From this view came the belief that man as existing is degenerate. This degeneracy, while popularly charged to occult influences, was early ascribed by scientists to physical causes. Aristotle, as Osborn[4] points out, appears to have recognised degeneration or the gradual decline of structures in form and usefulness, in his analysis of “movement” in connection with development. Degeneration is first met with as a term in an explanation of the origin of species by Buffon in the eighteenth century. The conception itself occurs in a criticism by Sylvius of Vesalius (1514-64), who had asserted that the anatomy of Galen could not have been founded upon the human body, because he had described an intermaxillary bone. This bone, Vesalius observed, is found in the lower animals but not in man. Sylvius (1614-72) defends Galen on the ground that though man had no intermaxillary bone at present this is no proof of its absence in Galen’s time. “It is luxury, it is sensuality, which has gradually deprived man of this bone.” This passage, as Osborn remarks, proves that the idea of degeneration of structures through disuse, as well as the idea of the inheritance of the effect of habit, or the “transmission of acquired characters,” is a very ancient one. Sylvius, while here recognising factors of degeneracy, erred in considering disappearance of the intermaxillary bone, not reappearance, as degeneracy. He failed to recognise, moreover, the law of economy of growth by which one structure is sacrificed for another or for the organism as a whole. This law, indicated by Aristotle, but clearly outlined by Goethe in 1807, and Geoffroy St. Hilaire in 1818, underlies the physiological atrophies and hypertrophies which play such a part in degeneracy.
The Twelve Cæsars of Suetonius (that stud book of imperial degeneracy as it has been styled) stamps the decided impression on its readers that Hippocratian notions of degenerate heredity strongly permeated Roman thought, to revive in those Arabic, Italian, and British (Roger Bacon) thinkers who created the scientific phase of the revival of learning.
In the science of medicine, as developed by Hippocrates,[5] the modern conception of degeneracy is evident. Hippocrates argues against the “sacred” nature of epilepsy, since it is a hereditary disease and hence comes under the operation of physical law. He furthermore points out, as did Aristotle, that epilepsy produced in the ancestor by traumatism and other physical causes may be inherited by the child.
As the degeneration phase of evolution was less antagonistic to the religious theory forced into biblical dogma by the Jesuit Suarez (in opposition to the evolutionary views of St. Augustine and St. Thomas Aquinas), being supported by biblical dicta (that when the fathers had eaten sour grapes the children’s teeth were set on edge) and fetichistic folklore, it retained a dominance that the advanced phase lost. From the time of Hippocrates, psychiatry (the science devoted to mental disorders) continued to accumulate data of the origin and transmission of human defects. The impetus given the evolutionary explanation of these data by the seventeenth and eighteenth century biologists (Harvey, Buffon, Lamarck, Erasmus Darwin, and others) laid the foundation for the modern doctrine of degeneracy.
Buffon[6] remarks that many species are being perfected or degenerated by the great changes in land and sea, by the favours or disfavours of Nature, by food, by the prolonged influences of climate, contrary or favourable, and are no longer what they formerly were. He regarded temperature, food, and climate as the three great factors in the alteration and degeneration of animals.
Erasmus Darwin[7] considers that all life starts from a living filament having the capability of being excited into action by certain stimuli. This capability is that whereby plants and animals react to their environment, causing changes in them which are transmitted to their offspring. All animals undergo transformations which are in part produced by their own exertions in response to pleasures and pains, and many of these acquired forms or propensities are transmitted to their posterity. Other effects of this excitability (such as constitute hereditary diseases, like scrofula, epilepsy, insanity) have their origin in one or perhaps two generations, as in the progeny of those who drink much vinous spirits. Those hereditary propensities cease again if one or two sober generations succeed, otherwise the family becomes extinct.
Benjamin Rush[8] (greatly influenced by the Erasmus Darwin school) remarks that through hereditary sameness of organisation of the nerves, brain and blood vessels, the predisposition to insanity pervades whole families and renders them liable to this disease from a transient and feeble operation of its causes. Insanity when hereditary is excited by more feeble causes than in persons in whom this predisposition has been acquired. It generally attacks the descendants in those stages of life in which it has appeared in the ancestors. Children born previously to the attack of madness in their parents are less liable to inherit it than those who are born after it. Children born of parents who are in the decline of life are more predisposed to insanity than children born under contrary circumstances. A predisposition to certain diseases, seated in parts contiguous to the seat of insanity, often descends from parents to their children. Thus it occurs in a son whose father or mother has been afflicted only with hysteria or habitual headaches. The reverse likewise takes place. There are families in which insanity has existed where the disease has spared the mind in the posterity, but appeared in great strength and eccentricity of the memory and of the passions, or in great perversion of their moral faculties. Sometimes it passes by all the faculties of the mind, and appears only in the nervous system of persons descended from deranged parents; again, madness occurs in children whose parents were remarkable only for eccentricity of mind. Among the diseases that attack the children of the insane, but did not exist in their ancestors, are consumption and epilepsy.
Similar studies were later published by Pinel, Tissot, Chiarrurgi, Stedman, Parkman, Brigham, Prichard, Esquirol, Jacobi, and other American, English, French, Italian, and German alienists. Based upon the data thus obtained, and upon the general principles thus outlined, then appeared—nearly at the same time as the like epoch-making work (on another phase of evolution), Darwin’s Origin of Species—Morel’s Treatise on Human Degeneracy, wherein the principle of natural selection was shown to involve the recognition of the physical conditions that constitute degeneracy, and, necessarily, to exclude primeval perfection. Morel’s definition of degeneration as a marked departure from the original type tending more or less rapidly to the extinction of it, forms the basis of commonly accepted definitions.
While Morel practically outlined the modern study of degeneracy, his theologic timidity forced an absolute definition of a state which, according to his own admission, was purely relative. After fencing somewhat with the position that there was a primevally perfect man,[9] he admits with Tessier the primeval lowness of man, but also thinks that the fall of man could create new conditions which, in his descendants, from heredity and from causes acting on their health, tended to make them depart from the primitive type. These departures from the primitive type have led to varieties, some of which constitute races capable of transmitting racial characteristics. Other varieties in the races themselves have created the abnormal states which Morel has denominated degeneracies. Each of these degeneracies has its own stamp from the cause that produces it. Their common characteristic is hereditary transmission under graver conditions than normal heredity. With certain exceptional instances of regeneration, the progeny of degenerates presents progressive degradation. This may reach such limits that humanity is preserved by its excess. It is not necessary, however, that the ultimate stage of degradation be reached before sterility occurs. Morel confines degeneracy to a pathologic type, criticising F. Heusinger[10] for applying the term degenerate to domestic animals which “throw back” to the wild or original type. Morel’s admission that causes influencing health produce deviations which, under favouring conditions, become racial types capable of indefinite transmission, saves him from absolute scientific inaccuracy, but renders inconsistent his limitation of degeneracy. It may be convenient to separate diseased states from anomalies, but such separation can only be very relative. From his conservatism and his plentiful data, Morel aroused much less antagonism than did a contemporary, Moreau (de Tours), who bore to him the relation of Darwin to Wallace.[11] While Moreau devotes much attention to the factors of degeneracy and its stigmata (or marks), like Morel, his main point is the expansion of the theory of Aristotle which Dryden epigrammatised into—
“Great wit to madness nearly is allied,
And thin partitions do their bounds divide.”