By Gregory Watry | October 1, 2025
Pilgrimages are ubiquitous across all major world religions. From the Camino de Santiago , a Christian pilgrimage that encompasses routes in southern Europe and ends in Spain, to the Kumbh Mela , a Hindu festival on the banks of India's Ganges River, hundreds of millions of people travel to various sites across the globe to engage in rituals and connect with their faith.
But how do pilgrimages get established? How do people become convinced to try something new? What makes a pilgrimage so special that it persists over generations, drawing people to it repeatedly?
Using a theoretical game model, University of California, Davis, anthropologists suggest that lucky outcomes — such as a lone miner discovering gold after a pilgrimage — can sometimes give rise to the perception that a new site cures, blesses, grants miracles or otherwise produces great outcomes in pilgrims' lives.
If these are common enough in a group, it can drive a critical number of people to journey to a new site. This then leads to the collective ritual becoming institutionalized, researchers suggest in a new study published in The Royal Society journal on Sept. 10.
Author Cristina Moya , an associate professor in the Department of Anthropology, said the model was informed by ongoing research she and her co-author are conducting at a new pilgrimage site in the Peruvian Altiplano known as Nuestro Señor de Pucara.
The ingredients of a pilgrimage
Nicolas Restrepo Ochoa, co-author and a postdoctoral scholar at UC Davis, noticed that pilgrimages share many features with an assurance game, also known as a stag hunt.
In the stag hunt, players choose whether to hunt a hare or a stag. The former can be achieved with a single player, while the latter requires multiple people and coordination for it to pay off.
"It's not really a pilgrimage if you go by yourself," said Restrepo Ochoa. "There is an element of coordination that is needed for a pilgrimage to be recognized by a community of believers as something worth doing."
Using the assurance game as a foundation, the researchers customized their theoretical model to include three factors relevant to the emergence of collective rituals. Those factors included prior beliefs about the payoff for participation, one's own economic uncertainty and the size of social groups involved in the pilgrimage.
The researchers incorporated those factors into a mathematical framework that models the likelihood that a new pilgrimage crosses a threshold to become established and persist. They found that uncertain conditions make it more likely for new collective rituals, like a pilgrimage, to emerge since it makes it more likely that people will perceive positive outcomes are a result of the new practice.
"It's exciting to be able to provide a simple statistical mechanism that can explain a long-standing empirical finding — that uncertainty is associated with ritualistic or religious practices," said Restrepo Ochoa.
A test site in Peru
On the north side of Lake Titicaca, at the base of a small mountain, is a sanctuary site known as Nuestro Señor de Pucara. Every August, thousands gather in the area to honor an image of Jesus that appeared on the side of a rock face, among other figures important to Andean traditions, including a toad and eagle. The pilgrimage site is adorned with flowers, bottles of champagne and other objects brought by pilgrims as offerings since 2014.
The origin story of the pilgrimage is that a miner saw the face of Jesus, prayed to it and then went to a nearby mine called La Rinconada and struck gold, Restrepo Ochoa said. "The miner then became rich and hosted the first celebrations. This matches well with the model's focus on uncertain economic outcomes."
With their theoretical model established and years of data collected from the site and pilgrims, Moya and Restrepo Ochoa are now homing in on the psychological motivations of the pilgrims who visit the site.
"If there is a way of capitalizing on those early associations — for example, because of the collective benefit provided in the assurance game," Moya said, "then those practices can spread and become institutionalized."
