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Adolescence and Religion: An Evolutionary Perspective

Abstract and Keywords

Throughout the world adolescence is deemed the appropriate life stage to “learn religion.” Nearly three-quarters of societies conduct adolescent rites of passage transmitting sacred rituals and beliefs. Neurophysiological changes that occur during adolescence render this an “experience-expectant” period for the transmission of religious schema and values. Brain regions critical to emotional, social, and symbolic processing mature, creating a plastic neural substrate for imbuing social and symbolic schema with emotional meaning and reward value. Religion in general, and adolescent rites of passage in particular, are optimally adapted for this task. Music-based ritual and emotionally evocative elements of religion optimize reinforcement learning. The costly and autonomically arousing ordeals of many rites ensure fear conditioning. Such learning shapes maturing neural networks, impacting choices and behaviors. Evolutionary anthropologists view religion as a costly signal of group commitment. Adolescent rites of passage are a powerful proximate mechanism for creating and maintaining cooperative, cohesive groups.

Keywords: adolescence, religion, rite of passage, brain plasticity, experience, expectant, costly, signal

Introduction

The rise of religiously inspired global terrorism has been a hallmark of the late 20th and early 21st centuries. Images of flag-waving jihadis rolling across vast swaths of desert have become dominant themes in the public media. These images are menacing, as they are meant to be. Yet, beneath many of the black balaclava that shroud the heads of these terrorists are the smooth countenances of young boys and the barely stubbled faces of teens. They are recent converts to a violently fundamentalist brand of Islam that conducts training lessons in beheading and promises, “Those who behead the infidels will receive gifts from God” (Abi-Habib, 2014, p. 1).

Many of these young recruits are the orphaned children of those killed by the terrorists. Traumatized by the attack itself and the slaying of their families, these youth face a stark choice between conversion to the terrorist cause or death. Some recruits are simply kidnapped; others are “sold” by impoverished and destitute families; still others voluntarily join the terrorists as local economies are shattered, secular schools are shuttered, and villages and their resources are seized.

Once recruited, these youth are taken to camps where they undergo indoctrination. Reports from those who have escaped paint a grim picture. Recruits are first desensitized by watching videos of beheadings. The humiliation, torture, and beheading of captured combatants follows. Severed heads are passed around the group to further dehumanize the enemy, and decapitated bodies are publicly displayed. The young recruits are encouraged to revile and defile them. Boys learn decapitation techniques. Those who resist are tortured; those who try to escape are shot. The program is brutal and barbaric; it is also effective in desensitizing recruits, dehumanizing the enemy, and indoctrinating and training young terrorists able and willing to kill, even if such killing requires them to sacrifice their own lives.

These terrorists are not the first to fight in the name of religion. Numerous groups throughout human history have used religion to justify violence, warfare, and brutality (Juergensmeyer, 2003). Nor are they the first to exploit the relationship between adolescence, violence, and religion. That relationship has broad and deep roots (Alcorta & Sosis, 2013). Unraveling that relationship requires that we first understand it.

Adolescence

Any parent of an adolescent can tell you that this developmental period is a time of change. The most obvious changes are physical, as the onset of puberty initiates a cascade of hormones that accelerate growth, induce development of secondary sexual characteristics, and begin reproductive maturation. Yet, puberty itself is initiated by neuroendocrine “triggers” in the developing adolescent brain (Plant & Shahab, 2002).

Adolescence has been described as a period “prone to erratic … and emotionally influenced behavior” (Dahl, 2004, p. 3). Adolescents are more impulsive and react with greater emotional intensity than either children or adults (Steinberg, 2007). They perceive events as relatively more stressful than individuals at other life stages, and show increased interest in and sensitivity to peers and social cues (Brenhouse & Andersen, 2011). During adolescence, both risk taking and novelty seeking increase, particularly among males (Dahl, 2004). Enhanced sensitivity to alcohol and drug abuse increases the risk of addiction, as well. Underlying these changes is a shift in the brain’s dopaminergic system that increases adolescent vulnerability to environmental stressors and puts them at greater risk for various mental disorders. All of these characteristics are more pronounced in males than females (Brenhouse & Andersen, 2011). These factors contribute to increased mortality rates, “with homicides, suicides, and accidents collectively accounting for more than 85% of all adolescent deaths” (Spear, 2000, p. 421). As brain development proceeds through adolescence, these risks gradually diminish.

Adaptive Functions

Many of the behavioral changes that mark adolescence, such as risk taking and novelty seeking, propel the individual away from the natal kin group and into the broader sphere of non-kin social and sexual interactions. This introduces new social roles and behaviors that differ both between sexes and across cultures. The interindividual play behaviors of childhood decline, and participation in coordinated and competitive group activities (e.g., dance, work, sports) increases. Coalitions, courtship, and competition become increasingly important (Alcorta, 2006). As adolescents move from predictable, kin-centered roles and relationships to the uncharted world of potential mates, collaborators, and competitors, they are faced with ongoing social judgments and numerous choices. Learning how to control impulses and emotions, determining who can be trusted and who cannot, identifying risks worth taking and when to take them, deciding when to subordinate immediate self-interest to the long-term interests of the group, and determining the best mating and fitness strategies within a particular socioecological environment are all behaviors that directly impact social and sexual success (Alcorta, 2009). It is “a period of life in which the sense of self changes profoundly” (Sebastian, Burnett, & Blakemore, 2008, p. 441).

Some theorists have proposed that the novelty-seeking, risk-taking behaviors of adolescent males constitute adaptations for reproductive success in a competitive reproductive environment (Steinberg, 2008). The same novelty seeking that entices males to venture away from the natal group and seek a wider pool of mates also serves as the impetus for other evolutionarily important behaviors. Adolescent impulsivity, novelty seeking, and risk taking are the source of much human exploration and innovation. The exploitation of new resources, the exploration of new habitats, and breakthroughs in technology are all likely benefits that derive from these adolescent traits. The founders of Apple, Microsoft, and Facebook were all 20 years old at the time of start-up.

These same behavioral attributes may temperamentally predispose adolescent males to participate in such high-risk endeavors as intergroup aggression and group defense. As in nonhuman primates, adolescent males in human societies constitute both the peripheral “fringe” and front guard of the social group. Adolescents and young adults make up the ranks of warriors and foot soldiers across human societies. Alexander the Great was 20 years old when he assumed leadership of the Macedonian army. The sociologist Mark Juergensmeyer (2003) notes that the vast majority of recruits to extremist religious organizations are predominantly young, unmarried males who perceive themselves as marginalized by the dominant culture. From a physical standpoint, adolescent and young adult males are the fittest members of the group; from a reproductive standpoint, they are the most expendable. Their greater propensity for novelty-seeking and risk-taking behaviors predisposes them to assume this role, while their social powerlessness relative to older group males may compel them to do so (Thayer, 2008).

