As any visitor to the Spectrum blog will recognize, the treatment of homosexuals and women by Seventh-day Adventists and other Christians has ignited intense debate. The Seventh-day Adventist Church officially restricts sexual activity to the marital relationship of a man and a woman, and prohibits women's ordination.
In recent decades, a schism in thinking and policy has developed among and within many Christian denominations. Some denominations no longer view monogamous same-sex relationships as necessarily immoral and now embrace women in leadership positions, whereas others prohibit both. Attitudes have certainly shifted within the SDA Church, with increasing favor toward inclusiveness when it comes to sexual orientation1 and leadership.2 This shift has strongly polarized opinion, and has prompted renewed study and discussion by the General Conference.3, 4 Although the Adventist Church takes a strong stance on religious liberty and against legislation of morality, many members and leaders have crossed the line by engaging politically on the defense of heterosexual marriage5, an institution that exists strictly on moral grounds.
Two dominant theological views toward gender and sex dominate the discussion. Although terms have not been formally applied to these views, the distinction is obvious, though heretofore masked by cluttered verbiage. As a biologist rather than a theologian, my goal here is not to wander into the theology of sexual morality and "male headship." My purpose, instead, is to summarize succinctly the unambiguous dichotomy between the two theological views, and the overlooked inconsistencies and ramifications that result from a theology focused largely on — of all things — external genitalia.
Cerebrocentric versus genitocentric theology
Cerebrocentric theology posits that God judges certain behaviors based on the constitution of the mind, which is shaped to a large extent by genetics, physiology, and experience. This view generally limits sin to a conscious act, and pardons sins of ignorance. Most of Christianity embraces this view toward sin. However, when applied to behaviors and roles that relate to gender, many SDAs and other Christians completely abandon this view. Those who retain it for this context, including those who generally self-identify as "liberal" or "progressive" Christians, interpret scriptural passages about homosexual acts and spiritual leadership independent of external genitalia. In their view, God judges sexual orientation and leadership character based on inherent qualities of the mind rather than the mere presence of a penis. Scriptural passages that condemn homosexuality or silence women must be understood in the context of the culture the authors lived in.
Genitocentric theology, in contrast, holds that God judges certain behaviors of people differently depending on the presence of external genitalia and associated secondary sex characteristics. With this view, God is either unable or unwilling to judge certain behaviors on the basis of the mind alone, because the presence of a penis must dictate how the mind should think and direct one's actions. While no obvious inherent quality of a penis should excuse how the mind thinks, the mind nevertheless cannot be excused unless it thinks the way the mere presence of a penis demands. This theological position is held largely by those who self-identify as "conservative" or "traditional" Christians.
The SDA Church fully embraces cerebrocentrism when it comes to worship, temperance, and other doctrines; God judges us with consideration of limits to our knowledge and understanding.
However, when it comes to same-sex relationships and the role of women in leadership, the Church officially embraces the genitocentric view, though it certainly does not express or acknowledge it in these terms. Here, the Church holds a strict line: it refuses to acknowledge that the brain — and the behaviors dictated by it — can be independent of outward sexual appearance. Although scripture never explicitly states how God defines a man or woman, the theological assumption is that gender can be defined only by the external genitals, without exception.
The Biology of Sexual Differentiation, Gender Identity, and Sexual Orientation
Regrettably, few who pronounce judgments on sexual behavior have a clue about the biological basis of gender differentiation, gender identity, or sexual orientation.
First, let's be clear about one thing: the distinction between male and female (sexual differentiation) is anything but black-and-white. The "gray" area is much broader than many assume. We need to give up any platonic notion that for each sex there is a single, universally correct developmental pathway and outcome.
In humans, males and females normally can be distinguished by numerous biological criteria, including distinct sex chromosomes (XY and XX, respectively), gonads (testes and ovaries), genitalia (penis and vagina), and internal ducts (derivatives of the Wolffian and Müllerian ducts). The presence of several key hormones directs the development of the gonads, genitals, and ducts, and these are under the direction of an increasing number of identified genes and transcription factors; however, the tissues themselves do not always respond to the signals. As the result of genetic and developmental anomalies — of which there are many — mismatches can occur among all of these entities. Estimates for disorders of sex development (DSD) or "intersex" vary, but constitute as much as 2% of the population.6 Two percent!
