Are Humans Getting Dumber (or is it Just Journalists and Sociobiologists?)

Human intelligence is on the decline, according to the Huffington Post, writing about a recent study suggesting that westerners have lost 14 I.Q. points since the Victorian Era. Study co-author, Dr. Jan te Nijenhuis, professor of work and organizational psychology at the University of Amsterdam, says that because women of higher intelligence tend to have fewer children than do women of lower intelligence, intelligence is being selected out of the affluent populations of the west.

The Kallikak family, promoted by eugenicist Henry Godard as proof of heritability of idiocy

There are probably many on the Left who would like to jump on these findings as an explanation for everything from the high numbers of Americans who believe in creationism or who deny climate change to the continuing popularity of the Republican Party among people devastated by their economic policies.

The problem is that this study and all others pointing to a causal relationship between birthrates and IQ are seriously flawed. Indeed, even the claim that IQs are declining is suspect.

Alfred Binet

Let’s start with the fact that the IQ test, developed by Alfred Binet, in France, wasn’t even created until 1903, two years after Victoria’s death, making it exceedingly difficult, if not impossible, to make a valid comparison of Victorian and modern Westerners’ IQs. Furthermore, the original test emphasized memorization, vocabulary and questions about appropriate behavior, none of which has much to do with intelligence. Even modern versions of the test contain some of these types of questions. IQ tests also tend to have a class bias, as well as cultural and linguistic biases (e.g., questions about appropriate behavior depend on one’s cultural background).

To address this problem, te Nijenhuis used proxies for intelligence (comparing a variety of different tests for which data does exist going back to 1884). However, he chose a very weak proxy, reaction time, which he presumed was an accurate proxy for intelligence since reaction time reflects a person's mental processing speed. However, it is not necessarily true that a person who has a quick visual reaction rate also has a quick mental processing rate for math, puzzles or other types of problem solving.

Another problem with the research is that it lacked valid controls, drawing into question the validity of the comparisons. Supposedly the Victorian and modern experiments used a similar test for reaction times, but they used different instruments for measuring the results. Thus, the average late 19th century reaction time of 194 milliseconds might have actually been much closer to or even slower than the average 2004 reaction time of 275 milliseconds had researchers used the same equipment and methods.

 

1920s pseudoscientific image trying to connect brain types to criminality

Bad Science in Service to Race and Class Prejudice

The researchers also used data collected by Francis Galton (Darwin’s cousin), who coined the term eugenics, which included the idea that poor people were poor due to their inferior intelligence, which they presumed was due to their “bad” genes, and that the affluent were wealthy due to their good genes. This pseudoscience was used to justify government interventions promoting or limiting birthrates among different races and social classes, forced sterilizations in many countries, including the U.S., infanticide, and genocide, as practiced by the Nazis. Thus, Galton had a significant bias going into his research, specifically an Experimenter’s Bias (i.e., observing what you expect, rather than what actually occurs). In Galton’s case, he would be expecting white and affluent people (who also had smaller families) to be smarter, and could have inadvertently designed tests that would have given him these results.

 

Image from Wikipedia, based on Galton's Ideas

Te Nijenhuis’s research suffers from some of these same problems, particularly the presumption that intelligence is essentially a heritable trait (i.e., passed through the DNA), a presumption still shared by a large number of scientists as well as the lay public, despite a lack of credible data to support this idea (more on this below). However, his race and class prejudices also come out in his belief that “high-IQ people are more productive and more creative,” and his nostalgia for the flourishing of creativity and brilliance of the Victorian era. He uses the term dysgenics in his work, a term that is often associated with the eugenics movement thanks to the work of Richard Lynn, who argued in his book Dysgenics: Genetic Deterioration in Modern Populations, 1996, that human genetic health was declining because criminals have higher birthrates than the rest of the population (there is no evidence they have higher birthrates and it is unlikely that criminality is heritable), leading many, including Lynn, himself, to renew calls for eugenic policies.

 

Many states had similar sterilization laws, resulting in 10,000s of forced and voluntary sterilizations in the 20th century

Genetics is Not Destiny

While large numbers of scientists and the lay public believe that intelligence is highly heritable, there is no conclusive evidence for this. Indeed, estimates of the heritability of IQ range from as low as 40% to as high 90%, suggesting that intelligence is at least partly, and possibly quite significantly, influenced by factors other than DNA. Part of the reason why there is so much controversy over the degree to which intelligence is heritable is that no genes for intelligence have been positively identified, (though recent research has located positions on certain chromosomes where some genes related to intelligence might be located).

Intelligence and IQ, like most phenotypes (traits), are influenced not only by DNA, but by environmental influences and sometimes even by random events that occur during development. ABO blood type, for example, is 100% heritable, meaning that it is determined entirely by the DNA inherited from the parents and no environmental factors influence it. Human height is around 94% heritable. However, even a relatively high heritability of 94% is not sufficient to presume a cause and effect relationship between DNA and a particular phenotype. A person with tall parents could easily wind up being short if he does not have access to a diet rich in protein and calcium. Indeed, when one considers stereotypically short ethnic groups, most come from regions of the world with high levels of malnutrition in which protein and calcium are relatively scarce. Similarly, average human heights in Western Europe and the U.S. have increased 4” over the past 150 years, according to Scientific American, most likely because of improvements in childhood nutrition that occurred during that period.

