With the spatial environments becoming highly dynamic, the human species have undergone significant modifications in their phenotypical characteristics as a result of speciation. The acknowledgment of human beings as interactors, rather than being replicators can be attributed to the currently experienced revolutionary changes to the current man to facilitate fitness in the marginalized environmental conditions. In this regard, reproduction is the key to adaptation and true natural selection as newly born organisms acquire modified structures to enhance their survival in changing habitats. Though genetic shift can be considered as the proximate cause of the changing phenotypical characteristics of human nature, natural selection has partly played a significant role in the overall human conditions to adapt to new environments. This paper examines how human beings are continually adapting to the changing conditions on earth and establishes the ultimate factors associated with the allegedly considered genetic shift in accordance with the changes in the natural habitats.
According to Faran race (614), adaptation of human beings has been necessitated by the extremely dynamic earth’s environments which have triggered alterations in the normal homeostasis process in the body. Since the human body functions optimally at certain environmental conditions, any changes culminate in changes in the normal psycho-physiological homeostatic regulation. Since the regulation of the homeostatic process is regulated by various bio-chemicals produced in the body as a result of a stimulus called stress reaction, standardization usually occurs with time as the body gets modified to adapt to the newly experienced environmental conditions. Though this explanation has little to do with reproduction, the changes in the phenotypical characteristics among the current generation may be attributed to the future generation through speciation. As argued by Gould and Lloyd (11907), though phenotypically acquired characteristics cannot be genetically transferred to the new off-springs, environmental factors are considered as the key players to shape the adaptability of new organisms to the changing environments by acquiring characteristics of fitness for their survival.
Moreover, Skulachev (1339) considers the existence of specialized mechanisms of evolution that are capable of saving intermediate forms of organisms from being eliminated by natural selection. In cases where a certain change in life strategy worsens a particular trait, adaptation mechanisms among such organisms are usually incorporated to facilitate the survival of the particular species, which prevents it from extinction. As revealed by Farrace (616), such cases necessitate the replacement of k-strategy, where the species undergoes significantly low reproduction rates which can be characterized by very long gestation periods, by r-strategy, where the species undergoes a high reproduction rate and short lifespan. With the currently increasing mutations among the human species as a result of the changing physical environment, the current man’s lifespan is generally shorter than some hundred years back. This explains how reproduction is one of the major strategies to facilitate adaptiveness to changing environmental conditions, as organisms experience specific fitness capable of enhancing their survival.
However, loss of physical fitness in a population may necessitate the development of other adaptive mechanisms like specialization with an aim of enhancing survival in marginalized environments. According to Kawecki et al (412), specialization involves the accumulation of mutations that are deleterious in the marginal habitats but neutral to the main habitats. Since the newly acquired specialization has negligible influence on the main habitats, it makes it possible for such an organism to survive in a wide range of environmental conditions. This theory can be used in contemporary human nature to survive in a wide range of environmental conditions, as the global climate advances to a high degree of instability and fluctuations. As argued by Lloyd (11909), deleterious mutations with regard to various habitat-specific expressions may contribute to ecological specialization and hence help in promoting evolutionary conservationism from one generation to another with respect to the specific ecological niches they operate in.
Further, Van-Dyken and Wade (561) reveals how conditionally expressed genes facilitates the carriage and transmission of genes, though in small fractions from one generation to another. Particularly, the consequence of this particular inheritance pattern allows accumulation of deleterious mutations within species which inhibits spreading of beneficial mutations from one generation to another. According to Kawecki et al (414), allowing mutation accumulation would lead to decline in adaptability to marginal environments, leading to pseudogenization as a result of phenotypic inelasticity. This theory connects gene-level with regard to polymorphism and the divergent special environments. This explains the adaptability of the current generation of human kind to the changing environments, and so is expected of the future generation with regard to the changing environmental conditions.
As it has been revealed, human beings will continually adapt to changes in the spatial environments, since natural selection is impacting very little in the current organisms. The acquirement of fitness through specialization in marginalized environments, while maintaining adaptability to the main habitats has been revealed as one of the major contributors of the human adaptability to the changing environments. Notably, deleterious mutation has been considered as a key strategy to facilitate fitness among the organisms to avoid accumulation of certain beneficial mutations to a specific environment. In this regard, reproduction has been revealed as one of the key adaptation and true natural selection to enhance sustainability of human beings in the currently dynamic spatial environment.
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