Adolescence is not confined to humans alone. It is an important developmental period across mammalian species and is impacted by genetic, nutritional, and environmental factors. What differs about human adolescence is its relative length. In nonhuman primates, adolescence extends between 2 and 4 years; human adolescence continues over nearly a decade. This is followed by a “young adult” period of maturation before adulthood is reached (Brenhouse & Andersen, 2011). Such a prolonged period of maturation is costly. Identifying benefits that offset these costs begins with the adolescent brain.

The Human Brain

The behavioral changes that occur during adolescence result from ongoing neurophysiological changes in the adolescent brain. The biologist Linda Spear describes human adolescence as “second only to the neonatal period in terms of both rapid biopsychosocial growth as well as changing environmental characteristics and demands” (Spear, 2000, p. 428). Brain maturation during adolescence is extensive, involving emotional, social, and executive functions. The relatively slow and late maturation of these functions in humans is unique among primate species.

The human brain is proportionally larger in comparison to body size than that of all other primates, and it is also the least developed at birth. Chimpanzees, with whom we share nearly 99% of our DNA, are born with brains approximately 40% of their final size at maturation. In contrast, humans develop 75%–80% of their total brain volume after birth. This development takes much longer in humans than it does in chimps. By the second year of life, only about 50% of human brain development is complete. The human brain does not reach its maximum size until adolescence. Thereafter, our brains are actually reduced slightly in size through the processes of myelination and “pruning” (Kolb, Forgie, Gibb, Gorny, & Rontree, 1998).

Neurons, Synapses, and Neural Networks

The average human brain is made up of approximately 100 billion neurons. Each of these neurons is interconnected with approximately 10,000 other neurons. When a stimulus activates a neuron, the neuron “fires,” sending an electrochemical signal that is transmitted to adjacent neurons across a small gap called the synapse. Repeated firing of adjacent neurons creates and strengthens the synapses between neurons, creating an associational network that is reactivated when the initial stimulus is again experienced. Synapses that fail to fire or fire only infrequently are eliminated, or “pruned” away, and their energy resources are reallocated to more active networks. These processes of “synaptogenesis” and “pruning” sculpt the genetically determined neural configuration with which we enter the world. As a result, “while genes provide the blueprint to construct the brain, experience sculpts the brain to match the needs of the environment” (Brenhouse & Andersen, 2011, p. 1698).

The shaping of neural networks through experiential learning is not simply facilitated by experience; it depends on it. If stimuli do not initiate synaptic firing, the unused synapses are eliminated, or “pruned.” Laboratory experiments show that covering the eyes of newborn kittens in the first few weeks of life functionally blinds them. Without the visual stimuli needed to initiate synaptic firing in the maturing visual cortex, the excitatory neuronal pathways originally allocated to vision are reshaped through pruning to fulfill other sensory functions (Lynch, Larson, Muller, & Granger, 1990).

Once neuronal networks have been shaped through synaptogenesis and subsequent pruning, myelin sheaths encase them, speeding up impulse transmission and creating the “white matter” of the brain. This process of growth, synaptogenesis, pruning, and myelination speeds up information flow in the human brain.

Patterns of Brain Development

Our brains do not grow and develop uniformly. Different brain regions mature at different times, with each successive region of maturation building on and integrating functional neural networks previously developed. Since different functional networks undergo maturation and pruning at different times, inputs experienced during infancy, childhood, and adolescence differentially impact the brain. As a result of this heterochronic growth pattern, neural changes that occur at earlier stages of development impact later stages. Simultaneously, stimuli and experiences that activate brain functions during periods of maturation will have greater long-term impacts on the associational networks of these functions than inputs experienced either before or after this period of maximal neural plasticity (Kolb et al., 1998).

During infancy, brain regions involved in sensory, motor, appetitive, and emotional processing undergo significant growth and development as the newborn learns to assess the environment, control movement, obtain sustenance, and bond with caregivers. This development lays the foundation for subsequent childhood learning that integrates these functions into more complex skills, including such things as interindividual play and language.

Adolescent Brain Development

Numerous brain changes occur during adolescence. Neural structures involved in emotional processing and memory peak in activity and regions responsible for our social, symbolic, and executive functions undergo maturation (Blakemore, 2008). This is accompanied by a shift in the brain’s dopaminergic reward system. These changes create a plastic neural substrate for experience expectant learning (Greenough 1986).

The Limbic System and Emotions

Many of the behaviors and vulnerabilities that mark adolescence derive from changes in the limbic structures of the brain. These structures, including the amygdala and hippocampus, are involved in both memory and the processing of emotional stimuli. Both of these structures reach peak volumes during adolescence, with male volume increases exceeding those of females (Spear, 2000). Whereas the hippocampus is central to the formation and consolidation of our explicit—or conscious—memories, the amygdala encodes and consolidates our implicit, emotional memories. The amygdala is involved in evaluating and processing both positive and negative emotions, assigning “weights” to stimuli (Phelps, 2004), but is particularly important in the appraisal of negative emotions and fear conditioning (LeDoux, 1996). Fear conditioning has been central to our survival as a species; as a result, our evolved negativity bias (Vaish, Grossmann, & Woodward, 2008) makes fear conditioning a particularly powerful motivator of behavior.

The amygdala also plays a role in the conscious and unconscious processing of facial signals and judgments of trustworthiness (Adolphs, 2002). This is pronounced during early to mid-adolescence. Adolescents exhibit “greater brain activity in the amygdala than in the frontal lobe when engaged in a task requiring the subjects to identify emotional state from facial expressions, while adults conversely exhibited greater activation in frontal lobe than amygdala when engaged in the same task” (Spear, 2000, p. 440).

The amygdala has direct interconnections with numerous brain structures, including the hypothalamus, responsible for regulating the body’s autonomic functions such as temperature, heart rate, blood pressure, and respiration. The amygdala-hypothalamic connection creates a powerful two-way link between emotional appraisal and autonomic response.

The amgydala also directly interconnects with the brain’s “pleasure center,” the nucleus accumbens, part of the ventral striatum. This brain region also undergoes maturation during adolescence and “has been posited to play a primary role in observed increases in adolescent sensation-seeking” (Larsen & Luna, 2015, p. 74). Release of the neurotransmitter dopamine in the ventral striatum makes us feel good and motivates us to continue to engage in the behaviors that initiated its release. This “reward” response has evolved to ensure that we value and seek out things important for our survival. Some things, such as food, sex, and music, have intrinsic reward value and automatically elicit dopamine release. Cocaine and other drugs of abuse also activate such release, giving rise to the neurophysiology of addiction (Daw, 2007).

Prefrontal and Temporal Cortices

During adolescence, the temporal and prefrontal cortices of the brain peak in volume and subsequently shrink. In early to mid-adolescence, the temporal cortex reaches its maximum volume (Paus, 2005). This region’s primary function is the processing of social stimuli, including facial and gestural recognition, mental-state attribution, and music and language processing. The increased importance of social stimuli during adolescence reflects heightened temporal lobe activity.

