MANNER OF DEVELOPMENT. 57 



out thorns and burrs, and hunt for each other^s parasites. 

 They roll down stones, or throw them at their enemies: 

 nevertheless, they are clumsy in these various actions, and, 

 as I have myself seen, are quite unable to throw a stone 

 with precision. 



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

 grasped clumsily ^^ by monkeys, " ?i much less specialized 

 organ of prehension " would have served them* equally well 

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

 to doubt that more perfectly constnicted hands would have 

 been an advantage to them, provided that they were not 

 thus rendered less fitted for climbing trees. We may sus- 

 pect that a hand as perfect as that of man would have been 

 disadvantageous for climbing; for the most arboreal mon- 

 keys in the world, namely, Ateles, in America, Colobus, in 

 Africa, and Hylobates, in Asia, are either thumbless, or 

 their toes partially cohere, so that their limbs are converted 

 into mere grasping hooks, f 



As soon as some ancient member in the great series of the 

 Primates came to be less arboreal, owing to a change in its 

 manner of procuring subsistence, or to some change in the 

 surrounding conditions, its habitual manner of progression 

 would have been modified; and thus it would have been 

 rendered more strictly quadrupedal or bipedal. Baboons 

 frequent hilly and rocky districts, and only from necessity 

 climb high trees ; % 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 atti- 

 tude, which forms one of his most conspicuous characters. 

 Man could not have attained his present dominant position 

 in the world without the use of his hands, which are so 

 admirably adapted to act in obedience to his will. Sir C. 

 Bell insists that *^the hand supplies all instruments, and 



*" Quarterly Review," April, 1869, p. 392. 



f In Hylobates syndactylus, as the name expresses, two of tlie toes 

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

 the case with the toes of H. agilis, lar, and leuciscus. Colobus is 

 strictly arboreal and extraordinarily active (Brehm, " Thierleben," 

 B. i, s. 50), but whether a better climber than the species of the 

 allied genera, I do not know. It deserves notice that the feet of the 

 sloths, the most arboreal animals in the world, are wonderful hook- 

 like. 



I Brehm, "Thierleben," B. i, s. 80. 



" The Hand," etc. " Bridge water Treatise," 1833, p. 38. 



