Questions Regarding Darwin’s Theory Essay

Darwin’s theory of natural selection is revolutionary and he himself is aware of the many difficulties that critiques might throw at him. In his book, â€Å"The Origin of the Species,† he explored these difficulties beginning with the question as to why there are often no intermediate or middle forms between species that are closely related. His answer to this is that the tough competition in nature combined with the small number of intermediate forms often led to their extinction. Only the well-adapted species survive in the wild, and so intermediate forms that don’t have the most adaptive characteristics are easily wiped out from nature. One of the key ideas in Darwin’s theory is that adaptive characteristics in animals are formed through time by numerous tiny modifications. He then posed the question whether it is possible for an animal to acquire certain characteristics that don’t fit its requirements for adaptation. He cited the fact that in most cases, animals have intermediate features that are adaptive to their needs. Thus, for example, flying squirrels may have evolved from simple squirrels and bats may have evolved from flying lemurs (Wichler, 1961, p. 35). There are also invertebrates with very simple eyes that consist of nothing more than pigment-coated optic nerves. Animals with more complex eye structures could have evolved from these creatures with very simple eyes. Darwin stated that his theory could be debunked if it could be illustrated that there are complex organs in nature that did not develop through numerous slight modifications through time (Wichler, 1961, p. 55). He concluded that since he couldn’t find such a case in nature, then his theory still was still true. Evolution does not only manifest in the physical characteristics of organisms, but also in their behavior. Darwin addressed the question of the development of complex behavior by discussing the behaviors of slave-making ants and honey bees that construct hexagonal cells in their hives. He explained that there is a wide range of patterns of behavior among different species. Ants that depend on slavery to survive may have evolved from ants that don’t need such behavior to exist. Similarly, honey bees that make hexagonal cells in their hives may have evolved from honey bees that make circular cells in their hives to reduce the use of wax. He concluded that the behaviors or instincts of organisms are not specially created, but rather result from the process of natural selection where, in a population with varied behaviors, only the fittest survive and the unfit, perish (Wichler, 1961, p. 60). During Darwin’s time, the primary belief is that hybridization is not possible because species have features that prevented fertile and viable hybrids from existing, which preserved the separation of species. Darwin argued that this was not the case, and that the difficulty of producing fertile and viable hybrids differed from one species to another, especially among plant species. There are cases where what were believed to be completely different species resulted in fertile viable hybrids, and cases where organisms that were believed to be varieties under the same species couldn’t easily produce hybrids. Darwin concluded that his theory of natural selection supported the idea that there are no fundamental differences between varieties and species (Arthur, 1987, p. 12). Supporting Research on Darwin’s Theory of Evolution Since Darwin’s time, a lot of progress has been made regarding his theory of evolution through natural selection. Today, biologists all over the world have synthesized the developments that were made for many years, resulting in the new synthesis of evolutionary theory. This synthesis draws ideas from the many branches of the discipline of biology, namely: paleontology, ecology, morphology, botany, systematics, cytology, and genetics (Arthur, 1987, p. 9). The new synthesis became possible because of the introduction of a reliable model of heredity, and the reconciliation of this model with models of natural selection emphasizing gradual evolutionary modifications through time. Scientists accepted many facets of Darwin’s theory and rejected some. Thinkers like August Weismann and Alfred Russel Wallace advocated neo-Darwinism which heavily emphasizes natural selection as a tool of evolution. They rejected Darwin’s claim that acquired characteristics also play a part in evolution. Today, the core concept of neo-Darwinism is understood as natural selection driving evolution with variations generated by recombination and genetic mutation (Arthur, 1987, p. 32). The search for a reliable model of heredity consistent with Darwin’s theory of natural selection led to a long debate by proponents of two schools of though: Mendelism and biometrics. Mendelians believed in Gregor Mendel’s research which was previously conceived to be incompatible with Darwin’s theory of natural selection. They believed that Mendel’s conclusions are compatible with saltationism however, which demonstrated evolution through jumps or big mutations. Karl Pearson and other biometrics opposed the Mendelians claiming empirical evidence pointed to the fact that variation was evidently continuous and not discrete in many organisms. Thus, Mendelism couldn’t be combined with Darwin’s theory during that time, and the Mendelians and biometricians debated hotly for about 20 years (Arthur, 1987, p. 40). Synthesis between Mendel’s and Darwin’s work only became possible through research conducted by RA Fisher, Sewall Wright and JBS Haldane. Fisher demonstrated how continuous variation observed by biometricians could result from the actions of several different genetic loci. Through this research, Fisher was able to establish that contrary to popular thinking, Mendelian genetics was consistent with Darwin’s idea of evolution through natural selection. JBS Haldane supported Fisher’s work by applying mathematical analyses to instances of natural selection in the real world. Haldane concluded that natural selection may work at a faster rate in the real world than Fisher assumed. Sewall Wright’s work further facilitated the synthesis of evolutionary theory by demonstrating genetic drift through the interactions of genetic combinations and inbreeding