Following his death in 1614, Camillus de Lellis, the founder of the Camillian order, had his heart removed before his body was buried in the altar of St Mary Magdalen’s Church in Rome. The heart is still a cherished relic, encased in a glass sacellum and brought out on special occasions, such as when it undertook a high-profile tour of Ireland in July 2010. The body parts of many other saints and holy men and women are revered by Christians today: the thumb of Thomas Aquinas resides in Milan, while pieces of St Francis Xavier can be found in Goa, Rome and Macau, and St Catherine’s skull and thumb still draw the faithful to the Basilica of San Domenico in Siena. Several ‘holy prepuces’ or foreskins said to belong to Christ could once be found in various locations around Europe, though no one today still claims to have one.

Since the Middle Ages, Christian relics have been destinations of pilgrimage, and they remain objects of veneration. Being near or – better still – touching objects related to a sacred person was and is believed to carry merit, or even to have miraculous effects. Most famous perhaps is the Shroud of Turin, a linen cloth with an image in negative of Jesus. Despite the fact that all evidence indicates that it is a 14th-century forgery, and its lack of official recognition by Vatican officials, the shroud is honoured by millions of devotees during short periods on display. Other relics alleged to help the modern-day believer relate to Jesus are fragments or nails of the ‘True Cross’, objects containing metal from these nails, or the seamless garment of Christ, claimed to be the possession of both the Cathedral of Trier and the parish church of Argenteuil in France.

Cults of relics are by no means confined to Christianity. According to legend, following his participation in the Hajj, Muhammad distributed his hair-clippings, seemingly aware of the power installed in these objects. Some recipients wore the strands on their clothes, others chose to be buried with the cherished locks in their mouth or nostrils. Hair, teeth, autographs, footprints and earthly belongings claiming to originate from the prophet Muhammad are known as āthār, and are still broadly venerated as ‘traces’ of the prophet. As in the case of Christianity, the veneration of saints (awliyā) who are believed to have produced miracles is a central part of popular Islamic practices. In Buddhism, Hinduism and other major religions, there are similar cults venerating especially auspicious persons, places of mythological significance or objects seen as containing special power.

Humans have a tendency to ascribe special powers and abilities to men, women, objects and places. Throughout history and in all cultural contexts – not just religious ones – people seem to spontaneously endow certain things with special powers, and to proclaim that contact with these persons and things, even by proxy, will have miraculous effects. These things hold a special force, recognised throughout a community.

In the early history of anthropology, this special power was referred to by the Polynesian concept of mana. Around 1900, the French scholars Marcel Mauss and Henri Hubert claimed that people everywhere experience this social force, which can exert a power on the individual to conform to the rules and expectations. And as this force is felt but imperceptible, it was understood as having a supernatural origin manifesting in certain persons, objects or places. In short, mana-like conceptions were found everywhere, and anthropologists once argued that mana played a central role in social organisation. But today, following the decline of grand explanatory theories in favour of particular ethnographies, mana is an ill-reputed concept. Its unfashionableness is also a consequence of the critical self-scrutiny of the discipline in the wake of decolonisation in the 1960s. But as is so often the case, the phenomenon described by mana did not evaporate with the popularity of the concept.

Why do humans so often ascribe special powers to things? One place to search for an answer is the cognitive processing that underlies the human understanding of force. How do we understand the force exerted in ordinary events, such as when one ball hits another on a billiard table? The problem, it turns out, is extremely complex, and has been addressed for centuries in various forms by philosophy, theology, psychology and linguistics. It involves questions about how we perceive causal relations (that one thing effects a change in another); about our intuitive expectations of what things we find in the world (our ontologies); and about how we codify these relations in language. But maybe recent theories in cognitive neuroscience can illuminate the intractable questions about force, and thereby help us to understand the power of mana.

Put simply, a prevalent model in cognitive science conceives of our brain as a kind of prediction-machine. In order to survive, we constantly try to predict what comes next, as the formation of reliable expectations gives us an edge in the battle of survival by increasing the speed and efficacy of our actions. This neurocognitive theory of ‘predictive processing’ also holds that the formation of strong predictions decreases the energy spent on processing information from the senses. Allowing our internal prediction-machine to adequately control our behaviour, we are thus free to spend our cognitive resources on other tasks at hand. Whenever this model fails to predict the world, however, an error-signal is produced prompting an update of our internal model until it once again adequately predicts what comes next. Imagine that you pick up what you believe is a bottle full of water. The prediction that it is indeed full makes you exert a certain amount of force in order to lift it – but if the bottle is empty, the amount of energy applied far exceeds what is needed, and your arm swings out. You must then update your model until it once again correctly guides your actions, allowing you to lift the bottle in a controlled manner.

