The community of Pygmies settled in Vyegwa-Gika provides an exceptional case study to
test the role of trust in the evolution of altruism. The Vyegwa-Gika Pygmies were forced to
migrate from rainforests to the savanna, changing quickly their environment, culture, and
socio-economic situation. Despite the high level of poverty they suffer in this new settlement,
we found evidence of strong altruistic attitudes toward trustees when playing an economic
game. In addition, Vyegwa-Gika Pygmies keep small personal trust networks despite the
fact they share frequent social interactions within the community. These results indicate the
great effectiveness of personal trust in fostering altruism, even if the circumstances make it
difficult to establish such kind of affective bonds. A theory of the evolution of altruism should
therefore also account for the evolution of psychology of trust, as a key element in the
process.
