Current Knowledge on the Genetic Mediation of Self-Transcendence and Spirituality
In 1902, William James in The Varieties of Religious Experience wrote, “[t]he unreasoned and immediate assurance is the deep thing in us; the reasoned argument is but a surface exhibitionâ€. Over a century later, scientific researchers are still extensively investigating the innate nature of spirituality, its interactions with environment-and perhaps even-its genetic origin. The discipline of behavioral genetics, specifically, has taken magnificent strides in reconciling battling theories of physical and human science. Consistent with the scientific method, however, we must still assess the use of empirical measures to evaluate spirituality as a human trait. As unique elements of personality, self-transcendence and spirituality cannot be measured solely, or conclusively, by utilizing animal models. Rather, to investigate this question properly, an emphasis on family, twin and adoption studies, human studies, association studies, and the corresponding techniques employed will be explored within the scope of spirituality, self-transcendence, and its genetic correlates.
The anthropological study of ancient near-eastern religions has enlightened us with the knowledge of emerging behavioral phenomena that are now ubiquitous among all cultures. Spiritual practice lies at the core of human existence; communication, tool-making, music, and art are central elements of cultural evolution as well (Previc 2006). Indeed, both Mircea Eliad and Paul Tillich encouraged an inclusive definition of a primitive religion, or homo religious, which emphasized that ancient man situated his habits, convictions and morals â€œbetween the holy and the profaneâ€ (Miller 1996). Scientific study has too, has made claims about humansâ€™ natural propensity to orient themselves around the spiritual, or that which is transcendental. In fact, Cloninger (1994), the developer of the Temperament and Character Inventory (TCI), provided clear evidence that self-transcendence is a valid indicator of spiritual orientation.
Self-transcendence, nevertheless, connotes a rather elusive state of being. According to Buttery and Roberson et al. (2005) self-transcendence describes emotional and spiritual states that are â€œindependent of traditional religious perceptsâ€. Therefore, self-transcendence does not necessarily encompass a belief in God or traditional demonstrations of religious practice, such as prayer (Buttery and Roberson et al. 2005). Accordingly, Kirk et al. (1999) operationally defines self-transcendence as â€œthe capacity to reach out beyond oneself and discover or make meaning of experience through broadened perspectives and behavior.â€ Past research has further described self-transcendence as a process incorporating elements of self-forgetfulness, transpersonal identification, spiritual acceptance, mystical experience and developmental maturity (Kirk et al. 1999, Buttery and Roberson et al. 2005). On a similar note, Kluger (2004) has found that individuals who identify as â€œspiritualâ€ score higher on the TCI than those who describe themselves as less spiritually-oriented. And, it has been reported that a correlation exists between highly self-transcendent individuals and a â€œpowerful sense of connectednessâ€ they report experiencing (Buttery and Roberson et al. 2005). A great deal of literature has been dedicated to exploring the possible relationship between individuals engrossed in religious activity and belief and the outcome of their psychological or physical welfare. Unfortunately, the wide-ranging investigation results in nothing more than conflicting results among studies. Complications are evidenced by the absence of efficient measures needed to evaluate religious precepts and general â€œconcerns regarding causationâ€ (Kirk et al. 1999).
Family, Adoption and Twin Studies
It is a commonly held notion that within the domain of behavioral genetics, family, twin, and adoption studies have verified that genetic mechanisms underlie, at least, some individual differences in personality traits and emotional behavior (See Levenson et al. 2005)1. In particular, adoption studies indicate that spirituality is not solely environmentally based. That is, while oneâ€™s religious orientation is measured by behavioral attributes such as church attendance or frequency of prayer-related activity, spirituality is found to be more innate (Buttery and Roberson 2005). On a similar note, twin studies have show that religious experience may harness a strong biological foundation to the extent that religiosity, like intelligence or creativity, may be genetically inherited (Previc 2006)2.