During mid-adolescence, the prefrontal cortex also attains its greatest volume. This region is the brain’s “executive center” and is critical for impulse inhibition, self-regulation, social judgment, personal decision-making, and our sense of self. It is also the locus of human abstract and symbolic thought (Dumontheil, 2014). The prefrontal cortex is the preeminent association area of the brain, sending output and receiving input from all other brain regions (Robbins, 2000). Direct connections between the prefrontal cortex and the amygdala ensure that emotional valuations are integrated into our social judgments and personal decisions. When this interconnection is disrupted, as it is in patients with “disconnect syndrome,” humans perform well on abstract reasoning tasks but are incapable of applying this reasoning to personal decision-making (Damasio, 1994).

The temporal and prefrontal cortices also have direct interconnections with the insula, an ancient brain structure that plays many different roles. The insula functions in pain perception and taste and is involved in “combining sensory awareness with higher cognition” (Dennis et al., 2014). Interconnections between the insula and the temporal cortex peak during adolescence.

Dopaminergic Reward System

Although much human learning occurs through emotionally conditioned responses, we also learn through reward reinforcement. Neutral stimuli that do not have inherent incentive value can acquire value through association with stimuli that do. Brain-imaging studies of cocaine addicts show that, over time, previously neutral stimuli such as places and paraphernalia associated with cocaine use stimulate dopamine release in the nucleus accumbens, even in the absence of the cocaine itself (Daw, 2007). When neutral stimuli are repeatedly paired with stimuli that have innate reward value, the neutral stimuli is eventually able to initiate dopamine release in the absence of the inherently rewarding stimulus. As a result of this process of reinforcement learning, neutral stimuli can acquire reward value and motivate us to seek out specific experiences and engage in particular behaviors (Dehaene & Changeux, 2000). Fear conditioning and incentive learning drive our behavior and personal decision-making (Bechara, Damasio, & Damasio, 2000). Both are largely subconscious processes, but they play a critical role in weighting our behaviors and choices (Coricelli, Dolan, & Sirigu, 2007; Soon, Brass, Heinze, & Haynes, 2008).

The emotion- and reward-processing centers of our brains exert greater control over our decisions and behaviors during early and mid-adolescence as a result of relative differences in dopaminergic activity between these regions and frontal areas of the brain. Social stimuli further influence such responses (Steinberg, 2008). Increased adolescent vulnerability to addictive substances and behaviors, the greater anhedonia of adolescents, and an increase in appetitive behaviors including food, sex, and music have been attributed to this difference (Spear, 2000; Steinberg, 2008).

From mid to late adolescence, the ongoing maturation of the prefrontal cortex results in a “shift” in dominance of the dopaminergic system, with the prefrontal cortex assuming increased control over both emotion regulation and impulse inhibition (Spear, 2000).

The Experience-Expectant Adolescent Brain

The maturational changes that occur in the human brain during adolescence make this developmental stage an “experience-expectant” (Greenough, 1986) period for creating emotionally valenced associational networks among emotional, social, and executive functions. Heightened activity in emotion- and reward-processing structures of the brain, and the dopaminergic “shift” in functional connectivity between the prefrontal cortex, amygdala, and ventral striatum optimize conditions for conditional and reinforcement learning. Simultaneously, the neural plasticity of the maturing temporal and prefrontal cortices facilitates the sculpting and strengthening of new associational networks linking social and executive functions.

Social Communication: From Signals to the Sacred

Learning the social skills required for group living is one of the greatest challenges humans face. The anthropologist Robin Dunbar has persuasively argued that it is precisely such social challenges that have driven increases in relative brain size in primates (Dunbar, 1996). Social challenges are particularly daunting during adolescence, as conspecific interactions increasingly shift from the shared interests of the natal kin group to those of non-kin collaborators, mates, and competitors.

The neural, physiological, and behavioral changes that occur during adolescence prepare the individual to take on these new social and reproductive roles, but many of the social behaviors that optimize individual fitness must be learned. In contrast to learning how to hunt a gazelle, build a house, or solve a math problem, learning how to effectively judge, communicate, and interact with conspecifics is fraught with difficulties. Accurate transmittal of a message from sender to receiver is complex and susceptible to both distortion and deception. As the genetic distance between communicators widens and the congruence of self-interest narrows, these problems increase and the potential for cheating and deceit escalate. Fitness costs of trial-and-error learning can be great: Misjudging collaborators results in lost time and resources; misjudging mates impacts reproductive success; and misjudging competitors can be lethal.

Signals as Social Communication

Signals have evolved as one solution to the social communication problem. The scent marking of dogs and the human smile are both signals that convey information about the state, condition, or intent of the sender. These signals communicate social information, but are relatively “closed” systems with limited scope and flexibility. They are also subject to mimicry and deception. Viceroy butterflies fool potential predators through their mimicry of the unappetizing Monarch, and females of the predatory firefly genus Photuris mimic the mating flashes of the related genus Photinus in order to lure males close enough to attack and consume them. Humans bluff, cheat, and lie in cards, war, and love.

Quality Signals

The evolution of “quality signals” that provide reliable information about the general condition of the sender is one solution to the deception problem. In birds, the intensity of plumage color is negatively correlated with parasite load—the brighter the plumage, the healthier the bird. The color brilliance of males is a quality signal, and females seek out males with the most brilliant plumage. In humans, facial symmetry, positively correlated with health, is a quality signal. Males and females worldwide find symmetrical faces more attractive (Scheib, Gangestad, & Thornhill, 1999).

Quality signals that incorporate both genetic and learned components have also evolved. Such signals provide more flexibility to meet changing ecological demands. Male passerine birds are genetically “primed” to learn their particular species’ song but must be exposed to it during a specific developmental window to do so. Human music and language are similar ontogenetic traits. Although we are all born with the capacity to learn song and language, socialization during specific developmental periods is required to do so. Like birdsong and the songs of humpback whales, human song and language convey information regarding the condition and intent of the individual sender, but they also convey information regarding the social group.

Quality signals benefit receivers by providing more reliable information, but they incur significant costs for the sender. Male peacocks with the longest, brightest tails and male songbirds with the largest repertoires not only expend more energy on the development and maintenance of these traits but also attract more predators than less showy individuals. The biologist Amotz Zahavi (1997) has proposed that high-cost signals such as these are adaptive for signalers precisely because they “handicap” the sender. Since only the fittest peacocks and songbirds are able to successfully produce and maintain the longest, showiest tails and the largest and most captivating song repertoires, it would be impossible for lesser competitors to “fake” these signals.

Ritual

Ritual is the costliest of signals. Nonhuman ritual calls attention to such evolved quality signals as the peacock’s tail by displaying these elements within an intricate and highly stereotyped sequence of behaviors. Such displays incur significant costs in time, energy, and resources and expose signalers to great risks and potential predation. Yet, when the stakes are particularly high, as in competition and mating, the structure of ritual optimizes honest, reliable communication.

