History of evolutionary thought

http://www.all-laptopfan.com/,http://www.all-keyboard.com/,http://www.laptopbattery-shop.co.uk/ 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 concentrated...to 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