Evolutionary Psychology and Suicidology

Evolutionary Psychology and Suicidology. John F. Gunn III, Pablo Malo, and C. A. Soper. SAGE Handbook of Evolutionary Psychology, Vol 3, Part 7, Chapter 69. https://www.researchgate.net/publication/332142286_Evolutionary_Psychology_and_Suicidology_Draft_chapter_for_SAGE_Handbook_of_Evolutionary_Psychology_2019

ABSTRACT: Suicide – deliberate, intentional self-killing – is a major cause of human mortality and a global public health concern. Suicidology emerged as an interdisciplinary field focused on the prediction and prevention of suicide. Progress has been disappointing: suicide rates resist efforts to reduce them, and there is no theoretical consensus on suicide’s causation. At least since the writing of Sigmund Freud, the search for a scientific understanding of suicide has included theories with evolutionary links. Apparently a human universal behavior, suicide presents a longstanding evolutionary puzzle: the fitness cost of suicide, of being dead, is predictably injurious for the individual’s reproductive future. Some adaptationist theories have been advanced from the neo-Darwinian idea of inclusive fitness: selection may produce behaviors that, while self-injurious for the individual, favor the reproductive prospects of individual’s genetic kin, but there are multiple theoretical and empirical problems with such proposals. Others suggest “by-product” explanations, that suicide is not in itself adaptive, but may be a noxious side-effect of evolved adaptations that are fitness enhancing overall. Most of these proposals coalesce around the central idea that pain, particularly social pain, a vital protective signal which demands the organism take action to end or escape it, may incidentally provoke suicide as a means to achieve that escape. A minimal level of cognitive functioning appears to operate as a second, incidentally suicidogenic, adaptation among adult humans. Together these twin “pain-and- brain” conditions appear to be both necessary and sufficient for suicide, a formulation that implicitly reframes self-killing as an adaptive problem in the evolution of the human species. The explanatory focus shifts, on this basis, from attempting to identify causes of suicide, to identifying adaptive solutions that operate to prevent suicide. A general framework recently proposed by Soper envisages multiple lines of “pain-type” and “brain-type” antisuicide defenses, transmitted culturally and genetically across generations. One class of evolved psychological mechanisms, “keepers”, is reviewed in detail. Soper posits keepers to mobilize as emergency interventions among people at imminent risk of taking their own lives. Challengingly, the hypothesized features of keepers appear to match symptoms of several common mental disorders, including depression, addictions, non-suicidal self-harm, and psychoses. The model would help to explain why it has not proved possible to predict suicide at the individual level: any and all usefully predictive clues would probably already have been exploited and exhausted by evolved antisuicide defenses. The framework may also account for, among other things, the close association of diverse, and often comorbid, psychopathologies with suicidal ideation, but the only weak association of psychopathologies with the progression from ideation to suicidal action. Major implications of, and problems with, Soper’s conceptual approach are discussed. In conclusion, it is suggested that evolutionary psychology offers fresh perspectives for suicidology, and potentially a means to achieve a long overdue, and much needed, integration and unification of suicide theory.

“Natural selection will never produce in a being anything injurious to itself, for natural selection acts solely by and for the good of each” (Darwin, 1859, p. 201).

Suicide, “the act of deliberately killing oneself” (W.H.O., 2014, p. 12) accounts for some million deaths around the world each year and ends about 1.4% of human lives: more people die by intentional self-killing than from wars, accidents, homicide and all other forms of violent death put together (W.H.O., 2013). Many millions of the living are affected, left to deal with the aftermath of others’ suicides (Cerel et al., 2019). A cross-cultural killer, suicide is viewed as a global public health challenge – a major, and preventable, cause of mortality and misery (Satcher, 1999; W.H.O., 2012, 2014). A new multi-disciplinary field of research emerged in the second half of the 20th century, suicidology, focused on trying to understand and tackle the problem (American Association of Suicidology, 2019; Shneidman, 2001).

But frustratingly, by most accounts, decades of concerted effort have made little impression. While other forms of violent mortality have markedly reduced (Pinker, 2011) the global suicide rate is probably much the same now as it was 50 or 100 years ago (Linehan, 2011; Nock et al., 2012; Nock, Ramirez, & Rankin, 2019). Indeed, self-killings in the USA are reportedly on the increase (Hedegaard, Curtin, & Warner, 2018). Progress in building a theoretical base has been equally disappointing, the causation of suicide remaining a scientific mystery (Lester, 2019; Soper, 2019b). As a report published by the World Health Organization admits, “we continue to lack a firm understanding of why, when, and among whom suicidal behavior will occur” (Nock, Borges, & Ono, 2012a, p. 222). Diverse ideas have accumulated over more than a hundred years of theorizing – reviews of prominent offers can be found in the general suicidology literature (Gunn, 2019; Gunn & Lester, 2014; O’Connor & Portzky, 2018; Paniagua, Black, Gallaway, & Coombs, 2010; Selby, Joiner, & Ribeiro, 2014). But perhaps reflecting widespread acceptance that the proximal causes of suicide are complex and multifactorial, no model has won a consensus of support (Hjelmeland, Jaworski, Knizek, & Marsh, 2019; Lester, 2019). Suicidology is fragmented to the extent that a recent meta-review describes the field as “still in a preparadigmatic phase” (Franklin et al., 2017, p. 188) – that is, still in its infancy.