in small isolated populations (Gould, 1979, p. 20). Work on evolution by field naturalists and population geneticists was synthesized by Theodosius Dobzhansky. In his work, Dobhansky showed that populations in the real world had more genetic variations than many population geneticists assumed. Dobzhansky demonstrated that Darwin’s natural selection maintained genetic diversity in the population and drove changes in the forms of species (Gould, 1979, p. 25). Dobzhansky’s work was complemented by another researcher, Edmund Brisco Ford. Modern ecological genetics draws heavily from Ford’s work that showed how natural selection worked in nature. Ford studied populations of wild moths and butterflies in nature, which verified Fisher’s predictions. Ford was also the first to define and describe genetic polymorphism and its role in human populations to provide protection against diseases (Williams, 2001, p. 45). The correlation between variations in different populations and environmental factors like climate was first established by Bernhard Rensch, a German biologist. Rensch’s work influenced Ernst Mayr who emphasized the significance of the geographical isolation of sub-populations in evolution (Williams, 2001, p. 50). The modern or new synthesis of evolutionary theory was further explored by George Gaylord Simpson who showed that paleontology was compatible with evolution. Simpson’s research was crucial because at that time, many paleontologists disagreed that natural selection was the driving force of evolution. Simpson explained how fossil records were consistent with the synthesized theory of evolution which depicted evolution as having irregular branches, instead of linear. Research on natural selection did not only focus on animals through the years. G Ledyard Stebbins, a botanist, contributed to the new synthesis by showing hybridization’s effects in some types of plants. After the many advances made in the 1930s and 1940s, the new evolutionary synthesis was refined even further by the works of John Maynard Smith, George C. Williams, and WD Hamilton. These scientists took Darwin’s ideas and refocused them to a view of evolution that concentrated on the genetic level. Today, the new synthesis, with Darwin’s discovery of natural selection at its core, encompasses other scientific fields and concepts such as genetics and DNA. New discoveries like these allow Darwin’s concepts to be analyzed mathematically, producing vital information on selection, speciation, and altruism. Darwin’s theory is continuously being reviewed by evolutionary biologists today. One interpretation of the theory is by Richard Dawkins who asserted that the only real unit of selection is the gene. Dawkins also applied Darwin’s idea of the survival of the fittest to realms outside biology. For instance, he utilized the concept of natural selection to analyze cultural memes. Scientists and experts from different fields are continuously reviewing Darwin’s theory to explore its usefulness to biology and other disciplines. Conclusion Charles Darwin’s seminal work on evolution through natural selection is very important in understanding how species attained their physical forms and specialized behaviors in nature. It debunked the belief that the forms of species are constant because they are reflections in the mind of god. Instead, Darwin showed that species are forever changing through tiny modifications in their physical aspects and behavior through time. Darwin was also the first to explore the fact that there are no significant differences between variations and species. While many thinkers of the time believed that different species cannot produce hybrids because they have characteristics that prevented them from doing so, Darwin showed how the difficulty of hybridization differed from one species to another. Thus, the tiny differences in the forms and behaviors of organisms are the essential driving force of evolution. Darwin’s theory was not solid however because of the lack of a reliable model of genetics to aide his observations. For this reason, Darwin accepted Lamarck’s view that acquired characteristics can also drive evolution. Darwin thought that the use and disuse of animals of their certain parts had effects on the evolution of a particular species. This flaw however, did not discredit Darwin’s more important observations on how natural selection drives evolution. The theory of natural selection is also important in understanding variations in organisms that exist today. Darwin was able to demonstrate how one species could have evolved from another to adapt to their environment. For instance, flying squirrels may have evolved from simple squirrels to get the food that they need to survive more easily. Complex structures of organs, such as a human’s hand, for instance, could have developed from the simple hands of a creature which other primates share ancestry with. Today, the concept of the survival of the fittest is not only important in the field of evolutionary biology but also in other disciplines, such as social theory and economics. Scientists today are continuously exploring Darwin’s ideas to develop more sound concepts. These concepts should be helpful in understanding how nature works and how humans might respond to its mechanisms. Humans can base agricultural and conservation practices on the many facets of Darwin’s theory to produce useful results in the real world. Evolution today is continuously happening and Darwin’s theory is a vital scientific tool to understand this process and apply it to real-world problems. References Arthur, W. (1987). Theories of Life: Darwin, Mendel, and Beyond. London: Penguin Books. Cuvier, G., et al. (2003). The Evolution Debate, 1813-1870. London: Routledge. Darwin, C. , et al. (1996). On evolution: the development of the theory of natural selection. Indianapolis: Hackett Publishing. Endler, J. & A. Endler . (1986). Natural Selection in the Wild. New Jersey: Princeton University Press. Gould, S. J. (1979). Ever Since Darwin: Reflections in Natural History. New York: Norton Wichler, G.. (1961). Charles Darwin: the founder of the theory of evolution and natural selection. London: Pergamon Press. Williams, G. C. (2001). Adaptation and Natural Selection. New Jersey: Princeton University Press.