@Article{Kurzban2005,
  author   = {Robert Kurzban and Daniel Houser},
  journal  = {Proc Natl Acad Sci U S A},
  title    = {Experiments investigating cooperative types in humans: {A} complement to evolutionary theory and simulations.},
  year     = {2005},
  number   = {5},
  pages    = {1803-7},
  volume   = {102},
  abstract = {Unlike other species, humans cooperate in large, distantly related
	groups, a fact that has long presented a puzzle to biologists. The
	pathway by which adaptations for large-scale cooperation among nonkin
	evolved in humans remains a subject of vigorous debate. Results from
	theoretical analyses and agent-based simulations suggest that evolutionary
	dynamics need not yield homogeneous populations, but can instead
	generate a polymorphic population that consists of individuals who
	vary in their degree of cooperativeness. These results resonate with
	the recent increasing emphasis on the importance of individual differences
	in understanding and modeling behavior and dynamics in experimental
	games and decision problems. Here, we report the results of laboratory
	experiments that complement both theory and simulation results. We
	find that our subjects fall into three types, an individual's type
	is stable, and a group's cooperative outcomes can be remarkably well
	predicted if one knows its type composition. Reciprocal types, who
	contribute to the public good as a positive function of their beliefs
	about others' contributions, constitute the majority (63\%) of players;
	cooperators and free-riders are also present in our subject population.
	Despite substantial behavioral differences, earnings among types
	are statistically identical. Our results support the view that our
	human subject population is in a stable, polymorphic equilibrium
	of types.},
  doi      = {10.1073/pnas.0408759102},
  keywords = {Agonistic Behavior, Animals, Anura, Behavior, Animal, Cues, Male, Research Support, Non-U.S. Gov't, U.S. Gov't, P.H.S., Vocalization, 15665099},
}

{"_id":"2KcfQHyqiK6uj9Fv8","bibbaseid":"kurzban-houser-experimentsinvestigatingcooperativetypesinhumansacomplementtoevolutionarytheoryandsimulations-2005","author_short":["Kurzban, R.","Houser, D."],"bibdata":{"bibtype":"article","type":"article","author":[{"firstnames":["Robert"],"propositions":[],"lastnames":["Kurzban"],"suffixes":[]},{"firstnames":["Daniel"],"propositions":[],"lastnames":["Houser"],"suffixes":[]}],"journal":"Proc Natl Acad Sci U S A","title":"Experiments investigating cooperative types in humans: A complement to evolutionary theory and simulations.","year":"2005","number":"5","pages":"1803-7","volume":"102","abstract":"Unlike other species, humans cooperate in large, distantly related groups, a fact that has long presented a puzzle to biologists. The pathway by which adaptations for large-scale cooperation among nonkin evolved in humans remains a subject of vigorous debate. Results from theoretical analyses and agent-based simulations suggest that evolutionary dynamics need not yield homogeneous populations, but can instead generate a polymorphic population that consists of individuals who vary in their degree of cooperativeness. These results resonate with the recent increasing emphasis on the importance of individual differences in understanding and modeling behavior and dynamics in experimental games and decision problems. Here, we report the results of laboratory experiments that complement both theory and simulation results. We find that our subjects fall into three types, an individual's type is stable, and a group's cooperative outcomes can be remarkably well predicted if one knows its type composition. Reciprocal types, who contribute to the public good as a positive function of their beliefs about others' contributions, constitute the majority (63%) of players; cooperators and free-riders are also present in our subject population. Despite substantial behavioral differences, earnings among types are statistically identical. Our results support the view that our human subject population is in a stable, polymorphic equilibrium of types.","doi":"10.1073/pnas.0408759102","keywords":"Agonistic Behavior, Animals, Anura, Behavior, Animal, Cues, Male, Research Support, Non-U.S. Gov't, U.S. Gov't, P.H.S., Vocalization, 15665099","bibtex":"@Article{Kurzban2005,\n author = {Robert Kurzban and Daniel Houser},\n journal = {Proc Natl Acad Sci U S A},\n title = {Experiments investigating cooperative types in humans: {A} complement to evolutionary theory and simulations.},\n year = {2005},\n number = {5},\n pages = {1803-7},\n volume = {102},\n abstract = {Unlike other species, humans cooperate in large, distantly related\n\tgroups, a fact that has long presented a puzzle to biologists. The\n\tpathway by which adaptations for large-scale cooperation among nonkin\n\tevolved in humans remains a subject of vigorous debate. Results from\n\ttheoretical analyses and agent-based simulations suggest that evolutionary\n\tdynamics need not yield homogeneous populations, but can instead\n\tgenerate a polymorphic population that consists of individuals who\n\tvary in their degree of cooperativeness. These results resonate with\n\tthe recent increasing emphasis on the importance of individual differences\n\tin understanding and modeling behavior and dynamics in experimental\n\tgames and decision problems. Here, we report the results of laboratory\n\texperiments that complement both theory and simulation results. We\n\tfind that our subjects fall into three types, an individual's type\n\tis stable, and a group's cooperative outcomes can be remarkably well\n\tpredicted if one knows its type composition. Reciprocal types, who\n\tcontribute to the public good as a positive function of their beliefs\n\tabout others' contributions, constitute the majority (63\\%) of players;\n\tcooperators and free-riders are also present in our subject population.\n\tDespite substantial behavioral differences, earnings among types\n\tare statistically identical. Our results support the view that our\n\thuman subject population is in a stable, polymorphic equilibrium\n\tof types.},\n doi = {10.1073/pnas.0408759102},\n keywords = {Agonistic Behavior, Animals, Anura, Behavior, Animal, Cues, Male, Research Support, Non-U.S. Gov't, U.S. Gov't, P.H.S., Vocalization, 15665099},\n}\n\n","author_short":["Kurzban, R.","Houser, D."],"key":"Kurzban2005","id":"Kurzban2005","bibbaseid":"kurzban-houser-experimentsinvestigatingcooperativetypesinhumansacomplementtoevolutionarytheoryandsimulations-2005","role":"author","urls":{},"keyword":["Agonistic Behavior","Animals","Anura","Behavior","Animal","Cues","Male","Research Support","Non-U.S. Gov't","U.S. Gov't","P.H.S.","Vocalization","15665099"],"metadata":{"authorlinks":{}}},"bibtype":"article","biburl":"http://endress.org/publications/ansgar.bib","dataSources":["xPGxHAeh3vZpx4yyE"],"keywords":["agonistic behavior","animals","anura","behavior","animal","cues","male","research support","non-u.s. gov't","u.s. gov't","p.h.s.","vocalization","15665099"],"search_terms":["experiments","investigating","cooperative","types","humans","complement","evolutionary","theory","simulations","kurzban","houser"],"title":"Experiments investigating cooperative types in humans: A complement to evolutionary theory and simulations.","year":2005}