Quirky Little Things

The science of the queer and the quotidian.

Jesse Bering is an experimental psychologist and Director of the Institute of Cognition and Culture at the Queen's University, Belfast. See full bio

July 17, 2008, Evolutionary Psychology

Comments on "When is Suicide Adaptive?"

When is Suicide Adaptive?

By Jesse Bering, Ph.D. on July 17, 2008 in Quirky Little Things

You might think that suicide flies in the face of evolutionary theory. If the goal is to spread one's seed as much as possible then why on earth would anyone "defy nature" by intentionally removing themselves from the competition? Read More

For how short it is, I found

Submitted by Cindy Taren on July 18, 2008 - 9:05am.

For how short it is, I found this to be one of the most intriuging articles that I've read on this site. Do you suspect that this adaptive trait may also be applied to entire races that implement genocide on their own people? This is a question that I have been thinking about for awhile (since learning of such atrocities as the Armenian and Bosnian genocides, Rwanda and Darfur). Could it be posible that a race of people may see itself as such a burden on the world that it instinctively or sub-consciously attemps its own extermination?

question

Submitted by KHP on July 18, 2008 - 10:35am.

but how doe these correlational studies help establish an adaptive link, since they don't allow you to rule out psychopathology, individual differences in resilience, etc. An adaptive argument makes sense in theory, I'm just not sure how deCatanzaro's studies, as presented here, bolster that argument.

Circularity

Submitted by Zombie Catcher on July 18, 2008 - 12:57pm.

This post exemplifies the kind of circular reasoning that evolutionary psychologists resort to on a regular basis. Confronted with the panoply of human behaviors that are clearly not adaptive (at least in terms of propagating the individual's genes), they come up with convoluted and fantastical explanations as to why those behaviors actually *are* adaptive. In this case, we're asked to believe that suicidal individuals do some kind of "subconscious" calculations about the supposed burden that their continued existence is placing upon their relatives' genetic success. That alone should set off alarm bells: any hypothesis that appeals to unverifiable and unmeasurable "subconscious" processes may be titillating, but it certainly isn't scientific.

If it is in fact adaptive for so-called "undesirables" to desire suicide and--it logically follows--to *act* upon that desire, then why is it that so few of them actually ARE suicidal? Suicidal tendencies are uncommon enough that we can assume that most people--even the aged, the infirm, homosexuals, and other reproductive dead-enders--aren't suicidal until proven otherwise. That being the case, it would be adaptive for all or at least most reproductive dead-enders and "freeloaders" to be suicidal. But it is self-evidently the case that most aren't. We'd be spending most of our time dodging the falling bodies if they were.

Let's take a look at some hard statistics about suicide. Statistics for the United States in 2005 (which can be found here: http://www.suicidology.org/displaycommon.cfm?an=1&subarticlenbr=21) show the following suicide rates by age group (all numbers are suicides per 100,000 people): 5-14 (0.7), 15-24 (10.0), 25-34 (12.4), 35-44 (14.9), 45-54 (16.5), 55-64 (13.9), 65-74 (12.6), 75-84 (16.9), 85+ (16.9). If there really were a correlation between reproductive fitness (even including the broader rubric of "inclusive fitness") we could reasonably expect a steady increase in the suicide rate with increasing age. What we see instead is an increase up until the 45-54 age bracket, and then a DIP such that the suicide rate for the 65-74 group is actually LESS than the rate for the three age brackets below it and ALMOST AS LOW as the 25-34 age group--i.e., the most reproductively fertile years for most couples in the United States (not the most biologically fertile years, of course, but the years when most couples feel most capable--economically, emotionally, etc., to bear and raise children). Other interesting facts: men are nearly four times as likely to commit suicide as women, and the suicide rate among whites is 12.3, while among non-whites it is only 5.5. Does that mean that whites and men are somehow less reproductively fit as a whole than non-whites and women? You'd have a hard time making that case.

The only reasonable conclusion that one can draw from this evidence is that reproductive fitness (even broadly defined) is not a reliable predictor of suicides, and therefore presumably of suicide attempts and serious (as opposed to idle) suicidal ideations. A causal link between reproductive fitness and suicidal tendencies is far-fetched at best. Depression, for example, is a far more reliable predictor of suicidal tendencies. Granted, some of the circumstances that often trigger depression (job loss, illness, etc.) also render one less "fit" broadly defined, but that doesn't necessarily mean that the loss of reproductive fitness is causally implicated in the depression or subsequent suicidal ideations. Social stigmas, loss of self-image, physical pain, and biological disease processes (which often trigger chemical imbalances that cause depression) are just as likely culprits.