To prove this hypothesis, Bouchard (1990) conducted a twin study reporting that genetic variation contributes to about 50% of individual variation in religiosityâ€”suggesting a biological underpinning. More recently, Kirk (1999) and colleagues at the University of Minnesota suggest that genetic makeup is responsible for approximately half of the variation in religiousness â€“including spiritual feelings and beliefs- from within twin siblings. Specifically, in twins both raised together and reared apart, they found that scores of self-transcendence for monozygotic male and female twins were more highly correlated for than for dizygotic twins, demonstrating a genetic influence (Kirk 1999). They also reported that the heritability of self-transcendence was estimated to be approximately 41% in women and 37% in men. In contrast to these findings, however, Tsuang et al. (2002) found that genetic and environmental influences did not differentiate clearly between aspects of spirituality. These results, however, might have been limited by a relatively small sample size.
Various sorts of association studies provide for most research pertaining to the genetic mediation of self-transcendence and spirituality. Before expanding further, it is worthy to note that according to Ebstein (2006) association studies based solely on self-report questionnaires are â€œunlikely to explain more than a small fraction of the genetic variance in personality traits and are perhaps an evolutionary dead end in this fieldâ€. Although these reports are crucial for generating candidate genes, the design itself has little bearing on the genetic construction of personality in general or on specific behavioral attributes (Ebstein 2006). In fact, a multitude of limitations concerning self-report have been shown; emphasis on this issue is imperative since measures of self-transcendence and spirituality are based upon self-report.3
With this concern likely considered, Comings and colleagues (2000) researched the efficacy of various approaches commonly utilized by association studies. Because it is difficult for family-based screening techniques, such as sib-pair linkage analyses, to identify genes with a small effect, Comings et al. concluded that the most efficient approach to study the influence of multiple genes on behavioral traits â€œis to examine the additive effect of multiple candidate genesâ€ (Comings et al. 2000). In order to achieve this, they performed a multivariate analysis of associations (MAA) to observe the relative effect of different groups of genes for behavioral traits offered in the TCI, which as aforementioned, includes self-transcendence. They then presented 63 polymorphisms and 59 genes and found that for self-transcendence, four genes, DRD4, GABRA1, CD4, and AR, were significantly correlated. Most importantly, the dopamine D4 receptor gene (DRD4) gene was involved in both self-transcendence and novelty seeking. 4 For the purpose of this analysis, DRD4 and its association with both self-transcendence and novelty seeking will not be further examined.
Dopamine D4 Receptor Gene (DRD4) and Self-Transcendence
Much research has been conducted regarding the relation that exists between the dopaminergic pathway and spirituality or self-transcendence. Reports of meditation, visual hallucination and trance states are consistent with hyperdopaminergic states (Previc 2006). Interestingly enough, Previc (2006) reports that the DRD4 is closely related to distorted perceptions of time experienced during transcendental states. It is no surprise, then, that the domaminergic system is implicated in near-death and out-of-body experiences, and that elevated dopamine transmission is linked to dreaming and heightened sensory awareness (Previc 2006). Expanding on the aforementioned study by Comings et al., a significant relationship between self-transcendence and DRD4 receptor polymorphism was found in 200 male subjects. These subjects were administered the TCI and then genotyped at the 48 base pair repeat polymorphism of the DRD4 gene. Their results suggested that â€˜â€˜spiritual acceptanceâ€™â€™ is considered the most highly correlated personality trait to the DRD4 gene (Comings et al. 2000). However, other researchers, including Hamer (2004), strived to replicate this exact finding and concluded that there is no valid correlation between the DRD4 gene polymorphism and self-transcendence.
5-HTT Gene Promoter Polymorphisms
Along with the dopaminergic system, current research provides much support for a biological underpinning specifically related to the central serotonergic system.5 Recently, Borg et al. (2003) identified a fascinating, though controversial, relationship between self-transcendence and serotonin 1A receptor binding potential, by employing position emission tomography (PET). The authors found much â€œvariability in 5-HT1A receptor densityâ€, which led them to speculate why individuals differ greatly in spiritual zeal (Borg 2003). In concordance with this finding, Lorenzi et al. (2005) reported that â€œthe gene coding for serotonin 1A receptors (5-HT1A) was mapped on the long arm of chromosome five (5q11.2-13) and it appears to be intron-lessâ€. The authors proposed that a new and functional variant in the promoter region of the 5-HT1A gene exists; the polymorphism included a â€œC to G substitutionâ€ (Lorenzi 2005). To achieve this finding, the researchers genotyped a sample of remitted subjects affected by mood disorders and administered the TCI. Results showed an involvement of the 5-HT1A gene in the individualâ€™s score of self-transcendence. Ham et al. (2004) conducted a similar study and genotyped a Korean population sample; they too found a 5-HT2A receptor gene polymorphism. Subjects were assessed using the TCI, and results showed a high correlation (Ham et al. 2004).6 Other studies, of course, disclose conflicting findings (Hamer 2004) and offer much criticism (Hall et al. 2004).
