Lecture 9- Darwinian Medicine - Lecture 9 Darwinian Medicine Levels of Analysis Medical science aims to o Understand etiology(cause of an illness

Lecture 9- Darwinian Medicine - Lecture 9 Darwinian...

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Lecture 9- Darwinian Medicine Levels of Analysis Medical science aims to o Understand etiology (cause) of an illness Doctors want to know what is causing the problem o Pathogenesis (mechanism) of illness They want to be able to treat the mechanism o Proximate causes Darwinian medicine o Proposes that evolutionary biology can aid in this process Looking at evolutionary biology that builds up to your now being six o Ultimate causes Darwinian Medicine General approaches o Understand pathogens as rapidly evolving species Organisms causing illnesses Not just a virus, it is a species undergoing evolution and is subject to the same NS pressures as any other organism o Understand responses to disease as potential adaptive responses Why We Get Sick: The New Science of Darwinian Medicine (1996) Nesse and Williams o Since publication, consideration of evolutionary biology in relation to disease rapidly growing o Most widely researched in regard to infectious disease, genetic disorders Darwinian medicine focuses on infectious disease and genetic disorders Evolutionary processes involve the persistence of genes throughout populations Video of bacterial evolution o They are talking about evolution of bacteria in terms of antibiotic resistance o Importance of viewing pathogens this way Why do we get sick? 5 perspectives Darwinian medicine can take: Arms race with pathogens Design compromises Maintenance of genetic disorders New environments o Diseases of civilization Adaptive responses to disease Evolution of virulence in pathogens Host mounts an immune response to eliminate the costs of hosting the pathogen. o Hen pathogen enters our body the immune system tries to fight the pathogen o Makes sense that the immune response influences the evolution and selection pressures of the pathogen All else being equal, pathogens with higher within-host reproductive rates should be transmitted to hosts more effectively.
o Pathogens that enter a host and reproduce rapidly are the most adaptive and have the highest fitness o If a pathogen enters a body and reproduces too quickly, it has such a detrimental effect on the host and then cant be transmitted o Have to battle the immune system but not fight so strongly However, too rapid a reproduction rate may debilitate the host so much that transmission is reduced. o Viruses that kill their host easily are easier to transmit HIV and AIDS A virus that can cheat the immune system o Attacks the immune system itself o Beats down the immune system so it can stay in the system but not so aggressively o Immune system is done, and this is when people get AIDS and their immune system has been knocked down and can’t amount a response to another pathogen o HIV forms an adaptation of attacking the immune system and going on the defensive by HIV itself doesn’t kill its host because it is hard to transmit it o It needs to stay in a host system to live long enough to transmit the virus Attacks T-cells of the immune system o

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