zoo 4513 Chapter 10- Cooperation

Cooperation

Cooperation is an outcome in which two or more individuals interact in a way that benefits all participants, even if they each incur some cost.

Two meaning of cooperate:

1. achieving teamwork within a group

2. Individual behaviors that enable the group to succeed

Benefits of cooperation

Why animals (or humans) cooperate:

• Access to food and water

• Protection and reduced aggression

• Lower tension or stress

• Coalition formation (social bonds)

• Group acceptance (“team player” advantage)

• Mating opportunities

Examples of cooperative behavior

1. Male-male alliances (stallions):

   subordinate males from alliances with dominant males

   both benefit through increased access to females and reduced conflict

2. Social grooming (allogrooming):

   one individual grooms another

   common in primates, horses, and mammals- builds bonds and hygiene

3. Symbiotic relationships:

   example: cattle egrets and horses- birds eat pests off large mammals

   both species benefit → mutualistic cooperation

The four paths to cooperation

There are four major evolutionary pathways to cooperation:

1. Reciprocity- exchange of favors

2. Mutualism- immediate benefits for all participants (no cheating temptation)

3. Kin selection- helping relatives to ensure gene survival

4. Group Selection- cooperation benefits the entire group, making it more successful than others

Reciprocity (exchange of favors)

Reciprocal altruism: helping unrelated individuals with the expectation of future help

Key mechanism: game theory- a mathematical model of strategic interaction.

Used to explain cooperation through prisoner’s dilemma and tit- for- tat strategies

The prisoner’s dilemma

Scenario: two prisoners are arrested. They can either cooperate (stay silent) or defect (betray each other)

Outcome:

Both cooperate → mild punishment (2 years) → mild punishment

One defects → betrayer goes free → partner gets 5 years

Both defect → both gets 3 years → both lose trust

• Key insight:

  even though cooperation yields the best group results, defection seems safer individually- creating a dilemma.

Game variables

T- temptation to cheat

R- reward for mutual cooperation

P- punishment for mutual defection

S- sucker’s payoff (for cooperating alone)

Must satisfy: T>R>P>S

Evolutionary stable strategy (ESS)

• an ESS is a behavioral strategy that cannot be outcompeted once adapted by most of the population.

• Axelrod & Hamilton used simulations to find that Tit- for- tat (TFT) is an effective ESS when players repeatedly meet

• Tit-For-Tat (TFT) strategy

Rules of TFT:

1. Nice- cooperate first

2. Retaliatory- defect when the partner cheats

3. Forgiving- return to cooperation after the partner does

Neurobiology of Cooperation

Human experiments (using fMRI and PET scans) during Prisioner’s dilemma games show:

• Brain activity increases during mutual cooperation

• Cooperation activates reward centers → emotionally satisfying

• Neuroeconomics studies how trust, empathy, and fairness influence decision making

Mutualism (Byproduct Cooperation)

• Definition: cooperation where everyone benefits immediately, and there’s no temptation to cheat

• Difference from reciprocity:

  no need to track past interactions or punish defectors

• Conclusion: learning and immediate benefits encourage cooperation better than delayed reciprocity

Group Selection (trait group selection model)

Definition: natural selection acts both within groups and between groups

• Within group selection → favors selfish individuals who avoid cost of cooperation→ reduces coorperation

• Between group selections → favors cooperative groups that outcompete selfish ones → promotes cooperation

Coalitions and Alliances

• Coalition: cooperative action by two or more individuals/ groups against another

• Alliance: long term coalition

Phylogeny and Cooperation

• Phylogeny: evolutionary history shows traits inherited from common ancestors

• Cooperative behavior may stem from shared ancestry, not independent evolution.

• Conclusion: some cooperation traits evolved once and were passed down through lineages

Interspecific Cooperation (Mutualism)

• Intraspecific: cooperation within a species

• Interspecific: cooperation between species- mutualism