Whichever formula may be preferred in the interpretation, it remains as an indisputable fact that even in some of the higher animals an exceptional appearance gives an advantage in courtship. It is needless to point out to how great an extent in civilised communities man is influenced in sexual preference by a bias for a peculiar appearance which distinguishes the chosen one from any other man or woman. This predilection, however, is always neutralised by a repugnance for everything that deviates too much from the common characteristics of the group. The two principles which have regulated the development of secondary sexual characters—to wit, the necessity of marks for accentuating sex-distinction and that of tribal signs—are thus brought into conflict with each other. This conflict is particularly conspicuous in the lower stages of development. Owing to the peculiar conditions of life which prevail here, the second principle will generally be of especial importance among the savage tribes of mankind. The observation has often been made that too great uniformity of work impedes the development of individual characters in physical appearance. In savage communities, where the division of labour is almost unknown, all men must necessarily be more or less like one another.[305] Especially if the home of the tribe be some closely defined area of uniform climatic conditions, there will be within the tribe almost no material for selection. Where endogamic marriage prevails, the conception “lover,” which is transmitted from mother to daughter, and which, by “objective heredity,” becomes imprinted on the mind of every girl that grows up in this narrow _milieu_, must therefore be one with a very restricted content. Alongside of this increasing predilection for a fixed and narrowly circumscribed type of the opposite sex there will, as its complementary feeling, develop a strong antipathy to every feature that diverges from this type. For the evolution of national ideals this negative influence has been of perhaps even greater importance than the positive preferences.