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Darwin's Theory Of Natural Selection

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Although up into the nineteenth century it was common belief that a divine being created life, life has evolved since its first appearance about 3.8 billion years ago. Darwin claimed in his book, On the Origins of Species published in 1859, because “ ...many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence…” small variations that occur in the mutation of genes and genetic recombination during reproduction. Some of these variations are bound to be better suited to their environment and will succeed. Those that are less favorable are bound to fail. This is a process called natural selection. This genetic advantage increases the likelihood that the …show more content…

An example of adaptation through natural selection is that of Darwin’s Galapagos Finches. On his voyage to South America, Darwin collected finches from each of the fourteen islands of the Galapagos. After examining his specimens, Darwin discovered that there were about a dozen of different species that had adapted to deal with the different kinds of seeds on their different native islands. On each island, over time, small variations were developed that were better suited to collect food eventually became dominant in the finches of the island. Henceforth emerged a new species. According to Big History, there are six key moments of life where new species with traits better suited to survive their environment emerged. Three and a half billion years ago, cells, known as prokaryotes, migrated from ocean rifts to the ocean surface. These prokaryotes evolved to process the vastly more abundant energy from the sun, in a processing system called photosynthesis. Oxygen is a byproduct of photosynthesis and over millions of years the photosynthesizing prokaryotes greatly transformed the atmosphere, from one rich in carbon to one rich in …show more content…

One billion years ago the first multicellular organisms appeared. Eukaryotes came together to form complex life forms. These organisms could contain billions of cells, each which had a different function. These multicellular organisms all shared the same DNA and could coordinate, cooperate, and evolve. The next key moment of life was the development of brains and spines. Multicellular organisms needed a way to coordinate all activities inside them; this was the job of special nerve cells. These nerve cells began to cluster in the head and down the spine, which created the first brain and spinal cord. Organisms with brains were much better suited to survive because they could process much more information than those without, react in complex ways, think, participate in more sophisticated activities, and maybe even reach a level of consciousness. About 475 million years ago life began to move onto land. The first multi-celled organisms to move on to land were plants and fungi. To survive on land organisms had to develop special skin cells to avoid drying out, ways to breathe out of water, and new ways to

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