The question could be asked: which criteria are most important in determining male or female sex? Given the frequent mismatches that result, the answer is not so simple; in fact, many scientists are moving away from a gonado- or genitocentric view of sex determination.7 An individual lacking a penis, for example, may possess a Y chromosome and internal testes. Is this a man or a woman? Similarly, an individual possessing a penis may lack either a Y chromosome or testes. Remarkable! And in considering these mismatches, we haven't even discussed the brain yet — the biggest sex organ of all.
Second, let's understand that sexual differentiation occurs separately from gender identity (conviction of belonging to the male or female gender) and sexual orientation (hetero-, homo-, or bisexuality). Primary differentiation of the sex organs occurs during the first third of pregnancy (weeks 6-12), whereas much of the sexual differentiation of the brain develops later, largely under the influence of a testosterone surge (or its absence) that begins during week 7, peaks between weeks 8–24, and continues through early infancy.8 Other factors also influence the developing sexual brain, including abundance of estrogens and progesterones (hormones), and perhaps alpha-fetoprotein which circulates in the plasma. Due to differences in timing, differentiation of the sex organs and brain can be influenced independently of each other, resulting in mismatches of gender.
Third, let there be no doubt that gender identity and sexual orientation reside in the brain. The brain's gender is determined by genetic, hormonal, and subtle environmental influences during embryonic development, resulting in measurable differences in structural and functional neuroanatomy. Many Christians deny that sexual identity and orientation have a genetic (biological) basis, but the evidence suggesting otherwise is overwhelming. Here is just a small sampling of the scientific findings which confirm the biological differences between heterosexuals and homosexuals:
- Numerous family and twin studies provide strong evidence of a genetic component for sexual orientation. Higher rates of homosexuality occur among the siblings and maternal uncles of gay men.9 Twin studies also reveal a substantial genetic component in sexual orientation, with estimates of heritability ranging from 0.31-0.74 (0 = entirely environmental; 1 = entirely genetic).10
- Chromosome linkage studies have identified regions on the X (Xq28) and other chromosomes (e.g., 7q36) that appear to be associated with homosexuality. Although doubt has been cast on Xq28's association, the sonic hedgehog gene, located in 7q36, appears to be strongly associated with male sexual orientation and plays an important role in brain organization.11 Women with gay sons also exhibit extreme skewing of X chromosome inactivation, suggesting an epigenetic influence on homosexuality (i.e., heritable changes affecting DNA packaging that are independent of DNA base pair sequences).12 Consideration of reduced androgen sensitivity in XX fetuses and enhanced sensitivity in XY fetuses leads to the conclusion that epigenetic modifications of androgen signaling may be more influential for mismatches between genitals and the brain than genetic (DNA base pair) mechanisms.13
- Each additional older brother increases the odds of a man being gay by 28–48%.14 This well-established fraternal birth order effect may result from an accumulation of Y-linked proteins (HY antigens) that induce antibody production in the mother, with the circulating antibodies, in turn, crossing the blood-brain barrier and altering the developing fetal brain.15
- Programmed gender identity within the uterus is largely irreversible, as illustrated by two unfortunate conditions.16 First, many cases of sex reassignment surgery to infants with ambiguous or damaged genitalia have failed miserably. Second, most individuals with 5α-reductase deficiency (colloquially referred to as "guevedoce," meaning "penis-at-12"), who are born without a penis and socialized as a girl until they unexpectedly develop a penis during puberty, usually transition to the male role, as dictated by their genes and their uterine hormone environment.17
- Substantial brain differences exist between heterosexuals and homosexuals. One region of the hypothalamus involved with sexual behavior (the INAH3 nucleus), for example, is much smaller in homosexual men compared to heterosexuals.18 It remains unclear whether this difference is a contributing cause or a consequence of homosexuality, but recent brain imaging studies reveal even more profound differences.19 Heterosexual men and homosexual women (both attracted to females) have asymmetrical cerebral volumes, with connections from the amygdala arising more from the right side and connecting primarily to the caudate, putamen, and prefrontal cortex. Homosexual men and heterosexual women (both attracted to men), in contrast, possess symmetrical cerebral volumes, with connections from the amygdala arising more from the left side and connecting primarily to the anterior cingulate.
