Intelligence is in the News Again

And now, hot on the heels of an entire issue of Die Zeit, a 3sat documentary special (g) on intelligence called (my translation): 'Born Dumb, and Haven't Learned a Thing? Intelligence Research between Racism and Flexible Genes'. OK, it's from last year, so not really a trend-confirmation. I haven't watched it yet, but I am wary of the fact that they've chosen rabble-rouser Thilo Sarrazin to state the hereditarian case, since there are many actual scientists who are likely much better-informed and not given to stupid generalizations. 

I wonder if what we're seeing is the Western mainstream press in delayed reaction to the scientific consensus, now pretty much ironclad, that intelligence is strongly influenced by heredity. And to the reality that the scientists who've found this out are quite likable, normal men and women, not cackling Peter-Lorre-esque mad scientists with terrifying underground 'la-BOR-a-tories' crammed with formaldehyde-filled jars full of aborted genetic experiments.


IQ is the Best Predictor of Human Achievement

For a bit of context, the good Dr. Thompson, on his excellent blog, gives a brief summary of the most important things to know about intelligence (emphasis added):

Intelligence does not guarantee good decision-making in all circumstances, simply better decision-making in more circumstances than a duller person.  Some problems forms are inherently difficult and ambiguous. For example, it is easier to understand natural frequencies than percentages with decimal point. Apart from intelligence, social pressures and emotional attachments influence decisions.
 
Modern IQ tests give one overall figure, and also figures for 3 to 4 component indices, usually verbal comprehension, perceptual organisation, working memory, plus processing speed. The single figure is usually the best predictor, but the others have their place in specific circumstances. The fact that one single number is the best predictor of human achievements is testimony to its power.
 
40% is the heritability estimate for children, but it rises to 60% plus for adults.  70/30 is not a bad estimate for wealthy countries, 50/50 for very poor ones.... People from profoundly different cultures make the same sorts of errors on culture reduced tests, and the pattern suggests a largely universal problem-solving capacity. The predictive power of intelligence is similar in culturally different countries.
The point in bold is key. Out of all the factors that people think explain why certain people fail at life and others succeed, intelligence, even as imperfectly but reliably measured by one simple number, is the most important. The way science discovered this is also interesting: by controlling for intelligence in studies of other factors. Level of education, parental socio-economic status, reaction times, etc. turn out to be strongly correlated with, and very likely caused by, intelligence. On average, in the aggregate, the wealthier you are, the smarter you are, and wealthy parents pass those genes onto their children.
 
This is very different from what many people believe, or wish were true.

The 'Blank Slate' is Now as Dead as Phrenology

The blank slate theory of human development holds that human beings are all born with roughly equal capacities, and that variations between humans on an individual and group level exist solely (or almost solely) because of environmental factors. This idea has always had its supporters, and they gained the upper hand in the early 20th century, bolstered by a few fairly primitive ethnographic studies and the ideological backlash against the crimes of 20th-century eugenicists, including genocide. To this day, the blank slate theory is often taught as proven fact in schools of education, which is a very foolish and dangerous thing to do.

One way to check the blank slate theory is to examine twins. They come in two flavors: monozygotic (one egg splits into two embryos) which are virtually genetically identical, or dizygotic, which are basically just siblings who happen to be born at the same time. Early twin studies began to seriously undermine the blank slate theory, which didn't surprise geneticists and psychologists but made some people quite nervous. Twins adopted into completely different cultures, unaware even of each others' existence, had similar traits at a rate completely incompatible with random chance. Modern genetics has also destroyed the blank-slate theory, but many people don't understand or trust these studies. Few people now subscribe to the full-on blank-slate theory, but there are still millions of people who are eager to downplay the influence of heredity as far as possible.