A subset of theories with evolutionary links shows a long-held, if often implicit, acceptance that a coherent understanding of suicide needs to take its place, alongside other fields of modern life sciences, within an evolutionary paradigm. A hundred years ago, Freud (1920/1991) proposed a potentially suicidogenic “death drive” in the context of his broader theory of libido, a framework which, in keeping with the evolutionist spirit of the age, sought to build on the Darwinian premise that selection is predicated on sexual success (Gilbert, 1989; Litman, 1967; Tolaas, 2005).

Psychoanalysis failed to find a satisfactory explanation for suicide, as its practitioners acknowledged at the time (Zilboorg, 1936a), although comparable ideas continue to circulate in suicidology (Selby et al., 2014). Many alternative approaches have been advanced in the intervening century, as we will discuss, but suicide is still widely viewed as an evolutionary puzzle (Aubin, Berlin, & Kornreich, 2013; Blasco-Fontecilla, Lopez-Castroman, Gomez-Carrillo, & Baca-Garcia, 2009; Confer et al., 2010). The conundrum follows from our opening quotation: how is it that, seemingly contradicting Darwin’s (1859) prediction, selection permits so self-destructive a behavior? 

In search of answers, we review and critique prominent ways in which evolutionary ideas have informed suicide research, and outline a new general approach, the modelling of suicide as an evolutionary by-product which, we believe, offers scope for long overdue convergence in suicide theory and, it is hoped, prospects for saving lives (Gunn, 2017; Humphrey, 2018; Soper, 2016, 2017, 2018).


7 Concluding comments

At one level this chapter carries an encouraging message. The evolutionary approach would seem, in principle, capable of bringing much needed and long overdue unity and coherence to suicidology’s current morass of unconnected theory. A “pain-and-brain” framework in particular could offer a rallying point for numerous, superficially disparate, theoretical positions, including IPTS (Van Orden et al., 2010), IMV (O’Connor et al., 2016), SPM (Gunn, 2017) and others, which essentially characterize suicide as a way to escape intolerable emotional states. None would appear incompatible with the view that pain, as a biological imperative, demands action to end or escape it, while regular adult human cognition offers intentional self-killing as an effective, but genetically destructive, means to answer that demand.

But the corollary, that humans are protected from suicide by evolved psychological mechanisms, may be harder to digest. Blind to our own instinctual motivations (Cosmides & Tooby, 1994), we may be oblivious to their functioning. The idea of antisuicide defenses is not new (e. g., Himmelhoch, 1988; Hundert, 1992; Miller, 2008), but it is only now gaining momentum in the research agenda (Humphrey, 2011, 2018; Soper, 2016, 2017, 2018, 2019a, 2019b; Soper & Shackelford, 2018). Their implications may run wide and deep, and call some long-held preconceptions into question: as Lester (2019) finds, accepting the ramifications requires close reading of the arguments.

Progress is not helped by what Soper (2018) believes to be a two-way blockage in communication between suicidology and evolutionary psychology that may go beyond the kind of institutional fragmentation seen elsewhere in psychological sciences (Staats, 2004). Soper posits that suicide and evolution, each for its own reasons, are concepts that many people, researchers included, find intuitively uncomfortable to think or talk about. It may be for this reason that, in one direction, evolutionary psychology has largely ignored suicide, as has psychology generally (J. R. Rogers, 2001): in view of the gravity and ubiquity of suicide as a human phenomenon, and the conspicuous evolutionary puzzle it presents, remarkably little has been written on the subject from an evolutionary psychology perspective, at least until recent years. It is a reticence traceable to Darwin himself: as Tolaas (2005) points out, it is remarkable that a thinker as fearless as Darwin did not confront suicide as a potential problem for his theory. In the other direction, suicidology has largely ignored evolutionary psychology. Illustratively, a review article promisingly titled “Evolutionary processes in suicide” (Chiurliza, Rogers, Schneider, Chu, & Joiner, 2017) attempts to appraise its research group’s ideas (and their ideas alone) without reference to evolutionary psychology’s corpus of texts and tenets – a surprising omission given that evolutionary psychology, “the study of behavior from an evolutionary perspective” (Cornwell, Palmer, Guinther, & Davis, 2005, p. 369), is centrally relevant.

This chapter proposes a pragmatic consilience between the two fields. An evolutionary stance would not seem in itself to entail a radical departure for suicidology: it would, rather, follow the lead set by Freud (1920/1991), Shneidman (1985), Joiner (2005), and other prominent researchers who have drawn on evolutionary ideas across more than a century. Evolutionary psychology could coalesce, not replace, suicidology’s existing theoretical content. There may be little to lose in such an incremental move. The upsides, on the other hand, may be great. Evolutionary psychology offers fresh perspectives and ready tools that could be decisive in a battle currently at stalemate. Evolutionary psychology and suicidology deserve each other’s attention.