Collectively, our growing understanding makes clear that the genitals and the brain can be mismatched. In other words, a male brain can be "trapped" in the body of a woman, and vice versa. At present, we do not fully understand the actual mechanisms that feminize or masculinize the brain, but it's clear that they are highly complex and numerous. Ongoing research, using both animal20 and human models, is bringing us closer to this goal. For those who object, we need to understand that no compelling evidence exists that the social environment can exert an overriding influence on the early events that organize the brain's sexual identity and orientation. The end result for those having mismatched genitals and brain, of course, is a natural predisposition toward same-sex behavior; however, this does not in any way translate to determinism. Although efforts to correct homosexual orientation almost always fail miserably,21 behaviors can be modulated, as exemplified by gay Christians who successfully choose abstinence or enter into heterosexual relationships.
The ultimate question is how God views one's gender, identity, and orientation. Does God align these three distinct outcomes of early developmental processes into a rigid dichotomy—male and female—or does he recognize the discord? If he judges behavior based on a rigid dichotomy, does he define "male" and "female" based on the chromosomes, genitalia, gonads, ducts, hormones, or brain? Clearly, these cannot always be in alignment, so God would have to choose among them. For the genitocentrist, the answer is simple: God relies entirely on the external genitals. The cerebrocentrist, in contrast, allows the possibility that God recognizes gender based on the brain's orientation instead, and acknowledges that God alone can know the mind, and judges accordingly.
Actually, God has clearly articulated a cerebrocentrist view (albeit in a cardiocentric colloquialism). "The Lord does not look at the things people look at. People look at the outward appearance, but the Lord looks at the heart." I Samuel 16:7.
Genitocentrism and Sexual Behavior
Consider Melinda, a second-generation Adventist in Kansas. Growing up, Melinda and everyone who knew her thought she was a girl. Her outward appearance was certainly female. In spite of that, she never had an interest in boys. Shortly after she hit puberty, she became increasingly interested in girls. Exposed to the rampant homophobia of her classmates in boarding academy, she initially kept a growing love interest to herself. However, when the relationship ended badly and Melinda slipped into anger and depression, word got out: Melinda was a lesbian. She immediately lost some of her more cherished friends. Out of concern for her salvation, her parents admonished her, reading out loud the plain words of scripture forbidding homosexuality. The academy chaplain and her home town pastor likewise counseled her to give up any inclination toward homosexuality. Unable to overcome her romantic and sexual interest in other women, and convinced that God despised her, Melinda gradually left the religion she grew up in and completely rejected God. She remained bitter toward those who treated her as a freak show and a sinner destined to hell.
Decades later, after remarkable medical advancements shed light on Melinda's condition, she discovered something no one else knew about her: she had two testes. They were inside her body all along. She also had the Y chromosome that distinguished her as a male. Her condition even had a name: complete androgen insensitivity syndrome. During early development, her tissues failed to respond to elevated testosterone levels. Most individuals with this condition view themselves as female, and develop a highly feminized physique (albeit with a shortened vagina), but some apparently emerge with a masculinized brain. Sadly, while Melinda eventually found a lifelong and faithful female companion, she never found her way back to God.
If Melinda lost her soul — which is something only a compassionate and loving God could decide — the genitocentric theology of those charged with her spiritual life certainly failed her. One could ask who was more deserving of the condemnation in scripture read out loud to her: Melinda, who found herself unable to heed the "clear" word of scripture, or those who killed her love of Jesus out of conviction her behavior was sinful. Of course, those who condemned her could plead ignorance; after all, a cerebrocentric judge would surely understand their genitocentric error.
One noted conservative and frequent commenter at Spectrum, Kevin Paulson, wrote at ADvindicate, a conservative SDA online blog: "How the orientation got there might be interesting to folks in various disciplines, but as we are not told in God's Word, it is best the cause of truth not get sidetracked by such controversy. What we know for sure is that homosexual behavior is sinful. The Bible says so."22
For Kevin and other SDA leaders who subscribe to a genitocentric theology, there is no leeway for Melinda and millions like her whose brains and sexual orientation do not match their external genitalia. Kevin seems aware that biology determines orientation, and concedes that "orientation [itself] is not a sin." However, he steadfastly maintains that "the choice to yield to a sinful orientation is what constitutes sin." To Kevin, Melinda had a sinful orientation, and any sexual activities that conformed to her orientation were sinful.
