Chap. IV.] MANxYER OF DEVELOPMENT. ]31 



reached their present homes." The early progenitors of 

 man miist also have tended, like all other animals, to have 

 increased beyond their means of subsistence ; they must 

 therefore occasionally have been exposed to a struggle for 

 existence, and consequently to the rigid law of natural 

 selection. Beneficial variations of all kinds will thus, 

 either occasionally or habitually, l\;ive been preserved, and 

 injurious ones eliminated. I do not refer to strongly- 

 marked deviations of structure, which occur only at long- 

 intervals of time, but to mere individual diiferences. We 

 know, for instance, that the muscles of our hands and feet, 

 which determine our powers of movement, are liable, like 

 those of the lower animals,^® to incessant variability. If, 

 then, the ape-like progenitors of man which inhabited any 

 district, esiDCcially one undergoing some change in its con- 

 ditions, were divided into two equal bodies, the one half 

 which included all the individuals best adapted by their 

 powers of movement for gaining subsistence or for defend- 

 ing themselves, would on an average survive in greater 

 niimber and procreate more oiFspring than the other and 

 less well-endowed half. 



Man in the rudest state in which he now exists is the 

 most dominant animal that has ever appeared on the earth. 

 He has spread more widely than any other highly-organ- 

 ized form ; and all others have yielded before him. He 

 manifestly owes this immense superiority to his intellectual 

 faculties, his social habits, which lead him to aid and de- 

 fend his fellows, and to his corporeal structure. The 

 suj^reme importance of these characters has been j)i-oved 



'■' Latham, 'Man and his Migrations,' 1851, p. 135. 



^5 Messrs. Murie and Mivart, in their " Anatomy of the Lemuroidea " 

 ('Transact. Zoolog. Soc' vol. vii. 1869, pp. 96-98) say, " some muscles are 

 so irregular in their distribution that they cannot be well classed in any 

 of the above groups." These muscles differ even on the opposite sides 

 of the same individual. 



