Scientists have described about five forces of human evolution. The common ones include genetic drift, mutations, natural selection and gene flow. Although some of the theories have raised disputes among biologists, each of the aforementioned phenomena has a tremendous impact on the population.
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Secondly, the isolating mechanism is a biological element, which interferes with continuous reproduction among species. Therefore, the next discussion gives a brief review on the population variation in relation to the evolution forces.
The first force of evolution is natural selection. Natural selection is whereby through gene adaptation and environmental changes the rate of reproduction among organisms is naturally balanced (Haviland et al. 100).
Through genetic variation, only the healthy organisms are able to reproduce. Within a population, only the healthy individuals have a longer life span while the weak organisms naturally die. In addition, the environment also comes in handy to select the organisms, which are fit and can subsequently reproduce.
More over, between populations, only those organisms, which can easily adapt to the dynamic environment, are higher in number. Each population has a different level of environmental adaptation thus, determining its survival rate. Therefore, natural selection can lead to the extinct of a specific (genetically weaker) population or individual.
Secondly, mutation is the alteration of Deoxyribonucleic acid (DNA) of an organism. Depending on the location of mutation, either this force can lead to detrimental /beneficial effects to an organism or it can pass unnoticed (neutral mutations).
Gross mutations can lead to the change of an organism’s characteristics such as color within an organism. For instance, Sickle cell anemia occurs because of mutation.
Through mutations, different population can present different characteristics. For instance in humans’ variation in skin color, emergence of diseases and other health fitness problems may arise.
Thirdly, genetic drift is an evolutionary force whereby there is random alteration of genes, which occurs through chance. According to scientists, this force commonly affects small populations whereby through elements like genetic bottleneck, there is significant reduction of the population size.
Subsequently, there is loss of genetic variation within or between populations. Due to genetic variation or loss, a new population may arise within a community/population or between populations.
Finally, the gene flow is an evolutionary force, which describes the movement of genes between or within populations. Through aspects such as migration, emigration and immigration there is exchange of genes within the organisms.
This commonly occurs through mating, which leads to the production of a hybrid organism. Therefore, through gene flow, a new population may arise or there might be modification of an organism within a population.
The aforementioned forces have a close relationship with the aspect of isolating mechanism whereby through natural means organisms are unable to breed. Scientifically, the main role of isolating mechanism is to space populations or organisms.
Isolation can occur through ensuring that organisms live in different habitats thus preventing them from breeding. Incase of plants, the flowering season differs while in animals there is lack of attraction between them.
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Sometimes gametes may be unable to pair up. Furthermore, through natural mechanisms, there can be sterility or invariability between organisms thus, preventing them from mating. The above mechanisms of isolation lead to speciation among populations.
In brief, natural selection, mutation, gene flow and genetic drift are evolution forces, which determine the viability or continuation of a specific population.
Through the evolutionary forces, a population may become extinct, expand or change in order to fit into the dynamic environment. Similarly, through natural forces, isolation mechanism prevents breeding between species thus promoting speciation.
Haviland, William, Prins Harald, Walrath Diana, and McBride Bunny. The Human Challenge. U.S.A: Wadsworth publisher, 2007. Print