The Structure of Ritual

Ethologists have defined ritual as “behavior that is formally organized into repeatable patterns” (Smith, 1979, p. 51). Laboratory experiments show that the basic elements of ritual optimize effective communication (Rowe, 1999). The first step in all effective communication is alerting and engaging the attention of the receiver. Ritual achieves this through the element of formality. Formality frequently involves the exaggeration of ordinary traits and behaviors to make them appear “extraordinary.” The “eyes” of a peacock’s long, iridescent tail prominently displayed during his ritual dance, the changing body colors of male squid as they gently jet water over a potential mate, and the ornate garments worn by human brides all represent formal elements of ritual that engage and focus the attention of ritual participants. These signals not only capture the attention of the receiver but also elicit neurophysiological responses. Ritual’s creation of the “extraordinary” through the exaggeration and elaboration of encoded traits and signals activates the alerting systems of the brain, including the basal ganglia, the amygdala, and the reticular formation. This focuses and directs attention, primes emotions, and prepares the body to react (Alcorta & Sosis, 2005).

Once the receiver’s attention is focused, the sequence, pattern, and repetition of ritual optimize processing time for memory and learning. Repetition of a stimulus alters molecular chemistry at the cellular level, inducing both dendritic growth and synaptogenesis. Sequenced repetition allows for focus time and processing time, permitting the brain to recycle CREB, a protein crucial to long-term memory function. (Lynch et al., 1990).

Ritual also impacts neuroendocrine function. Levels of neurotransmitters, neuromodulators, and hormones of both the sender and the receiver fluctuate during ritual, resulting in changes in the physiological, immunological, and behavioral responses of ritual participants. The release of noradrenaline in response to the formal elements of ritual, increases in dopamine resulting from ritual performance, and the recycling of CREB all impact affective state and learning.

The biologist Russell Fernald’s studies of cichlid fish (Haplochromis burtoni) from Lake Tanganyika in Africa dramatically illustrate ritual’s ability to impact physiology (Fernald & Maruska, 2012). Agonistic displays between cichlid males induce major changes in the hormones, external appearance, brain neuron sizes, and even the gene expression of winners and losers. Aggressive and brilliantly colored black, yellow, blue, and red males almost instantly morph into much less aggressive drab brown “satellite” fish when ousted from their territories by rivals. If the “satellite” later acquires a new territory, his color, hormones, hypothalamic neuron sizes, and gene expression again change.

Similar neuroendocrine changes in both senders and receivers have been documented across numerous species. The ritualized vocalizations of songbirds vary with seasonally fluctuating hormone levels and impact female oxytocin levels and sexual receptivity (Ball, 1999). In nonhuman primates, ritualized dominance and submission behaviors alter participants’ cortisol, dopamine, and testosterone levels (Sapolsky, 1999).

The elaboration of simple signals into complex ritualized displays is costly, but these displays allow signalers and receivers to reliably and effectively communicate important social information within a relatively “safe” context. Ritual creates frameworks of prediction and expectancy (Smith, 1979). It “provides individuals with some predictive grasp of their circumstances and thus enables them to make choices about their subsequent behavior” (Smith, 1979, p. 52). The greeting rituals of bonobos, the mating dance of sand hill cranes, and the classroom procedures of human college students all serve these functions.

Human Ritual

Human ritual is among the most elaborate and diverse across animal species. Cross-culturally it includes both secular and religious rituals, and exhibits a continuum of costliness.

Signals and Secular Ritual

Humans, like all other animals, are born with a repertoire of innate emotional responses to various classes of stimuli essential to survival. Human babies instinctively respond to smiles and frowns. Like our cousins, the bonobos and chimpanzees, humans everywhere use hugs, kisses, and facial expressions to identify and convey basic emotional states. As one of the most social species on the planet, humans spend much of their lives interacting with others. Human societies include kin, but they also include fictive kin, acquaintances, strangers, and sometimes even foes. The size, variability, and complexity of human social groups contribute to our cultural and technological success. It is not surprising that ritual plays an important role in human lives. Secular rituals structure our lives and organize our societies. Their adaptive function is apparent and their benefits are clear. That is not so with the costliest of human rituals.

Religious Ritual

Of all the rituals humans perform, religious rituals are the most elaborate and costly. They are also the most puzzling. They entail beliefs that are counterintuitive and rites that are seemingly nonfunctional. They require the investment of time and resources, and may also entail suffering, sacrifice, and pain. To outsiders, religious beliefs and rituals often appear bizarre and fantastic. Talking totems, feasting ghosts, and omnipresent gods all defy logic and violate natural categories. Fasting, self-flagellation, and circumcision require self-sacrifice and inflict pain. Religious rituals may, and sometimes do, result in death (Turner, 1967). Yet for adherents, religious beliefs and the strange rituals that surround them are not only credible but also inviolate. At the heart of these rituals and beliefs is the concept of the sacred. Understanding religion begins with understanding the sacred.

What Is the Sacred?

Sacred symbols have been described as “the small stimuli that elicit a large response” (Wallace, 1966, p. 236). The sacred is set apart and forbidden (Durkheim, 1969/1915), enduring and powerful (Eliade, 1959), unquestionable and unfalsifiable (Rappaport, 1999). Sacred things stir our deepest emotions and elicit feelings of joy, terror, and awe.

Sacred Things Are Emotionally Charged

The deep emotional significance of the sacred is its central attribute. Sacred things—whether places, artifacts, or symbols—evoke intense emotions. They stir our souls and touch our hearts. The Christian cross, the Islamic Quran, and the Wailing Wall of Judaism all elicit deep emotional responses in adherents. Desecration of these sacred things is dangerous and brings strong, spontaneous responses from adherents. It is not just inappropriate to treat sacred things profanely; it is morally, and even viscerally repugnant.

Sacred Things Are Social Constructions

Sacred things not only elicit a deep emotional response in single individuals but also evoke these same emotions in others. Temporal lobe epileptics often experience intense emotion in response to various stimuli, but in the absence of a communal response, such experiences are deemed symptoms rather than sacred. It is through shared emotional response across congregations of adherents that the sacred is invested with its power and meaning. “Liturgical orders, even those performed in solitude, are public orders and participation in them constitutes an acceptance of a public order regardless of the private state of belief of the performer” (Rappaport, 1999, p. 121).

Sacred Things Are Cultural Constructions

Sacred things do not exist in nature waiting to be discovered. They must be created. The Christian Bible has no emotional or motivational significance for non-Christians, nor do the ancestral ghosts of the African Ndembu have sacred meaning for Christians. Even sacred places only attain their sanctity in relation to a particular sociocultural system. Delphi and the Parthenon were both held sacred by the ancient Greeks; today they are tourist sites. Sacred things must be created. Religious ritual is the means by which this occurs.

Adolescent Rites of Passage

Religion is a universal human trait, and ritual is its behavioral manifestation. Of all religious rituals, adolescent rites of passage are the most ubiquitous and costly. These rites occur in approximately 70% of societies throughout the world (Lutkehaus & Roscoe 1995) and vary considerably from culture to culture. In some societies they involve single individuals, as in Judaism’s bar/bat mitzvahs. In other societies they encompass age-graded groups of adolescents, as in the male initiation rites of the New Guinea Ilahita. In still other cultures, these rites involve mixed-gender age-graded groups of adolescents, as in contemporary Christian confirmation programs (Lutkehaus & Roscoe, 1995; Paige & Paige, 1981).

