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Psyc 307 ch 11 notes.doc

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PSYC 307
Steven Heine

Chapter 11 Physical Health NOTES -chimpanzee footprints protrude directly off to side -Laetoli prints show early humans struck with heel first ten push from toes like modern humans -bipedal transition occurred over 3million years ago -bipedal advantages: hands free to carry food and make tools, cooled body by reducing amount of direct sunlight striking body, expose upper body to wind, improved long-distance travelling efficiency -differences of Laetoli prints and modern human prints: Laetoli wider front part of foot with big toe more separated from second toe and more pronounced arch -habitually wearing shoes tend to have narrower feet, first two toes closer together, and have lower arch -modern ppl who don't wear shoes have similar shaped feet to Laetoli -shape of feet is cultural product -ppl always ran without much protective covering on feet -barefooted runners tend to land on fore-feet or mid-feet compared to runners with shoes who land on rear-feet -barefooted children take smaller steps -cultural experiences shape ways we think and affect our bodies and health -explanations of biological variability of humans 1. humans in different parts of world subject to different selection pressures over many generations and result in human genome diverging across different populations (innate biological differences) 2. people living in different cultures have experiences within own lifetime that affect their biology (acquired biological differences) -people share many genetic variants esp. With those of same ancestral origins -humans evolve in response to selection pressures from environment -modern humans first emerged approx. 100,000-200,000 years ago and lived in africa until approx. 50,000-60,000 years ago -small population of homo sapiens expanded in africa before some left thus far less genetic variability across different races of humans than other species -more genetic variability among africans -humans less genetically distinct from each other but different populations of humans do differ from each other in many of their genes -ex. Skin color -skin color variation caused by body's ability to synthesize vitamin D for intestines to absorb calcium and phosphorus from food for bone growth and repair -skin need to allow enough UVR to pass through to synthesize vit. D but not too much to breakdown folic acid causing anemia, birth defects, skin cancer -africa high UVR, humans develop enough melanin (have darker skin) to let enough UVR penetrate but not break down folic acid -when humans moved to places where UVR levels lower, they need to absorb more UVR thus those with less melanin (lighter skin color) in skin had survival advantage over darker-skinned relatives -amount of UVR in different parts of globe correlate strongly with skin color with exceptions -exceptions supported by link between UVR and vit. D synthesis -ex. Inuit of Greenland have far darker skin than predicted by UVR level (low UVR) but they eat high vit. D diet thus don't require as much catalysis from sun -ex. Philippines, vietnam, cambodia have lighter skin than predicted but they migrated from higher latitudes only recently so have not yet evolved appropriately darker skin -ex. Pale skin of europeans and east asians emerged through different genetic routes -skin color is adaptive response to climatic differences among populations -those who adapt better to local climate will have more surviving offspring -ex. People in different regions have different genetic variants associated with heat stress -strong selective force on human evolution: local pathogens -ex. Spaniards had better genetic resistance to smallpox than Incans -ex. Regions where HIV infection is esp. High, it is expected that major genetic resistance against virus could evolve in as little as 50 years -cultural factors shape genotype -ex. Most adults in world who drink milk develop symptoms of lactose intolerance because don't have lactase enzyme in intestines--> lactase nonpersistence (present in ancestral population before they left africa) -some later developed mutation for lactase persistence (esp. Northern europe)--> where cows domesticated longest periods -diary framing predate selection of lactase persistence -parallel genetic mutation emerged among african cultural groups that raised cattle-different from europe--> thus pressure for digestion of lactose into adulthood strong enough to emerge at least twice independently -culture plays strong selective role in human genome -ex. Dietary practices 1. amount of starch eaten varies--> those from cultures where consume lots of starch more likely have genetic mutation that increases amount of amylase protein in saliva to help digest starch 2. asians less likely than europeans to have enzyme that sufficiently detoxifies alcohol-->Asians tend to have rapid increase heart rate and temperature, face turn bright red (asian flush) -asian flush makes drinking less enjoyable--> genetic variant protect against alcoholism -explanation for asian flush: people move to large cities face contaminated water supply --Europeans solve by drinking beer and wine --Asians boil water and drink tea -therefore europeans better digest alcohol than asians -culture can influence genome indirectly -ex. West african kwa-speaking farmers cleared forests to grow yam and created better habitat for malaria-carrying mosquitoes -malaria spread in these regions leading to evolution of genetic variant for hemoglobin associated with sickle-cell anemia thus more resistant to developing malaria -selective force for changing people's genetic resistance -genes predicting enhanced social sensitivity are 5-HTTLPR, A118G, and MAOA (all more common is Asian sample than european) -suggests genetic foundation underlie collectivism -collectivism either emerged as strategy among people with innate tendencies toward social sensitivity or socially sensitive people living in collectivistic cultures thrive more and had more surviving offspring -genes linked to social sensitivity expressed differently depending on people's experiences and studies only in West -studies exploring relations between genes and psychological variables across cultures commonly find opposite effects of genes across cultures -ex. Genetic variant associated with increased emotional-support seeking in times of distress for european-americans is associated with decreased emotional-support seeking among koreans -acquired physical variation across cultures ex. moken tribe- twice underwater visual acuity of european children --> gained through practice -obesity rates vary: Chinese women 1.5%; Samoan women 55% -cultural changes over time give rise to increase in obesity -key reasons of obesity: high-calorie foods (fast food, soda, larger portion sizes), less active lifestyle (more sitting and surfing Net), more suburban lifestyle (more driving) -US obesity rate 5 times rate of France -French cuisine: rich in fat and sugar-heavy products -french tend to have higher blood cholesterol than americans -french longer life span, thinner, lower heart disease rates -french paradox: rich fat diet + low rate of heart disease -possible explanation: 1. french drink more wine than americans which serves to inhibit platelet reactivity and reduces risk of coronary heart disease 2. french eat fewer calories per day than americans (smaller portions and more positive attitude to food-spend more time eating a meal than americans) -americans esp. Women have more conflicted attitudes toward food -top response among american females when thinking of related words to food is “fattening” -14%
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