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Ganesh Kulkarni

Apart from IQ, an environment and opportunities to put the IQ to right use are very important.

Eben Spinoza

Here's crude approximation of your point

IQ = IQg + IQe * (1+min(0,(class-uppermiddleclass)/uppermiddleclass))

IQ: Tested IQ value
IQg: Inherited genetic component
IQe: Environmentally contributed component
Class: household income
UpperMiddleClass: mean income of "upper middle class" households


As always a well written, thought provoking piece.

I just wanted to bring something else to the table though. The IQ tests require a certain level of knowledge.

Some of that knowledge isn't necessarily tightly linked to intelligence as to environment. For example if the tested lives in a neighborhood where exposure to certain types of environments or objects will never occur this has little to do with intelligence. And there are a certain number of questions on most IQ tests that assume the tested has been exposed to certain things.

I believe if you review a few of the most commonly provided tests you'll see that this is true.

That said, a rise in IQ points in middle or upper income brackets could be explained as increased exposure to a richer environment.

Just a thought.


As always a well written, thought provoking piece.

I just wanted to bring something else to the table though. The IQ tests require a certain level of knowledge.

Some of that knowledge isn't necessarily tightly linked to intelligence as to environment. For example if the tested lives in a neighborhood where exposure to certain types of environments or objects will never occur this has little to do with intelligence. And there are a certain number of questions on most IQ tests that assume the tested has been exposed to certain things.

I believe if you review a few of the most commonly provided tests you'll see that this is true.

That said, a rise in IQ points in middle or upper income brackets could be explained as increased exposure to a richer environment.

Just a thought.


It would be interesting to see if there is a correlation between siblings that are a few years apart. My brother and I, for instance, are almost 8 years apart, and our IQs are a full standard deviation away from each other (We've both been tested a few times... my IQ is around 150-155, his is around 135-140). He and I are alike in almost every way; we have similar tendencies when it comes to work, school, fun, etc. We both enjoy computer graphics, we're both good at math, we both underperformed in school because we didn't want to work hard (despite the fact that our parents were unusually active in making sure that we did work hard), and we both enjoy the same things. The only difference is that I'm a little bit better than him at everything.

I think I can attribute the difference to the fact that we were raised in very different environments. I lived in Pakistan until I was almost 4 years old, and then we moved to the US so that my parents could go to grad school. After they finished their master's degrees (soon after I turned 6), we went back to Pakistan (where we moved around a few different times) and my brother was born about a year and a half later. When he was 2, my parents came back to the US for more grad school and we've been here ever since.

In short, I've moved to different places and changed schools many times for various reasons. I grew up speaking two languages because I was shifting between countries. My brother, meanwhile, only speaks one language and hasn't moved around as often. I also got more attention when I was younger - not only because my parents only had one kid to take care of (instead of having to divide their attention between two), but also because we lived in a joint-family in Pakistan (my uncles/aunts lived in the same house) and I was the only child in the entire house.

Anyway, the story gets more complicated, but I'm sure that there are plenty of other families like mine. A study of those families would tell us a lot about the nature vs. nurture phenomenon.

As a side note, my mom's IQ is somewhere between mine and my brother's. My dad hasn't taken an IQ test, but I'm fairly confident that if he did, his IQ would be the lowest of the 4 (although it would still probably be at least 1.5-2 standard deviations above the mean).



I realize that this is a bit belated, but I have a few questions to raise about one of the points made in your May 16th 2005 article, “Brain Candy.”

In your review of Johnson’s Everything Bad is Good for You, you make the distinction between explicit and fluid knowledge. Books, according to your article and Johnson’s proposal, represent explicit knowledge while pop culture (particularly TV and video games) boosts one’s fluid intelligence. I’m concerned, though, that your claim that “When you read a biology textbook, the content of what you read is what matters” and your consequent assertion that “Reading is a form of explicit learning” are somewhat reductionistic. Perhaps this goes more for fiction than nonfiction, but I’d argue that when we read, for example, a novel like Hamlet or Moby-Dick or even a biology textbook, the goal is not pure retention of the plot or “explicit” content. Reading Hamlet or Moby-Dick can be just as disorienting as finding yourself in the “fully realized imaginary world” of Grand Theft Auto III or any contemporary video game, and can require just as much fluid intelligence. Moby-Dick, for example, comprises a range of narrative voices and styles (some chapters are written as theatrical scenes, some as chapters from a guidebook, some as encyclopedia articles) and Hamlet involves placing yourself in Elizabethan England (any novel – and any book for that matter – involves similar transposition to a new time, place, or frame of mind). The fluid intelligence needed to piece together the diverse strands of narrative in Moby-Dick and to make “order out of chaos” is extraordinary. And I wouldn’t imagine that most high-school teachers would like their students only to remember the obvious content of a certain novel once they’ve finished – remembering, for example, Captain Ahab’s last name is useless. Rather, instructors would like their students to be able to create “order” out of narrative chaos, and to be able to identify the larger themes pervading Hamlet, Moby-Dick or any work of fiction. Concerning nonfiction, wouldn’t teachers like their students to be able to organize the information in their biology textbooks into coherent theories of the biological world? While it is important to remember certain minutiae from any textbook, I think that what is more important (to students and teachers) is that the vast assortment of facts be synthesized in order to provoke thought. After reading a biology textbook, I’d like for my students not only to be able to name kingdom, phyla, class, etc. of certain organisms, but also to be able to tell me what they’ve noticed about the field of biology in general – what they’ve read between the lines of their textbook about the scientific method and mindset. Ultimately, knowing biological minutiae may not be as useful to students as understanding scientific reasoning (with which a standard biology textbook is not explicitly concerned). Reading both fiction and nonfiction, then, also involves fluid intelligence.

