Evolution of Morality Psychobiology NOH Hope Park 2005 Ins Canavarro Morais

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Evolution of MoralityPsychobiology NOH Hope Park
2005Inês Canavarro Morais
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Tinbergens four Whys

• Proximate causes of morality (e.g. emotions)
• Development of morality
• Ultimate (adaptive) function of morality
• Evolution of morality

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The problem of altruism

• Altruistic act an act that has a cost to the
  actor but increases the fitness of the recipient
• Reduces personal fitness
• Increases the fitness of competitors

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A Popular but Incorrect explanation of Altruism
Group Selection (community, species, ecosystem)

• Supposed examples
• Lemmings commit suicide to save species from
  starvation
• Stags fight so only the best males will pass
  their
• genes on to the species
• Wolves eat only the sick and old deer, keeping
  the deer species strong

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The problem of altruism

• Problem
• The selfish individuals
• contribute more to the
• next generation
• UNLESS
• Some other selection
• pressure selects for
• Altruism

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The Problem with GroupSelection

• Wynne-Edwards (1962) Group selection explains
  altruism
• BUT
• Individuals replicate faster than groups will
  win any conflict between them.
• Selfish individuals (mutants, immigrants) will
  take over unselfish groups.
• Freeloaders do better than altruists. Thus,
  altruistic genes should cease to exist

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Genes as the Units of Selection

• Why individuals dont replicate
• 1. We don't clone ourselves we reproduce
  sexually
• 2. Lamarck was wrong acquired traits aren't
  inherited.
• Genes do replicate
• Most genes are passed on intact in sexual
  reproduction
• The gene is the unit of selection giving rise to
  adaptations "The Selfish Gene."
• Replicators (genes) versus Vehicles
  (organisms)

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How to Solve the Puzzle of Altruism

• See how selfish (nonaltruistic) genes can
• give rise to unselfish (altruistic) individuals
• Genes are the units of selection, not organisms
• Difference between psychological (proximate) and
  biological (ultimate) explanations

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Two ways that Unselfishness canPay off for the
Genes

• Nepotism (kin selection, inclusive fitness)
• 2. Reciprocity altruism repaid by the recipients
  of altruism
• - direct reciprocity
• - indirect reciprocity
• Costly Signaling altruism signals some
  underlying quality
• Competitive Altruism

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Kin Selection

• Hamiltons rule c lt rb
• c cost of altruistic act
• b benefit to recipient
• r coefficient of relatedness
• Coefficient of relatedness proportion of genes
  that are identical by descent from recent
  common ancestor

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Examples of kin selection

• Helpers at the nest (Florida Scrub Jays)
• Alarm calls frequency of alarm calls given by
  Beldings ground squirrels in response to a
  predator is a function of the genetic relatedness
  of other squirrels present (Sherman, 1977, 1980).
• Inheritance Smith et al. (1987) inheritance
  more likely to go to close relatives.
• Age of Helping Essock Vitale and McGuire
  (1985), found that people were more likely to
  help younger than older people.

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How does kin selection operate?

• For altruistic behaviour to benefit kin, there
  must be some mechanisms by which kin and non-kin
  can be distinguished
• Learned mechanisms
• Familiarity it is likely that familiar
  individuals are related, so it pays to favour
  familiar animals (olfactory, visual, auditory
  cues)
• Location in social groups it is likely that
  neighbouring individuals (same nest, territory)
  are kin
• Prolonged social contact
• Genetic mechanisms
• Phenotype matching related individuals usually
  resemble each other
• Recognition allelles e.g. the green beard effect.

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Help to kin
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Predictions of Inclusive Fitness

• Humans will possess psychological mechanisms that
  produce behaviour that is effectively nepotistic
• Humans should be sensitive to the relatedness of
  others (or reasonable cues of it) when deciding
  to help
• Kin will be less likely to be harmed than non-kin
• People will be more tolerant when dealing with
  kin than with non-kin
• Feelings and behaviours towards kin should be
  sensitive to cues of the likelihood of those kin
  having offspring

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Two ways that Unselfishness canPay off for the
Genes

• Nepotism (kin selection, inclusive fitness)
• 2. Reciprocity altruism repaid by the recipients
  of altruism
• - direct reciprocity
• - indirect reciprocity
• Costly Signaling altruism signals some
  underlying quality
• Competitive Altruism

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Different types of Altruism

• Mutualism helper and recipient both gain through
  their interaction e.g. co-operative hunting by
  lionesses Stander (1992)
• Reciprocal Altruism (Trivers, 1971) Food Sharing
  in Vampire Bats, Wilkinson (1984, 1990). Can
  also be thought of as delayed mutualism
• Cooperation courtship in the Long-tailed Manakin
  (bird) Mc Donald (1989)

