1336 



HORMONAL REGULATION OF BEHAVIOR 



turned to the mothers, they were helped to 

 suckle from their own mothers. A control 

 group of 21 mothers was allowed to rear 

 their kids normally. The flock was not fur- 

 ther interfered with until 2 or 3 months 

 later when the animals were tested by plac- 

 ing a mother in an experimental room with 

 three kids, including her own. In this situa- 

 tion, the mothers which had been separated 

 from their kids during the hour following 

 birth nursed their own kids less than those 

 mothers which had not been so separated, 

 and nursed other kids more. 



Collias (1956) found that sheep are at- 

 tracted to newborn young by their odor. A 

 ewe could be attracted by a rag rubbed in 

 fresh birth membranes. Collias, like Blau- 

 velt, found that separation of newborn 

 goats and sheep from their mothers for a 

 short period of time resulted in rejection of 

 the infants when they were returned to the 

 mothers, although he found it necessaiy to 

 keep mother and young separated for some- 

 what longer times (2 to 4 hours) than had 

 Blauvelt. 



Unpublished observations by Tobach, 

 Failla, Cohen and Schneirla at the Ameri- 

 can Museum of Natural History show that 

 the maternal licking of the neonate kitten 

 appears to be in some respects an extension 

 of her self-licking immediately before par- 

 turition. The relationship between mother 

 and young, established in part through such 

 processes, forms the basis for the develop- 

 ment of detailed perceptual responses of the 

 animals to each other, as the mother and 

 young become mutually conditioned 

 (Schneirla, 1950, 1959). 



The results from an experiment by La- 

 briola (1953) warn us that the type of proc- 

 ess described in the preceding paragraphs 

 is by no means the only one contributing to 

 the development of the mother-young rela- 

 tionship, or at any rate that it is not of the 

 same relative importance in all animals. 

 Labriola compared the maternal behavior 

 of primiparous female rats who were al- 

 lowed to deliver their young normally with 

 the behavior of females whose young were 

 delivered by cesarean section. A further 

 comparison was made with nulliparous non- 

 pregnant animals. The animals were tested 

 for retrieving 24 hours postpartum, after 

 having remained with the young since par- 



turition; the test was repeated at 24, 48, 

 and 72 hours postpartum. All the normal 

 controls retrieved young on the first test. 

 Five of 7 cesarean-operated animals re- 

 trieved on the first test, 1 on the second, and 

 the last on the third. It is clear that, at least 

 in the rat, the events associated with par- 

 turition and the cleaning of the young are 

 not essential for the establishment of re- 

 trieving behavior in a majority of the ani- 

 mals. Labriola's subjects were kept with 

 their pups from the time of parturition until 

 the first test, and no observations are avail- 

 able to show what happened during this 

 time. The cesarean-operated females did 

 not lactate, but no observations are avail- 

 al)le from which we could decide whether 

 this was due to the effects of the operative 

 interference on the animals' endocrine con- 

 dition, or to the possible nonestablishment 

 of suckling stimulation immediately after 

 delivery. 



We may also remind ourselves that 

 camels, llamas and their relatives establish 

 suckling relationships with their young in 

 the complete absence of any tendencies to 

 lick the young, eat the placenta, tear the 

 membranes, or bite the imbilical cord (Fil- 

 ters, 1954). 



Recognition of young. The development 

 of recognition of their own young by mother 

 animals is another indication of the occur- 

 rence of learning based on originally par- 

 tially hormone-induced parental behavior 

 patterns. Earlier, in connection with our 

 discussion of the stimulation of retrieving 

 by external stimuli, we discussed a number 

 of cases in which such individual recogni- 

 tion of the young had been demonstrated. 

 It became clear from those cases that many 

 animals are able to recognize their own 

 young (Beach and Jaynes, 1956c), even in 

 species which, under other circumstances, 

 readily adopt young of other species 

 (Frisch and Kahmann, 1952). Some mother 

 chimpanzees have been found to react to 

 their own young differently from any other 

 infants after one year of separation, start- 

 ing at about one year after birth (Spence, 

 1937). 



Ramsay (1951) found that various do- 

 mesticated and semidomesticated species of 

 ducks will readily adopt birds of other spe- 

 cies hatching from eggs incubated by the 



