The longevity of these apes is largely a matter of conjecture, but from a cursory study of their dentition and other facts of their development, it appears that the male reaches the adult stage at an age ranging from eight to ten years, while the female matures between six and eight. These appear to be the periods at which they pass from the state of adolescence. Some of them live to be perhaps forty years of age, or upwards, but the average life is probably not more than twenty-one to twenty-three years. The average of life is, doubtless, 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. There are some facts to support each of these claims, but nothing is quite conclusive. The sum of the evidence that I could find rather points to a term of four and a half months, or thereabouts, as the true period. During the months of January and February the male gorillas are vociferous in their screaming, the young adults separate from the families, and other things indicate that this is the season of pairing and breeding. They may not be strictly confined to this period, but the inference that they are so is well founded. It is quite certain that the season of bearing the young is from the beginning of May to the end of June. It is about this time that the dry season begins, and it continues for four months. It would appear that nature has selected this period of the year because it is more favorable 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 with her young to the dense jungle, where she is less exposed to danger than she would be in the more open forest. It is uncertain whether or not the periods are the same with both apes. Native reports differ on this point. But it is probable that they are the same. The average of this season is about four and a half moons, or eighteen weeks. From a social point of view the chimpanzee appears to be of a little higher caste than other apes. In his marital ideas he is polygamous, but is in a certain degree loyal to his family. The paternal instinct is a trifle more refined in him than in other simians. He seems to appreciate better the relationship of parent and child and to retain it longer than others do. Most male animals become estranged from their young and discard them at a very early age. The chimpanzee keeps his children with him until they are old enough to go away and rear families of their own.