The Effect of Infectious Diseases on Humanity Essay

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In 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection, a work of literature that not only provided a working framework for the theory of evolution, “descent with modification” by means of natural selection, but also explained how the cumulative impact of natural selection influenced an organism and its environment. Darwin, however, neglected to mention how infectious diseases have served as a pivotal selective force in natural selection (Lederberg, 1999). Since animals first walked the earth, they have had to live with microscopic organism, including bacteria, viruses, fungi, and parasites. Not only did these microorganisms share an environment with animals, they interacted with them, causing both illness…show more content…
This has led to predator-prey-like arms race, in which increased resistance by the host immune system has led to increased host immune response and increased virulence of pathogens in some populations, and a milder virulence of pathogens and latent host immune response in other populations. Biologist use Malaria as a classic example of how infectious diseases can affect the gene pool of a population. Human biocultural evolution also affected the incidence of malarial infections. Increased sedentism and deforestation provided optimal conditions for the Anopheles sp. of mosquitoes, the primary vector for plasmodium sp., to thrive. The slashing of vegetation for propagation of soil, followed by rain, created pools of stagnant water, the perfect breeding ground of the mosquitoes (Inhorn & Brown, 1990). This increased the incidence of malarial infections in West Africa, making it endemic among the population. Sickle cell trait, the heterozygote condition in which a person has inherited one gene that codes for haemoglobin S on the beta-chain of haemoglobin, appeared in greater frequency in populations where plasmodial infection, the infectious agent that causes malaria, was endemic (Inhorn & Brown, 1990; Lederberg, 1999). In its exceptionally complicated lifecycle, the merozoite form of plasmodium must invade a red
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