New evidence on racial test score gaps

In the United States, past research has consistently found that Black teenagers underperform White teenagers by an average of about one standard deviation on tests of IQ and academic achievement. Substantial racial test score gaps are found as early as age five.

Roland Fryer and I have written two papers on racial differences in test scores in the past (see here and here). In those papers, we were able to answer some interesting questions, but we didn’t have the right sorts of data to get at the question of whether the differences in test scores across races that are commonly observed might have a genetic component.

In a new paper, we tackle that controversial issue, using a large U. S. government data set that administers a test of mental functioning to children aged 8-12 months. No one has ever looked carefully at racial test score differences in children this age using a large, nationally representative data set.

As they approach their first birthday, how do you think the Black children do relative to the White children on these tests? Our preliminary answer is here. But before you look, make your own guess as to the results.

I think we will be seeing a lot of Steve Sailer on this site in the near future — this issue is even closer to his heart than legalized abortion.


"Large racial gaps in test scores have been found in children as young as two years old, and the one standard deviation racial gap observed later in life is present by age three. Even after accounting for a host of demographic and socio-economic factors such as parental income, education, occupation, home environment, birth weight, region, and urbanicity, a substantial Black-White test score gap generally remains." (from preliminary answer).

In light of this statement, as well as the lack of data supporting a genetic difference in the new study, I think it is safe to say that one of two things is true. Either the genetic difference displays itself after 9-12 months and before 2 or 3 years of age, or the accounting of a host of demographic and socio-economic controls is unsuccessful/unreliable.

I find it hard to accept that either statement is correct. Given the relative short period of evolution leading to the distinct races, I don't think it is realistic to expect a significant genetic difference leading to IQ variances.

I then wonder how successful statisticians have been at controlling socio-economic factors. It is my guess that with better data / techniques we will discover that the true difference lies there, not in genetics.



Interesting finding at 1 year of age.

I was reading _The Bell Curve_ not long ago and was surprised at many of the findings - from data only looking at white respondents (to remove the racial impact from the data). The differing incedence of accidents/disability amoung groups of differing IQ in the same types of jobs was a completely unexpected finding to me. I work in the insurance industry and if you think credit rating is controversial in auto insurance - how about IQ based rating for risk factors?

Bottom line - for some people there can be no acceptable answer that finds a racial link to intelligence. I wish we could be more open on the topic - and I wish it wasn't career threatening for academics to tackle the topic.

Blacks seem to me to be better atheletes in many respects vs. other races... I'm prepared to accept the possibility that there might be a genetic component that creates a difference like this between the races. I'm willing to accept that Asians may have superior intellect to whites if that's what the data points to. And correctly controlling for socio-economic factors doesn't have to explain away all the differences. (Socio-economic factors don't have to explain why the fastest sprinters tend to be black, and they don't have to explain away other differences either to be valid.) That most studies indicate IQ is 40%-60% heritable should at least allow us to consider a large genetic component is involved.

I consider myself a fairly interested observer and that the science on this is still obscure general knowledge is bothersome. There are practical policy decisions that must be better informed.



KOKO the gorilla has tested 70-95 on a human IQ test but reached that IQ level at a much lower age than an average human child. Perhaps that supports the argument that genetic IQ differences are more to do with the length of intellectual development rather than intrinsic IQ at birth?


Beyond the fact that life would be much easier if their were no differences in average intelligence among races, doesn't that seem pretty unlikely when considered in light of the theory of evolution. Australian aborigine were completely seperated genetically from the rest of human beings 50,000 years ago. You're telling me there wasn't some divergence between them and western europians (whom they probably have been genetically isolated from for most of the existance of homo sapien) in the way the brain develops for 50,000 years? Despite their radically different cultures and the radically different skills that would make one successful in those cultures? Objectively, doesn't it seem like their has to be some difference in the way we think and develop. I mean, why would we see such strong evolutionary divergence in hair texture, but not intelligence type?


I just read an article about epigenetics, the study of genetic changes that don't involve mutations in DNA. The idea is that your 30,000 genes can release more or less proteins that affect you based on how you treat yourself and the environment you grow up in. Here is a quote :

“You inherit DNA, but it doesn't tell you if you are living in a rich or a poor environment. If it is rich, you don't have to store fat, don't need to be anxious,” Dr. Szyf said. “But if you are going to be thrown in a ghetto, that is a different thing.”

The article also states that these environmental adaptions can be passed on to your kids and even your grandkids. Maybe this has some relevance to why races test differently. Here is the link if anybody is interested:


Your result is not surprising to me. The range of genetic variation within a race is greater than the variation among races.


About six years ago, I wrote a piece about "The Bell Curve" in Psycoloquy, an online journal. Race differences in IQ were among the issues I discussed.

The entire sequence of articles (my original one, commentaries by Charles Murray, Arthur Jensen, and Joseph Buckhalt, and my reply) can be accessed at:


A couple little things to go along with my previous message (No. 7 above):

To access the actual articles, you click on the ID numbers in the far left column, once the Psycoloquy Table of Contents comes up.

The e-mail address listed for me on the Psycoloquy site no longer works, as we changed e-mail systems in my unit. My current e-mail is:


Realm of the Wombat » Blog Archive » New evidence on racial test score gaps

[...] In the age old debate of nature vs. nurture, chalk one up for nurture. [...]

