4/13 & 4/15 - Cooperation and altruism among nonrelatives, Proximate mechanisms for managing conflicts

How does the theory of 'reciprocal altruism' explain the evolution of altruistic

behavior? How does it differ from the theory of kin selection?

• Reciprocal altruism: trading of altruistic acts over time, in one or more than one ‘currency’, there is a time lag between giving and receiving

• Differs from kin selection: kinship not req, delayed gratification rather than altruism, not necessarily related to kin or reproduction

What conditions must be met for reciprocal altruism to evolve?

• Partners must meet repeatedly to there are opportunities for reciprocation

• There must be a net benefit to participating

• Participants must recognize partners, and remember past interactions, to interact selectively w/ those who previously provided benefits

What cognitive constraints may limit expression of reciprocal altruism? Are these constraints a problem for primates?

• Minimum cognitive requirements:

  • Individual recognition

  • Good memory of past interactions

    • Q threatens subject->subject hears grunt->subject approaches Q 

    • Q grooms subject -> subject hears grunt -> subject ignores grunt bc not interpret as threat bc no violence and not reconciliation bc no conflict

  • Distinguish between cooperators vs cheaters

    • chimps/capuchnis more likely to cooperate w partners who share rewards more equitably

  • Able to delay reward (difficult for non human primates)

    • Temporal discounting stronger in non humans than humans, might depend on reward, plus much variation among individuals

• can be a problem for primates

Do male baboons show reciprocal altruism when they form coalitions with one

another to get estrous females from a higher-ranking male? Discuss alternative

views of this form of cooperation, as revealed in different studies, packer

most likely not

• Study 1 (packer): one male helps another steal an estrous female away from a male that ranks higher than them both, helper/altruist fights, beneficiary sneaks off with female

  • Packer documented:

    • head-flagging, not actual turn-taking -> not altruism

Discuss alternative views of this reciprocal altruism form of cooperation, as revealed in different studies, bercovitch

• Study 2 (bercovitch): one male helps another steal an estrous female away from a male that ranks higher than them both, helper/altruist fights, beneficiary sneaks off with female

  • Bercovitch documented: 

    • Forming coalitions isn’t costly

    • 50-50 chance for each partner to get females

    • No reciprocation, no mutual preference for headflagging partners

    • Coalitions result from each male pursuing his self-interest

Discuss alternative views of this reciprocal altruism form of cooperation, as revealed in different studies, noë. why would a lower ranking male join coalition if never get female?

• Study 3 (noë): one male helps another steal an estrous female away from a male that ranks higher than them both, helper/altruist fights, beneficiary sneaks off with female

  • Noë documented:

    • Higher rank coalition partner always gets female

    • H1-4 highest ranking males, no coalitions

    • H5-7 form coalitions against top 4 males

    • Why lower ranking males join coalitions if they never get the female?

      • Vet game, one animal has veto power over others, H5 highest ranking coalition-forming male, coalition not successful unless he apart of it

      • More profit to choose lower ranking coalition, they want to have him on their side as veto player

      • Profit according to what they bring to the coalition

summary of the reciprocal altruism studies and lessons from each

• Packer -> initiator of coalition gets female-> believes was reciprocal altruism but no exchange of altruistic acts witnessed

• Bercovitch -> 50/50 who gets female-> not reciprocal altruism, low cost

• Noe -> higher ranking gets female -> not reciprocal altruism, little power

Most researchers today believe that acts of cooperation are rarely high-cost (i.e.

they are seldom altruistic), but reciprocal partner choice is still expected even if

animals exchange cooperative acts: what is the evolutionary logic for this

expectation?

• reciprocity is important in guiding partner choice: cooperate w those who reciprocate, want benefits back

What evidence exists for reciprocal partner choice? Consider examples involving

a single or more than one “currency”. (What is a “currency” in this context?)

• Evidence weaker with different currencies, meta-analysis, lower strength of correlation with different currency of behaviors exchanged

• reciprocation can involve 1 or 2 currencies

• Examples of one currency: many studies show that A grooms those partners most from whom it receives the most grooming, or A forms coalitions to benefit others according to how often those others form coalitions to benefit A

• Example of two currencies: Alpha male chimps tolerate mating by lower-ranked males (who aren't related) to the degree that they offer coalitionary support to the alpha.

When behavioral biologists refer to “market mechanisms” as explaining patterns

of cooperative exchange, what do they mean (hint: supply and demand)?

Give an example. We discussed an experiment that aimed to demonstrate how market

mechanisms influence partner choice in vervet monkeys: can you describe it, and

how its results supported the idea of market mechanisms?

