The Old Americans are seen to represent on the one hand a group of still considerable variability, but on the other hand a group that already comes closely to deserving the characterization of an anthropological unit. In other words, the "melting pot," while its work of unifying the many component elements is evidently not yet completely finished, has nevertheless advanced so much in that direction that the stock possesses already a moderately distinctive character.
The Old American stock, as it may now be called, stands in general nearer than any other branch of the whites to the stock of Great Britain. But it is not, or no more, identical with the same; it is American. There is some justification therefore in speaking of the "American type" of white people. This is near the English, Irish and Scotch types, but is at least as different from any of these as these are different from each other.
From a purely morphological standpoint all the more important characteristics shown by this Old American stock are favorable, showing in some respects perceptible improvement and in none a degeneration. With rational guidance the improvement may well be extended.
Geographically the stock differs remarkably little. The north and south show much smaller regional differences than generally believed. The only section of the stock that does differ perceptibly and in some important points disadvantageously from the rest, is that of the isolated Appalachian highlanders. The reasons appear to be inbreeding and lack of cultural development, both of which can be remedied. [p. 408]
The research was carried out between 1910 and 1924. Hrdlicka restricted his analysis to
those Americans whose ancestors on each side of the family were born in the United States for at least two generations--in other words, all those whose parents as well as all four grandparents were born in this country. The third native generation of adults means roughly an ancestry on each side of the family of at least 80 to 150 year American. As a matter of fact the mean "nativity" of those examined was nearer the latter than the former figure and for the whole series it probably surpassed an average of 150 years, for there were many who on one or both sides exceeded the minimum requirements of three generations. In a large majority of cases the American ancestry of the one examined, while only three or four generations on one side, extended to from four to eight generations on the other; and there were fairly numerous instances where the ancestry was pure native on both sides for four generations, while occasionally it was five, six, and in a few cases even seven generations. [pp. 4-5]
Ales Hrdlicka. The Old Americans. Baltimore: Williams & Wilkins, 1925.