For reciprocity to evolve a cost of act to giver

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For Reciprocity to Evolve: (a.) Cost of act to giver should be lower than benefit to receiver (i.e Vampire bats) Benefit is big (might get paid back in the future), cost is relatively low (b.) Individual recognition and memory Need to remember what they did for you last time (recognize who did what for you) (c.) Long lifespan and repeated interactions Interactions with the same individuals again and again (d.) Occurs in a variety of taxa, but uncommon Human Reciprocity Many human cooperative acts have hallmark of reciprocity Social interaction with known individuals Typically cost to giver low, benefit to receiver great Blood Donation Blood Donation: Donor will never meet recipient of their blood Potential Benefit: Develop reputation as a cooperator donating makes people feel good Donors are more likely to give if they are recognized For a wide range of charities Charitable donations revolves around social recognition in society (i.e Wearing a sticker that says “I gave blood”) Most donations are not truly anonymous/out of the public eye or the eye of society (usually other people know)
Understand That : People are more likely to donate if the fact that they did donate is recognized in the group Reciprocity in the EEA Studies of peoples with stone-age technology (a.) !Kung San (b.) Northern Ache (c.) Yanomamo !Kung San Khoisan ethnic group San tribe (hunter-gatherer society) Khoi (pastoral) a.k.a Hottentots Ancient hunter-gatherer monogamous culture Approximately 40% calories from meat, but highly variable depending on hunting success Hunt in 2 man teams, successful hunters share food with relatives Social Taboos (frowned upon): Failure to share and boasting of hunting Meat sharing likely result of kin selection and reciprocity Meat initially shared with relative,s and then with relatives of relatives Large game provides excess food that will spoil quickly Low cost to share, large benefit to receive Northern Ache Norther Ache Polygynous culture living in rainforest of easter Paraguay No contact with industrialized world before 1970s Nomadic hunter-gatherers living in groups of 15 - 60 people Men hunt much of the day, women forage, and group meets each day at camps Food is generously shared among group Men are expected to help provide for offspring that might be theirs (confusion of paternity) Sexual jealousy may lead to abuse Food Sharing Extensive food sharing in San and Ache has sometimes been used to romanticize hunter- gatherer culture Note that homicide and infanticide rates are much higher than industrialized cities Yanamamo Yanomamo Polygynous, hunter-gatherer of Amazonia
Hunting-gathering supplemented with slash-ben agriculture Semi-permanent villages Trade and gift-exchange (specialization) Violent rais on rival villages Men killed, women abducted (as many as possible) Typically recent based Long term culture of feuding Revenge as a retaliation for past raids against them (“pay back”)

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