But now, Nature Genetics has just published a blockbuster 14-million subject twin-study meta-analysis, possibly the most important research on heredity in decades, which has now definitively destroyed, once and for all, the blank-slate theory of human development. The authors studied dozens of human traits, from purely biological to social, and found the overall heritability for these traits about 49%. The strongest associations were for biological givens (height, bone density, etc.), the weakest proof for social attitudes (although there was still detectable hereditary influence on these). Cognitive ability, the best predictor of success in modern societies, is somewhere between, but still highly heritable, as Dr. James Thompson notes:

All human traits contain a substantial heritable element. The blank slate is totally false. If you have colleagues who doubts the twin method or who have difficulty accepting the power of ancestry, shall I repeat for them Rhett Butler’s last words to Scarlett O'Hara right now, or is it better that I tell you a little more about the findings?

I expect you have an interest in the results on cognition, so rest easy, heritability is high, though not as strong as for skeletal, metabolic, ophthalmological, dermatological, respiratory, and neurological traits. Usually there is a big difference (top line of figures) between the high correlations for monozygotic and the lower correlations for dizygotic twins, showing a strong genetic effect. The exception is social values, in which the environment makes a bigger contribution than usual, though not quite as big as heredity.

Cognitive traits correlate 0.646 in identical twins, 0.371 in fraternal twins, with miniscule error terms of .01 in these enormous samples. An additive model seems appropriate for cognition.

They conclude: Our results provide compelling evidence that all human traits are heritable: not one trait had a weighted heritability estimate of zero. The relative influences of genes and environment are not randomly distributed across all traits but cluster in functional domains. In general, we showed that reported estimates of variance components from model-fitting can underestimate the true trait heritability, when compared with heritability based on twin correlations. Roughly two-thirds of traits show a pattern of monozygotic and dizygotic twin correlations that is consistent with a simple model whereby trait resemblance is solely due to additive genetic variation. This implies that, for the majority of complex traits, causal genetic variants can be detected using a simple additive genetic model.

So, intelligence has a strong heritable component, and other personality attributes have weaker, but still quite important heritability. The blank-slate hypothesis is now folklore. It joins phrenology, alchemy, astrology, and thousands of other theories of human behavior in the Mausoleum of Disproven Hypotheses.


A Bleg: First-Person Accounts of Psychosis in German?

Ever since I worked in a mental hospital for a few years, schizophrenia has fascinated me. I now have a modest collection of first-person accounts of psychosis written by recovered patients, as well as some written by patients who have not recovered. My small library includes Daniel Paul Schreber's classic Denkwürdigkeiten eines Nervenkranken (full text in German), Thomas Hennell's The Witnesses, and many others. A recent acquisition is Barbara O'Brien's utterly fascinating Operators and Things, in which she recounts her 6-month journey around the U.S. in 1958 trying to evade the Hook Operators:

Whenever I think of the Hook Operators now, I see a picture of a man with a hook stuck in his back. The hook is attached to a rope and the rope hangs from a ceiling. At the end of the rope, unable to get his feet on solid ground, the man dangles in the air, his face distorted in agony, his arms and legs thrashing about violently.

Behind him stands the Hook Operator. Having operated his hook successfully, the Hook Operator stands by with his other instruments, the knife and the hatchet. He watches the thrashing man, speculating, considering, If necessary, he will move in and cut the victim’s throat, or with his hatchet cleave through the victim’s head.

The Hook Operator is a maker of tools and if he is an expert tool-maker, the hook alone will serve his purpose. The victim, in his thrashing to be free of the hook, will most likely cut into his back the crippling gorge the Hook Operator seeks. The Hook Operator waits and watches. What a man will do, once he is caught on the hook, is always a gamble. There is the chance, of course, that the man may squirm off the hook, in which case the Hook Operator will move in with his other weapons.

There is, too, the chance that the victim may accomplish more than the Hook Operator strives for and crack his backbone or, giving an unexpected twist to his thrashing, tear himself completely in two. Should break or schism occur, the Hook Operator as much as anyone may pause in distress, surveying a wreckage he did not seek and for which he feels no guilt. When he hooks, cuts, or cleaves, his object is not to destroy but to impede and remove. Not personal animosity but competition has impelled him to use his weapons. The man on the hook was not an enemy but an obstacle. Even had the Hook Operator cut his competitor’s throat he would have cut it sufficiently but no more; had he cleaved his skull, he would have cleaved it just enough. Of his weapons, the hook is considered the least barbaric, the one which requires the most skill and the one for which he will receive the least censure.

