The evolution of human health and medicine

The evolution of human health and medicineIntroductionThe evolution of human health and medicine mainly entails using contemporary theory of evolution to have a comprehensive understanding of human health, medicine and disease. Evolutionary health and medicine offers a complimentary scientific explanation to the existing mechanistic explanations that are more prevalent in medical science especially in the contemporary medical education and research (Carol and Melvin 58). Researchers in the evolution of health and medicine have made propositions that evolutionary biology should extend beyond being an optional subject in medical learning institutions to be one of the basic requirements in medical education. Human adaptation poses significant concerns in the field of medical research including the evolution of pathogens regarding to the core aspects of virulence, resistance to antibiotics and the subversion of the immune system of an individual (Lappé 145). Other posed concerns include the processes, constraints and trade-offs associated with human evolution; evolution of individual response to make possible protection, healing and recuperation from various infections and injuries and the underlying processes that serve to maximize physical fitness (Lindeberg 149). Human adaptation also poses significant concerns regarding how early human beings survived during their ancestral times and how this affects the present day human being. The main purpose of this paper is to discuss the evolution of human health and medicine.The concept of evolutionary medicine significantly depends on the evolution of pathogens, adaptations of human beings, evolution regarding defense mechanisms and the increasing instances of diseases associated with civilization. In his theory of evolution, Charles Darwin did not outline the underlying implications of his theories on medicine (McKenna and Trevathan 258). This laid groundwork for the adoption of the germ theory of disease and its significance in having a comprehensive view of the evolution of pathogens and the need to living organisms to continue defending themselves against the pathogens that are still evolving. Medicine did not take into consideration the evolution of pathogens, but rather laid much emphasis on proximate mechanical causes. The evolution of pathogens takes various forms such as bacterial, viral and microbial and parasite evolution is of significant value in the field of medicine since it poses the need to have an in depth of overview of issues related to antibiotic resistance, virulence of pathogens and pathogen evasion of the human immune system. These concepts are central in understanding the concept of evolutionary medicine and its significance in contemporary medicine (Merrill and Pamela 98).A notable outcome of the evolution of pathogens is antibiotic resistance, which is a form of drug resistance characterized by a microorganism having the capability to survive when subjected to an antibiotic. Although unprompted or induced bacterial genetic mutation can result to increased resistance towards exposure to antimicrobial drugs, there is a possibility that the genes that impose antimicrobial drug resistance are transferrable among the bacteria using diverse mechanisms such as conjugation, transduction and transformation (Moalem 145). This implies that there is a possibility of evolution through natural selection for the gene that is necessary for antibiotic drug resistance. In aIDition, this gene may be shared. The evolutionary approach suggests that continued exposure to antibiotics results to the development of an antibiotic trait. Most of the genes required for antibiotic drug resistance are found on the plasmids, which further accelerate their transfer. There are cases whereby bacteria may carry more than one resistance gene, resulting multidrug resistance. The increasing cases of bacterial infections that are resistant to antibiotics observed in clinical practice are as a result of continued usage of antibiotics in human medicine (Naugler 125). The clinical concern is because using antibiotics serves to increase the selective pressure within the bacterial population, which facilitates the thriving of resistant bacteria. Antibiotic resistance poses the need to have alternative treatment options. The basic inference from this is that antibiotic resistance poses a significant challenge in the field of evolutionary medicine. Some of the notable resistant pathogens include Staphylococcus aureus, Streptococcus pyogenes, and Pseudomonas aeruginosa. Treatment alternatives to prevent antibiotic resistance include using the antibiotics rationally and phage therapy, which mainly involves the use of lytic bacteriophages for the treatment of bacterial diseases (O’Higgins and Elton 236).Virulence is also a notable outcome of pathogenic evolution , whereby the potential effects that microbial organisms ca impose on their host differ including the pathogens significantly reduce physical fitness and microorganisms that are beneficial such as the symbiotic commensals. Significant number pathogens engage in the production of virulence factors that are responsible for either causing disease infections or manipulating the hosts in such a manner that they can thrive and spread. Owing to the fact that the fitness of a pathogen is primarily determined by the level of its ability to transmit its offspring to other human hosts, there is a probability that there was a moderation of virulence towards commensality. Virulence defines the level of pathogenicity of a specific parasite species, which is usually determined by the ability of the microbial organism to attack the tissues found in the body of the human host (Peter and Hanson 123). This usually determines its capability cause disease infections by its virulence factors. Evolutionary