So, the good news for RST is that there are many more modelling options available for signalling mechanisms than just ‘costly signalling’, and more models mean a greater diversity of target systems that can be potentially be modelled as evolved signalling systems. The bad news is that these considerations also suggest great complexity with respect to application, potentially demanding great attention to interpretive detail. And we should remain cognisant that this discussion is all at the level of mechanisms rather than big-picture theory. So, the plethora of signalling mechanisms in no way guarantees that they will feature significantly in the true evolutionary story of religion and society, nor that they would be its only heroes if so. Signalling that helps explain human religion is unlikely to operate in isolation and would almost certainly form part of (and be shaped by) larger causal complexes that might include close conceptual cousins (like CREDs), and other number of mechanisms from cultural evolution or the cognitive science of religion. Indeed, with complexity comes operationalizability and empirical tractability concerns. Interpretation issues like those just discussed these will be multiplied in complex human societies where there are many traits of
potential interest. This is especially applicable to complex rituals and participation procedures: different features or religious tropes can have distinct signalling functions, with different dynamics and evolutionary histories entail various trade-offs.
The more recent biological literature on signalling in ecology provides some sort of hope and perhaps a model to look to, in that signals are used as part of a multi-trait, multi-modal causal complex of signalling systems (Hebets et al. 2016; Hebets and Papaj 2005). In this literature, separate signalling structures (for example, different parts of insect legs) are interpreted as having different signalling roles which nevertheless work in concert in specific contexts (for example in mate selection, or predator signalling). Depending on the signal forms responsible, there may also be complex trade-offs to consider. One trade-off already discussed example is that differential cost-benefit and hard-to-fake signalling-systems operating on the same signal could put contradictory pressures on the evolution of signal cost. The animal communication literature also suggests properties of these overall complexes, such as having signals with redundant, overlapping, or pluripotent functions to manage overall trade-offs between robustness, efficiency and evolvability (Hebets et al. 2016).
Of course, the need for trade-offs in modelling is nothing new. Richard Levins famously highlighted the basic trade-off for population models, between precision, generality, and realism: we can have two of these in one model (if we’re lucky), but not all three at the same time (Levins 1966; 1968). Models can sacrifice generality for precision and realism (type I), sacrifice realism for generality and precision (type II), or sacrifice precision for generality and realism (type III). This is likely true for modelling religion and its social dynamics as well. But distinct modelling strategies can be complementary. For example, detailed study of the costs and benefits associated with specific, localised religious ritual traditions (with deliberate attention to the currency problem) could potentially permit tests that to validate or falsify some quite detailed signalling models, and/or discriminate between them. This would be a type I model, with the goal perhaps being an in-principle validation of the signalling mechanism in one narrow context. Abstract formal models like the ones in this dissertation are arguably more like type II models – they offer some general, proof-of-concept distinctions and/or predictions but are too highly idealised to be straight-forwardly applied to real religious target systems, but (at least with respect to signal form) there is at least some attendance to precision. Then there are imprecise, general studies of broad ethnographic phenomena, searching for a general signature of causal phenomena at the population level, such as we saw in chapter two with (J.
Watts, Greenhill, et al. 2015) and other ‘big-picture’ studies with respect to the Big Gods theory. Another type III-style method could be conducted at the local level, looking at correlations between participation religious participation and long-term outcomes.
Each of these approaches can do complementary explanatory work. In the context of this dissertation and my earlier characterisation of it, the ‘detail’ project of chapter 3-8 can be given a Levins-style gloss as being focused on generality, and (formal) precision. The ongoing argument is that details matter, and so narrowing down on how signalling models are constructed and applied can open up potential new approaches (potentially of both type I and type II) that can shed light on the explanatory potential of signalling theory and perhaps (in application) use it to make some novel, testable predictions.
The question then arises: how much detail need RST really get into? I suggest that this depends on how precise an empirical science it aspires to be, and that the aspirations should be realistic. As noted by Hebets and Papaj, after decades of research on the honeybee waggle dance there are still significant questions about how the different parts of the dance encode information and what other contextual factors are important – and this is on a relatively tractable, biologically universal target system. It seems questionable that detailed ethnographic analysis of specific human religious traditions as signalling complexes could approach even this level of detail. But in principle there is no reason why some degree of progress could not be made, perhaps along the lines of the level of precision seen in recent work on social networks and religious signalling in village-based religious communities (Power 2017). The level of detail that formal approaches to signalling theory allow might outstrip its scientific testability in many contexts, but it may still help inform more targeted empirical approaches, and at least some of the nuances should be taken into theoretical account, especially if moving beyond simple verbal models.