Biology 1001A Lecture Notes - Lecture 23: Heterozygote Advantage, Multiple Sclerosis, Toxoplasmosis
7 Dec 2017
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Evolutionary (ultimate) explanations for why we get sick: arms races with parasites, disease symptoms may be adaptations, mismatch to new environments, trade-offs between different aspects of fitness. Arms races: we are adapting to parasites (developing vaccines, antibiotics), but they are also adapting to us (develop resistance, selection factors favouring high virulence. Intermediary disease vectors (mosquitos: unprotected sex, selection factors favouring lower virulence, casual human-to-human transmission (sneezing, coughing, touch, protected sex. Inflamed muscle - warning signal that you should rest: anxiety/depression - adaptive responses to bad situations as a warning sign to pay attention to. Smoke alarm principle: defenses are often overly sensitive, severe response with no real threat -> minor convenience, ex. Being anxious for an exam: no severe response with real threat -> death, ex. Not throwing up when eating something toxic: selection favours response that are overly conservative and defensive, goal of selection is not to maximize human health, but favour traits that increase lifetime reproductive success.