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Reciprocal Altruism

• Gains in trade (simultaneous exchange)
• BUT
• The delayed exchange is vulnerable to cheating
  and requires discrimination against free riders
• Example grooming
• You scratch my back Ill scratch yours

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Requirements of reciprocal altruism

• Confer large benefit to others at small cost to
  self.
• Roles must sometimes reverse.
• Recognize other animals as individuals.
• Remember who helped, who hurt.
• Grant, withhold favors accordingly.
• NOTE Last three are predictions about psychology

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Prisoners dilemma(Axelrod Hamilton, 1981)
TgtR and PgtS, but the combined payoff for
cooperation (R) is greater than the combined
payoff for cheating (P)
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Formal structure of a prisonersdilemma

• Best individual payoff defect while other guy
  cooperates
• Lowest individual payoff cooperate while other
  guy defects
• Highest total payoff both cooperate
• Lowest total payoff both defect

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The Problem of PrisonersDilemmas

• If both parties are selfish, they end up worse
  off than they would be if both cooperated
• BUT if one decides to cooperate, he will be worse
  off than if he decides to be selfish, regardless
  of what the other one does
• SO both act selfishly, and both end up worse off!
• It then becomes an Evolutionary Stable Strategy
  (ESS) A strategy which, if adopted by all
  members of a population, can not be invaded by an
  alternative one or mutation
• Nash equilibrium pair of strategies such that
  each is the best response to the other (no
  incentive
• for either to switch)
• There is no solution to this paradox. But .

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The Iterated Prisoner's Dilemma

• Prisoners repeatedly encounter each other
• Tit for Tat Strategy (Axelrod Hamilton, 1981)
• Cooperate on first move.
• Thereafter, cooperate if partner cooperated on
  preceding move defect if partner defected.
• Requirements of Tit for Tat
• Interact repeatedly.
• Remember each other's behavior.
• Reciprocate.
• (Psychological predictions!)
• If the benefit to the recipient gt cost to the
  donor, both participants will gain if the help is
  reciprocated at a later date.

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What if you havent interacted yet?

• How do you know whether to cooperate or not?
• Can you spot cheaters before they cheat you?
• You can observe others interacting
• Cosmides Tooby proposed the existence of
  cheater detection modules in the brain

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Human Adaptationsto Reciprocal Altruism?

• Cognitive abilities
• 1. Memory for individuals (faces, names, voices).
  Mealey et al (1996), Oda (1997) faces of known
  cheaters are remembered better than other faces
• 2. Cheater detection sensitivity to someone
  taking a benefit without paying a cost.

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Evidence for Cheater-Detection

• People solve logical problem best when asked to
  look for examples of people breaking a social
  contract
• People are good at predicting whether others will
  cooperate/defect

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Cheater-Detection Strategies

• If an employee collects a pension, he must have
  worked for 20 years
• You work for the Benefits Office, and have to
  verify which of the following?
• A Collects a pension Worked how long?
• B Doesnt collect a pension Worked how long?
• C Worked 20 years Collects a pension?
• D Worked 15 years Collects a pension?

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Social contract

• Most people say A or A C
• Correct answer A D
• "Confirmation bias"
• People seek evidence to confirm, not falsify,
  their hypotheses

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Emotions adapted to reciprocal altruism

• Liking Initiate altruistic partnership to those
  likely to reciprocate (cooperate on first move)
• Anger Reaction to being cheated avoid and/or
  punish cheater (defect if other guy defected)
• Gratitude Reaction to being helped return
  favor in future. (cooperate if other guy
  cooperated)

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More Emotions Related to Reciprocal Altruism

• Sympathy Help those most in need (earn
  gratitude) (great benefit to other at small cost
  to self)
• Guilt Bestow extra benefit after cheating
  (cooperation compensating for defection)
• Shame Punish self when cheating has been
  discovered (avoid punishment for defection by
  showing that future defection is unlikely)
• Mencken "Conscience is the inner voice that
  tells us someone might be looking."

