The issue of natural and acquired aspects of behaviour is traditionally considered to be one of the most interesting in behavioural studies, aimed at finding hereditary patterns of human and animal behaviour. Scientists tend to think that most primitive animals have more natural behaviour, while higher animals are guided by learning or cultural inheritance.

Once world of biologists was divided into two parts – one part considered all character and behaviour ingredients to be predetermined, the other claimed character to originate from learning and no natural components, responsible for behaviour and character, could be pointed out, because there was always some environmental influence. As experimental biology advanced, current epigenetic theory formed. This theory suggests existence of a genotype, which genes are affected by an environment, thus an organism is formed as a result of a combination of the genotype and the environment.

Environmental effect is often a necessary condition for the next stage of organism’s development. It affects both brain development and general behaviour. Various animal species have various degree of dependence on environmental factors. Many experiments show complex character of this dependence.

Russian biologists studied natural behavioral patterns of two lines of mice. Mice of first line had bigger brain compared to body weight. They turned out to have better abilities for learning. This ability was proved in experiments. Mice with smaller brain appeared to be very shy, which can also suppress their ability for learning.

Mice with big brain were placed in two types of cages – standard ones and comfortable ones. They showed better cognitive abilities in comfortable cages, while mice with smaller brains showed no difference in abilities. The studies showed that staying in comfortable cages activates production of new neurons in special generative brain areas.

Humans always wanted to know what aspects of their behaviour are genetically predetermined. Such studies are performed within genetics of human behaviour – psychogenetics, which uses standard methods of genetics, such as ancestry analysis and expression of certain character patterns in generations. We all know remarkable examples of musical talents in the Bach family or the Bernoulli family, which gave the world several generations of brilliant mathematicians.

Twin studies are also successfully used in examining many complex human characteristics. Twins are natural experiment, which allows studying people, which are identical in their genotype. They are called monoval twins, or identical twins. If scientists have many twins at their disposal, they are able to check how similar their reactions to various events, answers to psychologist’s questions, or electrophysiological reactions are. The same technique is used for finding similarities of diovular twins, which developed from different eggs and differ as brother and sisters do. But their development conditions are more alike than that of brothers of different age. And it turns out that many temper characteristics, emotional reactions, reactivity and some specific intellectual abilities have significant genetic component.

Thus, psychogenetics allows making interesting conclusions in pedagogy and in human cognition of himself.

Anna Kizilova, 7 July 2006

Source:

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