO PCG-391L battery While the development of the great chain of being and the argument from design by Christian theologians contributed to the view that the natural world fit into an unchanging designed hierarchy, some theologians were more open to the possibility that the world might have developed through natural processes. Sony VAIO PCG-393L battery Thomas Aquinas went even farther than Augustine of Hippo in arguing that scriptural texts like Genesis should not be interpreted in a literal way that conflicted with or constrained what natural philosophers learned about the workings of the natural world. He felt that the autonomy of nature was a sign of God's goodness and that there was no conflict between the concept of a divinely created universe, and the idea that the universe may have evolved over time through natural mechanisms.[31] Sony VAIO PCG-394L battery However, Aquinas disputed the views of those like the ancient Greek philosopher Empedocles who held that such natural processes showed that the universe could have developed without an underlying purpose. Rather holding that: "Hence, it is clear that nature is nothing but a certain kind of art, i.e., the divine art, impressed upon things, by which these things are moved to a determinate end. Sony VAIO PCG-3A1L battery It is as if the shipbuilder were able to give to timbers that by which they would move themselves to take the form of a ship."In the first half of the 17th century, René Descartes's mechanical philosophy encouraged the use of the metaphor of the universe as a machine, a concept that would come to characterise the scientific revolution.[33] Between 1650 and 1800 some evolutionists, such as Benoît de Maillet, Sony VAIO PCG-3A2L battery produced theories that maintained that the universe, the earth, and life, had developed mechanically, without divine guidance.[34] In contrast, most contemporary theories of evolution, such of those of Gottfried Leibniz and J. G. Herder, regarded evolution as a fundamentally spiritual process.[35] In 1751, Pierre Louis Maupertuis veered toward more materialist ground. Sony VAIO PCG-3A3L battery He wrote of natural modifications occurring during reproduction and accumulating over the course of many generations, producing races and even new species, a description that anticipated in general terms the concept of natural selection.[36] Maupertuis's ideas were in opposition to the influence of early taxonomists like John Ray. Sony VAIO PCG-3A4L battery In the late 17th century Ray had given the first formal definition of a biological species, which he described as being characterized by essential unchanging features, and stated the seed of one species could never give rise to another.[7] The ideas of Ray and other 17th century taxonomists were influenced by natural theology and the argument from design.[37] Sony VAIO PCG-41112L battery The word evolution (from the Latin evolutio, meaning "to unroll like a scroll") was initially used to refer to embryological development; its first use in relation to development of species came in 1762, when Charles Bonnet used it for his concept of "pre-formation", in which females carried a miniature form of all future generations. The term gradually gained a more general meaning of growth or progressive development.[38] Sony VAIO PCG-51211L battery Later in the 18th century, the French philosopher G. L. L. Buffon, one of the leading naturalists of the time, suggested that what most people referred to as species were really just well-marked varieties, modified from an original form by environmental factors. For example, he believed that lions, tigers, leopards and house cats might all have a common ancestor. Sony VAIO PCG-51311L battery He further speculated that the 200 or so species of mammals then known might have descended from as few as 38 original animal forms. Buffon's evolutionary ideas were limited; he believed each of the original forms had arisen through spontaneous generation and that each was shaped by "internal moulds" that limited the amount of change. Buffon's works, Sony VAIO PCG-51312L battery Natural History and The Epochs of Nature, containing well developed theories about a completely materialistic origin for the Earth and his ideas questioning the fixity of species, were extremely influential.[39][40] Another French philosopher, Denis Diderot, also wrote that living things might have first arisen through spontaneous generation, Sony VAIO PCG-51411L battery and that species were always changing through a constant process of experiment where new forms arose and survived or not based on trial and error; an idea that can be considered a partial anticipation of natural selection.[41] Between 1767 and 1792, James Burnett, Lord Monboddo included in his writings not only the concept that man had descended from primates, but also that, in response to the environment, Sony VAIO PCG-51412L battery creatures had found methods of transforming their characteristics over long time intervals.