Some adolescent rites of passage are relatively brief; others last months or even years. Rites of the traditional Yamana and Halakwulup of Tierra del Fuego consisted primarily of the oral transmission of sacred knowledge from elder to youth (Eliade, 1994/1958). The Mukanda rite of the African Ndembu included kidnapping, seclusion, dietary and sleep deprivation, and prolonged psychological and physical torture, including scarification and genital mutilation (Turner, 1967).

All adolescent rites of passage begin with a separation phase, include a transformative—or “liminal”—phase, and conclude with the reintegration of the initiate back into the social group (Turner, 1969). Universally, these rites also include what the anthropologist Maurice Bloch has called “the distinguishing marks of ritual” (Bloch, 1989, p. 21).

Chanting, Music, and Dance: The Distinguishing Marks of Ritual

The heart of man has been so constituted by the Almighty that, like a flint, it contains a hidden fire which is evoked by music and harmony, and renders man beside himself with ecstasy. These harmonies are echoes of that highest world of beauty which we call the world of spirits, they remind man of his relationship to that world, and produce in him an emotion so deep and strange that he himself is powerless to explain it.

Becker (2001, p. 145)

Chanting, music, and dance are important elements of adolescent rites of passage throughout the world. From the shamanic religions of the Siberian Chukchi, to elaborate Balinese bebuten trance rituals, to contemporary Pentecostalists in Africa, Asia, and the United States, these rhythmic drivers are a central feature of religious ritual. A survey of US congregations found music to be the single most consistent feature of contemporary US religious services (Chaves, Konieczny, Beyerlein, & Barman, 1999). Even the most fundamentalist sects retain music as an important part of communal ritual (Atran & Norenzayan, 2004), and terrorist jihadis instruct young initiates to sing their songs (Abi-Habib, 2014). In many traditional societies, music is not only central to sacred ritual but also inseparable from it. The Igbo of Nigeria have but one word—“nkwa”—to describe both music and the sacred (Becker, 2001).

Music is intimately interconnected with a sense of the sacred, the numinous, and the divine. Music not only represents the sacred but also calls it forth and embodies it. The ability of music to invest the profane with sacred significance by eliciting feelings of joy, fear, and awe lies at the heart of its role in all religions. When combined with communal ritual the intense emotions stirred by music become powerful motivational forces (Alcorta, 2008).

Musical forms differ widely from culture to culture and even across subcultures within a society. Yet within each culture, the specific sounds and shared meanings of music are capable of eliciting strong emotions in listeners. “Music perception potentially affects emotion, influences the autonomic nervous system, the hormonal and immune systems, and activates (pre)motor representations” (Koelsch & Siebel, 2005, p. 578). Music’s alteration of affective states also impacts social judgment and cognitive processing style (Clore & Huntsinger, 2007). Decoding the culturally prescribed “meaning” of music entails the learning of emotional, autonomic, and cognitive associations, as well as the encoding of motor and sensory stimuli (Cross, 2003). Since the neural structures underlying these various functions follow different developmental trajectories, the cultural encoding of music is an ongoing developmental process.

Across human cultures, the predominant locus for listening to and performing music is the group, and the dominant emotion experienced during musical experiences is happiness and joy (Becker, 2004). In addition to its inherent ability to evoke powerful emotional responses in listeners (Koelsch, 2010), music also enhances the emotions elicited by nonmusical stimuli (Baumgartner, Lutz, Schmidt, & Jancke, 2006). When individuals share the encoded cultural meaning of music, the emotions evoked throughout the group and their associated autonomic and motor effects are also shared. This entrainment of mood and its associated autonomic responses has significant implications for the experience of empathy (Levenson, 2003).

Listening to music alters our autonomic functions, including heart rate, blood pressure, respiration, immunological function, and neuroendocrine responses (Chanda & Levitin, 2013). It also activates the brain’s reward circuitry, releasing the neurotransmitter dopamine, the “feel good” chemical involved in reward processing, memory, and reinforcement learning. Music increases release of oxytocin, a neuropeptide critical to interpersonal trust and affiliation (Ross & Young, 2009). Oxytocin increases in-group favoritism and “to a lesser extent, out-group derogation” (De Dreu, Greer, Van Kleef, Shalvi, & Handgraaf, 2011, p. 1262), and “can facilitate amygdala-dependent, socially reinforced learning and emotional empathy in men” (Hurlemann et al., 2010, p. 4999).

As the musicologist Ian Cross (2003) has noted:

Music is not only sonic, embodied, and interactive; it is bound to its contexts of occurrence in ways that enable it to derive meaning from, and interactively to confer meaning on, the experiential contexts in which it occurs, these meanings being variable and transposable. (p. 108)

Music is also inherently mnemonic. Much like the scent of Proust’s madeleines, a phrase of music can transport us to a different place and time. Like language, music is at once genetic and cultural, individual and social. And, as with language, although music is individually experienced, it is culturally created. Emotive and mnemonic, singular and social, transitive and transposable, music is both “in and out of time.” It evokes our emotions, instantiates our experiences, and solidifies our social bonds. It is at once signal and symbol, emotive and abstract, and may well be the genesis of humanity’s symbolic capacity.

Various nonhuman species, including passerine birds and humpback whales, regularly engage in song processing and production, and chimpanzees engage in tree drumming. Humans, however, are one of only a few species capable of synchronizing to the beat of music (Patel, Iversen, Bregman, & Schulz, 2009). This ability to synchronize to music allows us to entrain our autonomic and emotional responses with others, a response positively associated with both empathy (Levenson, 2003) and cooperation (Wiltermuth & Heath, 2009).

Adolescence and Music

During adolescence, chanting, music, and dance take on increased social significance and emotional importance. We remember songs from our teenage years because they are emotionally charged (Levitin, 2006). The enhanced reward value of music during adolescence makes it an effective mnemonic and emotional element of ritual. For teens, music is both emotionally engaging and socially significant. Hip-hop, rap, country, and heavy metal are not just musical styles; they are significant social markers.

Rites of Passage, Emotion, and Sacred Pain

The music, chanting, and dance of religious ritual principally evoke positive emotions of affiliation and joy. Other components of religious ritual evoke quite different emotions. Shadowed forests and caves, darkened cathedrals, masks that distort and disfigure faces, and statues that bleed all engage innate responses that arouse our alerting systems, eliciting fear, disgust, and terror. Many adolescent rites further amplify these effects through food and sleep deprivation, the use of psychoactive substances, and pain-inducing psychological and physical ordeals (Alcorta & Sosis, 2005). The cognitive scientist Robert McCauley’s description of Baktaman initiation rites vividly illustrates such practices:

The initiations bombard initiates’ senses in order to arouse their emotions. They are routinely deprived of food, water and sleep. They are repeatedly beaten and tortured. They are forced to eat what are, in their own estimation, all sorts of disgusting concoctions. They are forced to dance to the point of utter exhaustion…. Stimulating ritual participants’ senses is the most straightforward, surefire means available for arousing their emotions. The intuition is that the resulting levels of emotional excitement are often at least roughly proportional to the levels of sensory stimulation a ritual contains. These emotional responses are virtually always involuntary, and with particularly intense sensory stimulation, they are often difficult to control.

