Ingredients of 'rituals' and their cognitive underpinnings.

Ritual is not a proper scientific object, as the term is used to denote disparate forms of behaviour, on the basis of a faint family resemblance. Indeed, a variety of distinct cognitive mechanisms are engaged, in various combinations, in the diverse interactions called 'rituals' - and each of these mechanisms deserves study, in terms of its evolutionary underpinnings and cultural consequences. We identify four such mechanisms that each appear in some 'rituals', namely (i) the normative scripting of actions; (ii) the use of interactions to signal coalitional identity, affiliation, cohesiveness; (iii) magical claims based on intuitive expectations of contagion; and (iv) ritualized behaviour based on a specific handling of the flow of behaviour. We describe the cognitive and evolutionary background to each of these potential components of 'rituals', and their effects on cultural transmission. This article is part of the theme issue 'Ritual renaissance: new insights into the most human of behaviours'.