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Significance and Criticism of Darwin’s Theory
Charles Darwin, an English scientist of the nineteenth century, studied nature for nearly 20 years. He gathered observations on animal distribution and the relationship between living and extinct animals, eventually discovering that the current living animals share some similarities not only with one another but also with other species that existed millions of years ago, some of which have become extinct.
Significance of Darwin
Darwin's idea of natural selection destroyed all previous myths and beliefs. He provided a more reasonable explanation for the emergence of new species. Darwin's "Descent with modification" theory provided insight into evolutionary biology. He claimed that evolution is a long, progressive process in which lineages descend from a common ancestor in an unbroken chain, enduring significant alterations as they do so.
The initial species that diverge from the common ancestor are relatively similar but acquire differences over multiple generations and eventually vary significantly. Thus, Darwin was the first to demonstrate clearly that the properties of biological lineages change throughout time. His theory of natural selection and the thesis that changes in distinct people occur due to their capacity to live, reproduce, and adapt to their environment. Unlike Lamarck's linear idea, Darwin believed that evolution occurred branchingly.
To explain the method of inheritance, Darwin presented the notion of pangenesis in 1868. This hypothesis holds that every somatic cell in the body creates minute hereditary units known as pangenes or gemmules. He claimed that the blood transported these pangenes from the body's somatic cells and deposited them in germ cells. According to Darwin, gemmules are continually created at all phases of development. However, Weisman had previously presented the "theory of germplasm," which contradicts the pangenesis idea.
It should be noted that Darwin was not the only one researching natural selection at the time; other evolutionary scientists were also working on the same topics. Thomas Malthus' article on the "Principle of Population" also influenced Alfred Russell Wallace. He researched several species in Asia and the Amazon River area in South America and reached the same conclusion as Darwin.
The distinction between their work was that Darwin felt evolution was driven by competition between individuals, whereas Wallace believed the environment drove evolution. He claimed that animals evolved to adapt to their changing surroundings.
Criticism of Darwin's Theory
Darwin had no understanding of heredity. He could not explain where these inherited differences originated from. He was unable to explain the genesis of variety.
Darwin discussed survival of the fittest but was unable to explain the arrival of the fittest.
He could only explain the inheritance of helpful variants, not the inheritance of non-useful variations.
Natural selection is not the only source of new species. He knew nothing about mutations.
He emphasized minor and cumulative differences, claiming that they were directed.
Challenges to Darwinism
Even when molecular genetics was making significant advances in the excellent resolution of gene resolution using techniques like nucleotide sequencing and aminoacid sequencing in the 1960s, there were objections to the synthetic theory of evolution from molecular geneticists. They discovered several sequences of nucleotides repeated many thousand times in the genomes of humans and other creatures but with no function. Such meaningless and functionless gene duplications led to the conclusion that natural selection did not influence such acts.
According to molecular geneticists, some mutations were neutral and did not affect organism survival. This idea, known as the Neutralists theory, suggested that most evolutionary processes did not need natural selection. Natural selection theory proponents later argued that the assertion of molecular geneticists was false because neutralists mistook the average rate of evolution for a constant pace.
Paleontologists headed by S.J. Gould questioned the synthetic idea in the 1970s. They hypothesized that the fossil record demonstrated that evolution happened in spurts separated by vast periods of equilibrium or stagnation. Contrary to the phyletic gradualism in the current synthesis, the punctuated equilibrium hypothesis stated that evolution happened in jerks. With his adaptive grid model, G.G. Simpson demonstrated that organisms evolve through narrow and large adaptive zones, with nonadaptive zones in between—organisms that enter a limited adaptation zone face intensive natural selection - the period of seeming immobility.
As a result, the periods of stasis were also times when natural selection was active. As a result, the present synthesis theory of evolution has weathered the tests offered by several disciplines and cannot be refuted.
Although Darwin talked little about human evolution, this does not imply that Darwin considered human evolution differently than other species. Darwin predicted that "light will be shed on man's origin and history." In reality, no human fossils worth mentioning had been discovered during Darwin's time. However, there has been an extensive collection of fossils, especially from Africa, since the 1920s. These fossils have linked human evolution back to ape-like origins.
As a result, the contemporary synthesis theory of evolution provides the most plausible answers to the different difficulties offered by evolutionary biology. Evolution is a never-ending process. What happens after human evolution is a frequently addressed issue. The solution may not be straightforward, but increased efforts will be made to get a more profound and fuller knowledge of the current evolutionary process. Then our grasp of evolution could increase much further.
Darwin's theory of natural selection provided insight into evolutionary biology, demonstrating that changes in distinct people occur due to their capacity to live, reproduce, and adapt to their environment. He also presented the notion of pangenesis, which contradicted Weisman's theory of germplasm.
The present synthesis theory of evolution has weathered the tests offered by several disciplines and cannot be refuted. It provides the most plausible answers to the different difficulties offered by evolutionary biology, and the solution may not be straightforward.
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