Kevin and others who defend the genitocentrist view insist we must take the words of scripture at face value. Because God chose not to explain the subtleties of sexual orientation to the Israelites and to early Christians, and provided no context as to who was committing the forbidden acts and why, God clearly would never consider the brain in judging gender-appropriate behavior. And the SDA Church should do likewise. To yield the genitocentric interpretation in cases for which gender is mismatched between the genitals and other structures would lead to a "slippery slope." I have to wonder, though, whether Kevin and others would also take the cerebrocentric words from I Samuel 16:7 at face value.
Cerebrocentrist theology puts a very different spin on one key statement from scripture. In Romans 1:26–28, Paul described how "natural" sexual desires were given up for homosexual behavior, which he condemned. If the natural desire of a homosexual is defined by the brain rather than the genitals, then encouraging the homosexual to give up their natural desire could actually be sinful in the eyes of God. Without the extraordinary advances in imaging technology, Melinda would have never realized that "she" was actually a "he" all along (even if, externally, she possessed all the qualities of a woman). As brain scanning technology develops further and becomes more accessible, we might one day determine brain gender with relative ease and reliability, perhaps seeing "the heart" more like God does. Will we then be willing to judge any differently?
Genitocentrism and Women's Ordination
One of the more remarkable policies in Christendom that has resulted from genitocentrism is that of male-exclusive ordination. Those who oppose women's ordination hold that God requires a phallus as eligibility for "headship" in ministry. Of all the differences between men and women, and between an effective and ineffective leader, why should having a penis be a deciding criterion? What intrinsic quality within a penis would render a human more appropriate for spiritual leadership? What kind of God would devise such a fickle requirement? Could this be...[ahem]...a phallacy?
Those who maintain the genitocentrist status quo would surely insist that manhood conveys numerous qualities that go beyond the presence of a penis. But what, specifically, would those qualities be? Are the desirable differences morphological or physiological in nature (e.g., height, strength, stamina, spatial cognition, math comprehension)? Are they psychological (e.g., gregariousness, conscientiousness, emotional control, openness to ideas)? Are they related to communication ability (e.g., verbal skills, writing skills, communication effectiveness)? Or are they related to sociological or cultural advantages (e.g., male leaders garner more respect)? If there are any such advantages that accrue from, or are associated with, the presence of a phallus, then why does the Bible fail to specify these? I believe even the staunchest defender of male-exclusive ordination would concede that individual males and females overlap considerably in all of these aforementioned traits; in fact, the differences are generally very small,23 and many actually favor women. Yet, the genitocentrist insists that God requires the primary leader of every church to possess one trait that transcends any other: a penis.
The Bible certainly makes clear that spiritual leaders must possess a character that exemplifies Christian service. The attributes of character are obviously important, and are relevant for all cultures. They can also be difficult to discern. So what does a penis have to do with ensuring an appropriate Christian character, and why would its absence render one a weaker or less desirable representative in any given culture?
Ellen White seemingly recognized the priority of character: “It is not always men who are best adapted to the successful management of a church. If faithful women have more deep piety and true devotion than men, they could indeed by their prayers and their labors do more than men who are unconsecrated in heart and in life“ (5MR 323.1-3a).
Yet this inescapable reality remains: genitocentrism constrains the search for appropriate character. The presence of a penis, no doubt, has often been prioritized ahead of character when choosing spiritual leaders in the SDA Church.
What has Evolution Got to Do with This?
The debate about same-sex relationships and women's ordination has everything to do with biology and theology. Regardless of one's view toward origins, virtually everyone can agree that human biology has changed substantially from that of Adam and Eve. With death and genetic decay as a consequence of sin, our bodies — generation after generation — have accumulated propensities toward disease and sinful inclinations. The distinction between male and female has become dramatically blurred since the original creation. However, these changes in biology have been only microevolutionary in nature.
Many among the conservatives or traditionalists link the Church's theological position on sexual relationships and women's ordination to evolution. They argue that giving up anything on any of these three issues will usher in a creeping compromise on the others. This argument is patently false. The Church needs to formulate its theology toward same-sex relationships and women based on scripture alone, but informed by an understanding of the culture and its limited knowledge of human biology that inescapably influenced the prose of the author. No direct linkage exists between the theology of evolutionary origins and the theology of sexual behavior or spiritual leadership. The Church must decide its theology based on the merits of each issue alone.
