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Evolution of Life Forms

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Evolution of Life Forms - Lesson Summary

For many years, there has been speculation and fascinating stories about the creation of the earth and its numerous species. Most religions believe in divine creation of the world by assuming that an omnipotent God created the earth and its varied species. These religious theories have three connotations. First, that all living organisms around us have not evolved over time but are just as they were when originally created. Second, diversity among living organisms has been uniform since the time of creation and will continue to be the same in future as well. Third, that the earth is only four thousand years old.
These ideas faced opposition in the nineteenth century when English naturalist Charles Robert Darwin suggested that complex organisms have evolved from simple ancestors.
In December 1831, Darwin went on a five-year-long voyage in a ship, during this time, he conducted various natural history collections and studied the geology of many places. He published the Theory of Evolution in 1859 in his book ‘On The Origin Of Species’. Darwin pointed out that existing living forms share similarities to varying degrees among themselves as well as with life forms that existed millions of years ago. Several life forms have become extinct now. However, new forms of life have also come into existence during different periods of time. Therefore, life forms are constantly undergoing evolution. Darwin pointed out that natural selection was the mechanism of evolution. According to this concept, any population of organisms that adapts itself more readily to the natural conditions such as climate, food and physical factors has a better chance of survival. Darwin primarily emphasised the importance of reproductive fitness of the individual or the population. In other words, organisms with good fitness outbreed the others and therefore they are selected by nature. Natural selection preserves and accumulates advantageous genetic mutations.
Another British naturalist, Alfred Wallace, a contemporary of Charles Darwin, made similar observations by proposing the theory of evolution due to natural selection. Wallace did extensive field work in the Amazon River Basin and the Malay Archipelago. He also came to the conclusion that existing life forms share similarities and common ancestors which were present during different periods of the earth’s history. The Theory of Evolution most certainly established that the earth is billions of years old. It was also a path breaking theory because, it demystified the idea of divine creation.

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