ANTH1102Lecture 11Outline of Last Lecture I. EvolutionA. TheoriesB. Darwinian EvolutionII. Genetics and EvolutionIII. Biochemical GeneticsIV. Population GeneticsA. Four Forces of MicroevolutionOutline of Current LectureI. Evolution continuedII. Human Variation and AdaptationA. Human Biological Diversityi. Skin Colorii. Blood Type and Diseaseiii. AdaptationB. Allen and Bergman’s RulesC. High Altitude: Biological vs. Cultural AdaptationCurrent Lecture(Forces of Microevolution continued)- gene flow: exchange of genetic material through interbreeding; direct and indirect> decreases speciation- Punctuated equilibrium (Stephen Jay Gould and Niles Eldridge, 1972): long periods of stability with occasional evolutionary leaps (extinction and succession/replacement, mutations speed up evolution)HUMAN BIOLOGICAL DIVERSITY- clinal distribution-> gradual shift in allele frequencies between neighboring populations- forces of microevolution affect geological distribution of varied human traits- two types of natural selection: directional selection (a trait is selected for again and again) and sexual selection (particular trait(s) attract more mates)Skin Color- based on melanin and vitamin D synthesis- darker skin> within tropics (advantages)- screens out UV radiation, protects against skin cancer and sunburn, folate destruction, and neural tube defects (spina bifida)> outside tropics (disadvantages)- reduces UV absorption, increases susceptibility to rickets and osteoporosis- lighter skin> outside tropics (advantages)- absorbs UV, more vitamin D production-> prevents rickets and osteoporosis> within tropics (disadvantages)- susceptible to skin cancer, folate destruction-> neural tube defects and impaired spermatogenesis- Skin color is relative to proximity to equator.Blood Type and Disease- ABO types> A type (Europe)- Bubonic plague resistant, smallpox susceptible> B type (Asia)- smallpox resistant> O type (the New World)- syphilis resistant, smallpox/Bubonic plague/cholera susceptible- Sickle Cell Anemia and Malaria> tend to be simultaneously common in many parts of Africa> stabilizing selection and balanced polymorphism (HbA, HbS)Adaptation- lactose (in)tolerance- lactose enzyme (ability to digest milk); biological plasticity (ability to change biology or behavior to adjust to environmental changes)> tolerance in traditionally herder groups> 90% Northern Europeans, 80% Tutsi and Fulani (Africa) are lactose tolerant> scientist speculations: mutation occurred in Turkey 8,000 years ago (Mark Thomas); 3 different mutations occurred in Africa 6,800-2,700 years ago (Sarah Tishkoff)> There may have been strong selective pressure over short periods of time: Hypotheses: famine, contaminated water sources, fertility advantage, social prestige, and health advantageAllen and Bergman’s Rules- climate temperatures> hot-> tall, thin body types common> cold-> short, stocky body types common> This is because greater surface area leads to greater heat loss- in hot climates, people need to cool off more than those in cold climates who need to retain heatHigh Altitude: Biological vs. Cultural Adaptation- Quechua (Southern Peru) and Sherpa (Nepal) are cultures that live at high altitudes- hypoxia: when lowlanders find it hard to breath in high altitudes- biological adaptations: rapid physiological responses to stressful conditions (timeframe: minutes, hours), e.g. shivering, increased heart rate and red blood cells, and elevation of basal metabolic rates- developmental adaptations: physiological characteristics adapted over time to help survival (timeframe: years), e.g. increased lung volumes (Quechua) and greater lung volumes (Quechua and Sherpa)- cultural adaptations: clothing, housing, diet, and