|
Intelligence |
|
Why are you intelligent? |
| |
Breastfeeding is good - if it's in the
genes
The controversy about whether breastfeeding is crucial for
brain development is settled today by a study that concludes the answer is
yes - so long as a child carries a particular kind of gene.
05/11/2007
Daily Telegraph
The good news is that only one baby in ten carries a genetic variant that
means they will not have their IQ boosted by breast milk, though the
researchers point out that there are other health benefits of breast
feeding, notably in passing the mother's immunity on to her child to make
them more resistant to infection or allergy.
The research suggests that children one day could be tested to see which
could benefit most from breast feeding and could also lead to ways to
improve the uptake of brain healthy nutrients - fatty acids.
advertisementFatty acids present in breast milk were thought to be the
reason why children who are breastfed as infants attain higher IQ scores
than children not fed breast milk, an advantage that persists into
adulthood, though evidence of this from studies has been mixed.
To investigate, Profs Avshalom Caspi, Terrie Moffitt and colleagues at the
Institute of Psychiatry, London investigated this connection and report
their findings today in the Proceedings of the National Academy of Sciences.
They found that variations in a gene called FADS2 (fatty acid desaturase 2)
were associated with differences in the benefits of breastfeeding for IQ
scores in two independent groups of children: 1000 boys and girls born in
1972-73 and growing up in New Zealand, and 2200 boys and girls born in
1994-95 and growing up in Britain.
The finding puts another nail in the coffin of the idea that nature, our
genes, and nurture, our nutrition and upbringing, act independently to
influence intelligence.
In both countries, breastfed children had an IQ advantage of 6 to 7 IQ
points, but only if they had a certain kind of FADS2 gene. "Our finding
shows that genes may work via the environment to shape the IQ," said Prof
Moffitt. "This study must be repeated by other research teams in other
countries."
Prof Jean Golding of Bristol University commented: 'There have been a number
of studies which have shown a positive relationship between breast feeding
and the IQ of the child.
"This has been treated with scepticism by many who thought that the
explanation was not that breast milk was beneficial, but that either the
mere physical fact of being fed by the breast or some social factor that was
linked both to the mother breast feeding and the child having a higher IQ
was responsible.
"These findings identify, for the first time, the causal mechanism - and
show that breast milk is the key factor, but only if the child has the
relevant genotype. This is very exciting.'
|
Intelligence Fostered by Firstborn Treatment
Study of thousands of Norwegian men finds that firstborn
children (and those raised as firstborns) are brighter than younger siblings
June 22, 2007
Do you have an older sibling who always insists he or she is smarter than
you are? Your fears may not be unfounded: they really might be.
A study of more than 240,000 Norwegian men found that older siblings score
higher on IQ tests than their younger brothers and sisters. In cases where
the first child dies in infancy, however, the second-born child raised as
the firstborn assumes the mantle, performing as well as the actual elder
child on intelligence exams.
Study co-authors Petter Kristensen, a professor of epidemiology and
occupational medicine at the University of Oslo, and Tor Bjerkedal, an
epidemiologist with the Norwegian Armed Forces Medical Services, reviewed a
data set on 241,310 men, all 18 or 19 years of age, who were given IQ tests
after being drafted into the army from the mid-1960s to mid-1970s. This gave
the researchers access to an abundance of data on the test takers as well
as, in many instances, on other children within their families.
Their findings, reported today in Science: on average, firstborn males had
an IQ of roughly 103.2, whereas the second-born child scored about 100.4 and
third-borns 99. When the duo accounted for social rank, however, it turned
out actual birth order may not be the key to intelligence.
"We made the assumption that the actual rank among children in a family is
the social rankassuming that a second-born in a family where the first
child was deceased would be social rank one and biological rank two,"
Kristensen says.
After this adjustment, the scores of second-born children raised as the
eldest kid in their family jumped to 103 and the average IQs of third-borns
rose to 100.3. Third-born children who had lost two elder brothers averaged
the highest IQs of all, scoring 103.5.
Kristensen says that his findings indicate that this effect is likely
explained through simple resource allocation: "When there are more children,
he notes, the resources will be more scarce for everyone compared with the
firstborn who gets all the attention with no competition."
"Critics have long argued that such birth-order effects, which typically
emerge in between-family studies, are spuriousphantom artifacts of
uncontrolled differences in family size, socioeconomic status, parental IQ
and other background factors," wrote Frank Sulloway, a visiting scholar at
the University of California, Berkeley's Institute of Personality and Social
Research, in an editorial accompanying the study. "At least in the domain of
intellectual ability, the new Norwegian findings rule out this alternative
explanation."
|
| |
| |
|