It is now over 150 years since when Charles Darwin proposed one of the influential theories, the theory of evolution, through natural selection in human history. At its youngest years, the theory faced immense controversies. People inclined to evangelical conservatism came out to counter it via mega campaigns. At the same time, progressive intellectuals coupled with liberal-minded people were also not left out of controversy.
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Nevertheless, these controversies have not ceded. Even in the modern world, the theory of evolution through natural selection also attracts valid contest from a scientific society. In his scholarly work, The Origin of Species by Means of Natural Selection, Darwin prophesies, “in the distant future, I see open fields for far more important researches where psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation” (Darwin, 1859, p. 449). Today, this dream of Darwin is arguably realized. Evolutionary psychology has resulted in altering the manner in which psychologists conduct their studies on the human mind. Indeed, it is permitting psychologists to introspect human behaviors in more fascinating dimensions.
Nonetheless, the progression of any discipline attracts mixed reactions and ways of contextualizing the whole process of progression. Psychology, being one of the disciplines that call for the immense deployment of the power of reasoning, does not give clean pathways for the progression of the evolutional theory by natural selection in a way that Darwin could have anticipated. However, the concern here is not to explore why the theory of natural selection faces criticism. Rather, the aim is to discuss the manner in which Darwin formulated the theory of natural selection coupled with how his notion has changed since the modern synthesis.
How Darwin formulated the theory of natural selection
The popularisation of the term natural selection is owed to the scholarly works of Charles Darwin. In particular, his aim was to make his theory comparable with “the theory of selective breeding, what was priory termed as artificial selection” (Keightley & Otto, 2006, p.89). Natural selection entails a slow and gradual process through which certain biological traits of the population become more or even less common due to the deferential reproduction of the trait bearers.
Darwin noted that variation always takes place across all organisms in populations. In the modem day evolutionary psychology body of knowledge, among the contributors to these variations are random mutations, which lead to alterations of genomes of organisms. Such mutations are hereditary. During the lives of organisms, “…genomes interact with the environment-cells, other individuals, other cells, species and even abiotic surroundings” (Keightley & Otto, 2006, p.90).
However, in the context of Darwin’s theory, under natural circumstances, certain organisms that possess some variant traits may end up surviving and reproducing more than those that possess other variant traits. This way, the evolution of populations occurs. In his ideas of sexual selection, Darwin recognized, “the factors that influenced reproduction success were also critical in the evolution process” (Keightley & Otto, 2006, p.89). However, in times of Darwin, the theory of hereditary was not eminently developed. Consequently, his natural selection theory was developed in relation to phenotypic traits of organisms.
This means that natural selection theory operates on observable characteristics of organisms. With the knowledge of genetics, the natural selection theory process proposed by Charles Darwin acts as one of the processes through which the evolution of organisms may take place. In this context, Keightley and Otto (2006) note, “opposed to artificial selection, in which humans favor specific traits, in natural selection the environment acts as sieve through which only certain variations can pass” (p. 90). Since its proposal in 1859, the theory of natural selection has been a central cornerstone in the development of modern biology and evolutionary psychology.
Darwin formulated his theory of natural selection in a style similar to artificial selection in which people (breeders) choose certain traits in animals and plants for reproduction purposes. In this context, Darwin formulated his theory as a means of explaining speciation and adaptation. Precisely, the scholar wrote that natural selection is the “principle by which each slight variation (of a trait), if useful, is preserved (Darwin, 1859, p.331).
In this perspective, the concept of natural selection is simple but insightful as to what Darwin thought encompassed the evolution of species. At the heart of the theory, Darwin infers that only those individuals that are well suited to the new environments in which they live stand better chances of surviving so that they can reproduce. This means, “As long as there is some variation between them, there will be an inevitable selection of individuals with the most advantageous variations” (Keightley & Otto, 2006, p.91).