(McCauley, 2001, p. 119)

These ordeals not only “grind down” the initiate’s self-identity but also alter his perceptions and blur the line between self and other. They “differentiate between an order, realm, mood, or state of being that is mundane, ordinary, or ‘natural,’ and one that is unusual, extra-ordinary, or ‘supernatural’” (Dissanayake, 1992, p. 49). Manny Twofeathers’s description of the Native American Sun Dance rites conveys these effects:

I lay there on the ground, looking up into the sky. Then I handed Lessert my piercing bones. He got down on his knees next to me, and his father knelt by my left side. I felt both of them grab my chest and rub it with some dirt, because I was sweaty and slippery. This way their thumbs and fingers wouldn’t slip. They pinched my skin, and I felt as the knife went into my flesh. I felt a sharp, intense pain in my chest, as if somebody had put a red-hot iron on my flesh. I lost all sense of time. I couldn’t hear any sounds. I didn’t feel the heat of the sun. I tried to grit my teeth, but I couldn’t…. I prayed to the Creator to give me strength, to give me courage…. When I stood up, I did feel pain. I felt pain, but I also felt that closeness with the Creator…. The pain did not compare to what I was receiving from this sacred experience…. I was tied to the tree with that rope as securely as a child is tied to its mother by the umbilical cord. The only way off that cord was by ripping myself off. Every time I leaned back on my rope, I felt intense pain in my chest. It became a raw ache that reached all the way down to my toes…. It felt glorious and explosive. The energy was high and brilliant…. I went back, back. I looked at the tree and said silently, “Grandfather, please give me strength.” I ran faster and faster and faster. I hit the end of the line. I heard my flesh tear, rip, and pop. I saw the rope bouncing way up in the tree. It dangled there for a second, then dropped. While this was going on, I fell backwards. I had broken loose…. I was so happy, I let out a big yell.

(Glucklich, 2001, pp. 147–148)

The strong autonomic responses and intense emotions elicited by such experiences may subsequently be suppressed, but are nearly impossible to erase (LeDoux, 1996).

Ultimate Sacred Postulates

Among the most puzzling elements of religion for nonadherents and evolutionary theorists alike are the sacred beliefs of a religion, what Rappaport (1999) has termed “ultimate sacred postulates.” These postulates encapsulate the foundational principles of a culture and supersede all other “truths.” Ultimate sacred postulates differ greatly across cultures, yet they all “possess certain peculiar features” (Rappaport, 1999, p. 280). They are often counterintuitive, or even self-contradictory. They cannot “be derived from systems of higher logical type, for they themselves claim, as it were, to stand at the apex of the structures of discourse in which they appear” (p. 288). They are all impossible to verify objectively or logically, and equally impossible to falsify logically or empirically. They are, therefore, impermeable to logical or empirical proof. As a result, ultimate sacred postulates are unquestionable, unverifiable, and unfalsifiable. They are also boundless; for adherents, their truth holds in all times and all places. All of these properties render them awesome, powerful, and mysterious.

In nearly all known cultures, ultimate sacred postulates encompass a belief in supernatural beings (Sosis & Alcorta, 2003). These supernatural agents take very different forms, but always possess extraordinary powers and regularly violate natural categories and laws. The supernatural agents of some religions, such as those of the Arctic Inuit, are embodied in sacred animal totems. In other cultures, such as the Ilahita Arapesh of New Guinea, supernatural agents are ghosts of the recently deceased. In monotheistic religions, such as Islam, Christianity, and Judaism, a single god is considered to have omnipresent, omnipotent, and omniscient powers. Such social omniscience is a distinguishing feature of the supernatural agents of all religions. These beings are “full access strategic agents” (Boyer, 2001) with knowledge of all your social behaviors and transgressions.

Ontogenetic Development of Religious Concepts

There is growing evidence that humans exhibit a developmental predisposition to believe in socially omniscient supernatural agents. This predisposition appears in early childhood and diminishes in adulthood (Bering & Bjorklund, 2004). Cross-cultural studies conducted with children between the ages of 3 and 12 indicate that young children possess an “intuitive theism” (Kelemen, 2004) that differentiates the social omniscience of supernatural agents from the fallible knowledge of natural social agents (Alcorta & Sosis, 2005). As children reach adolescence, these agents are increasingly viewed as agents capable of acting on such knowledge, as well (Barrett, 2000).

Throughout the world, these innate predispositions to believe in powerful, socially omniscient supernatural agents are shaped by the cultures in which they occur. Totemic animals that talk, incorporeal spirits that eat, and powerful gods capable of transforming themselves into swans and volcanoes are highly memorable. They grab our attention because they violate universal expectations about the world’s everyday structure. At the same time, they engage sets of cultural beliefs with significant socioecological associations. When these “counterintuitive concepts” are embedded within engaging narrative frameworks, they are easy to learn and remember (Atran & Norenzayan, 2004). Yet, recalling counterintuitive stories and believing in their veracity are quite different things. The Greek myths read by American schoolchildren are memorable, but there are no temples to Zeus in America. Clearly, such constructs as animal totems, ancestral ghosts, and anthropomorphic gods are not intrinsically sacred, nor even necessarily believable. How, then, do these ultimate sacred postulates and other sacred symbols come to achieve veracity, social validity, and motivational force?

Creation of the Sacred

The intense emotions evoked by religious ritual in general and adolescent rites of passage in particular are fundamental to the creation of sacred symbols. These rites provide a means whereby specific stimuli can be emotionally valenced by “run[ning] the process through the body theater” (Damasio, 1994, p. 156). The result is “a collection of changes in body state connected to particular mental images that have activated a specific brain system” (p. 144). The neurophysiological responses evoked, amplified, and intensified through ritual participation facilitate fear conditioning, reinforcement learning, and paradigm shifting. When these responses occur within a social context and are associated with sociocultural symbols, the symbols themselves are invested with reward value, emotional valence, and social meaning. Through this process, religious symbols are rendered sacred and imbued with personal significance and motivational force.

The brain changes that occur during adolescence make this an “experience-expectant” period for creating sacred symbols and conditionally associating both with motivational reward value and emotion. The childhood predisposition to believe in supernatural agents has not yet diminished, but has, instead, evolved to incorporate a belief in agents capable of acting on such knowledge. During adolescence, ultimate sacred postulates are not only believable but also have motivational force.

