  Cooperation can be supported by indirect reciprocity via reputation.Thanks to
gossip, reputations are built and circulated and humans can identify defectors
and ostracise them. However, the evolutionary stability of gossip is allegedly
undermined by the fact that it is more error-prone that direct observation,
whereas ostracism could be ineffective if the partner selection mechanism is
not robust. The aim of this work is to investigate the conditions under which
the combination of gossip and ostracism might support cooperation in groups of
different sizes. We are also interested in exploring the extent to which errors
in transmission might undermine the reliability of gossip as a mechanism for
identifying defectors. Our results show that a large quantity of gossip is
necessary to support cooperation, and that group structure can mitigate the
effects of errors in transmission.
