46 THP DESCENT OF MAN 



CHAPTER II 



ON THE MANNER OF DEVELOPMENT OF MAN FROM 

 SOME LOWER FORM 



Variability of body and mind in man — Inheritance — Causes of variability 

 — Laws of variation the same in man as in the lower animals — Direct 

 action of the conditions of life — Effects of the increased use and dis- 

 use 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 struc- 

 ture — 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 tliat man is now subject to mucli varia- 

 bility. ISTo two individuals of tbe same race are quite 

 alike. We may compare millions of faces, and eacli will 

 be distinct. There is an equally great amount of diversity in 

 tlie proportions and dimensions of tbe 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 elon- 

 gated 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 homoge- 

 neous in blood, customs, and language as any in existence' ' 

 — and even with the inhabitants of so confined an area as 

 the Sandwich Islands.' An eminent dentist assures me that 



' ' 'Investigations in Military and Anthropolog. Statistics of American Sol- 

 diers," by B. A. G-ould, 1869, p. 256. 



2 "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. 81. On 

 the Sandwich Islanders, Prof. J. Wyman, "Observations on Crania," Boston, 

 1868, p. 18. 