Adolescents’ heightened emotionality, increased sociality, enhanced valuation of music, and increased capacity for abstract thinking offer fertile ground for sowing the seeds of the sacred. Maturation of brain structures specific to emotional, social, and symbolic systems provides the plastic substrate for creating symbolically triggered associational pathways between neural structures specific to cognitive, social, and emotional/reward functions. Simultaneously, the ongoing “shift” in the dopaminergic system from mesolimbic to prefrontal dominance creates an opportunity for assigning valuation to sociocultural stimuli through both conditioning and reinforcement learning. The psychologist Laurence Steinberg notes, “just as cognition has an important impact on emotion, emotion has an important impact on basic cognitive processes, including decision-making and behavioral choice” (Steinberg, 2007, p. 71).

Neurophysiological Effects of Religious Ritual

Not all adolescent rites of passage involve kidnapping, deprivation, and pain. Yet, even rituals that do not entail psychological and physical ordeals have neurophysiological impacts. Studies of adolescent Roman Catholic and Buddhist initiates demonstrate that the nature and intensity of ritual experienced during adolescence have both short- and long-term effects (Thananart, Tori, & Emavardhana, 2000; Tori, 1999). Individuals engaged in meditation and trance experience changes in brain wave patterns, heart and pulse rate, skin conductance, and other autonomic functions (MacLean et al., 1997). Repeated meditation impacts neuroendocrine levels, including testosterone, growth hormone, and cortisol, as well (MacLean et al., 1997). Participation in relatively low-arousal weekly Western religious services lowers blood pressure (Dressler & Bindon, 2000) and adolescent testosterone levels (Halpern, Udry, & Campbell, 1994), and is likely to affect the stress systems of the body (Koenig, 2008).

As transformative experiences, adolescent rites of passage have the capacity to change the way adolescents perceive and respond to both themselves and the world around them. Ritual’s ability to evoke emotion, engender empathy, and promote affiliation make it an excellent tool for enhancing social cooperation. The ultimate sacred postulates communicated through the counterintuitive concepts and metaphorical narratives of religious ritual are not only effective costly signals and mnemonic devices but also define appraisal criteria for interpreting events and communicating behavioral norms for social judgments and interactions. They create common “frameworks of prediction and expectancy” relevant to the new social and sexual roles and responsibilities of adulthood. As a result, they reduce ambiguity and anxiety, and facilitate social interaction. They also simplify decision-making, conserving time and energy that would otherwise be spent on the continuous calculation of risks and benefits for ongoing social discourse.

Religious ritual’s capacity to create and emotionally valence abstract sociocultural symbols is the source of the sacred. The meaning of these symbols must be created and recreated, both cognitively and emotionally, in each new generation. This provides opportunities to adjust and change cultural precepts and values with changing ecological and social conditions. For the experience-expectant adolescent brain, these rituals provide motivationally salient social algorithms that enhance self-regulation, influence judgment and choices, and facilitate social interactions. The inculcation of such algorithms should also reduce anxiety and depression, enhance impulse inhibition and self-regulation, increase prosocial behaviors, and enhance in-group social interactions and cooperation. Is there any empirical evidence of such results?

Religion and Health

Over the past several decades, an accumulating body of research has found significant, positive correlations between adolescent health and religion (Cotton, Grossoehme, & Tsevat, 2007.

The highest health risks for adolescents are not the communicable or chronic diseases that afflict children and adult populations, but are instead health risks associated with smoking, alcohol and substance abuse, sexual promiscuity, delinquency, stress-related mental health disorders, and other high-risk behaviors (Steinberg, 2008). As a result, much research has focused on studies examining the effects of religious beliefs and behaviors on adolescent mental health, prosocial values, and behavioral choices.

An extensive literature review undertaken by the psychologists Michael Donahue and Peter Benson in 1995 showed “religiousness is positively associated with prosocial values and behavior, and negatively related to suicide ideation and attempts, substance abuse, premature sexual involvement, and delinquency” (Donahue & Benson, 1995, p. 145). This finding was echoed in the 2003 National Study of Youth and Religion conducted by the sociologist Mark Regnerus and his colleagues (Regnerus, Smith, & Fritsch, 2003), and is supported by a more recent analysis of data from the National Longitudinal Study on Adolescent Health (Add Health) (Nooney, 2005). Research indicates that prosocial rewards, such as those promoted through religion, predict longitudinal declines in adolescent risk-taking (Telzer, Fuligni, Lieberman, & Galvan, 2013). Studies conducted by Michael Inzlicht and his colleagues found reduced activation of the anterior cingulate cortex in response to anxiety-provoking conditions in religious adolescents; these findings support the hypothesis that “religious conviction provides a framework for understanding and acting within one’s environment, thereby acting as a buffer against anxiety and minimizing the experience of error” (Inzlicht, McGregor, Hirsh, & Nash, 2009, p. 385).

The psychologist Sian Cotton and her colleagues at the University of Cincinnati’s Institute for the Study of Health echo these results:

Evidence over the last two decades or so of research in this regard is fairly conclusive: in general, adolescents who have higher levels of religiosity and/or spirituality fare better than their less religious or spiritual peers: those with higher levels of religiosity and/or spirituality have lower rates of risky health behaviors and fewer mental health problems—even when taking into account other factors that may affect health outcomes such as age, sex, or family income.

(Cotton et al. 2007, p. 146)

This research provides empirical evidence for adolescent fitness benefits derived from religion. They underscore the importance of ritual participation in realizing these benefits, and identify a central role for self-regulation in decreasing high-risk adolescent behaviors that lead to decreased fitness. Additionally, they indicate an important role for religion in reducing anxiety and thereby minimizing the body’s stress response. Stress impacts both mental health and many chronic illnesses that do not physically express until later in life (Koenig, 2008). If religion is a protective factor for stress, then adult mental and physical health measures should reflect these effects.

Studies of Western Christian adult populations do demonstrate significant, positive associations between religious participation and mental/physical health. Even when such participation is confined to weekly church attendance, those who regularly attend exhibit better health and greater longevity than their fellow community members who do not (Hummer, Rogers, Narn, & Ellison, 1999; Matthews et al., 1998). This predominantly positive correlation between religious attendance and health has been demonstrated in numerous other studies, as well (for reviews, see Koenig 2008; Matthews et al., 1998; McCullough, 2001). Religious participation also positively correlates with various measures of mental health (see Murphy, Ciarrocchi, Piedmont, Cheston, & Peyrot, 2000), including lower levels of depression and higher measures of positive affect (Francis & Kaldor, 2002).

Positive correlations exist between religious attendance and longevity, as well (Hummer, 1999). A meta-analysis of religiousness and longevity found, “People who are highly religious have 29% higher odds of being alive at a given follow-up than do people who are less religious” (McCullough, 2001, p. 61). Some of these effects may result from the inverse correlation that exists between religious attendance and suicide (Matthews et al., 1998, p. 120). In his review of social and economic indicators of nations around the globe, the sociologist Phil Zuckerman notes that suicide rates are “the one indicator of societal health in which religious nations fare much better than secular nations” (Zuckerman 2005, p. 59).

