ANIMAL AGGREGATIONS AND SOCIAL LIFE 349 



gregate in gangs; and Yerkes records various observations of groups 

 of chimpanzees engaging in play. 



The high degree of group integration and the division of labor 

 which may exist in social groups of monkeys are well illustrated by 

 the following extract from a personal communication from J. F. V. 

 Phillips, stationed in Tanganyika territory, East Africa. In writing 

 about the social habits of baboons, he quotes from Sclater (1900), 

 who says that these animals associate in groups of varying numbers 

 up to about a hundred individuals; that, when moving from place 

 to place, the old males are usually seen on the outskirts and always 

 form a rear guard; and that, when resting, a sentinel or two is 

 always placed on top of a rock to warn the troop of approaching 

 danger. 



Phillips comments: "This is entirely correct; the sentinel is ex- 

 ceedingly sharp and detects the least noise, scent, or appearance of 

 man or leopard. In East Africa I have seen another species of ba- 

 boon behaving in the same manner. The sentinels are often the 

 largest, strongest males, that is, with the exception of the real leader 

 of the group; they will remain faithfully at their post 'waughing' 

 (the typical note of danger is 'waugh,' 'waugh,' very guttural and 

 somewhat alarming) despite the proximity of danger. Upon these 

 notes of warning reaching the ear of the leader, he will immediately 

 assemble the leaders of the group, marshaling the males at the rear 

 and along the sides, the females and the young at the forefront, or 

 within the cordon of the males; he himself will alternately lead or 

 bring up the rear, according to the plan of flight or the degree of 

 danger. When things get too hot for the sentinels, they scamper off 

 a short distance, mount some high position, and give further warn- 

 ing to the leader. In times of slaughter, the young are protected 

 by the parents, often with great danger to the latter." 



The comparison of the behavior of this baboon horde with certain 

 aspects of human behavior of which we are justly proud is too 

 marked to need emphasis. Like behavior is frequently exhibited 

 in some degree by herds of various sorts of mammals. The group 

 defense of eggs or young by birds or of the nest by social insects 

 shows similar behavior elements. The baboon example is particu- 



