8o SCIENCE PROGRESS 



day, it is certain that instinct was developed earlier than in- 

 telligence. In the case of the human brain the growth of 

 intelligence was incompatible with the persistence of instinct, 

 and therefore the cells of the brain which inherited instinct 

 have disappeared as completely as those of the premaxilla. 

 To take an example. The survival of the mammalia is de- 

 pendent upon the mother knowing, as soon as the first emer- 

 gency arises, the proper way to dispose of the umbilical cord 

 and placenta. A primitive mammalian instinct has been uni- 

 versally inherited in regard to this matter. But in the case of 

 modern woman this instinctive knowledge has completely 

 disappeared, and one is safe in saying that the baby knows 

 more about the mother than the mother about the child. In 

 this case a few thousand years of tradition and teaching have 

 been sufficient to eliminate one of the most fundamental in- 

 stincts. The most probable explanation seems to be that the 

 type of brain which retained the primitive instinct has died out. 



Instinct appears to be less marked in the great apes than 

 it is in the baboon, and none of the primates have the mar- 

 vellous instincts of the beaver or the penguin. The chimpanzee 

 is terrified by lions, tigers, and bears, but learns to throw biscuits 

 into the mouth of the hippo from a safe distance. It has also 

 a well-marked building instinct. All the primates except man 

 seem to dread the snake. An Indian gibbon {hylobates agilis) 

 " sings in perfectly pure and melodious notes up and down 

 the scale of an octave, the distance between the notes being 

 exactly half a note." ^ This, however, is not a musical faculty 

 but camouflage, as all animals in the jungle are instinctively 

 afraid of thunder or any loud noise, as they infer that the 

 sound is proportional to the size of its author. 



All these examples of instinct represent the inheritance of 

 things of survival-value. Man has none of them, and it is 

 probable that the gorilla and orang are in the danger-zone 

 between instinct and intelligence. The bones of the arms and 

 legs of old males often exhibit the signs of former fractures 

 in positions which make it probable that they have been caused 

 by falling out of trees. These apes are slow and cautious 

 climbers, and the orang is said to test a branch before venturing 

 upon it. But they appear to make mistakes occasionally. 

 Now instinct never makes a mistake. Hence these apes may 

 have been too intelligent to acquire new tree-chmbing instincts 

 at the time when they took to the trees as the descendants of 

 the ground ape. On the other hand, the great air-pouches 

 of the orang and his deafening roar, like that of the panther, 

 are indications of the inheritance of structure and function 

 similar to that of the gibbons. 



* Haeckel, History of Creation, ii. 408. 