David Singerman

When StCheryl points out that "the range of genetic variation within a race is greater than the variation among races," what this really means is that there are no "races" at all. I don't know how this particular report divided up the country into "races" but you can be sure it wasn't in any way that had a kind of scientific validity. Races aren't real, but racism is very real, and in the end it's someone's perception of whether you are "black" or "white" that "makes" you that way. So in that sense it's not surprising at all that there is no cognitive difference at a very young age among what we mistakenly think of as "races", because the little kids haven't been socialized yet.


Interesting study.

An obvious alternative explanation of your results would be that the Bayley test of mental function among infants could be racially biased as a predictor of future IQ scores.

East Asians average the highest on IQ tests, but score the lowest on the Bayley, suggesting the Bayley is biased against Asians for the purpose of predicting IQ.

One possible source of racial bias in the Bayley that leaps out just on casual inspection is that one of the Bayley's five subtests is of "babbling." The more babbling by the baby, the higher the Bayley score. That's not implausible as a vague predictor of future IQ _within_ racial groups, but if Asians tend to be more reticent on average than whites or blacks (which much evidence suggests they are), then your approach inaccurately penalizes Asians for a personality difference that's not at all related to future IQ.

Because personality or behavioral differences among infants of different races can bias the accuracy of the Bayley test as a tool for examining cognitive differences, you should take a look at Daniel G. Freedman's classic paper "Ethnic Differences in Babies," which found strong average behavioral differences among newborns. Here's a summary from a 1980 article in the Journal of American Indian Education:

"Daniel G. Freedman, author of "Ethnic Differences in Babies," found striking differences in temperament and behavior among babies only 48 hours old from different ethnic groups. Dr. Freedman compared Chinese and Caucasian babies and found they behaved like two different breeds [of puppies]. Caucasian babies cried more easily, and once started, were harder to console. Chinese babies adapted to almost any position in which they were placed. In a maneuver called the "defense reaction" by neurologists, the baby's nose is briefly pressed with a cloth. Most Caucasian and Black babies fought this maneuver by immediately turning away or by swiping at the cloth. This is reported in most Western pediatric textbooks as the "normal" and expected response. The average Chinese baby in the study simply lay on his back and breathed through his mouth, "accepting" the cloth without fight. Many other tests were done and it appeared that Chinese babies were simply more amenable and adaptable to the machinations of the examiners and that the Caucasian babies were registering annoyance and complaint.

"In 1969, Freedman's experimenters arranged to work among the Navajo tribe in Tuba City, Arizona, on the reservation. After two months, they had tested 36 Navajo newborns. These babies outdid the Chinese, showing even more calmness and adaptability than found among the Oriental babies. Among Navajo babies crying was rare, the limb movements were reduced, and calming was almost immediate."

I wish you luck in assessing how racially biased the Bayley test is.


De Gustibus Non Est Disputandum

Raça Importa?

Parece que não. Estudo recém-saído do forno de Levitt e Fryer mostrou que não existe diferença de inteligência entre bebês de raças distintas. Bem, eu (e mais um monte de gente) acho que o conceito de raça não tem sentido...


I don't think there is much if any difference amongst races for IQ.

As for athletic ability amongst different races I have two theories. One is the seeming superiority of African-American's over Whites is a result of slavery. Two reasons, one was a measure of selective breeding to try and ensure strong young slaves. The other and probably more inportant is the horrendous physical conditions, and back breaking labor. The short, small boned, weaker slaves most likely died younger and had less opportunity to pass along their genes.

The other theory I have goes back to human migration out of Africa. Those that migrated to Europe had fewer large carnivorous animals to worry about, as well as needing the ability to store body fat for warmth. If you lived in Africa, it was more important to be able to outrun a predator than keep warm through a long cold winter. Look at professional football. The "speed" positions cornerback, running back, reciever and linebacker are dominated by African-Americans. Positions that reward bulk and quickness rather than speed, like offensive and defensive lineman are much "whiter".



I was going to post a reply to some of the points above, but as soon as I saw Steve Sailer's looooooong post, my brain froze over and I knew it was time to exit.


I have this comment about people who postulate that it is genetics that enables any particular racial group dominating sports.

It seems that people have a very short memory. Over the past hundred years of so in this country, as each new immigrant group arrived in this country, they would dominate sports.

Look at boxing, there have been Jews, Italian, and Irish boxers.

As these groups move up in the economic ladder they move on to other professions.


April 2001

From American Psychological Association
New model of IQ development accounts for ways that even small environmental changes can have a big impact,while still crediting the influence of genes

Where I've Been

Online but not posting


You may find this interesting:

A study links brain development (specifically the thickness of the cerebral cortex) to IQ. It may be interesting to study whether the brains in people of different races develop differently. If so, perhaps this is a factor in IQ score gaps between races.

Stereotypes Blog » Are Blacks Genetically Less Intelligent When Compared To Whites?

[...] Article right here! [...]


Perhaps we should design a test in which blacks perform much better than whites in adulthood. Intellegence is important to all cultures so I am less likely to believe that one group is smarter than the other. Though I am willing to accept that the focus of intellegence may be in different areas. From what i've noticed most adult IQ tests are memory based tests which for the most part I am slightly better than average. Though a european IQ test with patterns and shape associations to be deduced I scored 156 - a few points lower than the maxium for the test.