We thought that younger children, as they have "teachers", are smarter? It seems that the opposite is true. Various studies associate a higher IQ in the case of firstborn than in the case of the following children.
And as the child's birth position moves away from the first one, the decrease in intelligence levels increases.
That is, there is something that determines that a firstborn is smarter than a secondborn who, in turn, has an IQ slightly higher than a third born, and this one to a born fourth ... and so on.
But what are the reasons? There has been much speculation about it, indicating several possible explanations. And although there are those who point to biological and gestational causes, the conclusion reached by other studies seems more plausible, as we will see below.
This difference between siblings could be due to a social factor, which intervenes throughout the development of a person in relation to their birth position in the family. These would be some of the factors that would differentiate the older brother from the following:
- Older siblings benefit from more family resources than those who arrive later (I imagine that at this point, the availability of time and not only economic will have an important impact).
- The firstborn must cope with the pressure of what is expected of them as they are older.
- At the same time they have the possibility of acting as guardians of their younger siblings, which enhances their intellectual capacity.
The demonstration that the position occupied in the family could affect the IC by social factors, is that if the eldest brother died when the second was a child, the intellectual quotient increases to resemble that of the firstborn.
The same happens if one of the brothers is born in the third place and dies: the IC of a second-born child is adopted. And if both brothers die, then the one that remains would be like a firstborn also in terms of intelligence, although originally born in third place.
A study published in the journal "Science" in 2007 conducted with hundreds of thousands of Norwegian recruits offers these correlations very clearly. The number and type of social contacts that one establishes in relation to his position in the family has effects on intellectual development.
It shows that the relationship between the order of birth and the qualification of CI depends on the social status of the family and not on the order of birth itself.
So it wouldn't really matter if you were born first or second in the family, but the type of social networks that are locked around you according to your family order. How parents, other family members, environment relate to you ... and the likely greater stimulation and interaction with the first children.
For that reason, in the study, men who had been raised as elders, beyond being born in first, second or third place, had an IQ that matched their firstborn peers.
The study was directed by Petter Kristensen, from the University of Oslo, with the title of "Explaining the Relation Between Birth Order and Intelligence" (Explaining the relationship between birth order and Intelligence).
Although the reason is still unknown, the differences disappear between brothers born many years apart. Could it be that parents become "put the batteries back" when raising the baby? That we have more resources to move it forward? The previous study leaves many questions along the way.
Anyway, I believe that there are many factors associated with the development of intelligence, and trying to reduce the levels of intelligence to the result of one or a few factors does not seem correct or decisive. Nor do they take into account the size of the families, their economic status ...
No doubt in this case other clearer studies would be needed to explain, why firstborn children are smarter and the factors associated with this greater intellectual capacity. Although, as we will see for centuries, there is speculation about it offering different hypotheses.
