In the same way, it would be rash to associate the strong development of glottalized sounds in Chili with the analogous sounds on the Northwest Coast of America; the distinction between neutral and active verbs among the Maya, Sioux, and Tlingit; or the occurrence of three genders in Indo-European and in Chinook.
Our experience in Indo-European and Semitic languages shows clearly that extended borrowing of words may occur and that borrowed words may undergo such changes that their origin can be understood only by historical study. That similar phenomena have occurred in American languages is indicated by the distribution of such words as names of animals and of plants which are in some cases borrowed. Other classes of nominal concepts are not so subject to borrowing on account of the extensive use in many American languages of descriptive terms. Nevertheless, in mixed settlements considerable numbers of borrowed words may be found. An example of this kind is presented by the Comox of Vancouver island who speak a Salish language with a strong admixture of Kwakiutl words, or by the Bellacoola, another Salish people, who have borrowed many Kwakiutl and Athapascan terms. There is no particular difficulty in understanding the process which leads to the borrowing of words. Intertribal contact must act in this respect in a similar way as international contact does in modern times.
If these observations regarding the influence of acculturation upon language should be correct, then the whole history of American languages must not be treated on the assumption that all languages which show similarities must be considered as branches of the same linguistic family. We should rather find a phenomenon which is parallel to the features characteristic of other ethnological phenomena—namely, a development from diverse sources which are gradually worked into a single cultural unit. We should have to reckon with the tendency of languages to absorb so many foreign traits, that we can no longer speak of a single origin, and that it would be arbitrary whether we associate a language with one or the other of the contributing stocks. In other words, the whole theory of an “Ursprache” for every group of modern languages,
