MANNER OF DEVELOPMENT. 



CHAPTER II. 



ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME 

 LOWER FORM. 



Variability of body and inind in man Inheritance Causes of varia- 

 bility Laws of variation the same in man as in the lower ani- 

 mals Direct action of the conditions of life Effects of the 

 increased use and disuse of parts Arrested development 

 Reversion Correlated variation Rate of increase Checks to 

 increase Natural selection Man the most dominant animal in 

 the world Importance of his corporeal structure The causes 

 which have led to his becoming erect Consequent changes of 

 structure Decrease in size of the canine teeth Increased size 

 and altered shape of the skull Nakedness Absence of a tail 

 Defenceless condition of man. 



IT is manifest that man is now subject to much variabil- 

 ity. No two individuals of the same race are quite alike. 

 We may compare millions of faces, and each will be dis- 

 tinct. There is an equally great amount of diversity in the 

 proportions and dimensions of the various parts of the body; 

 the length of the legs being one of the most variable points. * 

 Although in some quarters of the world an elongated skull, 

 and in other quarters a short skull prevails, yet there is 

 great diversity of shape even within the limits of the same 

 race, as with the aborigines of America and South Australia 

 the latter a race " probably as pure and homogeneous in 

 blood, customs, and language as any in existence" and 

 even with the inhabitants of so confined an area as the 

 Sandwich Islands, f An eminent dentist assures me that 



* " Investigations in Military and Anthropolog. Statistics of Ameri- 

 can Soldiers," by B. A. Gould, 1869, p. 256. 



f With respect to the " Cranial forms of the American Aborigines," 

 see Dr. Aitken Meigs in "Proc. Acad. Nat. Sci.," Philadelphia, May, 

 1868. On the Australians, see Huxley, in Lyell's " Antiquity of 

 Man," 1863, p. 87. On the Sandwich Islanders, Prof. J. Wyman, 

 *' Observations on Crania," Boston, 1868, p. 18. 



