So far as our historical evidence goes, there is no reason to believe that the number of distinct languages has at any time been less than it is now. On the contrary, all our evidence goes to show that the number of apparently unrelated languages was much greater in earlier times than at present. On the other hand, the number of types that have presumably become extinct seems to be rather small, so that there is no reason to suppose that at an early period there should have been a nearer correspondence between the number of distinct linguistic and anatomical types; and we are thus led to the conclusion that presumably at an early time each human type may have existed in a number of small isolated groups, each of which may have possessed a language and culture of its own. Incidentally we may remark here, that, from this point of view, the great diversity of languages found in many remote mountain areas should not be explained as the result of a gradual pressing-back of remnants of tribes into inaccessible districts, but appears rather as a survival of an older general condition of mankind, when every continent was inhabited by smaller groups of people speaking distinct languages. The present conditions would have developed through the gradual extinction of many of the old stocks and their absorption or extinction by others, which thus came to occupy a more extended territory. However this may be, the probabilities are decidedly in favor of the assumption that there is no necessity to assume that originally each language and culture were confined to a single type, or that each type and culture were confined to one language; in short, that there has been at any time a close correlation between these three phenomena. The assumption that type, language, and culture were originally closely correlated would entail the further assumption that these three traits developed approximately at the same period, and that they developed conjointly for a considerable length of time. This assumption does not seem by any means plausible. The fundamental types of man which are represented in the negroid race and in the mongoloid race must have been differentiated long before the formation of those forms of speech that are now recognized in the linguistic families of the world. I think that even the differentiation of the more important subdivisions of the great races antedates the formation of the existing linguistic families. At any rate, the biological differentiation and the formation of speech were, at this early period, subject to the same causes that are acting upon them now, and our whole experience shows that these causes may bring about great changes in language much more rapidly than in the human body. In this consideration lies the principal reason for the theory of lack of correlation of type and language, even during the period of formation of types and of linguistic families.[4]