There are many environmental factors that influence learning, memory, and even reaction time. Memory and reaction time, for example, can be improved with certain exercises and practice. Exposure to high levels of stress can impair memory and learning due to overexposure to the stress hormone cortisol (see here, here and here). How parents communicate with infants and children can influence the size and depth of their vocabularies (see here and here), which can influence how they comprehend phenomena and their ability to solve problems. Malnutrition and hunger can lead to cognitive impairment (see here, here and here).

Another problem with te Nijenhuis’ findings is that low IQ parents, while they may have larger families, do not necessarily produce low IQ children (“Resolving the debate over birth order, family size, and intelligence,” Rodgers, Joseph Lee; Cleveland, H. Harrington; van den Oord, Edwin; Rowe, David C. American Psychologist, Vol 55(6), Jun 2000, 599-612).

Confusing Correlation With Causation

Despite the fact that te Nijenhuis is a scientist, he apparently has difficulty distinguish between correlation and causation. There is considerable evidence that populations with higher IQs have lower birthrates. Thus, I.Q. and birthrates have a negative correlation (i.e., as one goes up, the other declines). However, this does is not evidence that one is caused by the other. Rather, they could both be products of one or more other causes or the correlation could simply be a coincidence.

Social class also correlates with both birthrate and intelligence. Wealthier women tend to have fewer babies. There are several logical explanations for this such as delaying motherhood to pursue college and career, for affluent women, versus having children earlier and more often among poor women because children can help with the farm work and care for you in your old age.

Wealthier people, in general, also tend to have higher IQs. However, this may have far more to do with environmental and social factors (e.g., access to better nutrition and healthcare, better quality schools, being read to more often as babies and toddlers, less stress, greater access to enriching extracurricular activities, like travel abroad, summer school and camps) than genetics. Indeed, two studies done in Texas and Minnesota seem to support this. According to the studies, the correlation in intelligence between mothers and biological children were not only quite low (0.20 to 0.34, respectively), but not much different than the correlations between mothers and adopted children (0.22 to 0.29, respectively), suggesting that social and environmental factors likely had a greater influence on children’s intelligence than the genetics of their mothers (Richard Lewontin, Not In Our Genes). In other words, intelligent people may very well be intelligent more as a consequence of their social class privileges than their parents’ genes.

Passing the Buck, Or Robbing Peter and Paul?

The California Superintendent of Public Instruction Tom Torlakson, the State Board of Education, the state Department of Education and the attorney general's office all want a judge to drop a lawsuit brought against the state by the ACLU for illegally charging students to participate in classes and extracurricular activities, according to a recent report by California Watch.

It is a classic legal pissing match in which none of the parties are willing to accept responsibility, let alone acknowledge or address the actual problem: educational equality does not exist, nor has it ever existed, primarily because of inequities in school funding and a wealth gap that gives affluent students a large educational advantage over their lower income peers.

In the lawsuit, the ACLU claimed widespread instances of school districts charging parents and students exorbitant and improper fees for books, educational materials and extracurricular activities, thus denying lower income students access to many educational opportunities available to their more affluent peers, like athletics, arts and Advanced Placement classes.

While this does indeed happen and probably contributes to the achievement gap and inequality, the implications of the lawsuit are troubling and create their own problems. Forbidding the charging of fees, for example, does nothing to improve the financial status of lower income students. It does not get them to school well fed, provide for their medical needs, make sure their parents read to them as babies, or receive support at home for their academic progress. Likewise, schools that lack the resources and parental donations may be forced to stop offering expensive courses and extracurricular activities entirely. Furthermore, if the lawsuit is interpreted literally, it would forbid teachers from requiring students to purchase such basic and essential supplies as pencils and notebooks.

The state is not pushing back against the lawsuit for any of these reasons, however. Rather, they simply don’t want to be hassled or held accountable. They are placing the blame on school districts and saying it’s the legislature’s responsibility, thus passing the legal buck, but ignoring the much larger problems of the millions of students who cannot afford the materials necessary to succeed in school and the thousands of schools that cannot afford to provide these materials. Inequity between schools is thus ignored, as are inequities between students in terms of their readiness for school.

In response to the lawsuit, legislation was written by Assemblyman Ricardo Lara, D-South Gate, that would have created a complaint process for parents and required audits to make sure districts were not making parents and children pay for uniforms, classroom materials and extra activities. Gov. Jerry Brown vetoed the measure calling it "the wrong approach," as it would have required all 1,042 school districts and over 1,200 charter schools follow audit procedures, even when there have been no complaints or evidence of a violation.

The ACLU is worried that the dismissal of their lawsuit would be a green light for districts to thumb their nose at free public education and would end any real hope for disadvantaged students to use the public schools to achieve the American Dream. However, disadvantaged students never had much hope of achieving the American Dream, let alone becoming wealthy, regardless of the quality of their schools. Very few people transcend the class backgrounds of their families and schools serve to reinforce this tendency, even without charging extra fees. The class-based achievement gap, for example, which is already present before kids enter kindergarten (see Burkam and Lee and Hart and Risely), decreases the chances that a disadvantaged student will have the requisite skills necessary to succeed in a fee-charging advanced class. Likewise, students from lower income backgrounds tend to go to low income schools which often have fewer resources, course offerings and parental donations. They are also less likely to have parents with the experience, connections and self-assuredness to get them into enrichment programs, internships and mentorships that can increase the chances of getting into an elite university or secure a high status and high paying job.