Cain & Abel

Terrific Q & A with Frank Sulloway on birth order and intelligence.

John Ratey first told me about Sulloway years ago; John thought the guy was super-smart. Back then Sulloway was working on his book Born to Rebel: Birth Order, Family Dynamics and Creative Lives, which argued that firstborns are inherently more conservative than later-borns.^*


from the Q & A:

...the 2.3 I.Q. points that differentiate the average Norwegian firstborn from the average Norwegian second-born in a two-child family is equivalent to the firstborn having a 13 percent greater chance of getting into a better college. This difference is also equivalent to the firstborn having 1.3 times the odds of getting into a better college, compared with the second-born.

It is also worth noting that 2.3 extra I.Q. points (the advantage enjoyed by a firstborn over an immediately younger sibling) is approximately equivalent to scoring an extra 15 points on each SAT test, or a combined 45 points on the three current tests, which have a mean combined score of about 1,500 points. The cutoffs for acceptance to the best colleges, based on SAT scores, often hinge on where one stands within a range of just 40 to 50 points on the three tests combined.

Seen in this perspective, these documented differences in I.Q. by birth order are hardly negligible. However, as I said in a recent interview published in part by Nature, if I had the choice of having 2.3 extra I.Q. points or having the “enlarged curiosity” that Charles Darwin’s uncle, Josiah Wedgwood, recognized in his nephew on the eve of Mr. Darwin’s departure on the Beagle to circumnavigate the globe, I would unhesitatingly choose the latter.

So, yes, I.Q. is hardly everything, and much that makes people successful in life has to do with how people use their intelligence rather than with their intelligence per se. In addition, there is considerable evidence suggesting that siblings born later use their intelligence differently from the way firstborns use theirs. Indeed, later-born siblings would appear to have 2.3 extra points of one difficult-to-measure intellectual skill, associated with unconventional thinking, that firstborns sometimes lack.

brace yourself

When I.Q. scores were adjusted to account for differences in maternal education, parental income and parental marital status, the difference in I.Q. scores between firstborns and only children was reduced to just 0.6 points.

This remaining difference does suggest that Robert Zajonc’s theory about older siblings teaching younger siblings may help to explain why firstborns have higher I.Q.s than only children, since only children have no one to teach. However, this I.Q. difference is also consistent with the theory of niche partitioning within the family. Only children do not compete with younger siblings for parental favor. Hence they are presumably less motivated than firstborns with younger siblings to nail down the niche of the family “achiever.”

The news reports of this study will be used to justify heterogeneous grouping and peer-tutoring.

So be prepared.

The counter is:

a) sibling tutoring was not mentioned in the study

b) sibling tutoring is simply Robert Zajonc's hypothesis as to why this study and so many others should find that firstborns have higher IQs

c) to my knowledge, no one has presented evidence that firstborns routinely tutor their younger siblings (I had 3 younger siblings & I didn't spend any time teaching them how to read or do arithmetic)

d) until someone does present evidence that older siblings spend enough time tutoring younger siblings to raise their own IQs (and until we have some evidence that sibling-tutoring does raise the tutor's IQ) niche partitioning should be the preferred explanation



Sulloway on niche partitioning and Darwin

In the study, Norwegian epidemiologists analyzed data on birth order, health status and I.Q. scores of 241,310 18- and 19-year-old men born from 1967 to 1976, using military records. After correcting for factors that may affect scores, including parents’ education level, maternal age at birth and family size, the researchers found that eldest children scored an average of 103.2, about 3 percent higher than second children (100.3) and 4 percent higher than thirdborns (99.0).

The difference was an average, meaning that it varied by family and showed up in most families but not all.

The scientists then looked at I.Q. scores in 63,951 pairs of brothers, and found the same results. Differences in household environments did not explain elder siblings’ higher scores.

Because sex has little effect on I.Q. scores, the results almost certainly apply to females as well....

To test whether the difference could be due to biological factors, the researchers examined the scores of young men who became the eldest in the household after an older sibling had died. Their scores came out the same, on average, as those of biological firstborns.

“This is quite firm evidence that the biological explanation is not true,” Dr. Kristensen said in a telephone interview.

Social scientists have proposed several theories to explain how birth order might affect intelligence scores. Firstborns have their parents’ undivided attention as infants, and even if that attention is later divided evenly with a sibling or more, it means that over time they will have more cumulative adult attention, in theory enriching their vocabulary and reasoning abilities.

But this argument does not explain a consistent finding in children under 12: among these youngsters, later-born siblings actually tend to outscore the eldest on I.Q. tests. Researchers theorize that this precociousness may reflect how new children alter the family’s overall intellectual resource pool.

Adding a young child may, in a sense, diminish the family’s overall intellectual environment, as far as an older sibling is concerned; yet the younger sibling benefits from the maturity of both the parents and the older brother or sister. This dynamic may quickly cancel and reverse the head start the older child received from his parents.

Still, the question remains: How do the elders sneak back to the head of the class?

One possibility, proposed by the psychologist Robert Zajonc, is that older siblings consolidate and organize their knowledge in their natural roles as tutors to junior. These lessons, in short, benefit the teacher more than the student.

Another potential explanation concerns how siblings find a niche in the family. Some studies find that both the older and younger siblings tend to describe the firstborn as more disciplined, responsible, high-achieving. Studies suggest — and parents know from experience — that to distinguish themselves, younger siblings often develop other skills, like social charm, a good curveball, mastery of the electric bass, acting skills.

“Like Darwin’s finches, they are eking out alternative ways of deriving the maximum benefit out of the environment, and not directly competing for the same resources as the eldest,” Dr. Sulloway said. “They are developing diverse interests and expertise that the I.Q. tests do not measure.” [As one of four siblings I can tell you that niche partitioning is real.]

This kind of experimentation might explain evidence [ed.: but see below] that younger siblings often live more adventurous lives than their older brother or sister. They are more likely to participate in dangerous sports than eldest children, and more likely to travel to exotic places, studies find. They tend to be less conventional than firstborns, and some of the most provocative and influential figures in science spent their childhoods in the shadow of an older brother or sister (or two or three or four).

Charles Darwin, author of the revolutionary “Origin of Species,” was the fifth of six children. Nicolaus Copernicus, the Polish-born astronomer who determined that the sun, not the earth, was the center of the planetary system, grew up the youngest of four. The mathematician and philosopher René Descartes, the youngest of three, was a key figure in the scientific revolution that began in the 16th century.

Firstborns have won more Nobel Prizes in science than younger siblings, but often by advancing current understanding, rather than overturning it.

“It’s the difference between every-year or every-decade creativity and every-century creativity,” Dr. Sulloway said, “between innovation and radical innovation.”

update:

uh-oh

This is bad.

I wonder how much of this is going on?

Years ago, at a NAAR scientific advisory board meeting, one of the scientists - worked on dyslexia - told me that a very famous researcher had a practice of routinely threatening to sue any scholar who criticized his data or his results.

He had basically shut down the entire peer review process by means of private legal threats.

This researcher receives constant publicity; he seems to be on numerous reporters' Expert list - he's the person called first for comment.



trouble in Norway
trouble in Norway, part 2
Tyler Cowan's favorite things Norwegian

Cain and Abel
Independent George to the rescue


^* Born to Rebel is part of my Great Unread. Own it, haven't read it.