Altruism

altruism in multilevel selection (Wilson, 1977)

-individual level: gene not inherently altruistic (inevitably benefits itself as the organism is a vehicle for both genes) - selectively neutral -group level selection required for altruism to evolve

evolution of altruism

-kin selection -inclusive fitness -multilevel selection

altruism in inclusive fitness theory (Hamilton, 1964)

-altruism reduces invidiual's personal fitness but increases their inclusive fitness even where kinship not involved -e.g. social insects

Hamilton (1964) - Kin Selection Theory

-altruistic behaviour = strategy devised by selfish genes to increase representation in gene-pool at expense of other genes - only favours relatives w genes identical by descent -increases fitness of relatives who have high chance of also carrying altruistic genes -> increasing gene freq -degree of altruism increases the closer the genetic relatedness

Adaptive Paradigm

-altruistic behaviour evolves bc it is ADAPTIVE -genes not inherently selfish: cannot propagate itself w/o environment -how is a trait adaptive? -how does it promote fitness (not inclusive fitness)? -e.g. parents caring for young: if they didn't they would die, lineage would die out -altruism not a problem for evolution -EMERGENT PROPERTIES

benefits of multilevel selection (Wilson 1997)

-bridge between biological and human cultural evolution: within and between group selection -recognises complexity beyond gene-determinist view -gene-culture coevolution: culture evolves independently of genes and is another level selection operates at

Kamikaze bees (Dawkins, 1982)

-colonies of social insects -individuality is sacrificed for welfare of community - operating as a coherent superorganism at group level -sterile workers die when stinging honey-raiders to protect the queen (reproductive relative, through whom shared genes are propagated) -self-sacrificial behaviours that increase reproductive success of queen increases individual's inclusive fitness more than selfish behaviours would - propagating altruistic genes

Dawkins (1982) - evolutionary arms race between song-birds (Passifermes) and cuckoos (Cuclus canorus)

-cuckoo genes for deceptive mimicry -song-bird genes for mimicry detection -selfish genes increase freq in gene pool -individual selection amongst fittest song-birds and cuckoos promoted selection of selfishness,

Dawkins (1982) - dangers of altruism

-genes for individual selfishness have selective advantage of 100% certainty of individual identity -'kin-altruistic gene' at risk of mistaking identities and vulnerable to cheats or parasites -'subversion from within': altruistic groups exploited by 'free-riders' (benefiting from altruism without incurring costs) who out reproduce altruists and propagate selfish genes

classifying altruistic behaviour

-reduce donor's fitness -weak altruism: relative to recipient -strong altruism: absolute fitness -long-term symbioses outweigh short-term costs -> mutualism, reciprocal altruism

Dawkins (1982) - misfiring of altruism gene

-whales and dolphins aiding your/less fit individuals to reach surface for air - projected onto drowning humans - individuals programmed to help any similar organism in close proximity as it is likely to share genes -animal adoption not evolutionary stable -> arms race

inclusive fitness theory (Hamilton, 1964)

-wider branch of kin selection -neo-Darwinian synthesis based on differential gene reproduction -inclusive fitness = personal fitness of an individual (direct) + sum of weighted effects on fitness of every other organism in population (indirect) --> characteristics that affect reproduction need not affect the personal production of offspring; they can affect the survival and reproduction of genetic relatives as well

Sherman (1981) - kin selection in sage rats

alarm calls given by females more likely when escaping predators if close relatives nearby

biological altruism (Okasha 2013)

any behaviour that is selectively disadvantageous for the individual organism but beneficial for the survival and reproductive success of another individual/group

Criticism of Hamilton and Dawkins

based on 2 false assumptions (and uses gene's eye view): 1. genes are selfish 2. there is a gene for altruism and selfishness - mathematics is limited by validity of its assumptions

reciprocal altruism (Trivers 1971)

behaviour that benefits another with expectation that benefits will be returned in the future (tit for tat) -evolves when donors can recognise cheats, so only help those who reciprocate - sufficient pair-wise interactions

is behaviour real altruism if it has selfish motivation?

bio altruism not concerned w motivation - misleading personification of genes, inanimate molecules

multilevel selection and social insects (Wilson, 1997)

colony forms 'group mind': individuals so integrated they share cognition and communicate decision-making -bee colony w most efficient cooperation has greater reproductive fitness -> selection for group cognition/integration -BUT group mind not dependent on altruism, benefits of cooperation and communication benefit each individual equally

psychological altruism and cultural group-selection (Scheuring 2009)

emergent social structures allowed conscious beings to evolve - psych altruism emerged from bio altruism - primarily by cultural group selection -emergent property of genetics/physiology interacting w environment (Noble)

Williams (1966) - animal adoption

faulty regulation of reproduction mechanisms caused by selection pressures for maintaining certain parental behaviours

Darwin (1871) - group selection in 'The Descent of Man'

fitness variation between groups -a tribe w members who were always ready to give aid to each other and sacrifice themselves for the common good would be victorious over most tribes - this is natural selection -accepted til 1960s -human morals and conscious self-sacrifice (distinct from unconscious bio altruism)

individual selection (David Lack, 1950s-60s)

fitness variation within groups determines selection of better adapted individuals -pop size regulated by density-dependent survival (shortage of resources) and reproduction -'selfish genes' outcompete 'altruistic genes' so altruism cannot evolve

Hamilton's rule

for altruism to evolve: the benefit to the recipient, devalued by the coefficient of relatedness, must exceed the cost to the altruist. b > c/r -depends on direct and indirect fitness (inclusive fitness)

group selection of altruism (Wilson 1997)

groups w higher no. of altruists more likely to cooperate and outcompete a group of mainly selfish individuals

Wilkinson 1988 - blood sharing in vampire bats

individuals donate blood to non-related, well-known companions -starved bats which received blood reciprocated donation more often

G.C. Williams (1966) - William's Principle

mathematical models established that adaptation at a level requires selection at that level - so group adaptation requires group selection -BUT accidentally advantageous traits that now benefit a group don't mean they evolved bc of group selection - not group adaptation -may have emerged by CHANCE as product of individual selfish activities - based on inclusive fitness theory, evolutionary game theory and selfish gene theory

Maynard Smith

mathematically: group selection = inherently weak evolutionary force, so unlikely to produce altruistic behaviours

Dawkins (1982) - parental altruism

parental care just a special case of kin altruism -parents should devote as much care to sibling as own offspring (share 50% genes) -reiterates Hamilton's rule: dependent on probability of relatedness -estimation of relatedness and degree of certainty of relationship more important than true relatedness - so maternal altruism more common than sibling altruism -altruism must be taught to children: not part of biological nature

group selection (Wynne-Edwards, 1950-60s)

pops that exploit their food resources are likely to go extinct - exercising restraint allows survival -selection favours evolution of behaviours that limit fecundity -good of the species

multilevel selection (Wilson 1997)

same outcomes as inclusive fitness but distinguishes selection on individuals from groups -same conceptual framework to all levels of bio hierarchy: adaptive group units studied like individuals - compare fitness variations

Dawkins (1982) - where does altruism evolve?

species living/moving together in small, stationary groups - high probability of relatedness so altruism worth the cost

Briskie et al 2004 - manipulation in nestling birds

young birds beg to attract parent's attention, but may attract predators -begging is selfish and costly -greater in species w lower relatedness