Our experience of the world is predominantly guided by expectations (that is, by our internal model). However, when any such model is inadequate in predicting whatever comes next, increased error-signals lead to an update or even replacement by an alternative and competing model that fits the world better, thereby once again reducing the error-signal. Much therefore depends on the quality of our internal models. An organism’s development can be envisaged as a process of learning to create new, less error-prone models, and to refine existing models through continual feedback from the world. Humans might be born with certain dispositions that guide or even determine aspects of this process such as broad ontological categories that inform our expectations to the behaviour of things in the world. Very young children expect animals to be able to move by themselves, but do not form the same expectation of inanimate objects; and in contrast to trees and other plants, we expect both humans and animals to have mental states that guide their behaviour. Such ontological assumptions function as strong internal models that structure our expectations of what happens in the world.

There are therefore two guiding principles in the ongoing creation of strong predictive models that structure our expectations. One is based on deeply ingrained expectations as to what characterises entities in the world according to their ontological class. The other is based on the experience of regularity. Faced with error-signals, we consistently update our prediction model until it approximately fits the world. But here the tricky part arises: most of the cultural ideas described by the relics above defy this account. Holy men and women are exceptions to the rule. Miracles are by definition infrequent, and they are very often in direct violation of ontological expectations. So where do miracles fit into the predictive processing theory?

We have a proclivity to ascribe successful individuals a special essence

First, it must be acknowledged that worldly success is unevenly distributed. Whether due to skill or luck, some individuals are simply more successful than others, and we are all experts in tracking these successful individuals within our own social groups. When we perceive someone as repeatedly attaining success, this is likely to coagulate into representations of a general social prestige, which involves perks in other domains: successful hunters have more sex, better food and a larger say in communal decisions, even though these are not strictly related to hunting. This experience of unevenness makes us search for a cause that will justify the social prestige and power that follows. Humans do not like coincidence and we are all very poor statisticians. So instead we tend to either essentialise the persons themselves (they contain ‘the right stuff’), or we argue that they attained this mysterious essence from outside: they are said to be ‘in luck’, ‘especially gifted’ or even have been ‘bestowed’ superhuman attention and aid. In either case, our ability to identify successful individuals and thereby predict who will be a good social partner has, as a byproduct, a proclivity to ascribe successful individuals a special essence. And we tend to believe that it is this essence – this mana – that has made exactly these individuals particularly successful.

Social prestige also arises when people are simply told by others who and what is special and powerful, and these narratives are then used to form strong predictions about the characteristics of certain persons, places and objects. Social prestige is, then, as much a product of reputation as of experience. Two features of such stories are of particular interest. First, not all information is equally simple to transmit. Some stories are better recalled than others. Certain results from the cognitive science of religion indicate that stories which contain violations of ontological expectations are particularly well-suited to spread within a group. According to this theory, called the epidemiology of representations, stories with violations of ontological assumptions (eg, persons who can be at two places at once, or a hunter with a stone that attracts game) are more attention-grabbing and therefore better recalled than more quotidian stories without no such violations. Further, if these stories contain characters, things or places that somehow have or could have a direct impact on your life – that should matter to you personally – then these are both more memorable and more relevant. For instance, St Camillus de Lellis, patron saint of the sick, not only knows about your deepest wishes but is also able to influence your life by healing you or your loved ones. This makes him – and in a similar way all saints – particularly relevant and memorable. You might even want to visit his heart in order to accrue his favour.

Finally, models involving saints, charismatic persons or special places help to form strong expectations concerning what is likely to happen next – at least if they are considered true. Expectations formed through cultural transmission function like the predictive models that arise from our direct experience, and the stronger the model, the more likely it is to determine our experience of the world. That is, expectations based on particularly strong models will sometimes override contradicting information from the senses. In short, we often want to be fooled – we prefer to see the world as in agreement with our models. The existence of confirmation bias in many domains of everyday life is an old finding in psychology, and people must employ methods of circumventing it, whether refinancing a mortgage or conducting a science experiment. Seeking disinterested opinion is always a good idea, if we wish to avoid being fooled by our own proclivity to confirm the already-assumed.

However, in some domains – most notably but not exclusively religion – people tend to actively seek out information that confirms already cherished models. Religious believers generally experience what they expect to experience. Catholics see apparitions of the Holy Virgin and Hindus of Vishnu, but not vice versa. These need not be massive, life-changing visions. Devotees will report feeling the powerful presence of God, the healing power of the shaman, being possessed, or the manifestation of some poorly defined cosmic energy – and these reported experiences tend to appear in contexts associated with strong expectations. Believers expect to be possessed in a possession rite, and Evangelical Christians expect to feel the presence of God while praying. For some, these experiences arise fast and rather effortlessly, whereas for others it takes years of practice. Once achieved, however, experiences not only bolster the existing models by means of confirmation. They also skew our sense of frequency, and make the miraculous appear less irregular. Our cognitive system seems to allow the establishment of a feedback loop where strong internal models guide experiences that tend to strengthen the already-existing model. Having a strong internal model will weigh much more heavily than rather diffuse sensory information, just as a placebo in a double-blinded medical experiment will create both effects and side-effects based on expectations alone.

