Family dynamics, not biology, behind higher IQ
- From: ** <**@.org>
- Date: Sat, 23 Jun 2007 18:20:37 +0800
Family dynamics, not biology, behind higher IQ
By Benedict Carey Published: June 21, 2007
NEW YORK: The eldest children in families tend to develop slightly higher IQs
than their younger siblings, researchers were to report Friday, citing a large
study that could effectively settle more than a half-century of scientific
debate about the relationship between IQ and birth order.
The difference in IQ between siblings was a result of family dynamics, not of
biological factors like changes in gestation linked to repeated pregnancies, the
study found.
Researchers have long had evidence that firstborns tend to be more dutiful and
cautious than their siblings, early in life and later, but previous studies
focusing on IQ differences were not conclusive.
In particular, analyses that were large enough to detect small differences in
scores could not control for the vast differences in the way that children in
separate families were raised.
The findings, appearing in the Friday issue of the journal Science, are based on
detailed records from 241,310 Norwegians, including about 64,000 pairs of
brothers, allowing the researchers to carefully compare scores within families,
as well as between families.
Today in Africa & Middle East
Moroccan separatists claim police brutality
Influx from Zimbabwe to South Africa tests both
Top targets fled before U.S. push, commander says
The study found that eldest children scored about three points higher on IQ
tests than their closest sibling. The difference was an average, meaning that it
showed up in most families, but not all of them.
Three points on an IQ test, experts said, amounts to a slight edge that could be
meaningful for someone teetering between an A or a B, for instance, or even
possibly between admission to a leafy liberal arts college or a state
university.
They said the results would probably prompt more intensive study into the family
dynamics behind such differences, which are yet well understood.
"I consider this study the most important publication to come out in this field
in 70 years; it's a dream come true," said Frank Sulloway, a psychologist at the
Institute of Personality and Social Research at the University of California at
Berkeley. Sulloway, who wrote an editorial accompanying the study, added that
"there was some room for doubt about this effect before, but that room has now
been eliminated."
Joseph Lee Rodgers, a psychologist at the University of Oklahoma and a longtime
skeptic of the birth-order effect, disagreed, saying that the new analysis was
not conclusive.
"Past research included hundreds of reported birth-order effects" that were not
legitimate, he wrote in an e-mail. "I'm not sure whether the patterns in the
Science article are real or not; more description of methodology is required."
In the study, Norwegian epidemiologists analyzed data on birth order, health
status and IQ scores of 241,310 18- and 19-year-old men born between 1967 and
1976, using military records. After correcting for factors known to affect
scores, including birth weight, family size and parents' education level, the
researchers found that eldest children scored an average of 103.2, about 3
points higher than second children and 4 points higher than third-borns.
The scientists then looked at IQ scores in 63,951 pairs of brothers and found
the same results. Differences in household environments did not explain elder
siblings' higher scores.
Because gender has little effect on IQ scores, the results almost certainly
apply to females as well, said Petter Kristensen, an epidemiologist at the
University of Oslo and the lead author of the study.
His co-author was Tor Bjerkedal, an epidemiologist at the Norwegian Armed Forces
Medical Services.
To test whether the difference could be due to biological factors, the
researchers examined the scores of young men who had become 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,"
Kristensen said in a telephone interview.
Social scientists have proposed several theories to explain how birth order
might effect IQ 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 those youngsters, later-born siblings actually tend to outscore the eldest
on IQ 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, dumb down 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 older child's
head start with Mom and Dad.
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 juniors. These lessons, in short, could benefit the teacher more
than the student.
Another potential explanation concerns how individual 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, a better student.
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," Sulloway said. "They are developing diverse interests
and expertise that the IQ tests do not measure."
This kind of experimentation might explain evidence that younger siblings often
live more adventurous lives than eldest siblings. 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 in general
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 astronomer who determined that
the sun, not the earth, was the center of the planetary system, grew up the
youngest of four. René Descartes, the youngest of three, was a key figure in the
Scientific Revolution of the 16th century.
Firstborns have won more Nobel Prizes in science than younger siblings, but
often by advancing current understanding rather than overturning it, Sulloway
argued.
"It's the difference between every-year or every-decade creativity and
every-century creativity," he said, "between creativity and radical innovation."
iht
.
- Prev by Date: 10 commandments from Vatican
- Next by Date: Don't veto, don't obey
- Previous by thread: 10 commandments from Vatican
- Next by thread: Don't veto, don't obey
- Index(es):
Relevant Pages
|
Loading
