There are many theories that try and explain how Humans evolved. The Human evolutionary theory is one such formulation that has evolved from its basic form as propounded by Charles Darwin to include many other facets and disciplines. This essay focuses on the concepts of human evolutionary theory.
The earliest best-known theory of evolution was propounded by Charles Darwin, whose main thesis was that life has evolved from simple single-celled organisms to multi-cellular, complex living things through the process of natural selection and the primacy of the ‘survival of the fittest. According to Darwin, the environment forced organisms to adapt and led to incremental and random genetic mutations that equipped certain species to cope up and survive better than the others. These random genetic mutations became reinforced in successful species, and those that could not cope up with the environment suffered extinction. Darwin (1859) states that “Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap but must advance by short and sure, though slow steps” (p. 244). Man, too has arisen out of this process of natural selection.
In his thesis ‘The Descent of Man’ Darwin holds that man probably evolved from apes. Darwin(1871) theorizes that man’s position as the most dominant species was a result of his “intellectual faculties, to his social habits, which lead him to aid and defend his fellows, and to his corporeal structure” (p. 67). Darwin further adds that “through his powers of intellect, articulate language has been evolved; and on this, his wonderful advancement has mainly depended (p. 68)”. Modern evolutionary theory holds much the same conclusions as Darwin that the four main characteristics that made humans the dominant species were, Bipedalism; his ability to walk erect, thumb opposing the fingers, a cognitive intellect, and the power of the speech, which allowed the social organization of the highest degree.
The evolutionary theory holds that evolution is a product of natural selection, genetic drift, and gene flow. According to the natural selection mechanism, a genetic mutation that leads to the further reproductive success of an organism is reinforced, leading to a stronger organism that will survive over the other organism which does not have the beneficial mutation. These mutations happen gradually, very slowly over time to be beneficial. The evolutionary theory holds that most mutations are deleterious or harmful, and it is only the slow pace of mutation that allows for adaptation and reinforcement of the species.. However, that does not explain how humans have not mutated to more ‘horrible forms’ and have yet retained their beneficial traits. The reason is that since humans carry two sets of genes, one from the father and one from the mother, the ‘bad genes’ inherited from one of the parents get compensated by the genes of the other parent.
The evolutionary theory of humans has many detractors, who point to some significant gaps in information. For example, the evolutionary theory has till to date been unable to explain the ‘missing link’ between the theorized evolution of humans from Neanderthals to Homo sapiens and whether all humans originated ‘out of Africa’ or evolved differently in different parts of the world at the same time. Despite some promising paleontological finds in Ethiopia, the absolute validity of the evolutionary theory is a long way off from universal acceptance.
Works Cited
Darwin, C., & Darwin, F. (1896). On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. NY: D Appleton and Company.
Darwin, C., Desmond, A., & Moore, J. (2004). The Descent of Man (1871). London: Penguin Classics.