More details about measures of intelligence

Irrespective to everything, the IQ test gives us only an assessment of the actual intelligence. As already mentioned, it is affected by more factors which could roughly be divided in biological and environmental factors. Biological factors comprise also genetic features of an individual, which are supposed to have between 25% and 40% of influence in the case of children, and in the case of adults even up to 80%. However, the genetic system, that is responsible for the variations in IQ, is very complex and consists of many different genes. This makes their discovery very difficult, but certain genes or changes in them which are connected to intelligence were discovered.

The establishment or determining of an individual’s intelligence is best accepted on the basis of psychometrical testing or the intelligence quotient testing. But the initial intelligence quotient test strongly differs from today’s tests. The first designed test was found to be incomplete, as according to new theories more different factors are supposed to affect the intelligence. But to denote intelligence, the IQ designation is still usually used.
The IQ or intelligence quotient is an assessment which can be obtained only when using numerous different tests and its purpose is to assess an individual’s intelligence. The value obtained depends on various factors, such as the social status of parents, health condition, and also parents’ IQ values. Supposedly, it is also genetic, but debates in this area differ among researchers who are also not of the same opinion about its method of inheritance.

Polymorphism and gene functions

Scientists have found out that a SNP in the gene SNAP-25 has got a great influence on the higher or lower IQ value. The gene SNAP-25 encodes a membrane-bound protein, which suppresses the activity of Ca+2- dependant channels on the presynaptical membrane. This regulation is very important, because insensibility to Ca+2 ions can lead to hyperactivities and ADHD (attention deficit hyperactivity disorder).

A gene for a Cholinergic muscarinic receptor 2 (CHRM2) is situated on the chromosome 7. Many scientists believe that this gene is linked to memory and dynamic functioning of the brain. The CHRM2 gene activates a multitude of signalling pathways in the brain involved in learning, memory and other higher brain functions. However the researchers still do not understand how the gene exerts its effects on intelligence.

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