Therefore, according to Darwin, in the case of inheritance of variations, chances are that the success of differential reproduction truncates into making certain species of certain populations of organism evolve and become magnificently different from the original species. Prior to the postulation of Darwin’s theory of natural selection, reverend Thomas Malthus had noted in 1938 that, in case a population went on growing freely without checks, it grew in an exponential function while food supplies only grew arithmetically. Consequently, it is reasonable that, to maintain a balance between the two, a natural mechanism of the balance must exist.
In technical language, this implies that “inevitable limitations of resources would have demographic implications leading to straggle for existence” (Kauffman, 1993, p.81). In his formulation of the theory of natural selection, Darwin was smart enough to factor in the concept of the struggle for existence so that a population does not out power the resources provisions to support the growing population numbers. In this dimension, Darwin held that in a situation where the population may result powering resource provisions, naturally “favorable variations would tend to be preserved and unfavorable ones to be destroyed” (Kauffman, 1993, p.81).
The repercussion would be the emergence of new species. In chapter four of the origin of species, Darwin summarised his formulations for his theory of natural selection. He argues that, in the due course of ages of populations and under certain provisions or life conditions, organic beings differ in several elements of their organization. If this is true, he thinks that it is a fact, which cannot be disputed especially bearing in mind that there occurs “high geometrical powers of increase of each species, at some age, season, or year, and a severe struggle for life” (Darwin, 1859, p.234) takes place.
Again, he views this as a fact that cannot be disputed. “Considering the infinite complexity of the relations of all organic beings to each other and to their conditions of existence, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, I think it would be a most extraordinary fact if no variation ever had occurred useful to each being’s own welfare” (Darwin, 1859, p.231).
He further asserts that, in case variations that are useful to particular organic beings take place, those individuals who have the characteristics that are favorable to match the variations would stand better chances of being preserved in the quest to struggle for survival. Consequently, due to the principle of inheritance, such individuals would sire off springs possessing similar traits.
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Stemming from the above discussion, it is evident that Darwin and his like-minded thinkers thought of natural selection as largely being analogous to evolution by means of selective selection. Many scholars appreciated that tantamount to Darwin’s postulations, evolution had actually taken place in some magnitudes. However, they differed in the manner in which Darwin formulated his theory claiming that it did not explain the immense range of observable traits that exist among various organisms.
Eisley (1988) amplifies this position by further adding, “natural selection remained controversial as a mechanism, partly because it was perceived to be too weak to explain the range of observed characteristics of living organisms, and partly because even supporters of evolution balked at its unguided and non-progressive nature” (p.44). Arguably, this is the most crucial argument that has been pinpointed as the most important in the case against acceptance of the ideas of Charles Darwin and his theory of natural selection. However, this does not imply that the theory has not been received positively. The coining of the terms survival for the fittest by Hebert spacer is ideally the short description of the natural selection theory formulated by Darwin. Some scholars embraced the theory in an enthusiastic fashion.
However, inputting Darwin’s theory into perspectives of modern knowledge of genetics and hereditary, clear demarcations can be drawn on the circumstances leading to the evolution and emergence of new species of organization, which are more superior to their former parents. According to natural selection, species evolve to produce others that are better adapted to new environments. This also happens in the evolution of species due to genetic drifts and or mutations. However, the latter is random while the former is not. Rather, natural selection “preferentially selects for different mutations based on differential fitness” (Eisley, 1988, p.73).
Amid the many objections and or acceptance of Darwin’s theory of natural selection, and how it translates into the evolvement of the new species of organism, its concepts are central in the evolution process of evolutional psychology.
In a similar way in which natural selection provides mechanisms of reproduction of those organisms that are well suited to the environmental changes, within the psychology discipline, integration is crucial. This follows because “the fields of psychology remain a divided” (Fitzgerald, 2010, p.285). Amid this non-unification, arguably, many scholars within the sub-disciplines of psychology such as cognitive psychology, behavioral psychology, and social psychology among others have been inculcating the concepts of evolutionary psychology in the foundations of their arguments.