How would you respond to this argument, and would you argue consequently that contemporary fiction and nonfiction demand more of readers’ fluid intelligences today than they did a few decades ago? Would you (or Johnson, perhaps) find parallels between the increasing “smartness” in games and TV and contemporary “smartness” of fictional and nonfiction narratives that forces readers to more diligently read between the lines? Would you say that either of your own books employs challenging narrative structures? It seems that the episodic structures of both Blink and The Tipping Point are emblematic of pop culture’s “smarter” format, wherein individual anecdotes must be pieced together by the reader (or viewer, or player) in order to create “order” – or an overarching and useful theme – out of initially “chaotic” multiple strands of information. With more challenging narratives surfacing everyday – take Michael Ondaatje’s Divisadero, for instance, a book reviewed by Louis Menand in The New Yorker – are readers challenged more by narrative today than thirty years ago?


Craig Cypher


As a psychologist who does a great deal of assessments with children, there are a couple of issues that are at play when discussing a broad notion of "IQ". I'm glad you spent some time on the historical background of the Wechsler tests. One reason that I see for the rise in scores over time is that as time goes by the novelty of the Wechsler subtests decreases as their information becomes disseminated more widely and either consciously or unconsciously becomes a part of how we educate children. How we value/measure certain aspects of IQ becomes interconnected with our educational approaches in the classroom. This familiarity then increases IQ scores, not because children are getting smarter, but because we are "teaching to the test".

Also, anecdotally, IQ is not the fixed number statisticians and the popular press believe in. I have seen a great deal of fluidity in IQ scores in children that can be due to a number of factors, including defiance, psychosis, and trauma reactions, to name a few. An IQ is more like a snapshot of how the child is functioning cognitively at that moment rather than a fingerprint that will follow them forever without change. Therefore it is difficult to estimate to what degree we are looking at nature versus nurture in regards to IQ.

Also, the issues you state with IQ and a diagnosis of mental retardation have drastically affected our understanding of this diagnosis. These days you cannot base this diagnosis specifically on IQ (partially due to our understanding of how external and internal factors can affect performance on a test). So now we also look at measures of adaptive functioning such as daily living skills, communication, and social skills to get an estimate of developmental level alongside IQ. Only then can you affirm a diagnosis of MR.

As always, you present a very thought-provoking look at key topics in human development.



Flynn does not demonstrate that human intelligence is increasing. He shows that a flaw in one small area of nineteenth century tests prejudiced these tests in favour of urban modern populations. When the biased area of testing was removed the results indicated that human intelligence increase was minimal over a one hundred year period of radical environmental progress. The Flynn effect shows that environmental factors are of minimal significance.

Bernie Douglas


IQ is a culturally, socially, and ideologically rooted concept; an index intended to predict success (i.e., to predict outcomes that are valued as success by some people) in a given society. The items on these tests are devised impressionistically by psychologists, and simply mimic the psycholinguistic structures of schooling and middle class clerical/administrative occupations (Richardson, 2002), and are largely measures of achievement at various levels of competency (Sternberg et al, 1998a, 1999, 2003a). Alfred Binet, the IQ inventor, originally devised the test to screen children for educational difficulties, and made clear its conceptual foundations (See Richardson, 2002). Most traditional Intelligence tests measure specific forms of cognitive ability that are said to be predictive of school functioning, but do not measure the many forms of intelligence that are beyond these more specific skills, such as music, art, and interpersonal and intrapersonal abilities (Braaten and Norman, 2006). Nor do IQ tests, or any tests except dynamic tests (see Sternberg & Grigorenko, 2002a) that require learning at the time of the test, directly measure ability to learn. Traditional tests focus much more on measuring past learning, which can be the result of differences in many factors, including motivation and available opportunities to learn.

Although it has been shown that IQ tests have no clear link to what is commonly understood to be intelligence, which is still largely undefined (Schonemann, 1997), this has not stopped many enthusiastic advocates from arguing the IQ test’s practical merits for predicting academic and job success; some even going so far as to claim that black underachievement in these areas may be the result of inherently low IQ, while proceeding to ignore historical discrimination, poor methodology, criticism against heritability estimates and cultural differences between groups. For example Herrnstein and Murray (1994) claimed that a dysgenic trend exists in western societies that foresee the establishment of a “cognitive elite.” While other IQ advocates have argued that a general index of cognitive ability is the best single predictor of virtually all criteria considered necessary for success in life in the Western part of the developed world (Jensen, 1998; Schmidt, Ones & Hunter, 1992). It has also been promoted by many IQ advocates that the average IQ of an undergraduate (graduate) is expected to be no less than 115 (Ostrowsky, 1999; Gottfredson, 1998), while an IQ of 125 is expected for those with more advanced graduate level degrees (Gottfredson, 1998).

