74 THE DESCENT OF MAN. Part I. 



would have been right and the other wrong; but to 

 these terms I shall have to recur. 



Sociability. — Animals of many kinds are social ; we 

 find even distinct species living together, as with some 

 American inoDkeys, and with the united flocks of rooks, 

 jackdaws, and starlings. Man shows the same feeling 

 in his strong love for the dog, which the dog returns 

 with interest. Every one must have noticed how mise- 

 rable horses, dogs, sheep, &c. are when separated from 

 their companions ; and what affection at least the two 

 former kinds show on their reunion. It is curious to 

 speculate on the feelings of a dog, who will rest peace- 

 fully for hours in a room with his master or any of the 

 family, without the least notice being taken of him ; but 

 if left for a short time by himself, barks or howls dis- 

 mally. We will confine our attention to the higher 

 social animals, excluding insects, although these aid 

 each other in many important ways. The most common 

 service which the higher animals perform for each other, 

 is the warning each other of danger by means of the 

 united senses of alL Every sportsman knows, as Dr. 

 Jaeger remarks, 6 how difficult it is to approach animals 

 in a herd or troop. Wild horses and cattle do not, I 

 believe, make any danger-signal ; but the attitude of 

 any one who first discovers an enemy, warns the others. 

 Kabbits stamp loudly on the ground with their hind-feet 

 as a signal : sheep and chamois do the same, but with 

 their fore-feet, uttering likewise a whistle. Many birds 

 and some mammals post sentinels, which in the case of 

 seals are said 7 generally to be the females. The leader 

 of a troop of monkeys acts as the sentinel, and utters 

 cries expressive both of danger and of safety. 8 Social 



6 ' Die Darwin'sche Theorie,' s. 101. 



■ Mr. R. Brown in ' Proc. Zoolog. Soc/ 1868, p. 409. 



8 Brehm, ' Thierleben,' B. i. 1864, s. 52, 79. For the case of the 



