Humans have an instinct that is specific to arbitrary rituals, which we see as signaling group loyalty:

Show a child how to perform some action that they haven’t seen before, and they will faithfully replicate not only the steps required to achieve the goal, but also superfluous ones. Why they do this is a puzzle, especially as other animals do not. … What if children can identify actions as causally opaque? If so, perhaps their brains see them as a cue to switch from normal reasoning to a “ritual stance” in which they interpret the behaviour of others as social signals, and go out of their way to copy them. … Children copy apparently aimless sequences of actions more faithfully than sequences that move towards an obvious goal. …

Group one saw one person doing the actions, and watched the video twice. Group two saw videos of two people performing the same manipulation in succession. Group three watched two people performing the actions in synchrony. And group four saw the synchronised demonstration video twice. The accuracy with which the children subsequently copied the nonsensical actions increased progressively from groups one to four. … The children who had seen the spectre of ostracism copied more accurately, and the effect was especially marked when ritualistic actions were involved. … This effect is even stronger when kids are ostracised from a group with which they identify. …

Members of two groups spent 7 minutes making necklaces in synchrony with other group members, following a script such as “first we add a green heart, then an orange square”, and so on. Another two groups were simply given beads and allowed to spend 7 minutes stringing them up however they wished. … Those who had worked together ritualistically reported a greater sense of connection to their group than those who made freestyle necklaces. (more)