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The Importance of Reputation Character

• Dont have to see someone cooperate or defect
• With language, can hear about whether they tend
  to cooperate or defect
• Importance of gossip, reputation, honour.
• Test of importance of reputation The Ultimatum
  Game

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The Ultimatum Game

• First player (proposer) divides a jackpot
  (e.g., 10)
• Second player (accepter) either accepts the
  division (both get what the proposer proposes) or
  rejects it (neither gets anything)
• Optimal strategy for proposer 9 1
• Optimal strategy for accepter take anything
  above 0
• Actual strategy of proposers 5-6 for self
• Actual strategy of accepters reject anything
  less

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Why do accepters reject nonzero offers (spite)?
Hypothesis anger over being treated unfairly
fMRI during the Ultimatum Game (Sanfey et al.,
Science 2003)

• activation of insula (unpleasant emotions) when
  offer is low (1 vs. 5) and comes from a person
  (vs. a computer)
• (also dorsolateral prefrontal cortex (DLPFC)
  reasoning)
• (also anterior cingulate cortex (ACC)
  conflict)

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Being Seen as a Cheater

• People know that being unfair while being
  observed is not a good idea
• Ex. Dictator Game (Hoffman et al., 1994)
• One subject decides on the split, other player
  gets whatever is sent
• A refusal to help lowers ones reputation
  decreases the chances of one receiving help

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Coping with cheating

• Accepters spite is self-destructive over the
  short term, BUT advantageous over the long term
  via reputation
• Passionate anger makes threats credible
  prevents other guy from calling your bluff
• game of chicken
• chain self to tracks
• hes crazy enough to do it

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Altruistic Punishment

• Fehr Gachter (2002) The fear of punishment
  might induce altruism. People will pay to
  punish selfish others.
• Cooperation depends on reciprocity (Ill scratch
  your back etc.) but also on retribution (if I
  scratch your back, and you dont reciprocate, I
  will punish you, no matter what the cost to me)
• Mealey et al (1996) faces of cheats were
  remembered better than faces of truthful
  individuals.

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Why genuine altruism maysometimes be the best
strategy

• Niceness, honor, guilt as guarantors that ones
  promises are not double-crosses.
• The best way to convince someone youre nice is
  to be nice!
• Passionate niceness as guarantee that promises
  are not double-crosses.
• (cf. Passionate anger as guarantee that threats
  are not bluffs)

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Competitive Altruism

• Genuine altruism and generosity
• Leave tip in restaurant during a trip
• Donate blood
• Sacrifice life to save fellow firefighters
• Why?

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What about altruism towards groups?

• Public good something that individuals have to
  expend
• effort to provide (an altruistic effort), and
  once it is
• provided, everybody benefits from it. No one in
  the
• group can be excluded from benefiting.
• Examples national defense, public radio,
  big-game
• hunting, group projects in university

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Common Pool Resources (CPRs)

• Collective rights and/or abilities to use, and
  whose value is
• depleted by each individuals use.
• Ex. Fisheries, pasture, irrigation systems
• Incentive to overexploit CPRs, not contribute
  to their
• maintenance
• Tragedy of the Commons

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Why should we care if people know?

• Remember
• In reciprocal altruism and the repeated
  Prisoners Dilemma, you can punish other players
  by returning defection with defection. Punishment
  is selective.
• However
• In a standard public goods game (Ngt2), you can
  only punish by reducing your own contribution.
  This punishes everyone else whether they are
  cooperators or defectors!

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Competitive altruism

• Not all behaviour is explained by reciprocity or
  kin selection
• Individuals might get indirect benefits for being
  altruistic, people might compete for the
  attention of other altruists
• Competitive altruism could work as a form of
  sexual selection i.e. make you more attractive

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Psychological altruism

• Numerous human behaviours seem anomalous from the
  evolutionary point of view Think for example of
  adoption. Parents who adopt children instead of
  having their own reduce their biological fitness,
  obviously, so adoption is an altruistic
  behaviour. So although kin selection and
  reciprocal altruism may help us understand some
  human behaviours, they certainly cannot be
  applied across the board.
• Where human behaviour is concerned, the
  distinction between biological altruism, defined
  in terms of fitness consequences, and real
  (psychological) altruism, defined in terms of the
  agent's conscious intentions to help others, does
  make sense.
• What is the relationship between these two
  concepts?
• An action performed with the conscious intention
  of helping another human being may not affect
  their biological fitness at all, so would not
  count as altruistic in the biological sense.
  Conversely, an action undertaken for purely
  self-interested reasons, i.e. without the
  conscious intention of helping another, may boost
  their biological fitness tremendously.

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• Altruism is a complex phenomenon, one explanation
  is unlikely to account for all altruistic actions
• In the EEA, humans evolved in small kin-based
  groups. It is possible that the evolved
  psychological adaptations for altruism reflect
  this.
• Kin selection and reciprocity alone are not
  sufficient explanations for altruism in humans
• The role of proximate causes (e.g emotions) in
  the evolution of altruism!