The origin of species


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The origin of species

  2. 2. BIOGRAPHYThe most important evolutionary scientist of the nineteenth century was Charles Darwin (1809-1882). Student of the universities ofEdinburgh and Cambridge in England, completed his theological studies at the age of 22. Prepared for Protestant minister of theChurch, however, Darwins greatest interest was in the natural world.In 1831 he joined, as a naturalist, the crew of the British Navy ship "HMS Beagle", which would make a mapping expedition aroundthe world for five years. This trip was instrumental in the thinking of Charles Darwin. In the Galapagos Islands in the Pacific Ocean offSouth America, was impressed by the animal species he saw and, above all, by the subtle differences between birds of the islands of thearchipelago. From these observations, Darwin realized that these differences could be connected with the fact that each species living in adifferent environment, with different power. At that time Darwin began to outline his ideas about evolution.Darwin understood that any population of individuals is slightly different from one another. Variations between individuals makes eachone has different abilities to adapt to the natural environment, successfully reproduce and pass on their traits to their offspring. At thepassing of generations, the traits of the individuals best adapted to the natural conditions become more common and the population evolves.Darwin called this process "descent with modification". Similarly, nature selects the species best adapted to survive and reproduce. Thisprocess is known as "natural selection."
  3. 3. Darwins thinking was also heavily influenced by the ideas of Thomas Malthus, who wrotethat the human population tended to grow exponentially and thus to finish the food resourcesavailable. This causes crisis that leads individuals to compete against each other for survival.Darwin believed that variations in inherited traits of individuals made them more or lessable to face competition for resources.More than 20 years after he began to develop his ideas about evolution, Darwin publishedhis theory in his book The Origin of Species (1859). Its publication caused great controversyand opposed religious thinkers because he missed the creationist theory ground and movedhim from the center of creation. This book convinced scientists and the educated public thatliving things change over time
  4. 4. SYNOPSIS OF THEBOOKDarwin proposed in 1859 that natural selection, acting on heritable variation, is the driving force of evolution, but knew nothing aboutthe nature of these variations. From the work of Gregor Mendel, published in 1866 and rediscovered in 1900, genetics became anessential part of evolutionary theory. Incorporating genetics Darwinism led, around 1940, to the development of neo-Darwinism or"synthetic theory" of evolution that still considers that natural selection is the main explanatory factor of evolution.A common objection to Darwinism is that it does not explain the "macroevolution", ie, the origin of new species or types of living.Darwinism insists gradualism and says that big changes are the result of the accumulation of many small changes, but they have madealternative proposals. The main one is the theory of "punctuated equilibrium", proposed by Stephen Jay Gould and NilesEldredge, who argue that evolution is gradual, but it works hops: there would be long periods of stability punctuated by short intervalsin which take place large and sudden evolutionary changes. Gould and Eldredge claim that his theory agrees with the largediscontinuities that manifest the fossil record, which are no intermediate links. Neo-Darwinists, on the other hand, they say that bothviews are compatible, so that punctuated equilibrium could be integrated within Darwinism: geneticists say, that made the synthetictheory, and paleontologists proposed punctuated equilibrium, using two different time scales: the changes that take place over thousandsof generations seem sudden to fósil7 registration. Importantly punctuated equilibrium proposed by Gould and Eldredge Darwinianexplanations that are not but are evolutionists: the discussion is centered around the mechanisms of evolution, not about its existence.
  5. 5. Another theory that disagrees with Darwinism is the "neutrality" of Motoo Kimura, who proposed his theoryfrom 1967. Kimura says most of the genetic mutations that provide the material for the course have nothing to dowith advantages and disadvantages, and that therefore natural selection ranks main attribute Darwinists:evolutionary changes should the "genetic drift" of genetic mutations that are equivalent from the point of view ofnatural selection. Also in this case, Darwinists claim neutralism fits within his theory, although there arediscrepancies in interpretation.Interestingly, in this context, the importance of "gene duplication", that is, the existence of copies of a single gene.This allows genes liberated are available to experience changes that may be important in future new circumstances.So be understood that there may be significant changes that do not require the gradual accumulation of smallchanges.One of the greatest difficulties of evolution is, in fact, the explanation of new types of organizations that requirecomplex and coordinated multiple changes. In this current work are important about the "self-organization", suchas those by Stuart Kaufmann9. Theories is that, for now, are very hypothetical, that attempt to explain the originof evolutionary transformations based natural tendencies that we still know so very inadequate. Again, theseworks are sometimes presented as opposed to Darwinism, but Darwinists claim that fit into their theory and, inany case, are not critical to evolution, but attempts to provide deeper explanations of evolution.
  6. 6. The Origin of Species (1859) novel ideas.The theory of evolution that Darwin postulated had an enormous impact on European thought in the second half of the nineteenthcentury. The main arguments of the Origin of Species, published in 1859 are:1. Biological types or species are not fixed or static existence but are constantly changing.2. Life manifests as a constant struggle for existence and survival.3. The struggle for survival causes organisms less adapted to a specific environment disappears and allows the best adapted toreproduce, this process is called "natural selection."4. Natural selection, development and evolution require an enormous amount of time, so long that a human life can not appreciatethese phenomena.5. Genetic variations that produce increased survival probabilities are random and are not caused by God, or (as the religious thought)or by the tendency of organisms to seek perfection (as proposed by Lamarck).In addition to this book, Darwin wrote two more: Variations on domesticated plants and animals (1868) andThe Descent of Manand Selection in Relation to Sex (1871).Charles Darwins work laid the foundation of modern evolutionary biology. And although it is now known that species have evolvedover time, yet it is unclear how this has happened.
  7. 7. CONTROVERSITYThe current dispute between the religious vision of life and the scientific explanation of evolution that Darwin wassomewhat expected, perhaps not with the violence that occurred. Four days before The Origin of Species by Means ofNatural Selection went on sale, a review attacked the work for implying that man came from monkeys, and for believingthat man "born yesterday morning and perish ».The idea that species changed over time was seething in the first half of the nineteenth century. See, like Darwin, thevarious species of Galapagos finches, adapted to different ecological niches and needs of survival, suggesting that they allcame from a common ancestor, and had changed to suit different environments.The idea of the transmutation of species was rejected by the religious establishment and favored by scientists. But he couldstill be acceptable in religious vision. Leifchild, author of the review against Darwin, stated: "Why build another theory toexclude the Deity of the acts of creation renewed? Why not admit once that new species were introduced by the creativeenergy of the Almighty? "