Can Prudence Evolve?

previously we reached the following conclusions about the evolution of predation . . .

  • efficient predation is a form of selfishness and prudent predation is a form of altruism as defined in evolutionary biology -- altruism occurs when behavior is disadvantageous in the short run (in terms of the spread of alleles) for the individual performing the behavior but advantageous for others

  • selfish and altruistic behavior are often associated with short-term and long-term benefits respectively (as in the cases of efficient and prudent predation)

  • all other things equal, selfish behavior (including efficient predation) is an Evolutionarily Stable Strategy (ESS) with respect to altruistic behavior (including prudent predation)

  • efficient predation should evolve (spread in populations) to replace prudent predation
these conclusions apply to evolution as a general rule -- but are there special conditions in which prudence could evolve?

there are three possibilities . . .

  • altruistic prudence could evolve by kin selection
    provided C < rB where C is the cost to the (altruistic) actor, B is the benefit to the recipient, and r is the coefficient of genealogical relationship (the probability that an allele in the actor is present in the recipient as a result of descent from a common ancestor) -- the benefit to the recipient is devalued by the coefficient of genealogical relationship

    kin selection is a form of natural selection -- the spread of alleles in a population as a result of changes in age-specific fecundity and survival of phenotypes associated with those alleles whenever related individuals interact with each other

  • altruistic prudence could evolve by reciprocity
    provided reciprocating (cooperating) individuals (1) play tit-for-tat (respond to a partner by cooperating or defecting contingent on the partner's previous behavior to them), (2) recognize each other, and (3) interact repeatedly without a predictable end

  • in some situations prudence might be selfish (rather than altruistic)
    as we see below

prudent predation has an obvious analogy in human affairs -- prudent management of resources

human prudence often fails -- a situation called a tragedy of the commons -- suppose the people of a village graze their sheep on common pasture -- it would then pay for each family to put as many of its own sheep out as soon as possible -- even if the pasture is quickly destroyed and nobody can graze sheep there -- anybody practicing restraint would end up with less -- the tragedy of the commons is a clear case of efficient, short-term use of resources instead of prudent, long-term use of resources

humans might avoid this problem in two ways . . .

private property . . .
would allow individuals to manage their own resources for the highest yield in the long term
but only if property owners absorb their own costs and retain ownership of the property (it cannot be converted to another use and sold for cash)

social contracts or agreements among individuals to cooperate . . .
could also ensure prudent use of resources
but only if there is some mechanism to prevent (or at least to limit) cheating

notice two important results . . .

private property (with the conditions above) makes prudence a form of selfishness rather than altruism

social contracts are a form of reciprocity (I'll obey the rules if you obey the rules)

can "private property" promote the evolution of prudence in other vertebrates ?

territoriality (defense of an area by an individual or group) is like private property of humans because a territorial animal has exclusive use of the resources in its territory -- it is different because no territorial animal can sell its area

so territoriality could promote prudent use of resources -- provided three conditions are met . . .

to make defense of an area advantageous, resources must occur in predictable locations (predictability condition)

to make prudent use of resources advantageous, resources must also remain in the territory (sequestration condition)

and individuals (or their relatives) must retain control of their territories in the long run (persistence condition)

wolf packs defend territories -- moose ranges are smaller than wolf territories -- so the moose on a pack's territory one year are likely to still be there in the future if they survive (predictability and sequestration) -- each pack consists of one breeding pair and their progeny from preceding years -- so the same individuals or their progeny occupy a territory in successive years (persistence) -- so a pack that managed the moose within its territory to maximize moose available in the long run might increase each members' own survival and reproduction -- so we might expect them to practice prudent predation

wolf packs that prey on caribou face different conditions -- caribou herds migrate through the wolves' territories twice each year -- how does this situation change things? -- do you expect these wolves to practice prudent predation?

private property or territoriality (with the conditions above) promote prudence because in this special case long-term management of resources directly benefits each individual (selfishness) . . . so each individual spreads its own alleles by practicing prudence

without immediate benefits for each individual, prudence requires . . altruism occurs when each indiviudal provides benefits to others at a cost to themselves . . . altruistic actions unless the conditions for kin selection or reciprocity are met

by now we have seen that there are three ways that alleles can spread in a population . . .

  • as a result of kin selection
  • as a result of reciprocity with limitations on cheating
  • as a result of direct benefits to the actor

how should we think about human predation?