This means that possibilities may exist that all sub-disciplines of the broader discipline of psychology would evolve to deploy evolutionary psychology as its unifying media just as common needs for survival amid environmental changes in Darwin’s theory of natural selection form the media prompting the emergence of new species whose characteristics measure up to the new environmental demands. In this dimension, it is crucial to argue that the emergence of the discipline of evolutionary cognitive neuroscience evidences a merger or integration of cognitive and biological approaches to psychology. This integration has been instigated by a common methodology in both disciplines inspired by concepts of evolutionally meta-theory.
With this desired direction of evolution, the resulting new species is the synthesis of the two approaches to psychology discipline as a whole. This has truncated into the creation of evolutionary psychology as a discipline integrating both cognitive science and biological psychology. This proves the applicability of Darwin’s concepts of evolution by natural selection.
How Darwin’s notion of natural selection has changed since the Modern Synthesis
The modern evolutionary synthesis arose between 1936 and 1947. It reflects a consensus in the manner in which evolution proceeds through bridging of various specialties of biology providing accounts for the manner in which the process of evolution proceeds. Charles Darwin’s notion of evolution by natural selection has been altered by the “modern synthesis in that, modern evolutionary synthesis has brought in additional perspectives such as Gregor Mendel’s’ genetics coupled with the germ theory proposed by August Weismann on how evolution occurs” (Barrett, Dunbar & Lycett, 2001, p.84). In addition to these paradigms, modern evolutionary synthesis is also an amalgamation of other population genetics advances such as paleontology among others.
The notion of Darwin in the theory of natural selection was based on the argument that only organisms that are fit for survival would reproduce and hence maintain the presence of their species. This implied that organisms that were fitter than others were the only ones, which would stand higher chances of transmitting their genes down their generations. Therefore, after a couple of generations, organisms that had genes that were more successful than others would be favored.
It is also important that the process of natural section be subjected to some limiting factors for it to take place. These factors are “variation in a population, a difference in fitness between the different variations, and heredity (the ability to pass on these variations to offspring)” (Gould, 2002, p.41). During the times of Darwin, genetic blending was the most acceptable mechanisms through which heredity took place. Hence, it was akin to the conceptualization of Darwin’s hypothesis of natural selection. This mechanism was evidenced by the interbreeding of mongrels.
However, the notion of natural selection failed to account for reasons why certain favorable “variations are not rapidly lost within a few generations of breeding with normal populace” (Gould, 2002, p.47). In an attempt to provide solutions for this drawback of natural selections, some paradigms of the modern evolutionary synthesis have altered the original notion of Darwin. For instance, Gregor Mendel found out, “alleles (different forms of the same gene) are not changed when inherited; they are not ‘blended’ together, but instead remain distinct and separate in the offspring” (Gould, 2002, p.109). This means that, opposed to the notion of Darwin, variations are maintained within generations hence providing raw materials that create a breeding culture for natural selection to occur.
Modern evolutionary synthesis has also resulted in the updating of the theory of natural selection advanced by Darwin. While Darwin found out that natural selection was a crucial force for evolution, the modern synthesis finds a mutation, genetic drift, and gene flow as crucial forces resulting in the evolution of organisms (Barrett, Dunbar & Lycett, 2001, p.87). These three forces driving the perspective of modern evolutionary synthesis are reserves of the proceeds of populace genetics. Additionally, as Nash (2009) notes, “On the Origin of Species, Darwin struggled to explain how variation could be formed and maintained” (Para.5).
On the other hand, this notion is altered by modern evolutionary synthesis since the modern synthesis articulates mutation as the key driver of the maintenance of genetic variations across individuals within populations. Opposed to Darwin’s notion, the concepts of gene flow are introduced in the modern evolutionary synthesis as a paradigm of explaining how variations take place. Essentially, RNA and DNA flow embraces the transfer of inherent messages across populations. A typical example is where an individual migrates from one place to another creating a mechanism of enhancing accessibility of alleles to populations, which are geographically isolated.