African-born blacks comprise 16 percent of the U.S. foreign-born black population and are considerably more educated than other black immigrants (U.S. Bureau of the Census, 2000). The vast majority come from minority white countries in East and West Africa (e.g. Kenya and Nigeria), and less than 2 percent originate from North or South Africa (World Factbook, 2004; Yearbook of immigration Statistics, 2003). In an analysis of Census Bureau data by the Journal of Blacks in higher education African immigrants to the United States were found more likely to be college educated than any other immigrant group (also see U.S. Bureau of the Census, 2000). African immigrants to the U.S. were also found to be more highly educated than any native-born ethnic group including white and Asian Americans (see also, Logan & Deane, 2003; Williams, 2005; The Economist, 1996). Between 43.8 and 48.9 percent of all African immigrants hold a college diploma (Charles, 2007; U.S. Census, 2000). This is slightly more than the percentage of Asian immigrants to the U.S., nearly “double” the rate of native-born white Americans, and nearly four times the rate of native-born African Americans (Williams, 2005; The Journal of Blacks in Higher Education, 1999-2000). Black immigrants from Africa also have rates of college graduation that are “more” than twice that of the U.S.-born population, in general (Williams, 2005).

In 1997, 19.4 percent of all adult African immigrants in the United States held a graduate degree, compared to 8.1 percent of adult whites (a difference of more than double) and 3.8 percent of adult blacks in the United States, respectively (The Journal of Blacks in Higher Education, 1999-2000). This information shows that America has an equally large achievement gap between whites and African immigrants as there is between white and black Americans.

In the UK, 1988, the Commission for Racial Equality conducted an investigation on the admissions practices of St. George's, and other medical colleges, who set aside a certain number of places for minority students. This informal quota system reflected the percentage of minorities in the general population. However, minority students with Chinese, Indian, or black African heritage had higher academic qualifications for university admission than did whites (Blacks in Britain from the West Indies had lower academic credentials than did whites). In fact, blacks with African origins over the age of 30 had the highest educational qualifications of any ethnic group in the British Isles. Thus, the evidence pointed to the fact that minority quotas for University admissions were actually working against students from these ethnic groups who were on average more qualified for higher education than their white peers (Cross, 1994; Also see, Dustmann, Theodoropoulos, 2006).

Dustmann and Theodoropoulos (2006) provide a first thorough investigation of educational attainment and economic behavior of ethnic minority immigrants and their children in Britain. They studied how British born minorities perform in terms of education, employment and wages, when compared to their parent generation as well as to comparable groups of white natives, using 27 years of LFS data (Labour Force Survey). In terms of educational attainment their results suggest a strong educational background of Britain’s ethnic minority immigrant population. In addition, they show that second generation ethnic minorities do better than their parents, and substantially better than their white peers. For both generations Black Africans topped the list in both years of schooling/educational qualifications and wages/employment.

Again, when comparing immigrants in the United States one quickly finds that the racialist models adopted by many Psychologists do not always predict outcomes in the way one might expect. For example, it has been shown that black immigrants born from Zimbabwe (96.7 percent), Botswana (95.5 percent) have high school graduation rates that far exceed all white immigrant and native groups. Further, the average Nigerian immigrant (58.6 percent) is eight times more likely to have obtained a bachelors degree than the average Portuguese born (7.3 percent) (Dixon D, 2006; Dixon D, 2005).

The African born in the United States are concentrated in management or professional and sales or office-related occupations. Of the employed population age 16 and older in the civilian labor force, the African born are much more likely than the foreign born in general to work in management and professional occupations as well as sales and office occupations (i.e. clerical/administrative). Additionally, the African born were less likely to work in service, production, transportation, material moving, construction, and maintenance occupations than the foreign born in general (Dixon D, 2006). In the UK a study by Dr Yaojun Li, from Birmingham University, and Professor Anthony Heath, from Oxford University, found that Africans are more likely to be in professional and managerial jobs than white British men, with a large proportion, about 40%, holding these positions (Li and Heath, 2006).

The above information "strongly" suggests that African born blacks may have IQs that are as much as a full standard deviation (15 points) above that of American born whites and slightly less than a full standard deviation “above” that of whites in the UK (see, Gottfredson, 1998; Ostrowsky, 1999; Richardson, 2002; Cross, 1994; Williams, 2005 for details). In the United States African born blacks and their offspring, exceed American born whites in most socio-economic indicators in ways that resemble the gaps seen between native born white and black Americans (Le, 2007; Le, 2007). If these gaps can not be said to have originated because of institutionalized racism or historical discrimination against whites, then why do whites fare so poorly on those more cognitive SES indicators (e.g. educational attainment/occupational status)? The differences in educational attainment between African born blacks and native born whites are particularly striking and could, based on “IQist” like thinking (eg Jensen), be indicative of genuine underlying intelligence differences between the populations; a difference in favor of African born blacks. Higher cognitive indices are said to be predictive of more educational achievements and more education is predictive of higher intellectual outcomes (e.g., Brody, 1997; Ceci & Williams, 1997).

Furthermore, it should be noted that this group must also operate within a cultural framework that is not its own, and one that is typically hostile toward blacks - Further bolstering the argument of underlying intelligence differences in favor of African born blacks; that is, if one chooses to adopt a racist stance.

