136 HUMAN BIOLOGY 



Among existing vertebrates there may be observed 

 everything from total lack of maternal interest in offspring 

 and of affection and sohcitude for them to its obvious and 

 much vaunted degree of perfection in man. Radical differ- 

 ences are apparent even among existing classes of primate, 

 for the sentiment gains in strength and complexity of 

 expression, persistence, and likewise in degree of resemblance 

 to the human, as we progress from lemur to ape. 



In the monkeys the phenomena are deeply impressive 

 and irresistibly suggestive of human experience. Only 

 those who have had occasion to try to study a mother 

 monkey and her baby can appreciate the strength of her 

 attachment. She is continuously watchful, suspicious of all 

 comers, and she strenuously resents and resists every attempt 

 of the observer to approach the infant or to separate it 

 from her. This may occur even when she is on terms of 

 friendly intimacy with the observer. Of the chimpanzee, 

 to mention only that anthropoid ape for which information 

 is most nearly adequate, the same is true. If the infant ape 

 be injured or taken from the female, maternal distress is 

 commonly indicated by violent attempts at defense or 

 recovery, by extreme restlessness and appearances of 

 anxiety, and by grievous crying or screaming. 



Evidently parenthood as affective experience and expres- 

 sion more closely approaches our own in monkey and ape 

 than in the more primitive primates, such as the lemur and 

 tarsier, or in any other inferior mammal. Unless the observer 

 is biased, he is not likely to escape the force of the indications 

 that parental sentiment may very well have evolved from 

 the relative carelessness of the lemur to the intense sym- 

 pathetic attachment and solicitude of the anthropoid ape, 

 and thence to the experiences of man. 



Important also is the fact that whereas intimate relations 

 between mother and infant continue for only a few hours 

 or days in most mammals and are said to be relatively 

 transient even in the primitive forms of primate, they 

 last for weeks and months in the monkeys, and even for years 

 in the man-like apes. The chimpanzee may and often does 

 nurse her infant for two years, and even thereafter she may 

 protect and train or instruct it and attend to its needs. 