You can download the entire book for free here. Unlike many such accounts, O'Brien's book has a sort of happy ending: her subconscious generates an incredibly complex and ultimately successful strategy to knit her mind back together.

Now for the bleg: What are some other first-hand memoirs of psychosis in German? What I'm interested in are first-hand accounts written by people who experienced psychotic breaks and then went on to describe them in book or article form. They're pretty rare in any language, but I imagine there must be a number of them in German. Any tips will be gratefully acknowledged.

 


Human Nature Wins Again

From Slate, an interesting tidbit about what is often called 'slut-shaming':

New research into the science of slut-shaming has found that promiscuous women can’t get a break—even from other promiscuous women. For a study published in the Journal of Social and Personal Relationships, researchers from Cornell University asked college women to read a vignette describing a hypothetical female peer, “Joan,” then rate their feelings about her personality. To one group of women, Joan was described as having two lifetime sexual partners; to another group, she’d bedded 20. The study found that women—even women who were more promiscuous themselves—rated the Joan with 20 partners as less competent, emotionally stable, warm, and dominant than the Joan who’d only boasted two.

Apparently there's an international movement to combat what's called 'slut-shaming', with so-called 'slut walks' happening all over the developed world, even in Berlin, although the website looks pretty moribund right about now.

Now, I hold mainstream views on most of these issues. Discrimination is wrong, no means no, etc. But the crusade to end 'slut-shaming' strikes me as silly for a few reasons. First, this is a quintessential first-world problem. In most parts of the world, young, sexually-promiscuous women are going to face a fate much worse than mere social disapproval. Second, this seems to be a classic case of a social movement launching a frontal assault on an immutable component of human nature.

Note that most of the disapproval of sexually-promiscuous women comes from other women. The study quoted above shows, for what it's worth, that even women who bed-hop themselves attribute negative personality characteristics to their fellow, er, sluts. I myself have heard many women engage in 'slut-shaming' almost reflexively, seemingly unaware that this behavior is supposed to be considered anti-feminist.

It's all a matter of your station in life. If you're an attractive 20-year-old college student (note how the discussion so often focuses on the 25% of women who attend college, not the 75% who don't), you may well be interested in a an argument for social change that promises to allow you to experiment sexually without repercussions.

Now add 22 years to that same woman. She now has a husband, and two kids. Let's say the husband hires a young, attractive 20-year-old female intern with a slutty reputation. Will the wife and mother -- fondly remembering her younger, wilder days -- stand up for the young woman's right to sleep around and discover her sexual identity? Of course not. She will perceive her husband's daily exposure to an attractive, sexually available young woman as a potential threat to the stability of her family, and she'll be right. If you want to hear slut-shaming at its most vitriolic, listen to a 43-year-old divorcée discuss her ex-husband's new 23-year-old girlfriend.

Disapproval of sexually-promiscuous behavior by young women is as close to a cultural universal as you're going to get. And there are reasons for this, since young, attractive, sexually promiscuous women pose a threat to monogamy. Now, this isn't so much the case if the woman limits her partners solely to unattached males her own age. But the very idea of promiscuity implies reduced selectivity and impulse control. A woman who enjoys having a variety of lovers and being desired is likely, at some point, to sleep with all sorts of men (and women), including married ones. And since discovered infidelity generally leads to a serious marital crisis in Northern Europe and the U.S., one 'slut' could theoretically endanger many unions during her career of promiscuity.

Of course, this is a glaring double standard, since sexually-promiscuous males aren't subject to the same stigma. But thousands of double standards utterly permeate our social reality, so merely acknowledging something as a double standard doesn't argue for its elimination. And besides, a young, attractive man won't pose as much danger to these settled unions, because young, attractive men are interested primarily in mating with young, attractive women who are less likely to have settled down. The cougars might be out there, but they're the exception that proves the rule, and they're not catching many cubs:

After examining the age preferences expressed in 22,400 singles ads on popular dating websites in North America, Europe, Australia and Japan, he found no sizable cohort of women seeking younger men. To the contrary, almost all of them wanted men their own age or older. Nor did he find evidence for the proliferation of cubs: the overwhelming majority of men displayed their eons-old preference for younger women. "I do believe the cougar phenomenon is a myth and, yes, a media construct," [psychology prof Michael] Dunn, who specializes in human evolutionary psychology and mating behavior, told the Australian Associated Press.

