Results Almost Certainly Apply To Females As Well!

The New York Times reports today on a study published today in two papers in Science (Science 22 June 2007: Vol. 316. no. 5832, p. 1717) and Intelligence: "Research Finds Firstborns Gain The Higher I.Q."

The study could settle more than half a century of scientific debate! Frank J. Sulloway, psychologist at the University of California, Berkeley, says

"I consider these two papers the most important publications to come out in this field in 70 years; it's a dream come true...there was some room for doubt about this effect before, but that room has now been eliminated"


Get this:

The average difference in I.Q. was slight -- three points higher in the eldest child than in the closest sibling -- but significant, the researchers said. And they said the results made it clear that it was due to family dynamics, not to biological factors like prenatal environment.

And that, my friends, is enough to make all the difference between a life in obscurity and the Nobel Prize:

"You go to a certain school, meet a famous professor, and the next thing you know, you've gone on to medical school, made a great discovery and won the Nobel Prize," said Sulloway, who writes about family dynamics and personality development.

Here is my favorite part. The researchers - and the journalists - go on and on about "firstborns" and "siblings" and yet...and yet...the study looked at data on birth order, health status and I.Q. scores of 241,310....MEN!

The LA Times story (from whence the last quote) has the subheading "A study of 240,000 Norwegian men says eldest children have IQs 2 to 3 points greater than younger siblings'." Here we are meant to understand, without pausing to notice or question, that "studies of men (only)" yield information about "(all) eldest children and younger siblings (of both sexes)".

Not to worry, though:

Because sex has little effect on I.Q. scores, the results almost certainly apply to females as well, said Dr. Petter Kristensen, an epidemiologist at the University of Oslo and the lead author of the Science study.

Okay, but I have a question about that older sibling - Nobel Prize linkage: What if she's named Isabella???

More like this

I am sure all our lives are infinitely improved now that we know for sure. Perhaps the Nobels could refine their selection process so that only eldest siblings are eligible for consideration. The potential gains in efficiency are positively staggering. I suppose it would take the intelligence and achievement of a Nobel winner to figure out: how do they get funding for this nonsense?

Of course it's true for women - I'm an older sibling, so I should know. Sad to say, growing up I squandered my 3 extra IQ points on devising methods of calling "shotgun" faster and staying up past my bedtime, and nowadays my extra intelligence is used to pick out real messages from the spam in my email inbox. I am still waiting for my Nobel Prize.

Anyway, is there actual evidence that Novel Prize winners have higher IQs than others with similar educational backgrounds? It seems to me that it's not just smarts but a mixture of certain kind of intellectual arrogance, drive to succeed and a dollop of luck that sets Nobel Prize winners apart from the crowd.

Well, I'm an oldest, but I have a girly name, so that's probably why I don't have a Nobel.

If it really is environmental, it would be interesting to see if the results would hold up for girls IF the oldest child was a girl but the second oldest was a boy. That is, would it have anything to do with the parents treating the child differently (of course, this assumes that parents interact differently with male and female children) or is it more due to something inherent in being an oldest child (like having to be the one who paves the way for the younger siblings)?

What about the 'eldest' child being an only child? They would really have a higher IQ than their siblings which don't exist.

I guess I won't get a Nobel since I am not an oldest but a second. Since the oldest didn't go to college, I guess he won't be getting one either. Where do I register my statistical data? I don't suppose we can design a web site where we can self register our data and see what the results are?

By SuzyQueue (not verified) on 23 Jun 2007 #permalink

Same old same old. Who got tested?? White, Northern European males.

Hey, give the poor researchers a break. They were using a database of Norwegian conscripts, and Norway was only drafting men at the time. When you do sociological research, you have to work with the data you can get.

Still, it's an interesting study. As they point out:

"This study provides evidence that the relation between birth order and IQ score is dependent on the social rank in the family and not birth order as such."

A second son raised after the death of his older brother scores as well as an eldest son. The difference may just reflect increased maternal attention.

I too would like to see a more comprehensive study. Maybe someone can get similar data from a more sex balanced dataset, but we might have to wait for Norway to start drafting women.

Yes, you work with the data you can get - but then you don't make sweeping claims that your data applies to everyone, and to both sexes if you've only studied one. You don't present your data as if it's universal when in fact it is based on a limited and specific set of individuals (european males).

I don't give them a break for that.

I haven't read everything related to the article or blog in entirety, but I have read very interesting research before that indicated first-borns have first dibs on their mother's limited DHA store, fatty acids that are in short supply in western diets. By the time the second child arrives, the mother is more depleted of these fats and through breastfeeding and diet infants do not get enough. As we know, these fatty acids support brain development and neural effeciency, thus the recent surge in daily fish oil supplements. Could this be related to the higher IQ results?????

Sulloway is being heavily quoted on this. He's an Adlerian, and Adler made a big deal about birth order. There is some literature on family size, birth order, and IQ - the effects are modest (three points is trivial), but demonstrable if you use samples in the thousands.
As pointed above, the imnpact of personality and situational factors vastly swamps any small effect from IQ. It's worth going back to the Terman study of high-IQ kids, tested in California in 1920-1922 (I think). None of them acheived Nobel prizes, although 2 kids who didn't have exceptionally high IQs, did acheive these (Luis Alvarez and William Shockley).
Basically, mistrust any study about IQ that's reported in the newspaper, because they'll try to shove all sorts of things into one number.

The magnitude of the effect--even though statistically significant--is so small as to seem completely uninteresting.

By PhysioProf (not verified) on 25 Jun 2007 #permalink

The NYT article on this subject was terrible. I can't say the article itself was delightful. But, the NYT article expanded into all the unreasonable claims that weren't actually made in what was a pretty thorough (but limited) study. I think the reporter relied too heavily on Sullaway in writing the article Many of the questionable comemnts come from his work, not the new article.

For example, the article certainly does not make the claim that the same data would extend to women (who were not studied). That's the NYT, probably quoting Sullaway.


BJ, I'm afraid the claim that the same data would apply to women was a quote attributed to the author of the article, Kristensen, not to Sulloway. Read my blog post again.