African born Blacks tend to be concentrated in higher level occupations, considered more cognitively challenging, than the average occupation of either American or British born whites (Dixon, 2006; Li and Heath, 2006). According to IQ advocates, and social Darwinists this should also be indicative of higher level intelligence (e.g. Gottfredson, 1986). Moreover, most IQ tests in popular use today were designed specifically to predict academic success and occupational status. Thus, it could be argued, based on this well document research, that the west’s “Cognitive Elite” -- eagerly discussed in Herrnstein and Murray’s (1994) pseudo-scholarly work “The Bell Curve” -- might be better described as black men and women from Africa, if not simply as non-whites from aboard.

Something else to note, according to the New York Times (Roberts, 2005), for the first time in history more blacks are coming to the United States from Africa than during the slave trade. Since 1990, according to immigration figures, more Africans have arrived voluntarily than the total who disembarked in chains before the United States outlawed international slave trafficking in 1807. In other words: black African achievements can not simply be dismissed as those of a “small group” of elites entirely unrepresentative of the greater continent. Moreover, the Academic attainment levels and occupational achievements of African blacks are documented in the UK (Li and Heath, 2006; Dustmann, Theodoropoulos, 2006) as well as in Canada (Guppy and Davies, 1998; Boyd, 2002).

Crawford-Nutt (1976) found that African black students in westernized schools score higher in progressive matrix scores, a westernized concept, than American white students. The study was meant to examine the cultural-perceptual differences between groups, and demonstrated that one’s performance on western standardized tests may actually correspond more closely with quality and style of schooling than other factors. Super (1976) found that African infants sit and walk earlier than do their white counterparts in the United States and Europe. Black children in particular tend to show more advanced psychomotor development than European children, a finding that has been evidenced in a number of different studies. Some scholars argue that “African babies actually seemed to have been born at a more advanced stage of development, since many of their activities at less than a week corresponded to those performed by European children aged four to eight weeks” (Wilson, 1978). Others believe that the more advanced psychomotor skills demonstrated by black children may be better explained by various environmental factors.

In the United States, when matched for IQ with Whites, American Blacks show superior “Working Memory” (Nijenhuis et al., 2004); a finding that can not simply be explained as a mere byproduct of their educational experience or past learning, as African Americans are typically taught by less qualified teachers than their white counterparts and are provided with less challenging work (Hallinan 1994; Diamond et al., 2004). In Chicago, for example, the vast majority of schools placed on academic probation as part of the district accountability efforts were majority African-American and low-income (Bryk 2003; Diamond and Spillane 2004).

Finally: In a study conducted in the Caribbean, one that seemingly bypassed socio-cultural influences, Tizard and colleagues compared black and white orphans who had all been raised in the same highly enriched institutional environment. At five years of age, white children had IQs of 103, black children had IQs of 108, and children of mixed race had IQ of 106 (Tizard et al, 1972; Flynn, 1980).


Racial differences have been noted in the rate of pineal calcification as seen in plain skull radiographs. In Caucasians, according to studies, calcified pineal is visualized in about 50% of adult skull radiographs after the age of 40 years (Wurtman et al, 1964); while other scholars argue that Caucasians, in general, may have rates of pineal gland calcification as high as ¬60-80% (King, 2001). Murphy (1968) reported a radiological pineal calcification rate of 2% from Uganda, while Daramola and Olowu (1972) in Lagos, Nigeria found a rate of 5%. Adeloye and Felson (1974) found that calcified pineal was twice as common in White Americans as in Blacks in the same city, strengthening a suspicion that there may be a true racial difference with respect to this apparatus. In India a frequency of 13.6% was found (Pande et al, 1984). Calcified pineal gland is a common finding in plain skull radiographs and its value in identifying the midline is still complementary to modern neuroradiological imaging.

There is a surprising rarity of calcified pineal gland on skull roentgenograms in West Africans. Adeloye and Odeku (1967) working from a hospital where an average of about 2,000 skull roentgenographic examinations were done every year, encountered less than 10 cases of roentgenologically visible calcified pineal gland in the Neurosurgery unit during a period of 10 years. In the tasks of daily life, calcification in the pineal gland affects our brain's ability to function. Calcification of the pineal gland is shown to be closely related to defective sense of direction (Bayliss et al, 1985). In a tricentre prospective study of 750 patients lateral skull radiographs showed that 394 had calcified pineal glands. Sense of direction was assessed by subjective questioning and objective testing and the results noted on a scale of 0-10 (where 10 equals perfect sense of direction). The average score for the 394 patients with pineal gland calcification was 3.7 (range 0-8), whereas the 356 patients without pineal gland calcification had an average score of 7.6 (range 2-10). This difference was highly significant (p less than 0.01) (Bayliss et al, 1985). Also, the effects of disturbed sleep and memory are well documented.

The Pineal Gland looks like a miniature pine cone and is situated in the middle of the brain beneath the two brain halves, surrounded by the ventricles, under the roof of the corpus callosum (cross-beam connecting the 2 brain halves). This active organ has, together with the Pituitary Gland, the next highest blood circulation after the kidneys. The pineal gland is responsible for the production of melatonin, a hormone that is secreted in response to darkness, and is also the site in the brain where the highest levels of Serotonin can be found (Sun et al, 2001). In the pineal, 5-HT (Serotonin) concentration displays a remarkable diurnal pattern, with day levels much higher than night levels. Serotonin plays an important role in sleep, perception, memory, cardiovascular activity, respiratory activity, motor output, sensory and neuroendocrine function.