Opponents of women's ordination insist that a straightforward reading of scripture requires male headship. They further insist that male gender must be defined by the presence of a male phallus, regardless of the brain's identity or orientation. Ironically, most Christians view God the Father as a spirit who lacks a body, and therefore lacks a penis. Thus, all men are subservient spiritually to a being that lacks the single anatomical qualification of headship. Ironically, this would be condemned by scripture. As a spiritual leader, God would be breaking His own rules without possessing a penis.
While this argument may seem silly (I certainly believe it is), Scripture consistently and forcefully portrays God the "Father" in masculine terms. Or does He? What of Deuteronomy 32:18 (NIV): "You deserted the Rock, who fathered you (paternal analogy); you forgot the God who gave you birth (maternal analogy)?" God the Son is unquestionably masculine, and even the Holy Spirit is referred to as masculine. Perhaps I am pushing this view too far, as many Christians and Jews believe God the father has no gender. Nevertheless, it seems unfathomable that God would require a phallus for leadership if He failed to possess one Himself.
In spite of the unambiguously "gray" distinction between male and female, organized Christianity has a long history of genitocentric theology, with many adherents remaining tenaciously faithful to this view, even if they have not considered its obvious implications. The SDA Church applies a cerebrocentric theology to essentially all matters of behavior and temperance with one obvious exception: it applies a strict and unyielding genitocentric theology to sexual relationships and women's ordination. Given the beliefs, attitudes, and policies that prevail in broad swaths of Christianity and within the SDA Church in particular, one cannot escape the conclusion that God is perceived by many as genitocentric: He can only judge our bedroom behavior and qualification for Church leadership in the light of whether we possess or lack a penis.
This conclusion raises two important questions that every Adventist should prayerfully contemplate: Does scripture truly paint God as genitocentric, in apparent contrast to the plain words of I Samuel 16:7? And should the SDA Church maintain its genitocentric theology? I challenge the leading theologians in our Church to defend their genitocentric view. Where in scripture are we told that males and females are defined exclusively by their external genitalia? That God prioritizes genitalia ahead of the brain when He judges us? That what Paul referred to as "natural" in Romans 1:26–28 can be interpreted only with respect to the genitals while ignoring the chromosomes and other sex tissues, including the brain?
I am certain that many conservative or traditionalist Adventists will object to a genitocentric simplification of theology on my part. They will insist that I have shown disrespect for the Sacred Word, and trivialized the way in which God established His laws and how He judges us. But how else could they possibly explain their views upholding heterosexual-only marriage and male-exclusive ordination? The "morality" they espouse, and their belief in how God judges us, is unquestionably prioritized by one single but profoundly important organ: the penis. The brain takes a back seat to this almighty sexual — and apparently spiritual — organ. I personally can't fathom a God who prioritizes genitalia ahead of the brain, or an organized religion that does the same.
Jeffrey Kent, Ph.D., who occasionally posts at Spectrum as ProfessorKent, has taught biology at a handful of public and Christian colleges and universities for 33 years. He considers himself a faithful Seventh-day Adventist. As a heterosexual by nature and by choice, he resides in southern California in a monogamous relationship with his wife, with whom he enjoys travel, hiking, photography, gardening, and spending time with their progeny. Many ideas in this article were co-developed with a colleague at a SDA university who wishes to remain anonymous.
1. Grady CJ. 2013. Survey explores attitudes toward homosexuality among Adventists. Adventist Today.
2. Wright J. 2014. Tide turning on women's ordination. Spectrum blog.
3. Adventist Review. 2014. In God's Image: Summit on Human Sexuality. Daily reports from Cape Town, South Africa.
5. See this article, for example.
6. Blackless M, Charuvastra A, Derryck A, Fausto-Sterling A, Lauzanne K, Lee E. 2000. How sexually dimorphic are we? Review and synthesis. Am J Hum Biol. 12:151–166.
7. Arnold AP. 2012. The end of gonad-centric sex determination in mammals. Trends Genet. 28:55–61.
8. Hines M. 2010. Sex-related variation in human behavior and the brain. Trends Cogn. Sci. 14:448-456. Berenbaum SA, Beltz AM. 2011. Sexual differentiation of human behavior: Effects of prenatal and pubertal organizational hormones. Front. Neuroendocrinol. 32:183–200. Hines M. 2011. Gender development and the human brain. Annu. Rev. Neurosci. 34:69–88.Swaab D, Bao AM. 2013. Sexual differentiation of the human brain in relation to gender-identity, sexual orientation, and neuropsychiatric disorders. In Neuroscience in the 21st Century (pp. 2973–2998). Springer New York.
