This instance, although it is one of modern times and refers to relatively civilised individuals, can no doubt be considered as illustrative with regard to the distinguishing marks and dresses of primitive men. The outward signs of the tribe not only exercise a strong attraction upon all its members; they are also for outsiders associated with a repugnance which is perhaps equally strong. In the same way as it has been advantageous for the young of both sexes to have an appearance which appeals as powerfully as possible to the instinctive predilections of the opposite sex, it has been necessary for them not to exhibit qualities which could be confounded with those of the alien. The individual who endeavours to attract attention for his person by a conspicuous and extravagant appearance is, therefore, narrowly restricted within the boundaries prescribed by tribal sympathies and antipathies. The safest expedient by which to distinguish himself from others without outraging the national idea is, therefore, that of exaggerating the common characteristics of the tribe. These theoretical reasonings can be amply corroborated by ethnological facts. As early as 1814 Humboldt observed and commented upon the fact that the deformations which appear most arbitrary generally only tend to carry into excess some natural peculiarity of the tribe.[308] And since his time, numerous instances have been adduced in the ethnological literature, all pointing in the same direction. In the case of people who blacken their teeth it has been remarked that the dental enamel is naturally darker than usual; where heads are artificially deformed, it is found that there exists a general disposition to develop pointed or flat crania; where the hair-growth is scanty, baldness is artificially produced; and so forth.[309] By exaggerating and accentuating in their own appearance the common qualities of the tribe, the individual males or females have thus created a more and more differentiated tribal type. And the inherited predilections and aversions of the opposite sex have, on the other hand, by continuously influencing positive and negative choice, contributed to the fixing of these types as tribal ideals, not of beauty, but of sexual attractiveness. CHAPTER XVI THE ORIGINS OF SELF-DECORATION