Darwinian Evolutionary Theory

Darwinian Evolutionary Theory
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Darwinian Evolutionary Theory
Introduction
The concept of evolution by natural selection was first formulated by Charles Darwin and Alfred Russel Wallace and has since remained a cornerstone of modern biology and scientific reasoning about the origin of species (Costa, 2009). This essay is divided into three sections. The first part introduces the concept of Darwinian Evolutionary Theory and explains the development of new species, the accumulation of traits in new species, and changes in a species' genetic pool over time. In the second section, the paper discusses how paleoanthropologists think about how bipedalism developed using fossil evidence and the theory's logic to explain how bipedalism offered competitive advantages for hominins. Lastly, the importance of understanding Darwinian Evolutionary Theory is discussed while examining examples of how deliberate perversion of the logic has affected the underrepresented communities such as the Indigenous Americans and other minority populations.
Theory explained
Charles Darwin, the Father of Modern Evolution, recognizes the ability of organisms to adapt to changes rather than their strength and intelligence as fundamental to survival. Evolution is defined as the gradual development of an organism from its simplest to the most complex form (Zimmer, 2013). Darwin's Theory of Evolution concludes that species will undergo changes, allowing for natural selection to occur (Darwin, 1859). Lenski (2017) defines natural selection as an evolutionary process accounting for the fit or match between different features of an organism and the immediate environment in which they thrive. He also states that species undergo a change in the struggle for survival. Darwin conceptualizes that the evolution of species is largely driven by competition or struggle for survival and reproductive advantage (Cohen, 2016). In simpler terms, his theory can be explained as descent with modification.
Darwin explains the evolution of new species as a result of the struggle for survival or survival of the fittest, a process that can be fast or slow. In Darwin's Evolutionary Theory, this process occurs by natural selection and is a gradual change within a population resulting in the formation of new species. Darwin's sketches show that lineages develop from their ancestors by evolving a number of features over time (Safran & Nosil, 2012). He conceptualized that new species form either by one species splitting into two or one population diverging from its extant ancestors. There are population bottlenecks, including mutations, genetic drift, gene flow, founders' effect, and adaptive radiation. These bottlenecks lead to a drastic decline in population sizes (Wein & Dagan, 2019). Darwin argues that evolution is key to survival (Darwin, 1859). For instance, the birds that Darwin studied during his voyage between 1831 and 1836 on the Galapagos Islands had varying beaks. The warbler finches had thinner beaks, while cactus finches had beaks, which made them more adapted to survive on the available ecological resources or food. Some beaks became stronger to break harder seeds, some smaller for smaller seeds, and some evolved and became insectivores. When the environment suffered a drought, a visible decline in the small beak population was noted because they were unable to eat larger seeds or feed on anything else like the larger beak finches (Darwin, 1859). This scientific finding thus supports the development of new species and natural selection.
Darwin explains the accumulation of traits, or variation, in new species when he says that the "slightest idiosyncrasies in the shape of an individual beak can make a difference in what a particular bird can eat" (Weiner, 1995, p. 51). It can also determine if it lives or dies. From the words of Darwin, "the smallest grain in the balance, in the long run, must tell on which death shall fall, and which shall survive" (Weiner, 1995, p.51). Variations provide advantages based on resources and can be passed to future generations. Most of these variations are heritable, with a few cases where environmental factors cause variations. Darwin concludes that species in a population will inherit survival traits from their parents and pass them on to future generations, making them stronger than their peers at survival and reproduction. He also believes that sexual selection plays a role in survival. Nevertheless, research has shown that sexual selection works to hamper and augment species' adaptive capacity and tenacity, particularly when exposed to new environments (Parrett & Knell, 2018). According to Carlin (2011), mutation serves as the sole mechanism for creating new alleles and species within a population, and this process generates variations that natural selections act upon.
The change in a species' gene pool happens through time with genetic modification or the transfer of genes from one population to another, such as in microevolution resulting in antibiotic-resistant bacteria (Do Porto et al., 2021). Some populations change faster than others. The pace is dependent on the environment, and there are different ways that this can happen. Darwin's theory focuses on natural selection, a competitive reproduction of specific alleles for traits related to survival or adaptation. Darwin explains that the evolutionary process occurs daily and hourly and that all variations, either good or bad changes, are only observable to the human eye after generations (Darwin, 1859). For instance, the ability of some individuals to become resistant to malaria is due to a Sickle-cell gene that developed over time. This adaptation protects individuals with the gene from malaria due to genetic changes that occurred in the past generations.