One study has shown a reciprocal relationship between the pineal and pituitary gland so that if the pineal is impaired, it affects the pituitary (Karasek and Reiter, 1982). This has a whole cascade of effects on the other glands and hormone production. The pituitary gland is an endocrine gland located at the base of the brain, and produces hormones, such as growth hormone, luteinizing hormone, follicle stimulating hormone and thyroid stimulating hormone.

Pineal indolamine (e.g. Melatonin/Serotonin) and peptide hormones influence immune functions. Melatonin, in particular, increases immune memory while T-dependent antigene immunization stimulates antibody production. According to Maestroni (1993), in an article published in the Journal of Pineal Research a tight physiological link between the pineal gland and the immune system is emerging that might reflect the evolutionary connection between self-recognition and reproduction. He goes further, mentioning that Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin appears to have an immunoenhancing effect. An interesting observation is the apparent protection from autoimmune diseases in areas of West Africa and especially in places where malaria is a problem (Greenwood, 1968).

Scholars believe the reduction in melatonin with age may be contributory to aging and the onset of age-related diseases. This theory is based on the observation that melatonin is the most potent hydroxyl radical scavenger thus far discovered (Reiter, 1995). Prominent theories of aging attributes the rate of aging to accumulated free radical damage (Proctor, 1989; Reiter, 1995), and as Caucasians have higher rates of pineal calcification, which produces melatonin which is a vital free radical scavenger, some suspect that people of European descent may actually age faster than those from other continents.

Pineal gland calcification has also been implicated in the onset of Multiple sclerosis. Multiple Sclerosis is an autoimmune disease that affects the central nervous system (CNS). The CNS consists of the brain, spinal cord, and the optic nerves. Neuroradiological research has shown the pineal gland to be involved in the pathophysiology of Multiple Sclerosis. In a 1991 study by Sandyk R, and Awerbuch G.I published in the International Journal of Neuroscience, it was shown that Pineal Calcification was found in 100 % of MS patients. The strikingly high prevalence of pineal calcification in Multiple sclerosis provides indirect support for an association between MS and abnormalities of the pineal gland (Sandyk and Awerbuch, 1991). Multiple Sclerosis tends to affect Caucasians disproportionately, and is nearly unheard of in Africa and is rare among African Americans. A high prevalence of pineal calcification has also been linked to bipolar disorder.

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U.S. Bureau of the Census, 2000
World Factbook, 2004; Yearbook of immigration Statistics, 2003

William B. (2007). Quantification of Ca2+ binding to melanin supports the hypothesis that melanosomes serve a functional role in regulating calcium homeostasis. Pigment Cell Research. 20(2):134-139, April 2007.

Williams D.R. (2005). The Health of U.S. Racial and Ethnic Populations. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences 60:S53-S62 (2005)

Wilson A. (1978). Developmental Psychology of the Black Child. Africana Research Publications (December 1978).

Wurtman, R. J., Axelrod, J., and Barchas, J. D (1964). Age and enzyme activity in human pineal. Letter to the editor. 7. C/in. Endocrinol. & Metabol., 1964,24, 299-301

Bernie Douglas

GLADWELL – here is a letter I wrote to a friend of mine who teaches Psychometrics in Germany. He is also in serious doubt about heritability estimates. I and he both share a close relationship with Professor Peter Schonemann (Psychometrician). The letter deals exclusively with Heritability*

I, by the way, study Anthropology.


Another problem with heritability estimates is that they are related to tests that are both culturally bias, and according to many researchers, provide results that are unstable. It does not make much sense to assign a heritability estimate to a test that may not measure the same thing across individuals, or over time. For example, Carraher, Carraher, and Schliemann (1985) studied a group of Brazilian children and found that the same children who are able to do the mathematics needed to run their street businesses were little able to do school mathematics. Greenfield (1997) found that it means a different thing to take a test among Mayan children than it does among most children in the United States. The Mayan expect that collaboration is permissible and that it is unnatural not to collaborate.

One can not simply assign a heritability estimate to something that means different things to different people –variances in scores may be caused by anything; socio-cultural/cultural-perceptual differences, informational comprehension, interpretational differences, or even, lack of interest. It has also been shown that tests that are highly novel in one culture or subculture may be quite familiar in the next. That is, even if components of information processing are the same, the experiential novelty to which they are applied may differ (Valsiner, 2000).

Scores on IQ tests may vary by as much as 15 points from one test to another (Smith, 1991). In one study, ninety-nine school psychologists independently scored an IQ test from identical records, and came up with IQs ranging from 63 to 117 (Sattler, 1982). According to Thomas Sowell (an economist who often writes about IQ) IQs have varied by 40 points. One of the kids in a group that he had worked with went from a "mentally retarded" IQ range to an above average range inside of a year (Sowell, 2002). According to Capron et al. (1999) “the test retest reliability of an IQ test is less than 1. There-fore, the score of an individual on the same IQ test is unlikely to be exactly the same on two different occasions.” The logical question to ask here: Should heritability estimates also differ from one test to another, or depending on who is marking the test?

