human variation

human variation - Anthro 102 Lecture notes Human Adaptation...

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Human Adaptation, Infectious Disease Adaptation To survive, all organisms must maintain normal functions of internal organs, tissues and cells. Homestasis-maintaning balance within the body Human Variation: Biological Perspective Human variation now studied in light of evolutionary forces -Gene flow -Genetic drift -Natural selection -Mutation -Recombination Types of Adaptation Genetic adaptation : evolutionary changes characterize all individuals within a population or species. - all human can sweat 3-4 litres/hour Acclimation: Short term physiological response to stress (minutes to hours) -sweating when hot Acclimatization : Long term physiological response to stress (days to months) -Tanning following repeated UV exposure Developmental Adaptation : Changes in organ or body structure that occur during growth -Increase in chest size during growth at high altitudes Human Adaptations to Climate Skin Color Body size and shape Chest and lung size Pigmentation and Geography Before 1500, skin color followed a geographical distribution. Greatest amount of pigmentation found in tropics. Lighter skin color found in more northern latitudes. Clinal variation : gradual change in allele frequencies over geographic space Why dark skin near the equator? Folate depletion Folate and UV Radiation Folate is a B vitamin that isn’t stored in the body and must be replenished through dietary sources. Studies have shown that UV radiation depletes folate serum levels in lab experiments and light skinned individuals. In pregnant women, insufficient levels of folate are associated with numerous fetal developmental disorders such as spina bifida. Why lighter pigmentation at high latitudes?
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This note was uploaded on 12/05/2011 for the course ANTHRO 102 taught by Professor F during the Spring '11 term at CUNY Queens.

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human variation - Anthro 102 Lecture notes Human Adaptation...

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