[42] Charles Darwin's grandfather, Erasmus Darwin, publishedZoönomia in 1796, which suggested that "all warm-blooded animals have arisen from one living filament".[43] In his 1802 poem Temple of Nature, he described the rise of life from minute organisms living in mud to all of its modern diversity. Sony VAIO PCG-51511L battery In 1796 Georges Cuvier published his findings on the differences between living elephants and those found in the fossil record. His analysis identified mammoths and mastodons as distinct species, different from any living animal, and effectively ended a long-running debate over whether a species could go extinct.[45] In 1788, James Hutton described gradual geological processes operating continuously over deep time.[46] Sony VAIO PCG-51513L battery In the 1790s William Smith began the process of ordering rock strata by examining fossils in the layers while he worked on his geologic map of England. Independently, in 1811, Georges Cuvier and Alexandre Brongniart published an influential study of the geologic history of the region around Paris, based on the stratigraphic succession of rock layers. These works helped establish the antiquity of the Earth.[47] Sony VAIO PCG-5N2L battery Cuvier advocated catastrophism to explain the patterns of extinction andfaunal succession revealed by the fossil record. Knowledge of the fossil record continued to advance rapidly during the first few decades of the 19th century. By the 1840s, the outlines of the geologic timescale were becoming clear, and in 1841 John Phillips named three major eras, Sony VAIO PCG-5N4L battery based on the predominantfauna of each: the Paleozoic, dominated by marine invertebrates and fish, the Mesozoic, the age of reptiles, and the currentCenozoic age of mammals. This progressive picture of the history of life was accepted even by conservative English geologists likeAdam Sedgwick and William Buckland; however, like Cuvier, they attributed the progression to repeated catastrophic episodes of extinction followed by new episodes of creation.[48] Sony VAIO PCG-5P2L battery Unlike Cuvier, Buckland and some other advocates of natural theology among British geologists made efforts to explicitly link the last catastrophic episode proposed by Cuvier to the biblical flood.[49][50] From 1830 to 1833, Charles Lyell published his multi-volume work Principles of Geology, which, building on Hutton's ideas, advocated a uniformitarian alternative to the catastrophic theory of geology. Sony VAIO PCG-5P4L battery Lyell claimed that, rather than being the products of cataclysmic (and possibly supernatural) events, the geologic features of the Earth are better explained as the result of the same gradual geologic forces observable in the present day—but acting over immensely long periods of time. Although Lyell opposed evolutionary ideas (even questioning the consensus that the fossil record demonstrates a true progression), Sony VAIO PCG-5R1L battery his concept that the Earth was shaped by forces working gradually over an extended period, and the immense age of the Earth assumed by his theories, would strongly influence future evolutionary thinkers such as Charles Darwin. Jean-Baptiste Lamarck proposed, in his Philosophie Zoologique of 1809, a theory of the transmutation of species. Sony VAIO PCG-5R2L battery Lamarck did not believe that all living things shared a common ancestor but rather that simple forms of life were created continuously byspontaneous generation. He also believed that an innate life force drove species to become more complex over time, advancing up a linear ladder of complexity that was related to the great chain of being. Lamarck recognized that species adapted to their environment. Sony VAIO PCG-5S1L battery He explained this by saying that the same innate force driving increasing complexity caused the organs of an animal (or a plant) to change based on the use or disuse of those organs, just as exercise affects muscles. He argued that these changes would be inherited by the next generation and produce slow adaptation to the environment. Sony VAIO PCG-5S2L battery It was this secondary mechanism of adaptation through the inheritance of acquired characteristics that would become known as Lamarckism and would influence discussions of evolution into the 20th century.[52][53] A radical British school of comparative anatomy that included the anatomist Robert Grant was closely in touch with Lamarck's French school of Transformationism. Sony VAIO PCG-5S3L battery One of the French scientists who influenced Grant was the anatomist Étienne Geoffroy Saint-Hilaire, whose ideas on the unity of various animal body plans and the homology of certain anatomical structures would be widely influential and lead to intense debate with his colleague Georges Cuvier. Grant became an authority on the anatomy and reproduction of marineinvertebrates. Sony VAIO PCG-5T2L battery He developed Lamarck's and Erasmus Darwin's ideas of transmutation and evolutionism, and investigated homology, even proposing that plants and animals had a common evolutionary starting point. As a young student Charles Darwin joined Grant in investigations of the life cycle of marine animals. In 1826 an anonymous paper, probably written by Robert Jameson, Sony VAIO PCG-5T3L battery praised Lamarck for explaining how higher animals had "evolved" from the simplest worms; this was the first use of the word "evolved" in a modern sense.