Lecture 3 - reciprocity Flashcards
who was the idea of reciprocity devised by?
bob trivers (1971)
what phrase is reciprocity exemplified by?
‘you scratch my back, ill scratch yours’
what theory underpins reciprocity?
the prisoners dilemma game - 2 players in a game with choice of ‘cooperate’ or ‘defect’
what are the 4 possible outcomes in the prisoners dilemma matrix?
R = mutual cooperation reward – both have a cost but also both gain T = temptation to defect – if they defect a co-operator they get only pay off and have no cost S = if you cooperate with a defector you only get cost P = you defect a defector you are both punished
in a population of defectors what is the best option?
the best option is too defect - in a one off interaction the best ESS (strategy) will be too defect
Can reciprocity work and can individuals escape this dilemma?
NO…. if single encounter, or fixed number of encounters, defect is always ESS
YES… can work with repeated, indeterminate
encounters
describe the ‘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
- the conditions for this tit for tat strategy may actually be quite widespread in nature
describe the text book example of reciprocity in vampire bats?
- In roosts the bats form, unsuccessful foragers are fed by successful ones
- Within the roosts - there is low kinship overall - low average relatedness, however the kin were more likely to swap blood(food) than the others
- But the 3 key facts that point towards reciprocity taking place are:
1) high chance of future interaction (always come back to the same roost)
2) benefit to recipient high, cost to donor low
3) donation is reciprocated (observed during study)
what has been criticised by the wilkinson study on vampire bats?
- sharing is kin-selected
- sharing with non-kin is coercion, mistaken identity or indiscriminate altruism within kin groups
Carter and Wilkinson (2013) then did another study
The question was then asked of what blood donation depended on what were the possibilities?
1) blood recieved
2) Grooming received
3) Donor sex
4) relatedness
what was the result of the second study carried out by carter and wilkinson?
blood donation depended on blood received supporting the reciprocity interpretation
what is an example in primates of reciprocity?
Primate grooming and alliances - grooming tends to be reciprocated between individuals - however it’s hard to know if its reciprocal or mutualistic behaviour because they two individuals often take part in the act at the same time
- relatively few studies in primates
describe the best example of reciprocity in birds
- Experiment involved 3 pairs of flycatchers occupying next boxes
- At one nest box they caught the pair and put them In a cage
- They then presented a stuffed owl at a nest box and the pair started mobbing the owl - another pair not in the cage then also joined in the mobbing
- Then when owls were placed at the two other pairs (one of which now out the cage)
- The original pair then went to help the pair which helped them with the mobbing the first time - reciprocating the behaviour
- The original pair never helped the pair that didn’t help them the first time around
what are the 3 general conclusions about reciprocity
- Limited evidence in natural systems (Clutton-Brock 2009; but see Taborsky et al. 2016 - strong advocate for the idea)
- Interactions are rarely dyadic
- instead individuals will develop profitable relationships
and terminate unproductive ones
3.Defection PUNISHED / cooperation ENFORCED
- Cheating has high costs
what theory has the idea that interactions are rarely dyadic been formulated in?
The Biological market theory (Noë & Hammerstein 1994, 1995)
