HORMONES AND MATING BEHAVIOR 



1215 



was excluded in an experiment in which in- 

 bred and genetically heterogeneous young 

 were interchanged the day of birth. As 

 before, the sexual behavior of the inbreds 

 was significantly lower than that of the 

 heterogeneous males ( Valenstein and Young, 

 1953). 



Genetical factors are important deter- 

 minants of the character of the soma in the 

 female. Ovariectomized guinea pigs from 

 the inbred strains and genetically hetero- 

 geneous stock at Kansas have been studied 

 following their injection with controlled 

 cjuantities of estradiol benzoate and proges- 

 terone (Goy and Young, 1957b). As in the 

 male, differences were seen in every measure 

 of behavior studied: responsiveness to treat- 

 ment as determined by the percentage of 

 females brought into heat, duration of the 

 induced heat, length of the interval between 

 injection of progesterone and the beginning 

 of heat, duration of maximal lordosis, in- 

 terval between the beginning of heat and 

 maximal lordosis, and amount of male-like 

 mounting. The rank order of these measures 

 varies greatly and, with respect to the be- 

 havior of males from the same strains, 

 unpredictably (Young, 1957). 



Attempts have been made to study the 

 mode of inheritance of the elements com- 

 posing the patterns of behavior in males 

 and females. The display of courtship and 

 copulatory behavior in crosses of the two 

 fishes, Xiphophorus {Platypoecilus) macu- 

 latus and X. helleri, was recorded in an in- 

 herently difficult study (Clark, Aronson and 

 Gordon, 1954). Some influence of heredity 

 was revealed, but the genetical data were 

 not such that a precise analysis in Men- 

 delian terms could be made. No special cor- 

 relations were possible between known genes 

 and behavioral elements of the parental 

 species, between diagnostic morphologic 

 features and behavior, or between court- 

 ship and copulatory behavior. Intraspecies 

 crosses have been studied in the guinea pig 

 and their behavior reported briefly (Jak- 

 way, 1959; Goy and Jackway, 1959). This 

 species, and doubtless otlier mammals, pre- 

 sents some advantages not possessed by 

 fishes, notably the numerous well defined 

 measures displayed by the female. On the 

 other hand, as in the work on fishes, analysis 



has been of average rather than of indi- 

 vidual performance. In their inheritance, 

 elements of the patterns behave independ- 

 ently. Within the male, dominance of the 

 lathargic strain 13 type of behavior is 

 limited to the lower measures (circling, 

 nuzzling, mounting). A dominance of the 

 strain 2 type of behavior is suggested for 

 the higher measures (rate of intromission 

 and number of ejaculations). Within the 

 female three independent genetical factors 

 appear to determine the character of estrus. 

 Latency and duration of heat, and percent- 

 age of response show phenotypic dominance 

 of the strain 2 type. Duration of the maxi- 

 mal lordosis is determined by a single ge- 

 netical factor without dominance. Inherit- 

 ance of male-like mounting is also of an 

 intermediate type, but more than one ge- 

 netical factor is indicated and the possi- 

 bility of modifiers exists. Beyond observa- 

 tions of this type, little progress has been 

 made, but the possibility of further analy- 

 sis is clearly evident. 



The suggestion that the character of the 

 soma is influenced by experience or perhaps 

 better, until the type of experience can he 

 defined, by contact with other animals, is 

 based on studies of cattle, chickens, ring- 

 doves, turkeys, cats, rats, dogs, guinea 

 pigs, and chimpanzees. The problem is dis- 

 cussed by Beach (1942e, 19421, 1947, 1947- 

 48, 1958a), Ford and Beach (1951), Kagan 

 and Beach (1953), Valenstein, Riss and 

 Young (1955), Valenstein and Young 

 (1955), Valenstein and Goy (1957), Goy 

 and Young (1957a), Young (1957), Rosen- 

 blatt and Aronson (1958a, b), Zimbardo 

 (1958), Wortis and Rosenblatt (1959), 

 Wood-Gush (1958b), Schein and Hale 

 (1959). What seems to be the first demon- 

 stration of the importance of contact with 

 other animals for the organization of the 

 mature pattern of behavior was given by 

 Craig (1914) following his study of ring- 

 doves reared in isolation. For many years 

 little was done with the factors to which he 

 directed attention, but since 1940 the im- 

 portance of psychologic factors for the or- 

 ganization and modification of patterns of 

 mating behavior has been the subject of 

 many articles and discussions. 



Conditioned reflexes leading to copulation 