Except in a few urban enclaves or perhaps remote tribes, it will never be possible to remove the social stigma attached to female promiscuity. To ask whether this is good or bad strikes me as pointless. Is it good or bad that the sky is blue, or that deciduous trees drop their leaves each year?

If you ask me, the focus shouldn't be on a futile attempt to eliminate stigma in the Western World, but to address the dozens of societies in which a mere allegation of female promiscuity can lead to fates far darker and bloodier than social shaming. 


What Made the Black Death so Deadly

Maggie Koerth-Baker reports the pretty amazing fact that if you happened to get infected with Yersinia pestis -- the bacterium that caused the Black Plague -- today, you would have a 97% chance of surviving even without modern medical care. So why did it kill between 30-50% of Europeans in the 14th century? To find out, scientsts have been looking for ancient plague DNA:

 

In 2011, a team led by McMaster University paleogeneticist Hendrik Poinar became the first to reconstruct a full genome for Black Death era Yersinia pestis.

This was not a full and complete genome drawn from a single bacterium inhabiting the body of a single victim. Instead, the genome was patched together from bits and pieces of DNA in remains taken from London's East Smithfield cemetery. The small chunks were lined up to create a whole, similar to the way you make a panoramic photo by combining a series of different shots. Hendrik Poinar calls it a "draft" of the genome, rather than a smooth, polished work of biology.

The draft tells us a couple of things. First, the Y. pestis of the Black Death era is related to modern Y. pestis. In fact, it's probably the ancestor of all the strains of Y. pestis that exist today. Second — and this is the weird part — there is really not much difference between the old Y. pestis and the new. It boils down to about 100 genetic changes, few of which seem to have given the bacteria enough of an evolutionary advantage that they spread widely through the population.

Genetically, Y. pestis has barely changed. Its infection profile in the real world, though, has changed massively. That suggests that at least some of those small alterations in the genome must have been extremely important. But which ones? And why? To answer those questions, you could reverse-engineer the evolution of Y. pestis in the lab. "We'd have an opportunity to test those changes, one at a time, and find out," Poinar said. "... If we could do it in a form or fashion that wouldn't terrify people."

So, who's going to join me in volunteering to be infected with ancient plague for Science? After all, with modern medical care, there's probably at least an 80% chance of survival. I like those odds!


Condorcet v. The Circle-Squaring Cranks

Hobson_3While cloistering myself in the Natural Sciences Library to finish an article, I happened upon a book called Squaring the Circle, which is a minute historical exploration of that famous scientific problem, written in 1911 in impeccably dry English scientific prose by one E.W. Hobson, Sc.D, LL.D., F.R.S., Sadleirian Professor or Pure Mathematics, and Fellow of Christ's College, in the University of Cambridge. This biography of Hobson observes that he was '[b]rought up in rigidly Low Church surroundings ...' but 'developed strong views of rationalism, becoming ... an avowed radical and agnostic'. On pages 3 and 4, he notes that attempts to solve this famously insoluble problem* have occupied uncounted cranks over the centuries:

The solutions propounded by the circle squarer exhibit every grade of skill, varying from the most futile attempts, in which the writers shew an utter lack of power to reason correctly, up to approximate solutions the construction of which required much ingenuity on the part of their inventor. In some cases it requires an effort of sustained attention to find out the precise point in the demonstration at which the error occurs, or in which an approximate determination is made to do duty for a theoretically exact one. The psychology of the scientific crank is a subject with which the officials of every Scientific Society have some practical acquaintance. Every Scientific Society still receives from time to time communications from the circle squarer and the trisector of angles, who often make amusing attempts to disguise the real character of their essays. The solutions propounded by such persons usually involve some misunderstanding as to the nature of the conditions under which the problems are to be solved, and ignore the difference between an approximate construction and the solution of the ideal problem.

