1218 



HORMONAL REGULATION 



TABLE 19.3 



Comparison of sexual behavior of male guinea pigs raised in isolation with that of males raised unth females 



Data obtained from 7 tests, day 77 to 120, after all males were isolated. 



(From E. S. Valenstein, W. Riss and W. C. Young, J. Comp. & Physiol. Psychol., 48, 397, 1955.) 



Animals (Group) 



Heterogeneous males (I) 



Isolated day 25 



Social situation 



Strain 2 males (II) 



Isolated day 25 



Social situation 



Strain 13 males (III) 



Isolated day 25 



Social situation 



Heterogeneous males (IV) 



Isolated day 10 



Social situation 



Average 

 Score 



7.5 

 9.9 



3.6 

 3.0 



4.9 

 8.1 



1955). The subjects were from the geneti- 

 cally heterogeneous stock and the inbred 

 strains 2 and 13. Experimental males (the 

 isolated males) were placed alone with their 

 mothers from the day of birth until day 25 

 and isolated thereafter. Control males (the 

 socially reared males) were raised with ani- 

 mals of the same age from the day of birth 

 until day 73 when they were isolated; the 

 mothers were removed on day 25. Both 

 groups of males were given the first of 7 

 weekly tests on day 77. 



The data (Table 19.3, group I) revealed 

 that the performance of the genetically het- 

 erogeneous males raised in the social situa- 

 tion was somewhat better than that of the 

 males brought up in isolation, although the 

 difference is not statistically significant. The 

 clearest picture came from the results ob- 

 tained from strain 2 males in which the de- 

 velopment of the measures of behavior 

 above mounting seemed almost completely 

 dependent on the contact they had had with 

 other young animals (Table 19.3, group II). 

 The strain 13 males showed some develop- 

 ment of the complete sexual pattern follow- 

 ing their experience in the social situation 

 (Table 19.3, group III), but the level 

 reached, although significantly higher than 

 that attained by the isolated males, was con- 

 siderably below that of the strain 2 and 

 heterogeneous males. 



As the work progressed, male cage-mates 



were found to provide sufficient experience 

 for the organization of sexual behavior in 

 other males. Males raised with spayed fe- 

 males, on the other hand, performed more 

 poorly than males of the same strain raised 

 with intact females or males (Valenstein 

 and Goy, 1957) . Apropos of this, it has been 

 observed repeatedly in the Kansas labora- 

 tory that even a sluggish male mounted by 

 an estrous female is stimulated to mount in 

 return. Untreated spayed females, however, 

 liave never been observed to initiate mount- 

 ing. It is possible, therefore, that the poorer 

 performance of the males raised with spayed 

 females is explained by a lack of provoca- 

 tion to attempt mounting and thereby to 

 gain experience. 



A number of conclusions became appar- 

 ent. (1) The importance of contact with 

 other animals for the development of normal 

 patterns of sexual behavior in the male 

 guinea pig has been demonstrated. (2) The 

 influence exerted by contact with other ani- 

 mals operates within the limits of a certain 

 genetical background. (3) The influence of 

 contact with other animals can be exerted 

 very early in the life of an individual. 



Just how early in the life of a male con- 

 tact with other animals can be effective was 

 shown by Valenstein in an experiment de- 

 signed to test the hypothesis that the very 

 slight diffei'ences in the heterogeneous ani- 

 mals weaned on day 25 and brought up in 