Evolution of Bipedalism
Paleontologists often regard bipedalism as an unusual and highly specialized locomotion type in modern humans. While most members in the extinct primate taxa of Hominin were largely bipedal, the extent to which these members were bipedal has remained a contentious issue. Besides, although the early records of hominin fossils are obscure, evidence exists that there are at least two distinct shifts in adaptions. The first shift was the move to habitual bipedalism as witnessed among the Australopithecus members and other earlier genera such as the Orrorin and Ardipithecus. These taxa were largely bipedal but retained several important adaptations to arboreal climbing. The other shift was to completely obligate bipedalism coinciding with the emergence of the Homo genus. During the Pleistocene period, certain members of the genus had already acquired a postcranial skeleton, denoting a fully striding bipedalism witnessed among modern humans. The postcranial skeleton in early hominins facilitated posture and locomotion, especially among the Orrorins, who were partially arboreal and facultative bipeds, the Australopithecus and Paranthropus, who were terrestrial bipeds with climbing and suspensory abilities, and the Homo habilis who were obligate terrestrial bipeds with significantly reduced bipedalism (Arsuaga et al., 2015). Bipedalism is a defining feature among humans. While walking on two feet has been documented throughout history the reconstruction of hominin gait evolution is overly complicated due to sparse fossil records and difficulties in inferring biomechanical patterns from fragmentary and isolated bones (Hatala et al., 2016). Nevertheless, according to Carvalho et al. (2012), fossil evidence and the logic of the Darwinian evolutionary theory show that the development of bipedalism offered hominins competitive advantages in carrying tools, traveling over long distances, and seeing over tall bushes.
Homo sapiens are obligate bipeds, and unlike other mammals that are habitually upright, such as kangaroos, springhares, and jerboas, humans are the only extant mammals known to habitually stride only on their extended hindlimbs (DeSilva & McNutt, 2018). Facultative bipeds such as pangolins infrequently stride on two feet in their short bouts of location. Although it remains unclear about the purpose of bipedalism evolution, paleontologists believe that it relieved the upper limbs from locomotion while using tools and saved energy. Bipedalism became a posteriori benefit and played a role in the crystallization of obligate bipedalism in the genus, although earlier hominins largely utilized this feature to stretch for fruits in trees and use their hands to use tools and for communication purposes (Carrier, 2011). Although humans are comparatively slower than other mammals, upright walking is the most economical form of locomotion in terms of energy expenditure compared to quadrupedal movement. This reduced the cost of foraging (Khamsi 2007). Darwin's view that bipedalism was an important first derived feature among the hominin lineage is supported by the observation of the earliest hominins, including the Ardipithecus, Sahelanthropus, and Orrorin that have upright posture adaptations but are partially arboreal (Arsuaga et al., 2015). Nevertheless, paleontologists have always thought that the early hominins may have been facultative bipeds since the oldest evidence for obligate bipedalism only appeared 4.2 million years ago among the Australopithecus (Barak et al., 2013). In this regard, the australopiths efficiently walked with a modern gait with extended hips and knees instead of a bent-hip and bent-knee gait. Al-Imam (2017) notes that specific anatomical changes resulted in modern hominins becoming fully obligate bipeds, including the general adjustments of body architectural plan and cranial and postcranial modifications, especially at the pelvic level seen in Australopithecus afarensis about 3.6 million years ago.
Different hypotheses have been proposed about the selective advantages of bipedal gait among early hominins. These include the locomotor stamina and persistence in hunting, locomotor economy, thermoregulation during hot temperatures, aquatic wading and foraging, carrying objects, arboreal foraging in distal branches of tees, male provisioning of females, defense against enemies, freeing of hands, and aggressive encounters (Carrier, 2011). The selection for improved performance in fighting and mate selection may have played a significant role in habitual bipedalism evolution among the hominins, except for bonobos that resolve their conflicts...