9. Reviewed by Ngun TC, Ghahramani N, Sánchez FJ, Bocklandt S, Vilain E. 2011. The genetics of sex differences in brain and behavior. Front. Neuroendocrinol. 32:227–246.
10. Pillard RC, Bailey JM. (2013). Human sexual orientation has a heritable component. Hum. Biol. 70:347–365.
11. Hamer DH, Hu S, Magnuson VL, Hu N, Pattatucci AM. 1993. A linkage between DNA markers on the X chromosome and male sexual orientation, Science 261:321–327. Mustanski BS, DuPree MG, Nievergelt CM, Bocklandt S, Schork NJ, Hamer DH. 2005. A genomewide scan of male sexual orientation. Hum. Gen. DOI: 10.1007/s00439-004-1241-4. Wang B, Zhou S, Hong F, Wang J, Liu X, Cai Y, Wang F, Feng T, Ma X. 2012. Association analysis between the tag SNP for Sonic Hedgehog rs9333613 polymorphism and male sexual orientation. J. Androl. 33:951–954.
12. Bocklandt S, Horvath S, Vilain E, Hamer DH. 2006. Extreme skewing of X chromosome inactivation in mothers of homosexual men. Hum. Genet. 118:691–694.
13. Rice WR, Friberg U, Gavrilets S. 2012. Homosexuality as a consequence of epigenetically canalized sexual development. Quart. Rev. Biol. 87:343–368. For further discussion of epigenetic potential for brain sexual differentiation, see Auger AP, Auger CJ. 2010. Epigenetic turn ons and turn offs: Chromatin reorganization and brain differentiation. Endocrinology 152:349–353. Nugent BM, McCarthy MM. 2011. Epigenetic underpinnings of developmental sex differences in the brain. Neuroendocrinology 93:150–158.
14. Blanchard R, Bogaert, AF. 1996. Homosexuality in men and number of older brothers. Am. J. Psychiatr. 153:27–31. Bogaert AF, Skorska M. 2011. Sexual orientation, fraternal birth order, and the maternal immune hypothesis: A review. Front. Neuroendocrinol. 32:247–254.
15. Ibid. See also Blanchard R. 2012. A possible second type of maternal–fetal immune interaction involved in both male and female homosexuality. Arch. Sex. Behav. 41:1507–1511.
16. Swaab D, Bao AM. 2013. Op cit.
17. See references in Swaab DF, Garcia-Falgueras A. 2009. Sexual differentiation of the human brain in relation to gender identity and sexual orientation. Funct Neurol, 24:17–28.
18. LeVay S. 1991. A difference in hypothalamic structure between heterosexual and homosexual men. Science 253:1034–1037. Garcia-Falgueras A., Swaab DF. 2008. A sex difference in the hypothalamic uncinate nucleus: relationship to gender identity. Brain 131 (2008) 3132–3146.
19. Savic I., Lindström P. 2008. PET and MRI show differences in cerebral asymmetry and functional connectivity between homo- and heterosexual subjects. Proc. Natl. Acad. Sci. 105: 9403–9408.
20. Rams, for example, have been intensively studied: Perkins A, Roselli CE. 2007. The ram as a model for behavioral neuroendocrinology. Horm. Behav. 52:70–77. Rodents have been informative as well: Bonthuis PJ, Cox KH, Searcy BT, Kumar P, Tobet S, Rissman EF. 2010. Of mice and rats: key species variations in the sexual differentiation of brain and behavior. Front. Neuroendocrinol. 31:341–358.
21. Beckstead AL. 2012. Can we change sexual orientation? Arch. Sex. Behav. 41:121–134.
22. ADvindicate. Though I saved select quotes from comments by Kevin Paulson, this page was eventually removed, apparently due to the inflammatory topic involving church discipline that was being aired in the public. Kevin has posted similar comments elsewhere.
23. Hyde JS. 2014. Gender similarities and differences. Annu. Rev. Psychol. 65:373–398.
This is a companion discussion topic for the original entry at http://spectrummagazine.org/node/5978