5. Cooperation & Altruism Flashcards
What behaviours (as a result of evolution) benefit our genes?
Status seeking Competition Aggression Grooming Food sharing Charitable donations?
Traditional view of altruism
Due to group selection (people believed individuals acted for the good of the group)
However, any selfish individual invading a group of ‘complete’ altruists will benefit
If not group selection, must be other specific circumstances where altruism evolved
Early theories of evolution of altruism
Kin selection
Reciprocal altruism
Which early theory of evolution of altruism explains cooperation between non-relatives?
Reciprocal altruism
Examples of reciprocal altruism
Food giving among Hiwi and Ache families is based on reciprocity
Everyday examples in UK (childcare, buying drinks, peer support)
Male baboons help each other usurp higher ranked males to gain access to fertile females
Vampire bats share blood
Injured dolphins supported by non-relatives
Monkeys warn of predators with alarm calls
What are the conditions for reciprocal altruism?
- the cost of the altruistic act MUST be less than the benefit received later
- species capable of RA must be highly social (live in groups)
- species must have appropriate cognitive abilities (remember past interactions, learn from them)
In which species is reciprocal altruism most likely to occur according to the conditions for RA?
Humans and other primates
How can we experimentally examine reciprocal altruism?
Economic games
Prisoner’s Dilemma
2 players make decisions simultaneously + confidentially
Decision they make and their partner makes affects benefits they receive
Prisoner’s Dilemma: one-shot
always ‘defect’
this strategy guarantees a return (but not as beneficial as if both cooperate)
Prisoner’s Dilemma: iterated
best strategy is for both players to continue to cooperate (more beneficial)
Who organised the Prisoner’s Dilemma tournament?
Robert Axelrod (1981)
What was the purpose of the Prisoner’s Dilemma tournament?
Different strategies pitted against each other to determine the best way to play the iterated PD game
What is the best strategy for the Prisoner’s Dilemma?
TIT-FOR-TAT
Nice: cooperate on the first go
then copy what the opponent did on their last go…
Retaliatory: sees cheating and cheats too
Forgiving: forgives earlier cheating if opponent begins cooperating again
Choosing cooperative partners: evidence for physical attractiveness
Attractive people cooperated with more and more expected from them (Solnick & Schweitzer, 1999)
Also viewed as more trustworthy and punished more when they are not (Wilson & Eckel, 2006; Andreoni & Petrie, 2008)
Choosing cooperative partners: halo effect
Attractive individuals rated as having other positive traits
How does altruism help our mood?
Mood management hypothesis - helping alleviates temporary sadness (negative state relief model) (Cialdini et al., 1982)
Why would you help a person on the street? Proximate and ultimate explanations
Proximate: “it makes me feel good” (negative state relief model)
Ultimate: “it benefits my inclusive fitness through increased survival/reproduction” (evolutionary perspective)
Helping helps mood: oxytocin
Oxytocin leads to increased trust
It has increased role in social bonding + attachment
Possibly through lower aversion to betrayal
Helping helps mood: Eisenegger et al. (2009) (testosterone study)
Gave Ps testosterone or placebo
Ps played ultimatum game
Testosterone made Ps fairer
Ps who were less fair thought they received testosterone
Testosterone causes an individual to seek better social status
Helping helps mood:
Oxytocin is proximate mechanism that…
drives human cooperation for social interactions?
Helping helps mood:
Testosterone is proximate mechanism that…
leads to cooperation for reputational benefits?
Homo economicus Vs. Homo reciprocans
Homo economicus: humans are rational + self-interested
Homo reciprocans: humans are motivated to cooperate
Contemporary theories of altruism
Indirect reciprocity
Image scoring
Altruistic punishment
Costly signalling
What is the theory of indirect reciprocity?
Instead of recipient of act returning the favour, the favour is returned by a third party
Altruist broadcasts their cooperativeness to their own benefit (reputation)
What is the theory of image scoring?
Each individual in a group has an ‘image score’ based on their cooperativeness in previous interactions with other group members
Cooperative scenario - if they help, +1 to their score, but if they don’t help, -1 to their score
Altruistic punishment theory
Cooperation evolved because n on-cooperation was punished by others in the group
Punishment is severe and costly to perform
Altruistic punishment theory: public goods game
Group must play together to gain most, but people can play selfishly and still receive benefits
Punishment possible - highest levels of cooperation
No punishment - drop in contributions
Altruistic punishment theory: proximate explanation
The negative emotions we feel when we have been cheated
Participants rated anger with cheaters as very high
Punishment cross-culturally
People in larger, more complex societies engage in more altruistic punishment than people in smaller societies
Competitive altruism
Individuals compete with one another to be chosen as future cooperative partner
Cooperation among group - 2-stage process: assessment stage, partnered stage
Important to get cooperative partner for 2nd stage, so individuals compete to be most cooperative in 1st stage
Costly signalling
Cooperation - an honest sign of quality
Show you can afford the cost of being cooperative
The bigger the act of altruism, the more you can afford
Signals of quality to others
Altruism as a courtship display
A costly signal of quality to potential mates?
Signal of desirable traits, e.g. ability to cope with handicap (good genes), kindness (good parenting skills)
Altruism as a courtship display: examples
Men more likely to give money to female beggars, less when with another woman
Skilled turtle-hunters among the Meriam share catch with group and have greater reproductive success
The giving of costly but useless ‘gifts’ (e.g. flowers) in relationships is an evolutionary stable strategy
Altruism as a courtship display: Farrelly et al. (2007)
Both males and females more cooperative with attractive opposite sex partners
[see slides for more examples]
What is altruism signalling?
Evidence suggests that prosocial behaviour is important in human mating (but we don’t know why! Does it signal that the actor has good genetic quality or good partner/parent quality?)
Altruism as a signal of good partner/parenting quality
Both men + women rate altruistic partners as more desirable for long-term relationships
Altruism > attractiveness in long term for women
Different types of altruistic behaviour signal different psychological traits - trustworthiness, heroism
