Melancholia – The effects of melancholia

The case for sterilization becomes more difficult if the disease is caused by a single recessive, as in the case of amaurotic idiocy. There, two perfectly normal parents produce affected children. Although the affected children themselves die, two thirds of the surviving brothers and sisters transmit the disease. Consequently, this condition of amaurotic idiocy will have a slow increase as time goes on. In order to eliminate the disease, it is then necessary to sterilize all the brothers and sisters and possibly the first cousins also of an affected person. Since, however, some of these may not be carriers, and yet are indistinguishable from carriers until they themselves have offspring, it is clear that good human material and all its potentialities would be wasted. This kind of difficulty increases if the disease is caused by two recessives or by one dominant combined with one recessive. The condition known as melancholia is brought about by such a combination. Let us suppose that one parent carries one of the factors concerned and the other parent the second. Either factor by itself has no effect on the carrier. But in the children these two genes may meet and cause this type of insanity. In this case a smaller percentage of children will be affected than in the case of one recessive as in amaurotic idiocy, but at the same time more people are potential carriers, since they possess one of the genes. Yet this cannot be detected until several children have been born of the marriage of such a person and have moreover reached the age of susceptibility which for melancholia is in the early forties. Once it was established that heredity was responsible for a certain number of grave defects, such as deaf mutism and blindness of more than one kind, of which are transmitted by a simple heredity mechanism, scientists began to hold the view that in sterilization lay the hope of stamping out such defects. This hope proved to be somewhat exaggerated since abnormalities of this nature can be eradicated only if the mechanism is simple, if the defect is caused by a single dominant, or a single recessive, or by a sex linked dominant, or sex linked recessive.