The Trend of the Race; A Study of Present Tendencies in the Biological Development of Civilized Mankind (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III THE INHERITANCE OF MENTAL DEFECTS AND DISEASE "Our human civilized stock is far more weakly through congenital imperfection than that of any other species of animals, whether wild or domestic."?Francis Galton, Inquiries into Human Faculty. That many forms of mental deficiency and disorder are capable of hereditary transmission, has long been recognized, but it is only recently that attempts have been made to discover the precise rules according to which such transmission takes place. Much, however, still remains obscure in regard to this important topic. The vast literature on the subject contained in works on medicine and pathology, in numerous medical journals and various other publications consists mainly in the discussion of isolated cases of transmission, or the compilation of mass statistics from the records of institutions for the care of the mentally abnormal. Institutional records being often gathered in a more or less perfundtory manner, and by many different persons, are apt to include numerous inaccuracies and are pretty sure to fall short of the desired degree of fullness. The relatives of mental defectives from motives of family pride frequently conceal the existence of defects in other members of the family, and even when they honestly attempt to give all the information they possess they often fail to furnish data of any value. It is not surprising, therefore, to encounter wide differences of opinion among authorities concerning the extent to which various forms of defect depend upon a hereditary diathesis. Practically everyone whose opinion is of any value concedes to heredity a certain role in the causation of neuropathic traits. A part of the difference of opinion doubtless depends upon the circumstance that the relative potency of her...