Reciprocity Flashcards
Common in human societies:
A helps B today, then B helps A tomorrow
What about in other animals? - theory
- evidence
The prisoner’s dilemma
always more beneficial and ESS to defect because it’s single encounter
Can escape the dilemma with repeated, indeterminate encounters
‘Tit for tat’ strategy
- cooperate on first move, then do what partner did
- can be ESS if probability of re-encounter is high
- depends on social organisation, longevity, etc
Vampire bats
Unsuccessful foragers are fed by
successful ones in roosts
Low average relatedness in roost - kin more likely to swap blood
The donors are well-fed, therefore a small amount of blood will benefit their hungry kin much more than it will benefit themselves
But: high chance of future interaction benefit to recipient high, cost to donor low donation is reciprocated
Follow-up study on vampire bats
Criticisms of Wilkinson study:
- sharing is kin-selected
- sharing with non-kin is coercion, mistaken identity or indiscriminate altruism within kin groups
Blood donation depended mostly on whether the donor previously received blood
Tolerance traded with grooming in wild vervet monkeys
Recent grooming by subordinates increased dominants’ tolerance of them at food sources
Predator mobbing in birds (Krams et al. 2008)
Birds were more likely to mob predator at neighbours nest if neighbour was a co-operator
Reciprocity has limited evidence
because interactions are rarely dyadic (impossible to develop profitable relationships and terminate unproductive ones)
Reciprocity
Holding class - holds access to social commodity
Demanding class - seeks access to social commodity
Trade dynamics - supply and demand, advertisement, commodity value
Male-to-female grooming
89% to receptive females
37% led to mating
Grooming duration decreased related to increased supply of females
Direct reciprocity
- ‘you scratch my back, I’ll scratch yours’ - as described so far
Indirect reciprocity
‘help someone who is helpful’
- reputation may be important in social interactions
- can work in theory, some evidence (lecture 5)
Generalized reciprocity
- ‘help anyone if helped by someone’ - can work in theory, one good supportive lab expt
Defection PUNISHED / cooperation ENFORCED
- cheating has high costs
Punishment eg
Dinoponera ants (Monnin et al. 2002) No queen Dominant female (alpha) reproduces If challenged, alpha marks challenger who is then PUNISHED by other females
Current evidence suggests reciprocity is not
widely important
(except in humans)