Evolution itself has been scientifically established beyond a doubt. Evolutionary psychology, on the other hand, is unfortunately a morass of circular arguments, shifting definitions, unfalsifiable assertions, unwarranted reductionism, and cherry-picked evidence. It tries to explain everything and therefore, ultimately, winds up explaining nothing. Man is the singularly symbolic species--the advent of language and abstract thought was so overwhelmingly adaptive that it persisted even after it decoupled us from many of the more peripheral instinctual behaviors that had once been adaptive, genetically speaking, and replaced them with often less adaptive ones conditioned by culture and society or that arise as individual variations. These maladaptive behaviors are insulated from natural selection by the social and technological innovations made possible by that same language and abstract thought. I'm not arguing for a blank slate here; clearly our more primal behaviors have been evolutionarily selected for, but the kind of overreach shown by the argument above does more to discredit EP than to validate it.

Some more meat to chew on...

Submitted by Jesse Bering, Ph.D. on July 18, 2008 - 1:46pm.

From "Cognitive Vulnerablility to Emotional Disorders" by Lauren B. Alloy and Neil Riskind (2005, Lawrence Erlbaum): "Joiner et al. (2002), in a more stringent test of the model, replicated and extended the findings of de Cantanzaro. The authors found that perceived burdensomeness was significantly more predictive of suicide completer status than other relevant variables such as general emotional pain, hopelessness, and the desire to control one's own feelings or to control others. In a second study, a sense of burdensomeness was significantly correlated with lethality of suicide method, whereas the aforementioned other variables were not. Brown, Dahlen, Mills, Rick, and Biblarz (1999) similarly found among a sample of college undergraduates that perceived benefit to kin was significantly and negatively correlated with lethality of suicide method among Chinese suicide completers. Although this finding contradicts the notion that a perceived sense of burdensomeness serves as a cognitive vulnerability to suicide, the authors argued that the model is theoretically sound when interpreted from a multicultural perspective (i.e., a complete lack of burdensomeness in a collectivistic society such as the People's Republic of China may be indicative of detachment from one's environment, thus increasing the likelihood of suicidality among such individuals). As an aside, this illustrates and emphasizes the importance of developing and interpreting models of behavior from an appropriate cultural perspective."

If you insist

Submitted by Zombie Catcher on July 18, 2008 - 5:07pm.

The text you cite actually seems to move the discussion away from the evolutionary-psychological perspective on burdensomeness to the interpersonal and cognitive perspective: "While investigators of this model have traditionally emphasized the evolutionary-psychological notion of burdensomeness and suicide, the model also fits within the rubric of cognitive vulnerabilities to suicide. More specifically, the cognitive vulnerability involved in this model arises from interpersonal motives." (Alloy and Riskind, p. 140)

Interpersonal motives are not the same thing as evolutionarily adaptive motives. The example of Chinese undergraduates actually militates strongly against an evolutionary-psychological reading of felt burdensomeness. Chinese undergraduates' sense of burdensomeness is culturally conditioned and felt towards *their parents*, which, from an evolutionary standpoint, is kind of backwards. Because of China's one-child policy, most of these suicide victims are actually only children. By killing themselves--especially at an age when their parents are too old to have another child--they are effectively shutting down not only their own, but their parents', genetic prospects for good.

Have you convinced yourself yet?

Submitted by Jesse Bering, Ph.D. on July 19, 2008 - 12:30pm.

You sound intelligent enough for me to bother to say that it's a pity you're dead-set against evolutionary psychological theory. Your line about 'Man-as-Unique-Symbol-Maker' circa a 1974 lecture on Levi-Strauss suggests that your only exposure to evolutionary psychology was a postmodernist rant made by your social anthropology lecturer your second year of college. You're so inoculated against logical adaptationist arguments such as de Catanzaro's self-destruction model, and your confirmation biases are in such overdrive, that you're not processing this deeply enough to understand that natural selection isn't as concerned with the number of offspring you bear as it is with the proportion of your genetic material transmitted. Chinese undergraduate students committing suicide have not only biological parents (and, by the way, if these students are, say, 17-19 years old, their parents would likely still have some reproductive currency left, especially their fathers), but also cousins, aunts, uncles, and possibly half-siblings as well carrying about their genetic material. de Catanzaro's correlational formulae are sophisticated enough to capture these inclusive fitness effects. Suicides are culturally ubiquitous, far outnumbering homicides. To regard de Cantanzaro's empirically supported hypothesis as simply another 'Just-so-Story' in evolutionary psychology without fully appreciating its conceptual nuances could be a major misstep, especially if it interferes with possible interventionist strategies for preventing suicide. Clinicians would be wise not only to focus on the epiphenomenal thought processes attending suicidal ideations, but also to be aware of the possible natural selection mechanisms underlying such negative emotions. The last word is all yours, as I know you're just dying to have it. --and, by the way, evolutionary psychologists can explain why that reputational desire is also an artefact of your evolved mind.

I sure have.

Submitted by Zombie Catcher on July 19, 2008 - 3:00pm.

It's also a pity that you feel the need to resort to ad hominem mockery, caricatures, and silly assumptions about my education. By the way, "symbolic species" is an allusion to Terrence Deacon, not to Claude Levi-Strauss.

First of all, I'm not "dead-set" against evolutionary psychological theory--it clearly illuminates *instinctive* human behavior in the realms of self-preservation and reproduction (although the jury's still out on homosexuality), but has limited explanatory power when it comes to complex decision-making. The fact that human beings engage in widespread and refractory maladaptive behavior puts EP on the horns of a dilemma--either argue that evolution selects for maladaptive behavior (which is a contradiction in terms), or try to argue that that behavior is actually adaptive, which is what tends to happen. My objection to EP has nothing to do with postmodernism--it has to do with the scientific dubiousness of trying to twist the facts to fit the theory instead of the other way around.

It's evident that lack of reproductive fitness (even broadly defined) is neither a sufficient nor a necessary cause of suicide or suicidal ideation. It is not a sufficient cause because there are plenty of reproductive dead-enders who neither commit suicide nor consider it. It is not a necessary cause because there are plenty of inclusively fit people who commit suicide. Without a demonstration of sufficient or necessary causality, attribution of causality becomes suspect. Can lack of inclusive fitness be a contributing factor to suicide in some cases? Sure, why not. But then again so can bad weather, so that's really not saying much.

As far as clinical interventions go, one does not require an evolutionary-psychological *explanation*, i.e., recourse to inclusive fitness theory, to make use of the empirical correlation between things like job loss, illness, depression and suicidal tendencies. Too ardent a belief in that theory as an explanation for suicide, on the contrary, can blind clinicians to suicide potentials among otherwise healthy and "unburdensome" adolescents, which is a particular worry given that suicide is the third leading cause of death in the young.

As far as the Chinese undergraduates go, if you want to believe that vague, subconscious calculations about cousins and nephews trumps the instinct for self-preservation and reproduction, be my guest. No amount of reasoning can dissuade a person from a belief in something that is unseen and unverifiable--such is the nature of faith. I could just as easily argue that people also subconsciously incorporate hope into their calculations, hope that the current situation that makes them unfit in some sense can at some point be overcome, that their *long-term* fitness is not impaired. The crux of the question is why some people lose that hope. Your triumphalist assertions to the contrary, neither of us can actually *prove* that we're right. Logically, though, there's no good *evolutionary* reason why a 19-year-old Chinese elite (simply by virtue of being in college in the first place) should kill himself, even if he did get a bad grade on a test.

If a desire to get at the truth and tenacity in the face of unconvincing arguments counts as "dying to have the last word," then I'm guilty as charged. But it's odd that you ascribe it to "reputational desire" on my part when I'm writing under a pseudonym. The results of this exchange have no bearing on MY reputation as a named, social entity in any forum that counts for anything (although the same can't be said for you, so feel free to have the last last word). I'm also acutely aware of the opportunity cost incurred when I could be doing other things that could more concretely improve my reputation, fitness, and eudaimonia--yet I engage in this joyless exercise anyway. If you had ascribed it to my ego or a desire to maintain a certain self-image, that would have been a lot more convincing.

Nature vs. Nurture

Submitted by Bill McGonigle on August 1, 2008 - 6:50am.

Do we see any suicide in animals other than humans? High apes, for instance?

How does one tease apart an evolutionary trait from a learn and propagated behavior? Or can the evolution of a complex mind even be separated? Another way of asking this is, "when did the first person commit suicide?" Is there a general knowledge of suicide required for it to be an option or does it arise spontaneously? Perhaps there are studies of primitive 'found' or previously isolated societies where suicide either didn't or did exist?

Ha, ha, ha

Submitted by Adam Scott on October 7, 2009 - 5:16pm.

An animal kills itself. How are it's genes propagated? How? No wait, how are they propagated? The argument seems to be that it shares genes with others it's aware of and kills itself to ensure the survival of the others, thus carrying on _some_ of it's own genes. So, how does it know it shares genes with others? There's a gene that has gene recognition, and it also has a self-destruct sequence. Ha!

So if an animal's genes have a self-destruct button, where did they come from? Certainly not from those ancestors who killed themselves. Ha!

And of course I can cite the pedantry: This is fallacy of the consequent logic. Correlation is not causation. Emphasis on period.

But still, just before an animal dies of anything, isn't it more likely to reproduce if it has sex rather than kill itself?

Forget about adaptation, forget about fitness. The animal must reproduce. That is the first priority, the highest priority. If the genes do no propagate then the "program" dies.

If I were to try to argue for the hypothesis of this article, I might state that genes aren't finite things found on DNA strands, they are also part of thought systems. Thoughts can reproduce on their own and have their own style of DNA. In fact, this very thought seeks to reproduce by telling other thought receivers that suicide is not evolutionary adaptive. Ha!