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Evolution Outline

Evidence of Evolution • Fossil Records • Geographic distribution of living things • Homologous structures of organisms • Similarities in early development Fossil Records • Darwin proposed that Earth was millions of years old, not thousands. • During those millions of years, many different forms of species appeared, lived for a time, and then vanished leaving behind remains, or fossils. • One can examine fossils and view the changes of each one; observe the changes in offspring. Geographic Distribution • Each species is slightly different on Island A. Far away, on Island B, the species were also slightly different. • The species had changed over time as the populations in different places adapted to local environments. • The species had descended with modifications from a mainland ancestor – when Island A and Island B were combined as a contiguous land mass. • Different species exist on Island C and Island D. Similar structure and behavior were found in different animals which roamed similar environments. • As a result, one can conclude that the species now living on different islands had descended from different ancestors. • Some species, however, are similar because they were living under similar ecological conditions and thus exposed to similar pressures of natural selection. - Different animals ended up evolving certain striking features in common. Homologous Body Structures • Look at mammals, reptiles, and birds; each of those creatures has backbones. There are striking similarities, like limbs. - Some limbs are arms, some are legs; they can also be wings, or even flippers. Each limb has a different form and function, but all are composed of the same basic bones. • Each limb had adapted in ways so the organism can survive in different conditions. • Despite the different functions, limb bones all developed from the same clumps of cells in growing embryos; these are...

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Evolution Outline. (1969, December 31). In DirectEssays.com. Retrieved 08:05, August 21, 2014, from http://www.megaessays.com/viewpaper/22587.html