The question ofwhether the source of intelligence is genetic is one of the questions that everyone is curious about and the answer has always aroused curiosity.
To say thatintelligence is only genetic would be to bring an incomplete perspective to the subject. Because intelligence is a complex structure affected by both genetic and environmental factors. Scientists have conducted many studies on the genes that affect intelligence. The results show that genetics has an effect on intelligence, but they also show that environmental factors also improve intelligence.
It is not possible to ignorethe genetic source of intelligence. But it is not always possible to explain how and when high intelligence is passed on to the next generation.
What is intelligence?
There is no clear definition of intelligence. In dictionary terms, intelligence is defined as all human abilities from thinking to reasoning, from perceiving to comprehending objective facts and from judging to drawing conclusions. In other words, intelligence can be explained as the ability to reason and understand by thinking instead of instinctive and automatic behaviors.
Many definitions of intelligence include the ability to learn from experience and adapt to changing environments. Elements of intelligence include reasoning, planning, abstract thinking, problem solving and the ability to understand complex situations.
Environment and Brain Relationship
Research on the effect of environment on brain development varies. In other words, according to one study, the genetic effect on intelligence is 75%, while the effect of the environment is 25%, while another study emphasizes that it varies according to age. In other words, the genetic effect varies from 20% in young people to 40% in teenagers and 60% in middle age.
However, environment is an effective factor on intelligence. There are studies showing that proper education, nutrition and growing up in a good environment increase children's IQ levels by around 10 points. In fact, it can be said that the environment has a great unseen and unknown effect on intelligence.
What is a Synapse?
The brain is an organ located in the skull and works as the command center of the body. It controls all states of the human being, both mental and physical. A normal human brain weighs between 1200 and 1800 grams and has an average of 15 billion nerve cells. It contains approximately 15 trillion brain cells, or synapses. Synapses are connection points that allow nerve cells to transmit messages to other nerve cells, muscles or glands.
Synapse Overproduction
After birth, new synapses begin to form in the brain. There is an explosion of synapse formation in the 3rd and 4th months, especially for vision. At 4 and 12 months, the brain contains more than 150% more synapses per unit area than the brain of an adult. Young children have many times more synapses than adults.
Overproduction of synapses is a period of brain change, when experiences are formed. While this is high in the first years of life, it starts to decrease after 4 to 5 years of age.
What is Synapse Pruning?
While there are close to 15 trillion synapses in childhood, this number decreases considerably in adulthood. It drops to almost half. As we age, synapses between some nerve cells are severed. This is called synapse pruning. The aim here is to delete old information and make room for new information.
Research shows that underutilized synaptic connections are marked by a protein called C1q. Microglial cells detect this mark and bind to this protein. In this way, that synapse connection is destroyed, that is, pruned. The idea is to increase the capacity of the brain, to allow new connections to be made in order to learn more. Synapse pruning physically creates space for the brain to become stronger.
Experience-Dependent Nerve Cell Change
Genetics is not always sufficient to create structures. The formation of structures and connections is shaped by factors such as experience and environment. In other words, changes occur in nerve cells depending on experience. For example, this happens when vision is impaired in the eye due to cataracts. Because of the lack of vision, the nerves here cannot function. The nerve cells and connections here disappear over time.