| Concept/Content |
network reciprocity / vampire bats |
| Information caption |
Cheaters threaten any system of cooperation. However, organisms may guard against loss to cheaters by limiting their interactions. Consider vampire bats (profiled earlier). Their observed system of blood exchange seems stable, undisrupted by potential free-riders. Why? Here, the bats tend to roost in the same colony, a very simple social organization which forms a context for sustainable reciprocity. The bats do not share blood unconditionally. They are more likely to provide food for a bat that has fed them on a previous occasion or that is a frequent roostmate. The bats can recognize distinct individuals and remember past events. They learn to identify cheaters. A bat that does not repay previous "favors" does not get endless handouts. Bats that cheat ultimately do not benefit. Defection is thereby limited (Wilkinson 1984, 1988, 1990). Selective interaction leads to network reciprocity, a social cluster of cooperators insulated against invasion by selfish individuals (Nowak 2006). This illustrates the general principle that organisms may cooperate selectively with reciprocators.
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| Inquiry caption |
Consider again the vampire bats. Their observed system of blood exchange seems stable, undisrupted by potential free-riders. Why?
The bats tend to roost in the same colony, a very simple social organization. How might this affect potential cheaters?
How would you respond to an individual who was seeking a share of blood for a second or third time? How would you respond to an individual who had not provided you blood after one of your unsuccessful foraging outings? Indeed, the bats do not always provide blood when "begged" from another. They refrain more frequently in just these cases. A bat that does not repay previous "favors" does not get endless handouts (Wilkinson 1984, 1988, 1990). What consequences does this have for cheaters? What conditions or capacities are needed for the bats to be able to maintain their system of reciprocity?
[ The bats illustrate the general principle that organisms may cooperate selectively with reciprocators. Selective interaction leads to a social cluster of cooperators insulated against invasion by selfish individuals: a concept known as network reciprocity (Nowak 2006). ]
Target Concept: Organisms may cooperate selectively with reciprocators.
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| Photographer |
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| Credit |
Photo from the Centre for the Conservation of Specialized Species, conservationcentre.org. |
| SIZE in pixels [file size] |
544x408 |
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