or interindividual relations, demands space, struc- 
tured by goals, within which groups may form with 
integrity from other groups with whom they still 
have the opportunity of developing interrelation- 
ships, and demands time through which the ac- 
tivities by members of one generation can affect 
the activities and fate of members of the same or 
later generation. To the extent that these criteria 
are not met, full social behavior will not develop. 
Let us first examine the usual background of rats 
used in experimental studies of social behavior. 
The young gain their first experiences in the 
cramped quarters of a small cage structured only 
by a nest, a water bottle and a food hopper, and in 
association with an emotionally and behaviorally 
deprived mother. They are prematurely and 
abruptly weaned at 21 to 30 days and left in a cage 
made still more barren by the removal of nesting 
materal. Here the rat is left alone or in company 
with a few others of his own age and sex for the 
relatively long period of weaning to adolescence. 
Sleeping, eating, and drinking require the barest 
minimum of demand on the rat’s potentials of 
behavior. Even where antoagonistic behaviors 
develop, only poorly defined stable interrelation- 
ships can develop between any two rats, because in 
the confined quarters, more likely than not, the 
other members become involved in a general melee. 
Cooperative behavior is confined to huddling, and 
then only if perchance the cage is cold and drafty. 
Before passing judgment on the propensities of the 
rat for social life, reflect, if you will, on the extent 
of social behavior you might anticipate for human 
subjects reared in comparably sterile environments 
to adolescence. Some time during adolescence, 
roughly 60 to 100 days in most domestic rats, the 
rats are exposed to the experimental situation. 
These studies rarely extend into the prime adult 
period, roughly 210 to 270 days of age, much less 
beyond this into later life. 
Social facilitation, in terms of the speed or 
frequency of an activity, the attraction of one 
individual to another, and fighting, have been 
three of the principal areas of research. In general 
these results have been “disappointing”. Such 
social facilitation as has been demonstrated pri- 
marily involves unlearned behavior where each rat 
interferes with the activity of its associate. This 
interference apparently restricts the attention to 
the task at hand so that increased speed of action 
ensues. Other than attraction to a female in heat 
by males or to young by a lactating female, there 
has been little evidence in such studies of social 
attraction. The general lack of success probably 
stems from failure to provide a situation in which 
one rat learns to regard a specific other individual 
either favorably or unfavorably. Furthermore, 
there should be reciprocity of regard. Were such 
training provided throughout the period of devel- 
opment, the chances of eliciting social behavior 
would be greatly augmented. There is little reason 
to believe that the mere housing of two rats in a 
small bare cage would later cause one to be 
attracted or repulsed by the other. 
Certain behaviors, for example hoarding, have 
been studied extensively by experimental psycho- 
logists. Furthermore, ignorance of rats in their 
native haunts leads to erroneous statements such 
as Beach’s [p. 123, (50)] that it is not surprising that 
some rats never learn to hoard food “since Norway 
rats rarely hoard food under natural conditions”. 
In the context of these experimental studies the 
hoarding is unsocial. However, in a socially struc- 
tured population, a behavior such as hoarding has 
several social implications. The basic function of 
hoarding, of which the rat is not cognizant, is the 
dispersal of food through space such that a larger 
proportion of the population benefits from any 
given source. One could never have arrived at 
this conclusion from laboratory studies, which have 
given rise to the conclusions that hoarding is in- 
creased by such factors as early deprivation of food, 
decreased temperature, or familarity with the sur- 
roundings. My present studies showed that there 
was ample opportunity for some deprivation, par- 
ticularly among the progeny of socially lower rank- 
ing rats, both during the period of nursing and 
following weaning. Thus, the origin of intensity 
of hoarding (see example of female 43 and her 
young, pp. 147 to 148) has social implication. 
Furthermore, once hoarding behavior is initiated, 
it demands more trips between the rat’s home and 
the source of food than would otherwise occur. 
This increases the probability of contacting and 
interacting with other rats. Thus, the socially 
low-ranking rat is more likely to hoard because of 
early deprivations, but the increased contacts ac- 
companying hoarding increase the frequency with 
which such a rat is attacked by higher ranking 
associates. That is, the rat increases its probability 
of being punished for hoarding. Two consequences 
have already been detailed. These arc that non- 
harborage storing develops and that activity, in- 
cluding food transport, tends to become more 
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