This is significant in the determination of the population’s genetic pool, which in turn helps in fostering natural selection. In the case of genetic drift, it entails “the random fluctuation in frequency of different alleles of comparable fitness” (Gould, 2002, p.113). Under the perspective of genetic drift, a single allele possesses no ability to outcompete in totality with another allele. However, “random sampling errors can have a significant impact especially upon smaller populations; the smaller the population the more likely that one allele is completely lost due to an environmental catastrophe despite, there being no significant disadvantage in bearing one allele over another” (Nash, 2009, Para. 7).
Modern synthesis combines these three paradigms with Darwin’s natural selection theory to arrive at a mathematical model for explaining the way variations occur in populations and hence the evolution of species.
Another critical concern of modern evolutionary synthesis entailed the integration of paleontologists’ findings into the models of evolution. In particular, scholars who studied fossils immensely differed with the postulation of natural selection as the chief driver of the evolution process. Nevertheless, in 1944, the notion of natural selection as an explanation of evolution faced an immense boost following the publication of George Simpson’s (an American biologist) finding that “the achievement of paleontology studies was precisely compatible with the concepts of natural selection coupled with population genetics” (Keightley & Otto, 2006, p.91).
With this argument in mind, it is subtle to conclude that modern evolutionary synthesis brings together naturalists, paleontologists, and geneticists’ perspectives on evolution. This implies that the genetic principles developed by scholars such as Mendel are largely compatible with concepts of evolution as stipulated by natural selection. In this perspective, natural selection acts as the central force that operates on various variations existing in individuals.
However, for these variations to take place, small genetic alterations need to be accumulated in a process that is essentially gradual despite the fact that the changes may also vary at a rate similar to the rate of evolution. The amalgamation of geneticists, naturalists, and paleontologists’ notions of evolution indicate, “Evolution occurs within populations where gene flow and genetic drift can have effects additional to those of selection” (Nash, 2009, Para. 10) in the modern evolutionary synthesis.
Another concept of modern evolutionary synthesis that has caused alteration of the notion of natural selection is the concept of epigenetic. It entails the inheritance of certain genetic systems’ expressions due to changes that are non-genetic. A good example of this entails “the modification of proteins on which DNA is wrapped by environmental changes making the accessibility of the DNA either difficult or easier” (Barrett, Dunbar & Lycett, 2001, p.169).
Consequently, levels of various gene expressions may raise or fall. Hence, the accessibility of the genes is either restricted or enhanced. Though instigated by environmental changes, when these changes occur, they can are acquired by the germ cells of organism. This means that they can be transmitted across generations despite the fact that the DNA has not undergone alterations. Arguably, the concept of epigenetic is an alteration of the notion of natural selection postulated by Darwin.
This holds because selection functions in levels of individuals’ traits. Hence, “epigenetic inheritance is a central subject tied within the concepts of natural selection, gene flow, mutations, and genetic drift” (Barrett, Dunbar & Lycett, 2001, p.87). These concepts tie the discipline of epigenetic to form an integral building block of modern evolutionary synthesis.
In conclusion, based on the expositions made above, it is apparent that the pioneers of evolution steered by Charles Darwin had what it takes to garner the credit they have acquired for their efforts to broaden and sensitize the subject of evolution. When Charles Darwin proposed the theory of natural selection, controversies came up from various conservatism schools of thought, as well as from the scholarly community. However, amid the controversies, Darwin set a stage for research in the body of knowledge seeking to explain the causes of variations among individual organisms.
Darwin postulated in his natural selection theory that the chief cause of variations among species is the need to adapt to new changes in the environment. This means that a change in the environment required organisms to respond likewise. The organisms that respond to these changes become fitter to survive as opposed to those that do not change. Consequently, this leads to the evolution of species of organisms.
However, this notion has been changed by the modern evolutionary synthesis from being the sole explanation of why variations occur and why evolution takes place. Precisely, genetic drift, mutations, epigenetic, and gene flow concepts have been amalgamated with the original concept of natural selection to provide a mathematical model for explaining sources of variations in organisms and hence evolution.
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