Week 7 - cooperation

Outline Hamilton’s (1964) payoff matrix

involves mutualism, selfishness, altruism and spite

which of hamilton’s payoff matrix ‘shouldn’t have evolved’?

Altruism - because actor suffers a fitness cost for others

why is there a problem in cooperation?

free-riders share the benefits but not the costs, this is true for mutualism and altruism

what is inclusive fitness made up of?

total fitness of an individual’s genes =

• direct fitness (personal reproduction)

• indirect fitness (additional reproduction by relatives, e.g. brothers share same amount of DNA)

Hamilton’s rule

an act has a cost for the donor and benefits for the recipients

• cost/benefit analysis

• spread of a gene for altruism occurs when

• c (cost for actor) < coefficient of relatedness (r ), benefit to recipient (b)

why are we kind to kin?

kin selection can explain a great deal of altruistic behaviour, including the evolution of sterile worker castes (e.g. honey bees)

why are we kind to strangers?

• for the good of the species

• classical group selection (Wynne-Edwards) → but benefits have to go the individuals gene too

reciprocal altruism (Trivers 1971)

•  direct reciprocity, costs should be lower than the benefits, benefits should be delayed

  • Requirements:

    • Interact often

    • Be able to recognise one another and keep accounts

    • Be able to act contingently

• Direct reciprocity very rare in nature even though cognitive demands are often met

• Wilkinson (1984)/Carter & Wilkinson (2013)

• Vampire bats regurgitate blood to colony mates

indirect reciprocity

help others to build a reputation (downstream), help others as a form of niceness (upstream)

• means maybe someone will be nice to you

generalised reciprocity

Altruism without expectation of return, also called attitudinal reciprocity or 'warm glow' altruism

negative reciprocity

• Punishment

• Inflicting harm for harm done

• Important for deterring free-riders

• Third-party punishment particularly important and possibly uniquely human (chimps don’t do it but human children do)

strong reciprocity

Cooperate with others and punish noncooperators

cultural group selection of altruism

• Groups with altruists do better than groups without

• Between group competition can lead to the evolution of altruism under certain conditions

game theory

would predict to hoard as that is the best outcome

• maximising sucess depends on the fact that you assume other players are rational

How can cooperation arise from a prisoner’s dilemma

repeated games, iterated prisoner’s dilemma, winning strategy was tit-for-tat → kind retaliatory and forgiving

• BUT if number of rounds is known, backwards induction leads rational players to always defect

what is ‘cold’ cognition

reasoning →recognise one another, keep accounts, keep track of relationships of others

what is ‘hot cognition’

short cuts (heuristics) might guide our decisions, emotions can serve as ‘themostats’ of our social decisions

• measurement of whether we have achieved a desired outcome

what are the fortunes of others emotions? (Ortony, Clore & Collins, 1988)

• symhedionia - when both are feeling positive emotions

• schadenfreude - when someone is feeling positive and you are feeling negative

• jealousy - when someone is happy and you are sad

• empathy - both feeling negative

Einfühlung

empathy → feeling others emotions can motivate prosocial behaviour

what is tragedy of the commons?

‘increasing the herd without limits’ - in a world that is limited

what is an example of the tragedy of commons in real life?

climate change → free-riding means that public resources are lessened