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 monkeys, 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. 
Rabbits 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. 
7 Mr. R. Browne in ‘ Proc. Zoolog. Soc/ 1868, p. 409. 
8 Brehm, 4 Thierleben,’ B. i. 1864, s. 52, 79. For the case of the 
