Given that religious traditions prescribe norms and values which govern interpersonal conduct, costly signals provide (in the form of rituals) strategic information about the individual’s commitment to such norms and, as a consequence, to fair treatment of other coreligionists. Radim examines whether pilgrimages may function as a costly signal of commitment to group norms. First, he defines the concept of pilgrimage in a way that allows treating pilgrimage as a cultural institution distinguishable from other forms of human traveling, such as long-distance trade or war. Then, Radim develops a theory of pilgrimage stemming from the previous models of costly signaling, focusing on the argument that pilgrimages are costly behaviors inherently linked to normative cultural systems. Finally, the dissertation tests the proximate hypotheses derived from such a model using a case study of the pilgrimage to Santiago de Compostela. The case study shows that costs such as effort and discomfort resonate among pilgrims and play a role in constructing pilgrims’ identities. Moreover, three online experiments with the Spanish population suggest that pilgrims are perceived as more trustworthy than non-pilgrims and long-distance pilgrims more than short-distance pilgrims. The results are interpreted as support for the Costly signaling theory of pilgrimage. However, Radim concludes with the notion that this support is initial, related to one pilgrimage, and provides only a proximate understanding of the pilgrimage function. In sum, the thesis shows that pilgrimage might be adaptive nowadays as a signal of trustworthiness but the question whether the pilgrimage evolved as a mechanism of increasing cooperation is left for the future investigation.
You can find his thesis here: