Wednesday, January 02, 2008

Suicide and IQ; does it take smarts to kill yourself?

++Addition++Robert of the eponymous Robert's Rationale takes a look at the GSS and finds more inconclusivity.


In a search to find something, anything, socially pathological that correlates inversely with IQ at a statistically significant level, suicide rates seemed a plausible place to look. In the words of Lisa Simpson:
As intelligence goes up, happiness goes down. In fact, I made a graph... I make a lot of graphs.
A GNXP post alludes to an analysis that found a moderate relationship between intelligence and suicide at the international level (.39 for men, .46 for women). That is, as intelligence goes up, so do rates of suicide.

Using WHO and IQ and the Wealth of Nations data, I found an even stronger gender-combined correlation of .54. But unlike the IQ testing data, suicide rates are generally obtained from the governments of the countries themselves, so their reliability is always in question. For example, Egypt is apparently free of suicides, while most African countries do not report on rates at all.

Among nations of primarily European descent (Canada, the US, New Zealand, Australia, in addition to the actual continent), suicide rates and IQ actually correlate inversely, albeit weakly and without statistical significance, at .08. Among this same European club, purchasing power parity and suicide rates inversely correlate at .34. In the West, while IQ doesn't appreciably influence suicide rates, wealth mildly reduces them. Thus, it seems that there are biological and/or cultural differences other than intelligence that play into suicidal tendencies.

The findings of a 2005 study out of Sweden contradict Lisa's assertion:

In one of the largest studies on suicide ever conducted, researchers found that men with especially low scores on intelligence tests are two to three times more likely than others to kill themselves.

The study was carried out in Sweden, which, along with other Scandinavian countries, has one of the highest suicide rates in the world. Epidemiologist Finn Rasmussen at the Karolinska Institute in Stockholm and two colleagues monitored nearly 1 million Swedish men, measuring their IQ when they entered national service at 18 and following them until age 44. In that time, 2,811 men committed suicide, with the highest rate found among those who scored lowest on the logical component of the IQ test.
Men academically in over their heads--those with low IQs who had received at least some higher education--were the most likely to commit suicide.

This makes sense to me. Intelligent people tend to be more aware of what is attainable (very broadly speaking, in terms of knowledge, wealth, influence, entertainment) and also more able to attain it, than the average joe. The less endowed, in contrast, are generally less aware of what is out there and less able to attain it than others are. The smart want much, but also have the means to attain much. The modest can't obtain as much, but don't want as much, either. The want-have gap is roughly the same among those in these two broad groups.

In the cold are the less intelligent but relatively well-educated group that has more access to what can be attained, but little chance of actually attaining it. It is depressing to know what others have, especially when struck by the realization that you will never have it (I experience this feeling frequently while reading posts at GNXP!). This is the predicament those most at-risk to commit suicide are in.

With this inconclusive clutter as background, I ran the numbers using estimated IQ and suicide rates at the state level, to find about as inconclusive a correlation as possible, at .02 (no relationship whatsoever).

That Wyoming, Montana, and Alaska had the three highest rates of suicide, respectively, did stand out, however. The relationship between population density and self-immolation is in fact quite strong, at an inverse .64. Running a host of other variables, including racial composition (notably, despite comprising only 1% of the nation's total population, the percentage of a state's people who are Native American correlates positively with its suicide rate at .50), I found nothing at the state leve that correlates as strongly with suicide rates as population density does.

Humans are social animals, of course. The lack of meaningful interaction puts those already predisposed to pessimism and depression at greater risk to themselves. Solitude brings with it time to reflect, instead of being constantly distracting by the needs and opportunities other people create. In the words of Denys de Catanzaro (via GNXP's God Fearing Atheist):

"It may take an intelligent animal [with time for self-reflection] to know when the situation is hopeless, to realize that purpose for life is removed in those circumstances, and that death can be self-induced."

Catanzaro's theorizes that suicide offers an advantage for gene propagation. Those who are old, estranged from their families, unable to provide for themselves, or unsuccessful with the opposite sex are more likely to commit suicide than others are. Since all of these 'conditions' put burdens on family members or offer little chance at reproduction, removing the burden is beneficial for gene propagation in that other family members will have a better chance of successfully raising offspring with the deadweight off their backs, and through evolution the poor louse knows as much. So he 'heroically' takes himself out.

The relationship between suicide rates and total fertility rates at the national level lends credence to that idea (although at the state level, there is no statistically significant relationship). Using the same cautionable numbers mentioned above, the correlation is an inverse .60 (as fertility decreases, suicides go up). Having children to care for is the strongest evolutionary reason to keep on chugging. Having kids to live for makes one value his own life that much more.

The West is already failing to replenish itself. It doesn't need a gradual uptick in the number of its people killing themselves to go along with that trend.


Rob said...

AP, depending on when IQ is measured for an individual, it may affect the relationship between IQ and suicide. It appears depression lowers performance IQ, but not verbal IQ, and the damage may not go away. This should not affect the population-level correlations.

My guess is percent native american has a strong inverse correlation with population density, and that is why suicide and %native american correlate strongly. I'm sure you new, but I wanted it to be clear.

Also, firearms are more common in more rural areas, which makes impulsive self-destruction more lethal.

Also, Sailer should keep his tip jar open all the time, right after Christmas has to be a rough time to raise money.

Audacious Epigone said...


Thanks for pointing out the Native American/density relationship. I should have spelled it out more clearly, although it is fairly obvious.

I understand that charities get a huge chunk of their donations in the month of December, but the tax deduction 'benefit' doesn't apply to most people (although it probably does apply to most of Steve's readers).

Another commenter remarked that Steve should spell out his situation more specifically. I'm not sure it would be wise to make an open-book of the state of his finances, but his trust factor is enormous, so he could certainly pull it off. The worst thing that can happen is for him to announce that he's giving up full time writing, before warning explicitly that he's considering as much.

Dennis Mangan said...

AP: Excellent post. A while back I noted that Swedish IQ vs. suicide study on my own blog, and since then I've got lots of people coming by after googling for the link between IQ and depression. Apparently there are a fair number of very smart and unhappy people out there. As for American Indians (non-PC for "Native Americans"), I wonder whether there isn't a more direct link than population density. I mean, with all the alcoholism, welfare, etc. Oh, here we are:

"American Indians and Alaska Natives have the
highest suicide rates of all ethnic groups in the United
States, and suicide is the second leading cause of death
for American Indian and Alaska Native youth."

Anonymous said...

I predicted some years ago that black youth suicide rates would rise as crime rates declined, but with a lag of several years.
Not that my explanation of this is likely to be accepted, but anyway, what happens is that there are those who don't care much and fail to take precautions to keep from getting killed in a dangerous environment.
Remove a large part of the danger that was killing that element, and the underlying suicidal tendency gets unmasked.
Something like this would be happening in fanatically safety-firster Scandinavia. Accidents would otherwise have killed off a lot of those who don't care and are uncommonly careless, but safety-firsters become powerful and diligent, and the suicide rates afterwards rise. JSBolton

Audacious Epigone said...


Thanks for that.

Suicide rates for males are about 5times that for females. That meshes with the idea that men are more expendable from an evolutionary perspective.

The overall white rate is the highest among the four major racial/ethnic groups in the US, but the youth rate is highest among Native Americans.


So not as much suicide in a killing field, since homicide pushes it aside, then. While the rates for suicide among blacks declined during the nineties, among younger blacks today it is on the rise.

Chamoisee said...

"That Wyoming, Montana, and Alaska had the three highest rates of suicide, respectively, did stand out, however."

I think that there is a strong corrretlation between day length variability and suicide; i.e., the shorter the days in winter, the more risk of depression and suicide. Speaking strictly from experience, living as I do in northern Idaho. Of course, there are other northern states with short day lengths in the winter that may not have high suicide rates. However, the states you mentioned have a lower population density, which increases the risk of isolation during the winter.

LOTUS LEO said...

I will take my own example ..i have family history of many suicide..there is urge towards suicidal tendencies in me ...if i rate myself on the basis of intelligence i am above average as per my academic record..being more intelligence has its own side effect you learn things very quickly and you get bored after that again you try something new to remove your boredom and after experimenting with life there comes a point where every thing seems meaningless and purposeless then you want to suicide as i want but i want to stick with life to know whether i can defy my family history or not..

Anonymous said...

I'm more than a tad curious as to my current odds (within the limits of statistical analysis) for suicide. I'm physically disabled & in varying degrees of chronic pain due to spinal injury(s). Though I only possess a HS diploma, my last IQ test scored a 151. Careerwise, an acquaintance who happened to be the IT mgr at the IEEE Computer Society at the time wrote my resumé (which was a work of fiction). I'd been in a low wage data entry position with an insurance company, & he offered me a shot at escaping < $20K per year hell, "because I pick things up quickly," I then progressed to network engineer at two other large corporations over the 7 years. Post-injury, I was quickly back to relative poverty level on SSDI.
Since 2000 I've lived alone w/minimal contact with anyone, including my brother & his wife. I have a library of ~ 1,500 volumes, 99.9% non-fiction, across myriad topics. I read voraciously but feel my life is pointless. My mother was a diagnosed paranoid schizophrenic who attempted suicide 4 times that I'm aware of. I haven't touched another human in > 16 years. Heterosexual but celibate for that entire time. Contemplate self-termination frequently but dissuaded due to possible (if not probable) failure. Am physically habituated to opioid pain meds & benzodiazepines. Eating & sleeping erratic. Can travel & own a car (1989 Coupe DeVille), but rarely have a place to go. Best friend from kindergarten has me stay over for the weekend ~ 6 times a year (He's a millionaire w/a wonderful wife & two daughters - the oldest of which was born 9/11/01). We're both 50, but we've both been told we look much younger, by friends & strangers alike. Both my parents have passed, & I rarely see my brother because his wife, "doesn't approve of our upbringing." As I contemplate the future & senescence alone, I often become quite depressed. Living for 6 or so weekends a year isn't cutting it.
I live in a single family home owmed by another married male friend, but have no roommates. He's also 50, but has a 5.5 year-old daughter & 4 year-old son, for whom I've babysat for 3 hours or so on occasion. I'm a white male; don't drink or smoke (I used to do both, but alcohol doesn't play nice with the meds & it's a non-smoking house, despite my being the only tenant, which is fine, as I can't afford cigarettes anyway). Growing up w/a mom who was institutionalized for months at a time was...confusing, to put it mildly. My dad was quite intelligent, but utterly lacked any ambition. He was a bookkeeper & often worked 2 jobs for needed income (but I suspect a 2nd job also got him out of our apt, & away from mom's verbal abuse). I don't understand why he didn't avail himself of the G.I. Bill to attend college after WWII. In HS, my parents put me on the "vocational" track so I could start working ASAP. I realize this isn't a lot of info, but I've noted the Internet isn't a forum for long explicative dialogue.