Evolution theory explains about the history and origin of life. Scientists of the early age tried to explain the origin of life but they did not have any theories that could support their thoughts. The reigning paradigm at that time was the, “Natural theology”. The naturalist of the time believed that everything in the world had a key role in the economic of nature and the credit was given to an intelligent creator. In 1809 a French scientist Jean Larmarck came up with the first mechanism of evolution which he called “The inheritance of acquired characteristics.” Using the salamanders to explain his theory, he argued that salamanders lived in grassland making it very hard to make use of their short legs. With time the leg muscles became wasted due to lack of usage. They eventually passed this trait to their offspring and thus the emergence of legless salamanders by the virtue of inheriting the characteristic of having no legs. This theory did not stand the test of time as he did not present any experimental evidence and as result his theory collapsed (Freeman 24).
Charles Darwin born on February 12, 1809 in England became the most famous scientist for his theories of evolution. His first profession was medicine which he found hard to cope with. One major reason that made Darwin become more interested in life is his health condition where he suffered from sea sickness. As he grew up, he was a good reader of nature books and he spent most of his time exploring the environment around him collecting samples of plants and insects. Like all scientist he believed that life originated from a common ancestor gradually over millions of years (Darwin 3).
Darwin served as a naturalist on a British science expedition from 1831 to 1836. In 1831, he embarked on a journey to South America to carry out surveying work. In his trip, he read “Principles of geology,” by Charles Lyell which made him become interested in land forms (Darwin 10). He observed the aftermath of earth quakes and also the fossil shells of marine organisms. He supported the idea of Lyell that over time, earth quakes and Geologic processes would change land forms. He also realized that the species on the land had to adapt to this changes. He explored remote regions where he collected and recorded notes on plants, animals and fossils of extinct animals that were similar to modern species. As the expedition extended to different places, Darwin kept on collecting samples for further studies. It was in the Galapagos Islands in the Pacific Ocean that he noticed variations among plants and animals of the same type as those he had observed in South America.
In 1836, he returned to England where he spent considerable time conducting research and analysis on the samples that he had collected. Charles had collected finches from the Galapagos Island for his experiment. This helped him to form the ideas on natural selection. He sent this specimen to a bird’s specialist who reported that he had collected 13 similar but separate species of finches. (Darwin 20).
He observed that birds of this island were different from birds of another island in respect to the beak shape, the source of food and how it was captured. He discovered that this was as a result of the different environments the birds lived in. Birds in the different environments had variances in the shape and the size of their beak.
These variances were based on the kind of foods that the birds were feeding on. The birds had to adapt to their new environments and gradually they changed automatically in such a way that they were able to feed and reproduce. (Darwin 26).
Birds that had beaks suited for eating cactus survived in the arid areas while the ones that had beaks suited for nectar survived in different environment. Studies on the fossils that he had collected led to the classification of the remains of extinct mammals. He spent several years looking for evidence on his fossil record. His experiment involved fossils of different ages and he observed that fossils of relative ages were closely related than fossils of other relative ages. He compared the homologous structures, vestical organs and embryological developments of living species. He observed the changes in the domestic animal and plant breeds besides his personal breeds and experiments on seed dispersal.
In reference to the similarities observed in the finches, Darwin concluded that they had a common ancestor. The similarities between the fossils of the mammals and the modern mammals led him to believe that species changed overtime. (Freeman 34).
He observed that evolution actually occurred and that it was gradual over a long period of time. He also observed that evolution mechanism occurred through a process of natural section and that the different species today originated from one ancestor through a branching process called speciation. He noticed that in the process of natural selection, the animals or plants with characteristics best suited to their environment were more likely to survive and reproduce while the weak ones became extinct. He called this survival for the fittest. The desirable characteristics were passed on to the offspring and with time, they became common and this brought change to the species. If these changes were strong and dominant then they could produce a new species.
In 1938, Charles read, “The Essay on the principle of population” by Thomas Malthus (Darwin 16). The ideas of Malthus influenced Darwin in how the populations competed for resources in order to survive. Resources are scarce and the population therefore had to compete for them. Competition meant that the weak species would die making the individuals with advantageous variations to survive and reproduce.
In 1959, Charles Darwin published his theory to explain the origin of life in the entire human, animal and the plant species in a book he called, “The origin of species”( Freeman 28). His paradigm of natural selection depicts that life came from one common ancestor and it is also related.
This theory argues that life developed from non-life through a process of natural selection. The process of natural selection explains that complex creatures evolve from simple creatures over time, by the preservation of advantageous mutations that guarantee survival. (Darwin 30).
Complex organs are formed following numerous successful slight modifications. As the process of natural selection progresses, the inferior species are faced out.
Charles believed that variations were not as result of the environment but that they were already inexistence. Nature selected unconsciously individuals and plants suited for its conditions. In the natural process, the favorable traits in the species are passed on to the other generations through reproduction.
In summary, the process of evolution according to Darwin is characterized by variations in every population; species have to compete for the scarce resources, the species reproduce offspring with traits suitable for survival, the offspring bear genetic traits and that survival and reproduction is based on the natural selection (Darwin 46).
Darwin’s theory was faced with challenges. His paradigm was followed by opposing paradigms such as the interpretation by the religious bodies. It was met with mixed reactions especially by the religious bodies who believed that life was as a result of God’s creation as explained in Bible in the book of genesis. The theory therefore suggested that God had not created perfect creatures in the beginning. The idea of changes in the species collided with the Christian faith where humans had a special place in the world and superior to all other living things (Darwin 40). This brought the paradigm of, “Intelligent design”. This paradigm tries to link science and theology. The intellectual movement tries to challenge the naturalistic evolutionary theories by trying to bring understanding of the divine action. This paradigm brings to surface why the significance of miracles should be considered in evolution and also points out he questions that were not addresses in the natural theology.
Darwin unlike his predecessors brought forth a contribution that had gathered indisputable evidence. This theory overshadowed believes that life came from ancestral Gods. Darwin was able to accompany his theory with tested experiments which supported his studies a great deal. Many scientists became convinced that life was as a result of natural selection. This theory is still relied upon by the modern scientist (Freeman 48).
Work Cited
Charles Darwin. The Origin of the Species By Means Of Natural Selection.Uk John Murray: 1959, (03-48).
Darwin’s theory of evolution. Web.
Derek Freeman. The evolutionary Theories of Charles Darwin and Herbert Spencer. London: Taylor $Francis, Vol 15, 1974 (24-55).