Smaller "brains" in celibacy?
Does only the brain influence sex life, or does sexual activity also influence the development of nerve cells? A scientist from the University of Berkeley is trying to answer this question through experiments with male rats. It is usually assumed that the human brain is above such mundane things as sex. But now there is increasing evidence of a direct link between brain structure on the one hand and sexual orientation and activity on the other. There is compelling evidence that some areas of the brain known to play a role in sexual orientation are sized differently in males and females.
The debate on whether the brain should be considered a "sexual organ" continues, but the problem is more of separating cause and effect. Is it genes and hormones that shape the brain in a way that determines sexual orientation? Or is it also the sexual activity itself that then influences the development of the brain? To date, research has attempted to find an answer to the first question while avoiding the second. Not so dr. Marc Breedlove from the University of Berkeley. In his opinion, this second question can only be answered with a decisive "yes" (Nature from 10/23/97).
Dr. Breedlove compared specific nerve cords in the spinal cord of two groups of male rats. These are known to be influenced by sexual factors and are particularly high in the male sex hormone testosterone (VRML representation).
The first group was kept with continuously receptive females. The second group was less fortunate, their females were not ready to mate.
The result was clear: Sexual activity affects the structure of the nervous system. When "celibacy" was imposed on the rats, the corresponding nerve areas were smaller than in the active sex comparison group. Nobody can answer why and why so far. In any case, hormone influence cannot be the answer, since the testosterone level was kept constant in the compared groups. So there is still a lot of opportunity for science for further research.
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