• Market mechanisms: supply and demand determines partner choice 

  • Baseline measurements of grooming relations

    • Give out more grooming than receive

  • Phase 1: single low-ranked female ‘provides’ a food bonanza, 16x

    • inc grooming to inc trust and show non aggressive to get food

    • Actual: provider receives more grooming, more than she gives

  • Phase 2: add 2nd food cache, opened by a 2nd low rank ‘provider’ 16x

    • Expect initial provider to not be groomed as much since new one being groomed too, initial not as valuable 

    • Actual: initial provider gets groomed half as much

How does Noe’s observational study of male baboon coalitions exemplify a market mechanism

(hint: veto game/player)?

although lower rank almost never gets female, gets sometimes, nonzero chance, win social tolerance

What is the difference between cognitive or calculated reciprocity vs. emotional

book-keeping? Which is more cognitively complex?

• cognitive/calculated

  • What have you done for me lately?

  • Expecting a paycheck

  • Keeping track of interactions with others 

  • more complex than emotional book-keeping

• Emotional book-keeping: “we’re buddies”

  • Animals w mutual affection act cooperatively, not keep track of interaction

Inequity aversion might be related to reciprocal exchange: what experimental

result led to the claim that monkeys show “inequity aversion”? Why might it be

criticized as inconclusive?

• Capuchins exchange tokens for treats

• But not if their neighbor gets a better deal

• Refusals 2 different forms: subject not hand over rock or refuse award

• Criticisms of original study

  • Small sample size

  • Reuse of subjects

  • Alternative explanation:

    • Distracted?

    • Unmet expectations?

    • Simply frustrated?

• Some replications fail

  • Methodological improvements

    • Grapes visible even in equity condition

    • Varied order of equitable vs inequitable treatment

• Cooperation may not require inequity aversion, social bonds and associated emotions steer exchange?

Why is it important (i.e. adaptive) for social animals to manage conflict?

• What is conflict?

  • Conflict occurs when individuals have incompatible goals, interests, or actions

  • Conflict is costly, so best to avoid it

    • Risk of injury, trauma

    • Defeated goals

    • Relationship suffer

What are the five mechanisms that primates use to manage conflict? Be prepared to

give non-human primate examples of each conflict management mechanism.

• in order from prevention to minimizing consequences:

• Conventions

• “Preconciliation” = anticipatory reassurance

• Inhibition of aggression

• Consolation

• Resolution

examples of conventions, define too

• “A set of rules/expectations that prevent conflict”

• ex: ownership convention in hamadryas baboons through respect for possession, one of the behavioral mechanisms that maintains OMU integrity

  • males herd females, females comply

  • studies: no previous owner → (fight then) take female, previous ownership → respects possession

  • relative power/rank makes no difference if males from same troop

  • respect less complete if males from diff troops

  • hybrids of anubis and hamadryas: hybrid males act like hamadryas in proportion to how much they physically resemble hamadryas, suggests genetic basis to behavioral diff of males

  • transplant experiments, anubis female learn to act like hamadryas, female behavior learned while male genetic

examples of preconciliation

• celebrations before potential conflict reduces later aggression in chimps

• fusion dynamics in spider monkeys: embraces reduce aggression after fusion

examples of inhibition of aggression

• open mouth threat by macaque

• mild conflict, harmless forms, threats and not physical, short

example of consolation

• first make eye contact, then pat on shoulder

• third party relieves some of deleterious effects of conflict

example of resolution

• bring goals of opponents into alignment after conflict

• sharing (rare), negotiation/compromise, reconciliation

What behavioral mechanisms are responsible for the integrity of hamadryas one-

male units? How did (Kummer's) experiments demonstrate one of these

mechanisms: “respect for possession”? Which of the five conflict management

mechanisms does this behavior exemplify?

• convention

• An ownership convention is one of the behavioral mechanisms that maintains OMU integrity

• the non-owning hamadryas very much avoid confrontation once ownership of a female is established

How does hamadryas social organization differ from that of olive baboons?

What different proximate mechanisms are involved, and which exemplifies a behavioral convention?

How did experimental studies shed light on this convention?

• hamadryas: OMU, m f always close, females always follow males closely (convention)

• olive/anubis: multim multif, only estrous f close to m, females more ind

Experiment:

• Female anubis transplants learn to act like hamadryas females

• Female hamadryas transplants act quickly like anubis females

How does the behavior of hybrid animals, and of transplanted animals, support the idea that patterns of male behavior, specific to either hamadryas or olive baboons, drives differences in the social organization of these taxa?

Female behavior is learned and flexible, wheras male behavior is genetically canalized, and drives the species differences.

What is "reconciliation" in primates and how do we recognize it behaviorally? What

factor/s influence the likelihood of reconciliation following aggressive conflict?

• occurs via friendly post-conflict reunions within minutes of fight

• selective attraction to former opponent, not just anybody, after aggresive conflict

• often grooming

• reconciliation is most likely if the partner is valuable

What functions does it have, and how do we know it has these functions?

2 functions

• reunions reduce tension associated with aggression

• repair social relationship damaged by aggression, drinkin exp show repair

  • reconciliation ‘resets’ relationships, restores time takes to be near again

  • prevents fight in future, keep bond

• exp: see takes longer for 2 monkeys to drink together after aggression but if reunion follows aggression then baseline restored