medicine lays emphasis on the ultimate causes, which refers to the various evolutionary pressures that result to the development of viral traits that takes place in a given strain of pathogen species. The inherent ability of bacteria to inflict disease infections is measured with regard to the population of the infecting bacteria, the entry routes, the effects it causes on the defense mechanisms of human host and its intrinsic virulence factors, which contribute to the ultimate causes of disease infections. According to the concept of evolution of human medicine and health, optimal virulence tends to increase with horizontal transmission and reduce with vertical transmission. This is mainly due to the fact the host’s fitness is determined by vertical transmission and not horizontal transmission (Pontarotti 458). This implies that there is a probability of evolution of the pathogen population if it finds itself in the human host. In the event that a pathogen attacks a new environment on the host, which is likely to result poor adaptation towards the intruder due to the fact that the pathogen has not established immunological defenses. When changes takes place in the host environment, the pathogen significantly depends on the fitness of its present host, this implies that virulence tends to increase in environments that have dominant immune dysfunction. On the other hand, virulence tends to decrease in populations that are healthy due to the fact that hosts tend to acquire resistance. Some of the approaches used to explain the evolution of pathogens to result to virulence include the Trade-Off Hypothesis, Short-Sighted Hypothesis and the Coincidental Evolution hypothesis. The point of consensus in all the theories is that they all provide ultimate explanations relating to virulence among pathogens (Williams and Nesse 47).Immune evasion is the third notable outcome of the evolution of pathogens that is of great significance in evolutionary health and medicine. The success of pathogens is determined by their abilities to escape the immunity from the human host. This implies that evolution in pathogens includes the methods that they can use to cause infection in the human host while at the same time avoid their recognition and destruction of the immune system of the human host. Some of the aspects of immune evasion due to evolution include hiding within the cells of the human cells, hiding within protective capsules, the secretion of compounds that aim at misdirecting the immune response of the host, binding of its antibodies, alteration of the surface markets and masking the surface markers with the molecules of the human host (William and Walrath 89).Human adaptation also imposes significant challenges in evolutionary medicine. It is notable that human adaptation takes place within constraints, involves the making of tradeoffs and compromises and takes place in varying methods of competition. The concept of adaptation constraints implies that human adaptations can only take place of they have the capability of evolving. Notable examples of this include the inability of human beings to biosynthesize Vitamin C, implying that human beings are at risk of scurvy; there are no ways that can be used to avoid somatic replication corruption of DNA, implying that diseases such as cancer, which is mainly due to somatic mutations, cannot be done away with by the process of natural selection. The adaptation constraints can result to potential conflicts, which poses the need for compromise to ensure that optimal cost-benefit tradeoffs (Stearns 74).Evolution in the defense mechanism also imposes significant concerns in the evolution of human health and medicine. Human evolution and adaptation has played an integral role in selecting the defense mechanisms that are used for protection from injuries and infections. Examples include fever, expulsions, nausea, itching and many more. Evolution of defense mechanism is usually costly because of an increase in the usage of energy and the potential risk associated with damaging the human body. For instance, fever tends to increase the Base Metabolic Rate by about 10-15 percent while vomiting imposes significant risks on aspiration. This means that defense mechanism is deployed selectively in cases whereby the advantages far outweigh the costs, which results to fitness advantage. Human evolution has also resulted to onset of diseases of civilization. Contemporary lifestyles predispose human beings to diverse health risks imposed by diet, life expectancy, exercise and cleanliness. Contemporary diet can impose health problems associated with fat health risks and dental caries; life expectancy imposes diseases that are associated with old age. Cleanliness of the contemporary man has the potential of causing allergies, infections that are autoimmune and helminthic therapy.ConclusionIt is arguably evident that evolution of human health and medicine poses significant challenges in medicinal practice, which in turn requires that treatment approaches should take into consideration the implications of evolution on human health and treatment. This paper has highlighted that human adaptation poses significant concerns in the field of medical research including the evolution of pathogens regarding to the core aspects of virulence, resistance to antibiotics and the subversion of the immune system of an individual. Other highlighted concerns include the processes, constraints and trade-offs associated with human evolution; evolution of individual response to make possible protection, healing and recuperation from various infections and injuries and the underlying processes that serve to maximize fitness of human fitness. All the evidence highlighted in the paper attempt to justify the use of evolutionary approach to medicine.
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