Chap. IV.] MASKER OF DEVELOPMENT. 135 



It seems to me far from true that because " objects are 

 grasped clumsily " by monkeys, " a much less specialized 

 organ of prehension " would have served them 62 as well 

 as their present hands. On the contrary, I see no reason 

 to doubt that a more perfectly constructed hand would 

 have been an advantage to them, provided, and it is im- 

 portant to note this, that their hands had not thus been 

 rendered less well adapted for climbing trees. We may 

 suspect that a perfect hand would have been disadvanta- 

 geous for climbing ; as the most arboreal monkeys in 

 the world, namely Ateles in America and Hylobates in 

 Asia, either have their thumbs much reduced in size 

 and even rudimentary, or their fingers partially coherent, 

 so that their hands are converted into mere grasping- 

 hooks. 63 



As soon as some ancient member in the great series of 

 the Primates came, owing to a change in its manner of 

 procuring subsistence, or to a change in the conditions 

 of its native country, to live somewhat less on trees and 

 more on the ground, its manner of progression would have 

 been modified ; and in this case it would have had to be- 

 come either more strictly quadrupedal or bipedal. Ba- 

 boons frequent hilly and rocky districts, and only from 

 necessity climb up high trees ; G4 and they have acquired 

 almost the gait of a dog. Man alone has become a biped ; 

 and we can, I think, partly see how he has come to assume 

 his erect attitude, which forms one of the most conspicu- 

 ous differences between him and his nearest allies. Man 

 could not have attained his present dominant position in 

 the world without the use of his hands, which are so ad- 



62 'Quarterly Review,' April, 18G9, p. 392. 



63 In Hylobates syndactylies, as the name expresses, two of the digits 

 regularly cohere ; and this, as Mr. Blyth informs me, is occasionally the 

 case with the digits of //. agilis, lar, and leuciscus. 



• 4 Brehm, ■ Thierleben,' B. i. s. 80. 