It is a common occurrence that such a person sends his solution to the authorities of a foreign University or Scientific Society, accompanied by a statement that the men of Science of the writer's own country have entered into a conspiracy to suppress his· work, owing to jealousy, and that he hopes to receive fairer treatment abroad. The statement is not infrequently accompanied with directions as to the forwarding of any prize of which the writer may be found worthy by the University or Scientific Society addressed, and usually indicates no lack of confidence that the bestowal of such a prize has been amply deserved as the fit reward for the final solution of a problem which has baffled the efforts of a great multitude of predecessors in all ages.... It is interesting to remark that, in the year 1775, the Paris Academy found it necessary to protect its officials against the waste of time and energy involved in examining the efforts of circle squarers. It passed a resolution, which appears in the Minutes of the Academy, that no more solutions were to be examined of the problems of the duplication of the cube, the trisection of the angle, the quadrature of the circle, and that the same resolution should apply to machines for exhibiting perpetual motion. An account of the reasons which led to the adoption of this resolution, drawn up by Condorcet, who was then the perpetual Secretary of the Academy, is appended. It is interesting to remark the strength of the conviction of Mathematicians that the solution of the problem is impossible, more than a century before an irrefutable proof of the correctness of that conviction was discovered.

Apparently the problem is insoluble because pi is a transcendental number, a fact which was proven in 1882. After this introduction, Professor Hobson proceeds, over hundreds of inadvertently Kafkaesque pages, to minutely detail every single failed attempt to solve this problem. One of the more exotic ones gave rise to this diagram:

Squarcircle

Continue reading "Condorcet v. The Circle-Squaring Cranks" »


Crime on the Decline Germany, Probably Because There's Less Lead Around

I've been following with fascination the debate in the U.S. about the relationship between crime rates and early childhood lead exposure. One of my favorite bloggers, Kevin Drum, recently wrote a fantastic piece for Mother Jones arguing that America saw dropping crimes rates in the 1990s in part because the U.S. banned leaded gasoline in the 1970s, saving an entire generation of children from exposure to lead, a fiercely potent neurotoxin which permanently lowers intelligence and disrupts impulse control in children. Read it here. Drum reports on reactions to the article and takes on critics here.

And now for Europe:

Here's the latest crime news from the Guardian:

There has been a surprise 8% drop in crime across England and Wales, according to official figures, suggesting the long-term decline in crime since the mid-1990s has resumed.

As near as I can tell, crime declines are always a surprise to the folks who look for answers solely in social trends. But Britain's continuing decline isn't a surprise to everyone. Europe adopted unleaded gasoline in the mid-80s, and EU countries all showed drops in lead emissions in subsequent years. In Britain, lead emissions began to decline about a decade later than the United States, but they made up some of that gap via a much steeper drop. So, to the extent that the crime decline is a function of less lead exposure among children, they're about five years or so behind us. This means they probably still have a few years of crime decline ahead of them.

So, you might be wondering, if Germany began seriously reducing lead emissions in the the mid-1980s, what impact might that have had on teenage criminality in the late 1990s, when children born in the mid-1980s became adolescents? Here's the relevant graph for Germany, from this source (g, .pdf):

TatjugendThe top line shows total criminality, the middle line criminality among German adolescents, and the bottom line among immigrants. Interesting, isn't it? The much smaller decrease you see among non-German offenders could well be explained by the fact that some percentage of them probably did not grow up in Germany.

Of course, the standard caveats apply that correlation is not causation, other factors are at work (especially the crime increase following reunification), etc.. But if you want to be convinced that lead exposure is a powerful (though, of course, not the only) explanatory factor, read Drum's piece -- and, more importantly, the studies it links to.

If this theory holds, it has to be one of the best pieces of news in a long time: because of a wise policy choice made decades ago, we will enjoy less crime -- and less of all the social ills and expense it causes -- for years to come. Kind of restores your faith in humanity, doesn't it?