Costly Signaling Theory says that although costly, altruistic acts may benefit the
altruist indirectly, by establishing a ‘reputation’.
By demonstrating the sincerity of one's good intentions, costly signalling encourages others to engage in
reciprocal altruism. Since a costly act shows ability and access to plentiful resources
it may also give advantage as regards mate selection.
Smith and Bird state that for behaviour to count as constly signalling,
it must be:
Frequently cited examples of costly signals are drawn from human hunter gatherer societies,
for example the laying on of public feasts or other elaborate public displays.
This is sometimes mentioned in connection with philanthropy as "competitive altruism".
As forms of public display go, this is socially far more positive than wasteful
signalling methods such as Veblen's "Conspicuous consumption".
Beneficial to others
Observable by others
Costly to the signaller in ways that can't be reciprocated
Associated with some strength or fitness of the signaller
E. A. Smith & R. Bird: (1999) Turtle hunting and tombstone opening - Public generosity as costly signaling, Elsevier Evolution and Human Behavior 21 pp.245-261
Francis McAndrew: (2002) New Evolutionary Perspectives on Altruism - Multilevel-Selection and Costly-Signaling Theories, Current directions in Psychological Science 11 (Issue 2) pp.79-82
Thorstein Veblen: (1902) The Theory of the Leisure Class - An Economic Study of Institutions, Macmillan New York