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Download 2.1.5 Darwin`s evolution
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Darwin's Theory of Evolution The basic idea behind the theory of evolution is that all the different species have evolved from simple life forms. These simple life forms first developed more than three billion years ago - the Earth is about 4.5 billion years old. After studying animals and insects from different countries, Darwin came to the conclusion that all living things had evolved over a period of time to suit the environment in which they found themselves. Each generation of animal improved and evolved to survive. Natural selection The theory of evolution states that evolution happens by natural selection. Here are the key points: Individuals in a species show a wide range of variation. This variation is because of differences in genes (genetic material inherited from our parent). Individuals with characteristics most suited to the environment are more likely to survive and reproduce. The genes that allowed the individuals to be successful are passed to the offspring in the next generation. Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed to the next generation. Given enough time, a species will gradually evolve. Evidence for evolution - fossils Most of the evidence for evolution comes from the fossil record. Fossils show how much, or how little, organisms have changed over time. One of the problems with the fossil record is that it contains gaps. Not all organisms fossilise well, and there will be many fossils that have been destroyed by the movements of the Earth, or simply not yet been discovered. Evidence for evolution - rapid changes Evolution is difficult to observe because it usually takes many years to happen. This is one reason why the theory of evolution is still a theory, not a law. Since no-one was around millions of years ago to make observations, take notes and carry out experiments, evolution cannot be proved in the usual scientific sense. However, rapid changes in species have been observed that support the theory. According to scientists, apes have common genetic material with human beings, and this indicates that humans evolved from apes. Extinction Individuals that are poorly adapted to their environment are less likely to survive and reproduce than those that are well adapted. Similarly, it is possible that a species that is poorly adapted to its environment will not survive and will become extinct. The fossil record shows that many species have become extinct since life on Earth began. Extinction is still happening and a lot of it occurs because of human activities. We compete with other living things for space, food and water, and we are very successful predators. How does Darwin’s theory challenge a belief in God? Darwin’s theory suggests that God did not create all life uniquely; rather, all life evolved from one source. The theory of evolution casts doubt on the Genesis account of creation because scientists argue that life on earth evolved during a period of over three billion years and not six days. Also, scientists argue that human beings have evolved from apes because of the genetic material we share, rather than from Adam and Eve. Therefore, many people reject the idea of God (atheists) because they cannot accept the Genesis account of creation.