Vesicular Monoamine Transporter 2 (VMAT2)
As previously shown, most studies have focused on serotonergic and dopaminergic neurotransmission to explore the genetic nature of spiritual states. In addition, drugs and medications typically act on the monoaminergic system as well, which as a result can adjust attitudes, feelings, personality traits, and mimic or induce states of spiritual consciousness. Hamer (2004), author of The God Gene, found an association between a monoaminergic gene polymorphism and self-transcendence. Hamer genotyped his subjects for the VMAT2 gene and administered the TCI. Hamerâ€™s findings concluded that research participants with the VMAT2 single nucleotide polymorphism A33050C scored significantly higher on self-transcendence tests than those with polymorphism A33050A (Buttery and Roberson 2005). Nevertheless, while Hamerâ€™s results are intriguing and centered empirically, many researchers criticize Hamer’s methodology as being â€œmonocausalâ€ and consider his reductionist approach â€œa futile effort to find empirical proof of religious experienceâ€ (Fuller 2005; Kluger 2004; Broadway 2004). Finally, is important to note that Hamer (2004) did not find any conclusive evidence supporting the association between DRD4 or 5HT polymorphisms and self-transcendence; his hypothesis was based primarily on his findings regarding VMAT2.
Spiritual Practice and Genetic Mediation/Regulation
Dance, Spirituality, SLC6A4 and AVPR1a
Bachner-Melman et al. (2005) emphasize the practice of dance within a spiritual context. As evidenced by the role of dancing in sacred rituals, the authors explain, it is obvious that dancing, to some extent, â€œtaps into human spiritual resourcesâ€. Because serotonergic neurotransmission in some human studies, as previously mentioned, can indirectly mediate human spiritual experience, the authors hypothesize that the association between the serotonin transporter SLC6A4 and the arginine vasopressin receptor AVPR1a reflects an array of social behaviors, one of which is described as â€œthe spiritual facets of the dancing phenotypeâ€.
To conduct their research, Bachner-Melman at al. genotyped 85 performing dancers and their parents for SLC6A4 (promoter region HTTLPR and intron 2 VNTR) and AVPR1a (promoter microsatellites RS1 and RS3). In addition, they genotyped 9 competitive athletes and a group of nondancers/nonathletes as controls. Results found that dancers scored higher on the Tellegen Absorption Scale, a questionnaire that correlates positively with spirituality and altered levels of consciousness (Bachner-Melman et al. 2005). Furthermore, single-locus analysis showed significance for the RS3 marker and a two-locus haplotype (RS1 and RS3). When the AVPR1a polymorphisms were analyzed on the SLC6A4 polymorphisms, significant differences in allele and haplotype frequencies were found between dancers and athletes. Finally, using a family-based design, they reported an association between the AVPR1a gene, the SLC6A4 gene, and scores on the TAS. The most common SLC6A4 haplotype shows the strongest association with high TAS scores; the two-locus RS1 and RS3 haplotype was also significantly associated with high TAS scored. Importantly, the authors stress that they compared creative dancers to performing athletes and also deliberately validated the case-control design using a family-based study in order to prevent the limitation â€œof a comparison control group that might be contaminated with polymorphisms contributing to creative dancingâ€ (Bachner-Melman et al. 2005). In conclusion, this study suggests that the combination of polymorphic variants contributing to dancing and by extension, spiritual tendency, is greatly represented in creative dancers.
