Even in the mixed populations of modern states, the connection of mental with physical heredity is manifest. Commenting on the population of France, Dr. Collignon observes: “To the difference of races, a purely anatomical fact attested by the form of the skull, the colour of the eyes and hair, and similar bodily traits, there corresponds a cerebral difference, which shows itself in the prevailing direction of the thoughts, and in special aptitudes.” These contrasts are shown by the statistics of Jacoby, who examined the birth and lineage of the most eminent men of France in all departments of activity. He found that the Normans were decidedly ahead in the exact sciences and practical affairs, while in poetry, romance, and works of imagination in general the people of the Midi were far superior to them.
Heredity is believed to present itself in another aspect, which has excited much attention. I refer to that form of it called “atavism” or “ancestral reversion,” or “retrogression,” in which a child “takes after,” not his immediate parents, but some remote ancestor; even, as has been often claimed, so remote as beyond the limits of our own species. Such traits have been called “pithecoid” (ape-like) reversions, as they are alleged to be derived from some four-footed precursor of man, an ape, or even a lemur.
Evolutionists whose enthusiasm transcended their discretion have pointed out many such features in the human skeleton. A few years ago (1894) I gathered these together, and in a paper read before the American Association for the Advancement of Science, I undertook to prove that these features can be satisfactorily explained by mechanical and functional processes acting in the individual life or in that of his immediate ancestors, and that we have no occasion to appeal to hypotheses of descent, which have, at least, never been proved. Other American anatomists (Bowditch, Baker) endorsed and supported by further evidence this position, so that physical anthropologists, in our country at least, have said less about atavism than formerly; and the final blow to it has been dealt quite lately by a Dutch writer, Dr. Kohlbrügge. He has established the thesis that “all so-called atavistic anomalies are meaningless for the race-type. They are brought about by arrests of development or general variability. They depend on disturbances of nutrition, leading to excess or deficiency of productive energy, presenting a deceptive appearance of progressive or retrogressive evolution.”
The consideration of these questions in physical heredity is necessary in psychology, whether individual or ethnic, not merely because the laws of physical run parallel to those of psychical life, but as well for the valuation of those expressions about “men recurring to their brute ancestors” in habits or feelings, so frequent in popular literature.
Hybridity.—The intermixture of human races or stocks, human hybridity as it is sometimes called, has been recognised by all anthropologists to be a prime factor in ethnic psychology, in the psychical history of Man.
But, strange to say, the opinions about its results could not have been more divergent. On the one hand we have a corps of authors, Gobineau, Nott, Broca, Hovelacque, Hervé, etc., who condemn the admixture of human races as leading inevitably to mental and physical degeneration, infertility, and extinction.
In direct contradiction to them we find the not less distinguished names of Quatrefages and Bastian, who maintain not only that such “miscegenation” is harmless, but that it has been the main factor of human intellectual progress! That owing chiefly to it certain tribes and nations have by unconscious selection drawn to themselves the strong qualities of many lines of blood, and thus won the foremost place in the struggle for existence. This was notably the opinion of Quatrefages, who defended the thesis, “In race-mingling the crossing is unilateral and is directed under unconscious selection toward the superior race.”
This is supported by many well-known examples. In our own country, the superiority of the mulatto to the full-blood negro is proved by history and is familiar to all observers; and Dr. Boas has shown by statistical researches that the half-blood Indian is mentally superior to his companion of pure lineage, while the half-blood Indian women, instead of revealing diminished fertility, average two more children to a marriage than their red sisters of unmixed lineage.
But it will not do to ignore the array of facts of contrary tenor which has been marshalled to show that in divers instances the result of race-mixture has been disastrous.
Many of these may easily be explained by the unfortunate social condition of children in such unions, mostly illegitimate, or at odds with extreme poverty and its ill surroundings. If they do inherit an increased ability, it is, under modern conditions, more apt to be directed against than in favour of the social order.