The Berkeley Guidance study (Honzik, Macfarlane & Allen, 1948) investigated the stability of IQ test performance over 12 years. The authors reported that nearly 60% of the sample changed by 15 IQ points or more from 6 to 18 years of age. A similar result was found in the Fels study (Sontag, Baker & Nelson, 1958): Nearly two thirds of the children changed more than 15 IQ points from age 3 to age 10. Rees and Palmer (1970) combined the data from five large-scale longitudinal studies, selecting those participants who had scores at both age 6 and age 12 or at both age 12 and age 17. They found that about 30% of the selected participants changed by 10 or more IQ points. Flynn (2001) and Ceci (1990, 1997) also argue the effects of learning and schooling on IQ. For example Ceci and Williams (1997) suggest that IQs respond to adequate intellectual challenges and grow as an outcome of successful educational experiences.

The inventors of the IQ did not believe they were measuring fixed intelligence. Alfred Binet had a radical malleable theory of intelligence. He believed that students' intelligence could be transformed through education. Many developmentalists have adopted a view of reciprocal causality between cognitive development and education: Higher cognitive indices are predictive of more educational achievements and more education is predictive of higher intellectual outcomes (e.g., Brody, 1997; Ceci & Williams, 1997).

Carol Dweck has also done research showing that people who hold beliefs about fixed abilities tend to underperform academically when compared to those who believe in intellectual development. In this sense it is very counterproductive, even dangerous to promote the idea of fixed abilities.

Turkeimer (2003) shows that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse (Turkheimer et al., 2003).

Peter Schonemann (our friend) has done a lot of empirical studies dealing with both heritability and IQ and has demonstrated that most heritability estimates are completely worthless on mathematical grounds (e.g. Schonemann, 1997). Indeed, Peter once requested Plomin’s raw data through the help of a congress woman, and Plomin refused! I think there is something odd about that. To me it is obvious; there is dishonesty among IQ and heritability researchers. There have never been any genes shown to correspond with IQ; Behaviour Geneticists are simply drawing conclusions.


Capron C., Adrian R. Vetta, Michel Duyme, and Atam Vetta (1999). Misconceptions of biometrical IQists. Current Psychology of Cognition 1999, 18 (2), 115-160

Carraher, T. N., Carraher, D., & Schliemann, A. D. (1985). Mathematics in the streets and in schools. British Journal of Developmental Psychology, 3, 21–29.

Cole, M., Gay, J. Glick, J.A., & Sharp, D.W. (1971). The Cultural context of learning and thinking. New York: Basic Books

Turkheimer, E., Haley, A., Waldron, M., D’Onofrio, B., & Gottesman, I. I. (2003). Socioeconomic status modifies heritability of IQ in young children. Psychological Science, 6, 623–628.

Greenfield, P. M. (1997). You can’t take it with you: Why abilities assessments don’t cross cultures. American Psychologist, 52, 1115– 1124.

Sattler, J. (1982). Assessment of Children’s Intelligences and Special Abilities. (Allyn & Bacon, 1982), 60.

Schonemann P.H. (1997c). Models and muddles of Heritability. Genetica 99, 97-108.

Smith, C.R., (1991). Learning Disabilities: The Interaction of Learner, Task, and Setting. (Allyn & Bacon, 1991), 63.

Sowell, T (2002). The IQ exemption. Townhall.com February 27, 2002

Valsiner, J. (2000). Culture and human development. Thousand Oaks, CA: Sage

Michael Wheeler

I am very intriqued with social-genetic argument around IQ. I am a pharmacologist/ geneticist who has been interested in the "gives and takes" of the nature verses nurture debate.
With the recent advances in the study of epigenetics , that is how environment influences our genes, has anyone that you know of looked at the epigenetic factors associated with generational IQ changes?
There are remarkable studies that show that rodent dams who have nutritional deficiencies pass on the biochemical disfuctions to their offspring and to their offspring (ie, the environmental effect persists across multiple genetic passes).

I have always thought that the IQ scale was soft on the lower end, meaning that it was easier to move up the IQ scale if you started at the lower end verses making the same upward progress if you had a higher starting point.

Could it be that once a person arives at some IQ threshold, there are genetic (or epigenetic) switches that become fixed and transferable. Whereas, those below the threshold have not yet been epigenetically imprinted?

I don't know enough of the ins and outs of the IQ debate to know whether this epigenetic paradigm fits the argument.

Any thoughts?

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medical videos research news

good topic


Your terms are so broad and indefinitive that I'm not sure what you’re trying to argue. You take these terms and theories (that are often times antithetical to one another) and string them together. The term RACE and IQ are no longer consider legitimate terms by scientist and researchers.

Stephanie P.

First, let me say I loved "The Tipping Point" and I am enjoying your blog. I am a psych. grad student and I really appreciate the way you consolidate information.

In response to the line: "and that end of the scale, Turkheimer's data suggests, environment doesn't play a big role"- The environment's influence on IQ is just as potent for the middle to upper SES baby as it is for the low SES baby. A high SES baby put in an understimulating environment with poor schools, stress, poor nutrition, unhealthy living conditions, etc. will likely test into a low average IQ range, at best.
There is less room for variability in the middle to upper class group, because these kids are probably getting pretty accurate test results. They have been in an enriched environment all along that provides ample opportunities to grow in the areas the IQ tests put so much stock into- namely Verbal Comprehension. I am pretty sure you agree with this point, but it wasn't completely clear to me from your essay.
Also, in my opinion, the flaws of IQ measures should always be considered in these discussions. Scores are best reported as ranges- that is, confidence intervals. Scores change because tests are not perfect. Even if IQ was 100% genetically determined, people would receive different scores at different times. IQ is a construct, not something that can be measured with absolute certainty, no matter how standardized the measure.

