HORMONES AND MATING BEHAVIOR 



1183 



daily the behavior decreased, whereas overt 

 sexual behavior increased. 



Relatively few castrated infrahmiuin i)ri- 

 mates have been studied. Thorek (1924) 

 castrated six male monkeys and reported 

 that impotence set in gradually. About the 

 end of 4 or 5 months all were sexually im- 

 potent and unable to react with an erection 

 in the presence of females. A baboon, Papio 

 hamadryas, was castrated by Zuckerman 

 and Parkes (1939) in November, 1934. Un- 

 til the middle of 1935, they wrote, he seemed 

 aggressively masculine in his general and 

 sexual behavior, but thereafter his attitude 

 became more feminine. Beginning in No- 

 vember 1936, testosterone propionate was 

 given weekly. From then on there was a con- 

 siderable increase in the animal's vitality, 

 aggressiveness, and sexual interest. The con- 

 clusion that "the development of sexual be- 

 havior in the prepuberally castrated chim- 

 panzee is similar to that in the normal 

 animal" (Clark, 1945) would be more con- 

 vincing if data from systematic tests of the 

 castrated male and control individuals had 

 been presented. Even though no data are 

 given, Zuckerman's comments in the dis- 

 cussion of a paper by Beach (1952) are 

 relevant : 



"I recall some experiments of my own — 

 I am afraid the details escape me now — on 

 a male drill, and on a few male rhesus mon- 

 keys, which suggested that after castration 

 sexual activity declined rather consideral)ly. 

 In the case of the drill I certainly remember 

 that its sexuality became intensified after 

 injection of androgen. The other thing I re- 

 member is that the intact adult male chim- 

 panzee may occasionally manifest weak sex- 

 uality." 



A conspicuous feature of many of the 

 studies reviewed above is that the behav- 

 ioral changes following castration are not 

 as immediate as the changes in the ac- 

 cessories. Hypotheses have been advanced 

 to account for this fact by Steinach (1894), 

 Nissen (1929), and Beach (1942e, 1944a). 

 The essential similarity of those proposed 

 by Steinach and Beach is a reminder that 

 there is probably no other phase of the 

 problem of the hormones and mating be- 

 havior in which our progress in that time 

 has been so negligible. 



"Dementsprechend wiirde sich die That- 

 sache, dass das Begattungsvermogen beim 

 Menschen und, wie wir sahen, auch bei cler 

 Ratte monatelang nach der Castration un- 

 veriindert erhalten bleibt, durch den Ums- 

 tand erklaren, dass die zur Zeit gesteigerte 

 Erregbarkeit der betreffenden Centralor- 

 gane den Ausfall der von den Keimdriisen 

 zufieissenden Impulse iiberdauert und erst 

 nach liingerem Fortbestehen ganz allmiih- 

 lich abklingt" (Steinach, 1894, p. 338). 



"Since testicular hormones are probably 

 dissipated within a few days after castra- 

 tion, the more prolonged survival of sexual 

 responsiveness is best explained on the basis 

 of a relatively enduring change in the nerv- 

 ous system. It may be suggested that once 

 the c.e.m. (central excitatory mechanism) 

 has been sensitized by androgen, this neural 

 mechanism remains in an excitable state 

 for some time after the responsible hormones 

 are withdrawn. In the absence of testicular 

 androgens the essential central nervous ele- 

 ments gradually lose their responsiveness" 

 (Beach, 1944a, p. 130). 



Nissen 's hypothesis contains inconsist- 

 encies, •'* but is mentioned here because of 

 the emphasis subsequent workers (Carter, 

 Cohen and Shorr, 1947; Lehrman, 1956;-^ 

 Rosenblatt and Aronson, 1958a ) have placed 

 on the possibility that gonadal hormones 

 exert their action through peripheral rather 

 than central nervous structures. The gradual 

 decrease in sexual behavior in the male, he 

 postulates, is associated with tlie gradual 

 loss in the capacity of the penis for tumes- 

 cence, and thus in the capacity for initiating 

 the sensory impulses resulting in sexual l)e- 

 havior. 



A hypothesis entirely different from those 

 advanced by Steinach, Nissen, and Beach 



-'The postcastrational changes in the uterine or 

 \aginal cpitheHum which Nissen postulated may 

 mediate sexual behavior in the female, must have 

 been presumed to be rapid because he was aware 

 that the changes in behavior following ovariectomy 

 are immediate. However, he cited no histologic evi- 

 dence, and the writer knows of no evidence, that 

 what he calls "interpolated structures" atrophy 

 more rapidly in the spayed female than in the 

 castrated male. 



Lehrman's \-iew expressed in 1956 has been 

 modified. See his tiioughtfully prepared discussion 

 in his chapter in this hook. 