Religion: A Costly Signal

The positive associations that exist between religion and health provide empirical evidence for individual fitness benefits of religion and support the proposed proximate mechanisms. From an evolutionary perspective, however, the most significant benefits of religion are likely to derive from its ability to promote intragroup cooperation and overcome problems of collective action (Bulbulia & Sosis, 2011; Irons, 1996; Norenzayan & Shariff, 2008; Sosis, 2006). Some researchers have argued that religion achieves these benefits by providing a “costly signal” that ensures honest, reliable social communication (Alcorta & Sosis, 2005; Bulbulia & Sosis, 2011; Sosis 2006).

Cooperative Benefits

Humans live in the largest, most complex social groups of any primate. These groups offer many genetic, cultural, technological, and competitive advantages (Alcorta & Sosis, 2013). As human social groups increase in size, however, new problems of free-riding, control, and cooperation emerge. Religion solves these problems by facilitating intragroup cooperation (Norenzayan & Shariff, 2008; Sosis & Alcorta, 2003). Participation in religious rituals promotes such cooperation.

Empirical research conducted over the past decade demonstrates that religious ritual is an effective tool for increasing group cooperation and cohesion (Norenzayan & Shariff, 2008; Sosis & Bressler, 2003; Sosis & Ruffle, 2003, 2004; Xygalatas et al., 2012). Additionally, prosocial behaviors are significantly and positively associated with adolescent religious attendance while juvenile delinquency is inversely related to it (Donahue & Benson 1995; Regnerus et al., 2003). Costly religious rituals also provide a mechanism for adjusting costs in relation to socioecological stressors. Intergroup aggression and warfare are among the greatest such stressors encountered in human populations. This is particularly true in prestate, predrone societies. The costliest religious practices should, therefore, occur in societies engaged in such aggression.

Adolescent rites of passage are among the costliest of religious rituals. Cross-cultural research demonstrates that the costliness of these rites is positively correlated with intergroup violence; adolescent rites of passage that entail the most pain, violence, and bodily harm occur in preindustrial societies that exhibit the highest rates of warfare (Sosis, Kress, & Boster, 2007).

Violent and painful initiation rites not only sanctify group values and neurophysiologically bond “brothers-in-arms” but also prime initiates’ response systems for threat, thereby producing higher levels of out-group aggression (Niehoff 1998).

Military boot camps and paramilitary terrorist training camps effectively employ violence and pain to the same end (Nesser 2008). Extreme rituals do, indeed, promote prosociality (Xygalatas et al., 2012), Adolescents who participate in such rites are changed forever.

Conclusion

Although there remains considerable debate regarding the time of emergence of adolescence in human populations, dental evidence suggests that the prolonged period of human adolescence appeared “relatively late in human evolution,” around 300,000–800,000 years ago (Dean et al., 2001). The costs of prolonged adolescence are considerable. Adaptive benefits to offset these costs may have included the expansion of the resource base through exploration and innovation. The greatest benefits, however, are likely to have been realized in relation to intergroup conflict and group defense. Adolescent males are particularly well suited to this role, both physically and psychologically. They are also the most reproductively expendable members of the group.

The oldest known archaeological evidence of human symbolic ritual is the ground and incised red ochre found at archaeological sites in South Africa dated around 100,000 years ago (Henshilwood, 2001; Marean, 2010; Marean et al., 2007). These sites also include sophisticated tool kits and evidence of a large, relatively sedentary population. Although it is impossible to know the purpose of the first human symbolic rituals, the environmental shift occurring at this time is likely to have increased competition between human groups. Under such circumstances, larger group sizes would have provided adaptive advantages in relation to technological innovation resource extraction, and intergroup competition. Larger groups also represent a broader, deeper gene pool for dampening demographic fluctuations and avoiding genetic bottlenecks. Larger groups with many adolescent males represent potential “brothers-in-arms” for intergroup warfare and defense. Yet, as group size increases and genetic relatedness decreases, problems of cooperation and defection emerge. Costly religious rituals help solve these problems (Alcorta & Sosis, 2013).

It is impossible to know when symbolic ritual first appeared in human evolution. Ritual is likely to have played an important role in human groups prior to the incorporation of symbolic elements. Humans are one of a very few “singing” primates. Like the “dueting” gibbons and most songbird species, and in contrast to our closest primate relatives, gorillas, bonobos, and chimpanzees, humans also exhibit pair-bonded mating systems. Song-based mating rituals in early hominin groups may have constituted the genesis for symbolic ritual. The prolongation of human adolescence and selection for enhanced intragroup cooperation in large social groups are likely to have propelled its evolution.

In contemporary Western societies and in Communist nations throughout the world, many of the functions served by religion in prestate societies have been transferred to specialized professionals trained and controlled by the secular state. In these societies, the validation and inculcation of social behaviors are no longer religiously mandated and sanctioned, but are instead monopolized by the legal and educational powers of the state (Alcorta & Sosis, 2013). A professional military responsible for intergroup conflict eliminates the role of religious ritual in creating “brothers-in-arms.” Church attendance in nearly all Western nations has steadily decreased over the past two decades (Norris & Inglehart, 2004). As a result, fewer adolescents experience the religious rites and rituals that traditionally served to define social roles and relationships, inculcate group values, and promote intragroup trust and cooperation. This shift from religiously inculcated value systems to secular systems of education and law is likely to promote greater individual freedoms and reduce religiously based in-group/out-group conflict in a multicultural society. Yet, it also alters the dominant mode of transmitting social values during adolescence. In contrast to the highly structured and neurophysiologically engaging elements of religious ritual, the teaching mode of secular states is predominantly cognitive in approach. Adolescents developmentally primed to experientially shape emotionally weighted sociocognitive models must do so largely through personal trial-and-error experiences. The individual models that result may or may not be shared by others, or even adaptive for the adolescent.

Cross-cultural research indicates that how an individual interprets his or her experiences is an important determinant of stress (Flinn, 1999; McDade 2002). The mental models we employ to process our experiences not only focus our attention but also shape our perceptions and appraisals. When mental models are shared, social prediction, communication, and cooperation is facilitated. Whether a particular stimulus activates our stress response is as much a function of the way we view it as of the stimulus itself.

Significant inverse correlations between adolescent religious participation and a host of behavioral and mental disorders, including anxiety, depression, addiction, and suicide, have been documented (Cotton et al., 2007; Donahue & Benson, 1995; Regnerus et al., 2003). Religion’s effectiveness in creating shared, value-anchored mental models that shape our perceptions, judgments, and social behaviors are likely to be central to these correlations of religion and health.

The role of religion in human evolution is intimately intertwined with both the prolongation of human adolescence and intergroup competition. An evolutionary understanding of the relationship between human adolescence and religion can shed light on the religiously inspired terrorism of the 21st century and offer insights into both its roots and proliferation. Fragile, corrupt, and failed states across the globe provide fertile ground for the rise of religiously inspired terrorism. Understanding the role religious ritual plays in shaping the adolescent social brain and in promulgating group trust and cohesion is an important first step in successfully turning back this rising tide.

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