Thanks for hosting such an important conversation. The nature vs environment (thank you J.R. Harris) debate is always a fun one.


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Side1: IQ from genes.
Side2: IQ from nuture (environment).

More precisely, side 2 data seems to be saying that moving the environment up to middle class affects IQ while moving up further economic rungs has little impact.

And of course, obviously, both sides are right. Common sense and human experience would support both.

I would be more sympathetic to those using Side 2 to support their policy goals if they introduced policies that actually worked at the underlying problem that Side 2 data implies: "kids growing up in poverty".

For instance, other data, some just announced today, shows pretty conclusively that the leading cause of kids in poverty is divorce and out of wedlock births.

So Side 2... Propose some "aggressive social programs" that might actually work.

How about instead of "Head Start" why not "Stay Married". Instead of "Sleep Around , We Will Make Him Pay", why not "It might be wise to be married first" programs?

Or get really crazy and do other things known to eradicate poverty... lower taxes,streamline regulation, make it easier to hire, get rid of the minimum wage.

Like I said, totally crazy things but that just might work...




In response to Steve Sailor's comments, I am not sure if Murray, et.al. actually have followed the data wherever it lead them. After taking a whole class on the issue during graduate school, and going through the data and the methods in "The Bell Curve" book with Prof. Mel Kohn of Johns Hopkins University, I came up with different conclusions regarding genetics and intelligence using the same data, but correcting for a couple mistakes in coding data. For instance, one often uses "dummy variables" to record responses yes/no, such as Married (yes/no). Murray's trouble was that they overused dummy variables that overlap in meaning (For instance, poor/rich and single-parent/two-parent are both dichotomies are related to each other and can be used together, only if you correct for their interrelatedness in analysis. Unfortunately, Murray and Co. did not.) only on the genetics side of the argument, thereby giving a higher correlation to genetic predisposition than to other interpretation.

Yet even with this in mind, I find the whole question slightly misleading from the start because it does false dichotomize the issue of nature v. nurture.


IQ is like a Computer's ability. You have the processor that is fixed but you can overclock it analogous to taking nootropics, you have the base Operating System that is pretty much fixed and you have the software to tell the computer what to do.

There is not much you can do when the child is born - it is after the fact, but the brain makes new connections since birth to adulthood and here the environment will define what can be achieved.

Even during conception, the influence of DHA on fetus can be substantial even though the parents DNA is fixed.

There are so much flexibility that the IQ should not be considered fixed from the parents DNA. Nature gave us that flexibility, otherwise we would still be like other animals.

Barbara Saunders

The assertion "if IQ were genetic it would be fixed at birth" is nonsense. A lot of things that are genetic are not fixed at birth but potentiated by lifestyle.

eric F

From an elementary reaction kinetics perspective, IQ exhibits a shift in rate-limiting steps. At low levels of stimulation, the amount of stimulation in the surrounding environment drives the ability to acquire and process knowledge, regardless of inate biological ability. At reasonably high levels of stimulation, the rate at which information can be processed or acquired is determined by the biology of the individual, with a strong genetic component.

Presumably the "reaction" is a process that results in the formation of new neuronal connections in the brain. Neronal contacts increase with stimulation, but also must have an inherent limiting rate of formation.

Wendy Ragiste


Thank you for an excellent discussion of an issue that can never be resolved to everyone's satisfaction (no matter where the truth may lie)


What an odd discussion. It feels very much like having wandered from the early 21st century into an 18th century debate about the mysterious causes of illnesses, or a salon musing on the provenance of "dragon's bones" (dinosaur fossils).

It's worth noting that despite the paradigm shock that quantum mechanics introduced into physics in 1927, an awful lot of people still think of electrons as point-like things whizzing orbitally around a nucleus. Quaint, but more than 80 years out of date.

To the discussion at hand: it feels like listening in on a number of cartesian-caged cyclops (we focus on one thing at a time out of two, okay?!) with an addictive zero-sum thinking habit (whatever is gained by one side is lost by the other). Not from everyone for sure, by any means, but from enough folks to make one decidedly nervous. I'll be brief, as this is - mostly - just an observation:

1. Our present understanding of DNA has wrought some brutal clarifications in age-long 'race' myths and biases. One, there are no (as in none) scientific bases, facts, concepts, etc. for the notion of "race." No objective evidence can be marshaled to demonstrate "race" as an objective scientific reality.

No mainstream scientist of standing can point at or towards any such evidence and there exists, not even mythically, any common misconception of it (there are, of course, numerous varieties of misconception). "Race" doesn't scientifically exist.

Both DNA and epigenetic evidence are unrelenting in this respect: humans are one species (of great variation to be sure, as recent discoveries in copy number variation show, indicating a DNA-level similarity of ~95%, where it was once reckoned to be ~99%), but not a whiff of this ~5% variation constitutes a set of genetic and/or epigenetic features that can be packaged into a neat observable and differentiating portmanteau called "race".