Qigong Practitioners and Gene Regulation
Li et al., in their pilot study, introduce an ancient Chinese activity created to help stimulate improved health by holistically energizing the body, mind, and soul. Many of these practices are called Qigong and are defined today as â€œtransitional health practices and healing techniquesâ€ (Li et al. 2005). Falun Gong (FLG) constitutes one sort of these ancient Chinese Qigong practices, and consists of â€œexerciseâ€“meditation to energize the physical body, along with an emphasis on the spiritual practiceâ€ (Li et al. 2005). Moreover, Li and colleagues report that this exercise generates spiritually uplifting effects on practitioners. Therefore, they hypothesized that FLG practice may in fact exert transcriptional regulation at a genomic levelâ€”, which is determined by the genomic profile and function of neutrophils in practitioners.
To test their hypothesis, neutrophils were isolated from the blood of six Asian FLG practitioners and six Asian healthy controls. Their blood was then assayed for gene expression, (using microarrays and RNase protection assay), for function (phagocytosis) and for survival (apoptosis).7 Using these measures, the researchers found that changes in gene expression had occurred and were evidenced by a downregulation of cellular metabolism and enhanced immunity, among other altered levels of gene expression. In short, results revealed that among FLG practitioners, â€œthe lifespan of normal neutrophils prolonged, while the inflammatory neutrophils displayed accelerate cell deathâ€ (Li et al. 2005). Although the authors recognize that new approaches are still needed to study how genes are regulated by personality traits and cognitive attributes unique to humans, this study does take small strides at challenging the mind-body interaction at genomic levels of expression.
Mystical, spiritual and self-transcendent experiences are substantial not only to the believer, but also to ailing individuals and, as shown, to scientific, medical and behavioral-genetic researchers. Nevertheless, researchers themselves are hesitant to construe the results reviewed as verification of a rigid biological foundation for religiousness and/or spirituality. Although the human studies, association studies, twin, adoption and family studies disclosed in this review have been adapted as approaches to explore the multifaceted issue of spirituality, it is important to underscore the inconclusive nature of this subject matter. To put it differently, Dean Hamer (2004) contends that spirituality is but a â€œa complex amalgamation in which certain genetically hardwired, biological patterns of response and states of consciousness are interwoven with social, cultural, and historical threadsâ€ (Hamer 8). Certainly, it is the dedicated work of behavioral geneticists that can fully validate such â€œmeaningfulâ€ claims.
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1 Here, Levenson et al. cites the following authors, all of which have expanded upon the genetic and environmental influences on family, twin or adoption studies: Plomin and Rowe, 1977; Jang et al. 1996; Jang et al. 1998; Nigg and Goldsmith, 1998; Borkenau et al. 2001; McCrae et al. 2001; Ono et al. 2002; Farmer et al. 2003
2 Previc (2006) refers to the following studies for a further investigation regarding this issue: Dâ€™Onofrio, Eaves, Murrelle, Maes, & Spilka, 1999; Eaves, Martin, & Heath, 1990; Waller, Kojetin, Bouchard, Lykken, & Telelgen, 1990.
4 Note: In a recent study whereby the TCI was administered to 391 individuals, Levenson et al. found that novelty seeking was the strongest positive predictor of self-transcendence along with meditative practice (Levenson 2005). I mention this relation between novelty seeking and self-transcendence only because it is a point of contention among researchers. Those in favor of a â€œgenetic origin to self-transcendenceâ€ often form this association to prove genetic predispositions. For more information, please refer to Hamer (2004).
5 It is important to note that the same issue regarding animal models arises with the 5-HTT gene as occurred with the DRD4 gene. Currently, there is no method to measure self-transcendence or spirituality in animals. However, research shows that â€œp-chlorophenylalanine induces greater sensitivity to sensory stimuli and facilitates greater perceptual arousal in rodentsâ€ (Borg 2003). These observations do support the finding that the serotonin system is at least partially responsible for the inhibition of sensory stimuli and spontaneous arousal; decreased serotonin transmission may therefore account for phantom sensory stimuli (Borg 2003). According to Borg et al. these characteristics strike great resemblance to human spiritual experience, though animal models in this context are ineffectual.
6 Both Lorenzi et al. (2005) and Ham et al. (2004) discuss the limitations of their study. Firstly, other genes and regulating processes may have accounted for these findings. Secondly, there were broad differences observed in the sample, and the study was limited by a small sample size. With regard to the Lorenzi et al. (2005), there is a likelihood of â€œepistatic interactionsâ€ among the various genes that are associated with personality. This is important, considering the fact that subjects were patients suffering from mood disorders.