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Chapter 3

Chapter 3 Evolutionary Psychology.docx

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York University
PSYC 3420
Irwin Silverman

Chapter 3 Evolutionary Psychology  Problems of survival: combating the hostile forces of nature: o Differential reproduction is bottom line of evo process o Darwin-struggle for existence in some kind of circumstance; o Climate, weather, food, toxins, disease, parasites, predators, other tribes o Fol biology-intuition that living things come in discrete packets that correspond to distinct species ; each ahs internal essence producing it growth and powers  Emerges early in life and universal  Ppl divide species into plants and animals; everything has a function and essence  May be cognitive adaptation  Emerges early w.o. instruction, universal, central to solving survival problems  Food acquisition and selection:  Diet is primary of adaptations; more hours searching for food than anything else  Consuming calories calcium, sodium, zinc without toxins was a struggle then  Recognizing it, capturing, and consuming, and digesting  Crucial for omnivores- increases odds of poison-toxins  Toxins may be the adaptations that reduce odds that the plant is eaten; help plants o Social and cultural aspects of food:  Sharing strategy for courtship, r.s., reconciling conflicts  Gand thongs Ashanti- women seek divorce if no food  Permeates our psychological preoccupations verbal discourse interaction and religion o Food preferences:  21% income in US spend on food, second to leisure  Less wealthy-India china; 50% food  Food center of p/c interactions- mother milk Page 1 of 10  Human and rats evolved taste preferences for sweets=calories; even infants  Dislike bitter n sour which have toxins; adjust habits due to water, salts...  Neophobia-strong aversion to new foods-small doses; new foods separate=learn abt their effects o Disgust: the disease-avoidance hypothesis:  Defense vs. microbial attacks- strong withdrawal and nausea  Hyp: Should be evoked from disease foods; should universal across cultures  Empirical evidence supports both; rotting flesh, dirty food, smelly, leftovers, moldy, insects, dirty hands cause disgust  Feces across cultures seen as disgusting-toxins  Women find disease images more disgusting than men; they deal with it more than men  Poor hygiene, evokes disgust  Feces of own child less than others; humans can shut or override disgust if need be for adaptive problems o Sickness in pregnant women: embryo protection hypothesis:  Nauseous reaction to foods- morning sickness; 75-89%  Vomiting lower at 55%; if food aversions added; 100% in first trimester  Profet-pregnancy is adaptation preventing mothers from eating teratogens- toxins for the baby  Moms need to get nutrients w/o toxins; find meat, alc, veggy, coffee distasteful  3% reported aversion to bread, and none said no to cereals  Carcinogens induced smell aversion  This is an adaptation to prevent toxins  Most vomiting in 4 wks after contraception due to toxins vulnerability  Women who don’t have preg sickness in 1 trimester are 3x more likely to abort  Cross cultures show same; o Fire and cooking:  Ket emergence of modern humans; most uncooked have more effort to eat Page 2 of 10  More easily digestible and safer than raw- large human brains  Wrangham-1.cooking provides predictable increase in energy  2. Digestible 3. Human universal 4. Calories for brain to function and hard stuff can’t give off 5. May lose ability to reproduce and succeed  Cooking therefore had to be 1.6-9 million yrs ago when homo erectus ancestors appear in fossil records-larger brains  Cooking didn’t occur till 500000 yrs ago; strong evidence until 200000 yrs ago- skeptics in this hypothesis o Why humans like spices: antimicrobial hypothesis:  Cooking killed off many microorganism, spices in food act by killing other organisms just like they previously did on plants  Antimicrobial hypothesis-spices kill microorganisms and toxin production  More spices used in hotter climates where unrefrigerated items spoil; more spices used in meat than in veggie dishes;  Maybe discovered by accident and not adaptive o Why humans like to drink alcohol:  Sugar and ethanol in fruits; main diet of chimps; ripeness  Frugivory by-product hypothesis the human isn’t adaptation but a by-product if adaptive fondness to ripe fruit  All humans have adaptation that favour rupe o Hunting hypothesis:  Tool making, large human brain, language skills for hunting evolved  Ecological change took place in Africa-global cooling; more grassland, plants scarce and animals attractive as food resource  Eat more meat than any other species; chimps 4%; human 20-40%  Central for thousands of generations  Human gut has small intestines unlike primates; provide place of protein breaking such as meat  Thin tooth enamel shows heavy wear on meat  Vitamins a/b12 shown in meat; needed for survival  Bones cut marks Page 3 of 10  The provisioning hypothesis:  Males unique among primates in heavy parental investment in children-provisioning  Meat economical food source- heavy investment men towards kids  Emergence of strong male coalitions explained-transient  Large game hunting needs others  Strong reciprocal altruism and social exchange- yrs of r.s. unlike chimps  Favour food sharing where consistency unlikely  Leftovers spoil  Sexual division of labor-means larger upper body strength to throw  More women gather fruits; sexes exchange foods  Stone tool use found near bones of animals dating 2 mill  The show off hypothesis: completion among men:  Meat comes in large packages, sometimes more than hunter can consume right away; 2 a wk can be followed by failure...  Sharing can then be adaptive  Hawkes-show off-women like show offs- rare pieces of meat as neighbours  Makes sense to reward them then  Increased sexual access increasing odds, survival, reproductive success  Better hunters-more mates, desirable ones, higher offspring survival  Ache- shifted camps daily; 84% shared ; 58\% gathered shared outside family  Hadza-pure provisioning, social alliances, mating success  Show off a rival to hyp of provisioning, but men hunted for sharing so survival increases ; not incompatible o Gathering hypothesis:  Maybe stone tools used for getting plants; move to savannah more economical Page 4 of 10  Hunting cam later and wasn’t as big a role  35% of modern hunter-gatherers consist of plants  Time women spent depends on husbands brining o Comparing the hunting and gathering hypotheses:  If gathering were sole method; why would men hunt; doesn’t account for division of labour  Hunting- can explain the division- more cost effective  Gathering doesn’t show investment of human males, coalitions, and why they went to places w/o plants  Why do we also have small intestines for proteins  Why should women share with men who would sponge and give meat?  Exchange makes sense  Gathering hyp falls short in seeing division of sexes, investments, intestines  Were omnivores not definitive evidence though o Adaptations to gathering and hunting;sex diffs in specific spatial abilities:  Irwin-spatial abilities dues to sex diffs; orientation, find way home  Gathering-spatial config
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