Today, as in current scientific thought, we talk about 'population genetics' - and can categorize populations of people based on genetic features as determined with statistical population genetics methods. No single one, or any group, of these features qualifies as (or is even deterministic and stable enough) to bear the nice box unscientifically bandied about as "race." (One of the practical challenges in developing "controlled?!" "ethnic" bombs).

Using, for example, skin color as a proxy for the fictional scientific concept of race is as 'scientific' as using 'eye color' as a proxy for race - and then calling the offspring of a green-eyed person and a blue-eyed person "biracial." And it's unscientific in exactly the same way that calling the offspring of a dark-hued Kenyan and a Victorian-pale skinned Kansan woman 'biracial' would be. Hello 2008! (Give me a break, scientifically!). Whatever your pro or con biases are socially.

Maybe the "in the head distinctions" that create the - NOT scientific - but socioeconomic and cultural-political psychological constructs of "race" (where and how can we draw a line between "them" and 'us"?) will, like the still unfamiliar notions of quantum mechanics, take 80 or more years to seep into the mainstream culture. Whereupon, no doubt - at such a rate - awareness will dawn among the many in sufficient time for folks to get over the widening shock that it's not been a government conspiracy (or an alien one), that we (humans) share, for example, some 40% of our DNA with bananas! (scientific fact).

2. In my opinion, the nature vs nurture debate is a set 'em up head-fake as unimaginative as it is ancient. And tired. It's inaccurate in a complex, adaptive systems reality of many-valued logics, present neurobiology facts, and ways of viewing and evaluating IQ other than with a - drum-roll please - binary, excluded-middle, cartesian thinking and analysis. It seems - as is naturally and usually a present habit (there being no 'training' upgrade widely available from the culture as yet) - that the mass of folks talking about matters like 'IQ' and "race" are busy beating on ideas and perceptions with the rickety and increasingly vintage facts, concepts and logics that pre-Victorian sociobiology and Aristotelian thinking have held hostage in the basement of western thinking for too many years. Isn't time to perhaps unlearn a few fixities whose time has passed? And look afresh at what's being discovered?

There's been, for example, in my opinion, enough wider/deeper thought along the interacting three-factored lines of nature (genes), nurture (environment including culture), and notion (initial, inherent, and ongoing complex systems dynamics), to kick aside this tired, dusty, and lazy zero-sum - and not so useful - 2-sided way of cutting up the world in this illusory way.

It's been some 90+ years already since Albert Einstein showed that our minds follow different rules than the “real” world does. In 1915, in the General Theory of Relativity, Einstein disproved the universality of Euclidean geometry that had been accepted until then without question as the underlying structure of the universe. Similarly, in 1936, John Von Neumann, along with Garrett Birkhoff, published a paper that, in laying the grounds for quantum logic - along with a later reformulation of quantum mechanics done with Wigner - disproved the universality of both classical Aristotelian logic and its modern symbolic form, which until then had been accepted without question as a natural reflection of the nature of reality. Some things really change. A lot.

Von Neumann's key observation? A state of being is an experience. A description of a state of being is a symbol. Symbols and experiences do not follow the same rules. The rules that symbols follow they called classical logic. The rules experience follows they called quantum logic.

Further dynamiting the classical foundations of mathematics - and any last refuges we might have claimed as to the classical dimensions or certainty of reality - Kurt Godel, Alan Turing and Gregory Chaitin, in various works, showed that, respectively, most mathematical truths can never be proved (incompleteness), most things can never be computed (uncomputability), and that some mathematical statements are true for no reason, they're true by accident (randomness).

Kaboom! Time to let in the fresh air of widening and deepening horizons in how we see, you'd think. Well, not yet, it's clear, in the either/or binary thinking world of (as Americans seem to see and relish in it) prehistoric facts and feelings about "IQ" and "race".

3. Which brings me to my last and brief observation: Why the heck are we discussing/arguing about bankrupt and fictional concepts like "race" and "IQ" instead of discussing the more recent brain, cognitive, systems, and neuro-you name it -studies (there are more than a few), that - like quantum mechanics - illuminate ever more brightly the fact that our current notions of intelligence, brain function, plasticity, performance, IQ, etc. - at least as on display here -are, at best, quaint?

Is this really a socio-cultural dispute in disguise, using Grandma's favorite china for weapons? Albeit, adjusted for inflation, cultural trends, terminology, and the like? And if "you" win, does that mean you can really feel "better" about social budgets, fossilized sociocultural thinking and behaviour, and all the socioeconomic goodies that have gone and still go with that?

As I started - and I'll stop here - this is a really odd discussion. Too much like a Star Trek episode where the Enterprise and Co. drop in on a "D-Class" civilization still brutally intent on determining social status and performance based on the results of a centuries old war with ancient technology that one side won and the other never recovered from, and swearing to the death that it's all fair in the 'Almighty's' name. And done in his image too.

Like I said, strange. Maybe Alvin Toffler said it best: "The illiterates of the 21st century will not be those who cannot read and write, but those who cannot learn, unlearn, and relearn.”


Our modern society's fetish with "intelligence" is at display here. Wouldn't it be a different world if we were equally concerned with compassion and kindness, or placed those qualities at the same level as intelligence?

No Name

Sailer does seem rather pathetic through out the comments. The flag-waving for all things white bread must have tuckered the little guy out...

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