The anatomy and physiology of the various American tribes present, indeed, great diversity, and yet, beneath it all is a really remarkable fixedness of type. We observe this diversity in the shape of the skull, which may be, as among the Botocudos, strictly dolichocephalic, while the Araucanians are brachycephalic; the nasal index varies more than in the extremest members of the white race; the tint of the skin may be a dark brown with an under-color of red, or of so light a hue that a blush is easily perceptible. The beard is usually absent, but D’Orbigny visited a tribe who wore it full and long.[[25]] The height varies from an average of six feet four inches for adult males in Patagonia to less than five feet among the Warraus of Guiana; and so it is with all the other traits of the race. There is not one which is not subject to extensive variation.
On the other hand, these variations are not greater than can be adduced in various members of the white or black race. In spite of them all, there is a wonderful family likeness among tribes of American origin. No observer well acquainted with the type would err in taking it for another. Darwin says that the Fuegians so closely resemble the Botocudos that they seem members of the same tribe. I have seen Arawacks from Guiana who in the northwest would have passed for Sioux.
In spite of the total dissimilarity of climate and other physical surroundings, the tribes of the tropics differ no more from those near the Arctic circle than they do among themselves. This is a striking lesson how independent of environment are the essential characteristics of a race, and it is a sweeping refutation of those theories which make such characteristics dependent upon external agencies.
A still more remarkable fact has been demonstrated by Professor J. Kollmann of Bâle: to wit, that the essential physical identity of the American race is as extended in time as it is in space. This accurate student has analyzed the cranioscopic formulas of the most ancient American skulls, those from the alleged tertiary deposits of the Pampas, those from the caverns of Lagoa Santa in Brazil, that obtained from Rock Bluff, Illinois, the celebrated Calaveras skull from California, and one from Pontemelo in Buenos Ayres of geologic antiquity. His results are most interesting. These very ancient remains prove that in all important craniologic indicia the earliest Americans, those who were contemporaries of the fossil horse and other long since extinct quadrupeds, possessed the same racial character as the natives of the present day, with similar skulls and a like physiognomy.[[26]] We reach therefore the momentous conclusion that the American race throughout the whole continent, and from its earliest appearance in time, is and has been one, as distinct in type as any other race, and from its isolation probably the purest of all in its racial traits. This is a fact of the first order in establishing its prehistoric chronology.
Geologic. I have left the geologic data to the last, as it is these which carry us with reasonable safety to the remotest periods. No one who examines the evidence will now deny that man lived in both North and South America during and after the glacial epochs, and that he was the contemporary of many species of animals now extinct. As you are aware, the attempt has several times been made to fix the date for the final retrocession of the glaciers of North America. The estimates have varied from about 12,000 years ago up to 50,000, with a majority in favor of about 35,000 years.
There have also been various discoveries which are said to place the human species in America previous to the appearance of the glaciers. Some remains of man’s industry or of his skeleton have been reported from interglacial, others from tertiary deposits.[[27]] Unfortunately, these finds have not always been sufficient, or not of a character to convince the archæologist. I have before adverted to the impossibility, for instance, of an archæologist accepting the discovery of a finely-polished stone implement in a tertiary gravel, except as an intrusive deposit. It is a violent anachronism, which is without a parallel in other countries. Even the discovery of a compound implement, as a stemmed arrowhead, in strata of tertiary date, is, with our present knowledge, quite out of the question.
Although there are well recognized signs of glacial action in South America, it is not certain that the glacial epoch coincided in time in the two continents. That there was a reasonable approximation is probable from the appearance of later deposits. We may suppose therefore that the habitable area of the New World was notably less at that period, and that the existing tribes were confined to a much narrower space. This would force them into closer relations, and tend powerfully to the production of that uniformity of type to which I have before referred.
We might also expect to discover in the tropical regions of America more frequent evidence of the primitive Americans than in either temperate zone. This has not been the case, probably because the geologic deposits of the tropics have been less investigated. Throughout the West Indies there is an entire absence of palæolithic remains. Those islands were first peopled by tribes in the polished stone stage of culture. In the valley of Mexico human remains have been disinterred from a volcanic deposit of supposed tertiary age, and you have all heard of those human footprints which Dr. Earl Flint has unearthed in Nicaragua. These are found under layers of compact volcanic tufas, separated by strata of sand and vegetable loam. There can be no doubt of their human origin or of their great antiquity; but no geologist need be informed of the difficulty of assigning an age to volcanic strata, especially in a tropical country, subject to earthquakes, subsidence and floods.[[28]]
It would not be in accordance with my present purpose to examine the numerous alleged finds of human remains in the strata of the tertiary and quaternary. All such furnish data for the pre-historic chronology of America, and should be carefully scrutinized by him who would obtain further light upon that chronology. I must hasten to some other considerations which touch the remote events to which I am now alluding.
Since a comparison of the fauna of South America and Africa, and a survey of the sea-bottom between those continents, have dispelled the dream of the ancient Atlantis, and relegated that land connection at least to the eocene period of the tertiary, no one can suppose the American man to have migrated from Africa or southwestern Europe. For other and equally solid reasons, no immigration of Polynesians can be assumed. Yet zoölogists, perfectly willing to derive man from an anthropoid, and polygenists to the utmost, hesitate to consider man an autochthon in the New World. There is too wide a gap between the highest monkeys and the human species in this continent.[[29]] Discoveries of fossil apes might bridge this, but none such has been reported.