There is an objection here to be dealt with: didn’t the theory of predictive processing specify that our internal models are updated or even replaced whenever they are contradicted by incoming sensory information? The theory in fact claims that the prediction model will be updated only in cases where the error-signal rises above a certain threshold. The threshold depends on both the robustness of the internal model and how strongly we trust the incoming sensory information. For example, say you are convinced that there is a stranger in your house on a stormy night. The darkness of the house makes the incoming sensory signal both weak and untrustworthy, and therefore it becomes harder to overcome the predictions stemming from the internal model that someone is there. And if you just watched a horror movie, say, your internal prediction model might be further strengthened, making it even more difficult for incoming information to oust the prevailing – and terrifying – interpretation. This everyday example illustrates the ways in which cultural technologies (in this case, a movie) can influence the balance between our expectations and the incoming stream of sensory information.

Cultural technologies can produce ideas of mana too. If holding mana entitles one to social prestige and political power, relying solely on real-world success and social reputation in its production would involve a high risk of perpetual social instability since success tends to fluctuate and reputation might dissipate. It would therefore be extremely handy if one could artificially make people believe that a particular person, place or thing is a holder of mana. A strong candidate for a cultural technology that fits this function is cultural ritual. That a relation exists between ritual and mana is far from a new insight, but previous research has mostly looked at mana as a requisite of ritual. (The bishop can perform a mass due to the mana he is ascribed prior to the ritual.) It might, however, be the opposite way around: that ritual behaviour often produces representations of mana.

In order to understand why, we need to return to how humans understand ordinary actions. As described above, actions involve a feedback structure between prior expectations and sensory input. If I expect the bottle to be full prior to lifting it, I exert a certain amount of force; finding out that it is in fact empty, I recalibrate my actions based on an updated model. However, in ritual behaviour this feedback structure breaks down as there is no immediate way of telling whether a ritual succeeded. The relation between ritual actions and ritual goals are either rather diffuse (did the ritual make the harvest abundant? Did the Eucharist really put me in a state of grace?) or situated in a far-away future (eg, salvation).

Leaders from Ramses to Mao harnessed this force for their own good, concentrating mana in their own persons

The opacity of the relationship between rituals and their results has a number of interesting effects. In contrast to most ordinary actions, where success is evaluated based on result, ritual’s success is predominantly judged in terms of correct execution. Rituals therefore consist of more or less culturally fixed action sequences that must be performed in the correct order. Second, as there are no feedback loops between the actions and the result, repetition equals investing more energy into the ritual itself. Rituals are therefore able to condensate invested energy into persons or objects present in the ritual, thereby transforming these into bearers of mana. Thus, increasing the amount of energy invested by participants means that more energy is available for reinvestment. Circling a maypole 30 times rather than seven invests more energy in it; having 300 people do it rather than 10 will have the same effect.

The ability to condensate mana in particular persons or objects makes its accumulation and redistribution possible. If mana has the assumed direct relation to social prestige and political power, we should expect different types of societies to handle mana in different ways. For instance, it might be likely that members of an egalitarian society based on small cooperative units are sceptical about condensations of mana. In order to avoid the introduction of institutional inequality, such societies would employ techniques to instantly redistribute any mana that would appear as a side-effect of unevenly distributed success. However, as soon as social complexity grows through the construction of alliances between two or more cooperative units, the mana created through ritual allows objects or persons to function as joint depositories of the force, and thereby as symbolic rallying points uniting otherwise distinct groups. This might take different forms, such as totemic classifications found in Australia and Africa, or the ‘big man’ system found in Polynesia. Both cases, however, can be seen as the basic form of imagined communities that unite individuals into coalitions whose members do not know each other.

Meanwhile, in socially complex societies involving a hierarchical political structure and an uneven distribution of wealth, we are likely to find a different pattern emerging. City-states such as those found in Mesopotamia, China, India, Mesoamerica and around the Mediterranean are characterised by greater concentrations of political power and by the emergence of polities based on cooperation between anonymous individuals built on an extended division of labour. This correlates with the emergence of temple-religions involving large collective rituals, specialised priesthood and the emergence of a literate class. The relationship between the two is often conceived as a tradeoff. Religious cults provide legitimacy to rulers who, in turn, protect a number of legitimate religious centres from competitors. However, if we understand these cultic centres as depositories of force, or as mana-banks, we can refine this picture. Temples and other holy centres generate, condensate, accumulate and redistribute an enormous amount of psychological energy, created through such activities as mass ritual, processions and offerings – an energy that believers experience as both real and effective, and therefore seek access to. No wonder that political leaders, from Ramses to Mao, have sought to harness this force for their own good and concentrate the mana in their own persons.

Examining the distribution of mana in today’s world is a complicated task, but perhaps one prevalent example will do. An undistinguished light-blue scarf, old, sun-bleached and sweat-stained, is likely not worth much of anyone’s time or money – unless it was a scarf worn by Elvis Presley on stage. In that case, the scarf could earn you several hundred dollars, if not more. A pair of his pants is worth around $7,500. Or take one of the outfits of Diana, Princess of Wales: auctions can fetch $145,000 for a dress that, if worn by nearly anyone else, would be worth much less. A paper tissue used by Scarlett Johansson was even sold for $5,300 in 2008. In this world of celebrity-worship, the mana power of objects touched by the prestigious (if not the saintly) clearly still helps shape the world we live in.