1246 



HORMONAL REGULATION OF BEHAVIOR 



DBA/2 mice have a high incidence of 

 mammary tumors and marked susceptibility 

 to lethal audiogenic seizures, whereas the 

 C57BL 10 strain has a low incidence of 

 mammary tumors and susceptibility to au- 

 diogenic seizures. Both lines had been 

 through extensive artificial selection and 

 always reared in small cages with a re- 

 stricted social environment. He wished to 

 ascertain whether exposure to a more com- 

 plex physical and social milieu than pre- 

 viously experienced in many generations of 

 rearing would provide a marked taxing of 

 the physiologic homeostatic mechanisms 

 available to the mice. Four colonies, two of 

 each strain, were established in standard- 

 ized pens with 17.5 M.- of floor space. The 

 arrangement of nests, food, and water en- 

 couraged social interactions. The DBA's 

 fought more frequently and intensely than 

 did the C57's, and the latter developed more 

 toleration and made more passive social ad- 

 justments. The C57 mice were more suc- 

 cessful in reproduction and died off at a 

 lower rate than did the more aggressive 

 DBA mice. 



B. METEOROLOGIC FACTORS 



Some of the more immediate effects of 

 meteorologic factors on reproductive and 

 parental behavior can be readily observed. 

 Modification of other forms of social be- 

 havior, such as shifts between group living 

 and territoriality, have been reported in 

 some vertebrates to be associated with 

 marked changes in the weather. Petersen 

 (1955 1 noted that the activity of migratory 

 bank swallows on arrival in the spring was 

 influenced by weather conditions. Days of 

 fair weather with temperatures near or 

 above normal appeared to be necessary for 

 taking up territories. Collias and Taber 

 (1951 j found that ring-necked pheasants 

 roosted closer together and in larger groups 

 when the weather was very cold. According 

 to Stoddard (1931), the male of the bob- 

 white quail {Colinus virginianus) tolerates 

 other males until the first warm days of 

 February. Actions preliminary to pairing 

 may be noted, although the coveys do not 

 break up normally until late April, and 

 even then may reassemble to a certain 

 extent when the weather is cold and raw. 



Apparently, adverse weather conditions ex- 

 ert some suppressive effect on aggressive- 

 ness, and with increased toleration the ter- 

 ritorialism reverts to flocking. Scott and 

 Fredericson (1951) concluded that heat and 

 probably cold tend to reduce the amount of 

 fighting behavior in mice and rats. Combats 

 between mice were more sluggish and 

 shorter at temperatures over 28°C. ; inex- 

 perienced mice did not fight at 27 to 28° C. 



C. PSYCHOLOGIC FACTORS 



In a social organization based on domina- 

 tion, each individual forms special habits 

 toward each member of the group. As these 

 habits of domination or subordination be- 

 come well established, the agonistic be- 

 havior patterns are reduced in intensity and 

 become symbolic. This mutual interindi- 

 vidual adaptation promotes toleration and 

 has been called social inertia. Such adjust- 

 ments have been demonstrated in small 

 flocks of chickens (Guhl and Allee, 1944; 

 Guhl, 1958). Evidence that the principles 

 of complex learning apply to agonistic be- 

 havior would seem to have been provided 

 following the training of chickens (Radlow, 

 Hale and Smith, 1958), mice, rats (Gins- 

 burg and Allee, 1942; Scott and Fredericson, 

 1951) , and rhesus monkeys (Miller, Murphy 

 and Mirsky, 1955; Murphy, Miller and 

 Mirsky, 1955) to be either dominant or 

 subordinate. In connection with all this, it 

 is appropriate to ask what effect the psycho- 

 logic state associated with social inertia 

 has on the behavioral response to hormonal 

 treatment, be it reproductive or social. 



Taking the former first, Baerends and 

 Baerends-Van Roon (1950) found in the 

 cichlid fish, Hemichromis, that males that 

 were unsuccessful in establishing territories 

 lacked color markings, but when the domi- 

 nant and territorial male was removed 

 one of these showed reproductive markings 

 and set up territory. When the new domi- 

 nant was removed a third male reacted 

 similarly. They concluded that ''although 

 many of the members of the school are 

 physiologically able to assume reproductive 

 markings and to perform reproductive ac- 

 tivities, in a number of them the reproduc- 

 tive motivation was suppressed by the ac- 

 tivities of the territorial fish." In chickens, 



