SOCIAL AND MENTAL QUALITIES 53 



doubtless not more than twenty-two or twenty-three 

 years. The average of Hfe is more uniform with 

 them than with man. These figures are not 

 mere guesswork, but are deduced from reliable 

 data. 



The period of gestation in both these apes is a 

 matter that cannot be stated with certainty. Some 

 of the natives say that it is nine months, while 

 others believe that it is seven months or less, and 

 there are some facts to support both of these claims, 

 but nothing quite conclusive. The sum of the 

 evidence that I could find rather pointed to a term 

 of three months or thereabouts as the true period. 

 During the months of February and March the 

 male gorillas are vociferous in their screaming, the 

 young adults separate from the families, and some 

 other things indicate that this is the season of pairing 

 and breeding. Such may not be the case, but the 

 inference is well-founded. It is quite certain that 

 the season of bearing the young is from the be- 

 ginning of May to the end of June. It is about this 

 time that the dry season begins and continues for 

 four months. It would appear that nature has 

 selected this period of the year because it is more 

 favourable for rearing the young. During this 

 season food is more abundant and can be secured 

 with less effort. The lowlands are drier, and this 

 enables the mother to retire to the dense jungle with 

 her young, where she is less exposed to danger than 

 she would be in the more open forest. 



It is not certain whether the periods are the same 



