Evolution of Morality Lecture 2 Minna Lyons lyonsm2hope'ac'uk

1
Evolution of MoralityLecture 2Minna
Lyonslyonsm2_at_hope.ac.uk

• (Chapters 2,3 and 4 in Barrett, Dunbar Lycett,
  2002)

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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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Morality and altruism
The problem of altruism

• Altruism any behaviour that has a cost to the
  donor and benefits the recipient
• Costs and benefits are measured in terms of
  evolutionary fitness, the offspring reproduced
• Problem of altruism how do nice genes get
  transferred from one generation to another
• In biology, no true altruism

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Selfish genes VS Group selection

• Wynne-Edwards (1962) Group selection explains
  altruism
• Dawkins (1975) Selfish gene
• Group Selection is not an Evolutionarily Stable
  Strategy (ESS)
• Freeloaders do better than altruists. Thus,
  altruistic genes should cease to exist

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Frequency dependent selection

• fitness of a phenotype is dependent on its
  frequency relative to other phenotypes in a given
  population.
• Positive frequency dependent selection the
  fitness of a phenotype increases as it becomes
  more common
• Negative frequency dependent selection the
  fitness of a phenotype increases as it becomes
  less common.

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How does altruism evolve?

• Kin selection
• Reciprocity
• Indirect altruism (reputation)
• Altruism as a costly signal
• Punishment

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Kin selection- degree of relatedness

• Co-efficient of relatedness (r)
• Parent-offspring 0.5
• Individual full sibling 0.5
• Grandparent-grandchild 0.25
• Individual- cousin 0.125
• Individual- identical twin 1.00

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Kin selection-Hamiltons rule
To explain altruism between relatives,
Hamilton(1964) developed the theory of inclusive
fitness. Altruistic behaviour should be observed
if rb - c gt 0 c cost to the donor b
benefit to the recipient r degree of
relatedness of the donor and recipient (e.g.
siblings are related 0.5)
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Game theories-Prisoners Dilemma

• Axelrod (1984) Computer PD Tournament
• Tit for Tat emerged as a winning strategy
  Co-operate on the first move, and then mirror the
  actions of your opponent
• Requires that people meet more than once, and can
  detect cheats

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Can we detect cheats?

• Cosmides and Tooby have suggested that people
  have a cheat detection module in their brain
• Mealey et al (1996), Oda (1997) faces of known
  cheaters are remembered better than other faces
• Yamagishi et al (2003) Cheaters look different
  from co-operators
• Can we recognise altruists as well?

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Indirect altruism

• By behaving altruistically, an individual might
  gain more prestige within a social group, and be
  more likely to receive help from others
  indirect altruism
• Nowak and Sigmund (1998) altruism can exist if
  individuals know the reputation of others
• Criticism- altruists are still open for
  exploitation by social scroungers-not an ESS

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The public goods dilemma

• Hardin (1968) Tragedy of the commons
• When people use a common good, free-riders do
  better (e.g. TV license, clean air)
• Legal institutions and punishment an evolved
  response?
• Moral sentiments (anger, guilt etc) maintain
  cooperation?

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What is morality?

• Alexander (1985) Moral system is a society with
  rulesrules are agreement about what is permitted
  and what is not, about what rewards and
  punishments are likely for specific acts, about
  what is wrong and what is right
• Morality reinforced by the society-
  cross-cultural differences?

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• Planalp (1999) to behave morally is to judge
  right and wrong, good and bad, and to behave
  accordingly
• morality comes from within- are there moral
  universals?

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How can we explain morality?(Lahti and
Weinstein, 2005Alexander, 1989)

• During human evolution, there was competition
  both between and within social groups
• Moral behaviour is facultative, and evolved both
  for inter and intra-group purposes
• People adhere to moral rules when there is an
  external threat to the group
• Relaxation of morality more likely when the
  social group is stable
• Both group selection and selfish genes
  explanations!

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Taking Stock

• 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!