33 
and dominance hierarchy. This was foreshadowed by Petrucci’s 1905 text, Les Origines 
Naturelles de la Propriété: Essai de Sociologie Comparée, which concluded: . 
En effet, la matiére vivante se maintient non seulement en ocupant un espace détermingé, 
mais encore en exploitant le milieu et en défendant sa propre structure contre toute 
influence nocive. Les éléments essentiels de la propriété sont contenus dans cette activité. 
(Petrucci, 1905, p. 219) 
Apparently, psychologists of the day failed to appreciate the important differences in 
explanatory power between biology’s instinct to defend a territory and psychology’s instinct to 
grasp an object. 
At the same period that psychologists were abandoning instinct theory, animal ethologists 
were developing the theory of territoriality. This is described in Ardrey’s (1966) best-selling 
Territorial Imperative: A Personal Inquiry into the Animal Origins of Property and Nations. 
Petrucci was not cited by Ardrey (1966) nor by others writing on territoriality. According to 
Ardrey (1966), the development of territoriality theory was delayed until the zoological study of 
captive animals was displaced by the ethologicai study of animals in their nature habitat. Early 
ethologists of territoriality were Huxley (1934), Lack (1933), Gordon (1936), Noble (1939), Burt 
(1943) and psychologist Carpenter (1934, 1942). Some of this early work on territoriality did 
appear in psychology journals. For example, Kirkman (1940) described how gulls act as owners 
occupying and defending their territories. Carpenter (1934) described the communal defense 
of communal territory by howler monkeys. Ethologists of territoriality were aware of the bearing 
of their work on discussions of the natural origins of property. For example, Hediger's opening 
sentence in his review of territoriality was this: 
it can be assumed that the natural history of territoriality in the animal kingdom represents 
the introduction to the first chapter of the history of property in mankind. (Hediger, 1961, p. 
34) 
However, it was not until the 1960's that territoriality became of interest to psychologists, 
and then primarily to animal psychologists and to a lesser extent environmental psychologists. 
A tabulation of Psychological Abstracts cumulative index entries under “territoriality” shows a 
rise from 0 per year from 1927 to 1943, to .33 per year by 1960, 4 per year by 1968, jumping to 21 
per year by 1974, 33 per year by 1977, 47 per year by 1980 and remaining at about that level since. 
As discussed by Tiger and Fox (1971) and Edney (1974), there are important differences 
between territory and property. For example, people exchange property whereas animals never 
exchange territory; human property behavior is variable whereas animal territorial behavior is 
stereotypical; property need not be contiguous whereas territory always Is. Nevertheless, the