英文阅读：为何老大智商高
你哥哥认为他比你聪明吗?哼，他可能是对的。根据一项发表在《智力》杂志上新研究，家庭中最大的孩子智商可能最高，最小的智商最低。Does your older brother think he's cleverer than you? Well, he's probably
right. According to new research due to be published this week in the journal
Intelligence, the oldest children in families are likely to have the highest
IQs, and the youngest the lowest.
The research is based on more than 1,000 children whose IQ was tested
through childhood and adolescence up to the age of 18. The Dutch study shows a
birth-order effect on intelligence in each of the tests. Overall, the IQ of the
first-born child was higher than the second-born, which, in turn, was greater
than that of children who had two or more older siblings.
This is only the latest research to suggest that the order of birth can
have a fundamental effect on diverse factors, ranging from the risk of cancer,
asthma(哮喘) and eczema(湿疹), to weight and even premature death.
It can also affect personality, achievement, and career, with first-borns
being more academically successful and more likely to win Nobel prizes. However,
eldest children are less likely to be radical and pioneering. Charles Darwin,
for example, was the fifth child of six.
It has even been suggested that birth order can influence sexual
orientation, left or right handedness, and the number of sexual partners someone
has in a lifetime.
Exactly why there should be such differences is not clear, and there are a
number of theories, with many homing in on environmental influences on the
child.
The so-called dilution hypothesis suggests that as family resources, both
emotional and physical, as well as economic, are finite, it follows that, as a
result, as more children come along, the levels of parental attention and
stimulation will drop. Another theory is that the intellectual environment in
the family favors the first-born who has, at least for some time, the benefit of
individual mentoring
Here are some of the factors that scientists believe may vary with birth
order, and why.
INTELLIGENCE
A number of studies have suggested that IQ scores decline with birth order.
In the most recent study, at Vrije Universiteit, Amsterdam, researchers looked
at men and women whose IQ had been tested at the ages of 5, 12, and 18.
The results, which show a trend for the oldest to score better than the
youngest in each test, confirm the findings of a study at the University of
Oslo, involving about 200,000 people. That showed that first-borns had a
three-point IQ advantage over the second-born, who was a point ahead of the next
in line.
The theory which enjoys the most support is that the extra time and
patience that the earlier borns get from their parents, compared with those
arriving later, gives them an advantage.
PERSONALITY
This is one of the most researched areas. A study at the University of
California (and several other institutions) based on more than 2,000 families
from six countries, suggests that the parents' most favored child tends to be
the last-born. The rebel of the family also tends to be born later that his
siblings, but he will not necessarily be the last-born, and rebels tended to
feel less close to their parents
First-borns are . . . achievers, who are dominant, religious, conscientious
and neurotic. They earn more, are more responsible, anxious and organized, and
they stick to the rules.
Middle-borns are . . . rebellious, less religious, impulsive and open to
new experiences. They perform worse at school and often procrastinate but act as
peacemakers.
Last-borns are . . . agreeable, warm, sociable, extrovert and creative.
They are the most favored child, often a joker and questioning of authority.
BROTHERLY LOVE
One theory of sibling relationships suggests that older siblings invest
more time and effort in younger ones than vice versa. To test the theory,
researchers at Newcastle University looked at whether first-borns were more
likely to keep in touch with their siblings than middle-borns or later-borns,
based on a sample of 1,558 people.
First-borns were found to have significantly more frequent face-to-face
contact, every week with their siblings than middle-borns or last-borns, even
after taking into account geographic distances. Middle-borns and later-borns
were less likely to have frequent contact with each other.
MORTALITY
Later-borns are more likely to die prematurely. A study that followed
14,000 boys and girls born between 1915 and 1929 until they died shows that even
when birth weight, gestational(妊娠期的)age, diseases, social class and other
factors are taken into account, the youngest born have a higher risk of
mortality. “The general tendency was for later-born siblings, particularly girls
and women, to demonstrate a higher mortality risk than first-borns,'' say the
researchers from Stockholm University.
One possible explanation is that later-borns are also associated with
greater risk-taking.
WEIGHT
Later-borns are less likely to be overweight, according to a study based on
8,000 school children. Researchers at the University of Toyama in Japan found
that the risk of being overweight in boys in particular was significantly lower
with increasing numbers of elder siblings or a sister. They also found that boys
from three-child families had a significantly lower risk of being overweight
than only children. Just why is not clear, but one theory discussed by the
researchers is that over-protection and overfeeding are probable mechanisms
leading to obesity because, they say, mothers are more concerned with persuading
children to eat in small families. Another possible mechanism is that there is
less food for each child in large families.
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