[54][55] In 1844 the Scottish publisher Robert Chambers anonymously published an extremely controversial but widely read book entitledVestiges of the Natural History of Creation. Sony VAIO PCG-5T4L battery This book proposed an evolutionary scenario for the origins of the Solar System and of life on Earth. It claimed that the fossil record showed a progressive ascent of animals, with current animals branching off a main line that leads progressively to humanity. It implied that the transmutations lead to the unfolding of a preordained plan that had been woven into the laws that governed the universe. Sony VAIO PCG-61111L battery In this sense it was less completely materialistic than the ideas of radicals like Robert Grant, but its implication that humans were only the last step in the ascent of animal life incensed many conservative thinkers. The high profile of the public debate over Vestiges, with its depiction of evolution as a progressive process, would greatly influence the perception of Darwin's theory a decade later.[56][57] Sony VAIO PCG-61112L battery Ideas about the transmutation of species were associated with the radical materialism of the Enlightenment and were attacked by more conservative thinkers. Georges Cuvier attacked the ideas of Lamarck and Geoffroy Saint-Hilaire, agreeing with Aristotle that species were immutable. Cuvier believed that the individual parts of an animal were too closely correlated with one another to allow for one part of the anatomy to change in isolation from the others, Sony VAIO PCG-61411L battery and argued that the fossil record showed patterns of catastrophic extinctions followed by re-population, rather than gradual change over time. He also noted that drawings of animals and animal mummies from Egypt, which were thousands of years old, showed no signs of change when compared with modern animals. The strength of Cuvier's arguments and his scientific reputation helped keep transmutational ideas out of the mainstream for decades. Sony VAIO PCG-71111L battery In Britain the philosophy of natural theology remained influential. William Paley's 1802 book Natural Theology with its famouswatchmaker analogy had been written at least in part as a response to the transmutational ideas of Erasmus Darwin.[59] Geologists influenced by natural theology, such as Buckland and Sedgwick, made a regular practice of attacking the evolutionary ideas of Lamarck, Grant, and The Vestiges of the Natural History of Creation.Sony VAIO PCG-7141L battery Although the geologist Charles Lyell opposed scriptural geology, he also believed in the immutability of species, and in his Principles of Geology (1830–1833), he criticized Lamarck's theories of development.[51] Idealists such as Louis Agassiz and Richard Owen believed that each species was fixed and unchangeable because it represented an idea in the mind of the creator. Sony VAIO PCG-7142L battery They believed that relationships between species could be discerned from developmental patterns in embryology, as well as in the fossil record, but that these relationships represented an underlying pattern of divine thought, with progressive creation leading to increasing complexity and culminating in humanity. Owen developed the idea of "archetypes" in the Divine mind that would produce a sequence of species related by anatomical homologies, Sony VAIO PCG-81113L battery such as vertebrate limbs. Owen led a public campaign that successfully marginalized Robert Grant in the scientific community. Darwin would make good use of the homologies analyzed by Owen in his own theory, but the harsh treatment of Grant, and the controversy surrounding Vestiges, showed him the need to ensure that his own ideas were scientifically sound. Sony VAIO PCG-81114L battery It is possible to look through the history of biology from the ancient Greeks onwards and discover anticipations of almost all of Charles Darwin's key ideas. For example, Loren Eiseley has found isolated passages written by Buffon suggesting he was almost ready to piece together a theory of natural selection, but such anticipations should not be taken out of the full context of the writings or of cultural values of the time which could make Darwinian ideas of evolution unthinkable.[64] Sony VAIO PCG-81115L battery When Darwin was developing his theory, he investigated selective breeding and was impressed by Sebright's observation that "A severe winter, or a scarcity of food, by destroying the weak and the unhealthy, has all the good effects of the most skilful selection" so that "the weak and the unhealthy do not live to propagate their infirmities".[65] Sony VAIO PCG-81214L battery

No comments:

Post a Comment