The Origin of Life - from Single-Celled to Intelligent Beings - Term Paper Example

The major component of Darwin’s Theory of Evolution is natural selection in which, beneficial mutations are persevered in the organism’s genetic code to help aid survival, as a mechanism of evolution that focused on adaptations of the Candollean system. It has made us realize that organisms are what they are now because of the totality of the environmental factors that they are subjected to and that determine the characteristics that will be passed on from generation to generation.

Because the terrain on Earth ranges from water to land, we see different organisms with their respective identifying characteristics that are essential to their existence. Although life on Earth has been existent for billions of years already, the organisms that it holds do not steadily increase with time. Through dinosaurs and other fossils, we are made aware of the fact that the composition of life on Earth change as much as its environment does. Indeed, the success of a species lies on their ability to survive the ever-changing surroundings.

  A major, catastrophic event, such as asteroid impacts, volcano eruptions, a release of methane gas, that changes the Earth is capable of changing the biological composition of the planet as well. During the Ordovician Period (48.4 to 443.7 mya) of the Paleozoic Era (570 to 290 mya), the oceans were dominated by a wide range of aquatic organisms:  invertebrates, such as mollusks and arthropods; the reef ecosystem, such as algae and sponges; and the first true evolving vertebrates, jawless fish.

  The Ordovician strata exhibited large numbers of varied conodonts, trilobites, blastoids, corals, snails, clams, cephalopods, crinoids, bryozoans, and osteoderms.  The most eventful occurrence was the beginning of land colonization with the diversity of life from the oceans.  However, ice age resulted in mass extinctions. High sea levels and a warm global climate during the Devonian period (416 to 359.2 mya) created key diversity and lineages of fish. The poor penetration of sunlight leads to natural selection in favor of free-sporing vascular plants that began to spread across the dry land.