There was a paper recently in PNAS on “The cognitive and neural foundations of religious belief“. A couple of bloggers, Epiphenom and I Am David, come to opposite conclusions. Epiphenom says that the study shows that religion is not a side-effect of the evolution of cognitive processes, while IAD says that is exactly what it shows.
The paper purports to show that when thinking about God or beliefs about God, the very same areas of the brain are used that are used in ordinary social interactions and so on:
The MDS results confirmed the validity of the proposed psychological structure of religious belief. The 2 psychological processes previously implicated in religious belief, assessment of God?s level of involvement and God?s level of anger (11), as well as the hypothesized doctrinal to experiential continuum for religious knowledge, were identifiable dimensions in our MDS analysis. In addition, the neural correlates of these psychological dimensions were revealed to be well-known brain networks, mediating evolutionary adaptive cognitive functions.
The findings support the view that religiosity is integrated in cognitive processes and brain networks used in social cognition, rather than being sui generis (2?4). The evolution of these networks was likely driven by their primary roles in social cognition, language, and logical reasoning (1, 3, 4, 51). Religious cognition likely emerged as a unique combination of these several evolutionarily important cognitive processes (52).
Does this mean religion is not an adaptation? Well, yes, and no. It depends on what you are trying to explain.
Anything that has evolved for one reason was based on pre-existing traits or organs that evolved for another. Nothing comes from nothing in evolution; at least, nothing complex. And whatever else one might think of religious cognitive behaviours and capacities, they are complex. That they occur on a prior substrate of cognitive features is no surprise. Are they now being used in that way because there is an adaptive benefit? There’s the rub. Also, fMRI is a relatively blunt instrument. I have heard it described as trying to work out how the internet works by checking the overall throughput at various exchanges. So there can still be special adaptations, although as yet there’s no evidence of it.
One of the major explanations of religious dispositions is that it parasitises, as it were, existing cognitive capacities. So it is explained as a non-adaptive byproduct. But if it were an adaptation, what else would it subsist upon? Our ability to walk bipedally subsists upon a quadrupedal locomotory system, but nobody thinks that is maladaptive or nonadaptive (or at least I hope they don’t). Since everything that is an adaptation is a modification of some prior organ or trait, the question for any possibly adaptive trait is, when was it subjected to selection?
If religious cognition was subjected to selection, say, after the growth of various other capacities, such as symbolic communication or the ability to recognise a certain number of social agents, then it would be subsequently adaptive.To show that religious behaviours and cognition are not adaptive, we have to show that there is no reasonable account of them being subjected to selection, and that is actually a far harder thing to show.
One way we might do this is by showing that every case of religious behaviour actually lessens the fitness on average of its bearers. But that isn’t even true in the case of celibate clergy or priests – inclusive fitness means that their families rise in status and have access to all kinds of support and resources. In some Catholic countries, to be a priest’s nephew meant advancement in business and society. Moreover, highly organised religious societies do tend to compete well against disorganised societies (think of the Csarist Russian encroachment against the Siberian tribes in the 18th century), although how much that is due to social cohesion from religion versus social cohesion from other causes is moot. At the very least religion is used as a social glue, a point noted by Machiavelli and Burke among others.
So there could be “fine-tuning” selection for religious dispositions based upon the existing social cognitive functions of human beings, and indeed they may have made that sort of selection possible, and fMRIs will not tell us one way or the other.
How to prove the alternative hypothesis? I cannot say. A metalevel analysis of religiosity and social cohesion might show no correlation, or even a negative one (in which case we could usefully ask, why does religion persist at all? One answer might be the Dawkins/Dennett “mind virus” explanation – religiosity is evolving separately from human biology and so the adaptation is for the memes not the bearers of the memes. I find this very unconvincing, for several reasons. The main one is what I’ll call the Ewald Objection. Paul Ewald, in a major book on the coevolution and virulence of diseases, pathogens and their hosts, noted that as the replication rate of the disease approaches that of the hosts, commensuality evolves as their genetic interests tend to coincide. Religion is mostly transmitted vertically, and so the “interests” of the religion and the interests of the hosts/adherents are pretty much the same. So religion ought to be a commensual rather than a parasite. And in most societies it is. Only when there are major social and political upheavals, such as in the early second millennium BCE, or during the rise of Islam and the shifts in both directions, or in the height of the Christian imperial period, and today, do religions not transmit with parentage. In these cases, religious ideas may be quite deleterious to their hosts if they are selectively advantaged.
So I tend to think that religion is adaptive at various levels in various conditions, and no general claims can be made about it. The capacity to be religious is clearly an outgrowth of other evolved capacities, but that does not mean either that it is not itself an adaptation, nor that it is adaptive either. We have to find out rather than assert a priori if that is the case.