8 - The role of innate motor patterns in ontogenetic and experiential development of intelligent use of sticks in cebus monkeys

Summary

In particular cases there is as much difficulty in classifying certain actions as instinctive or rational, as there is in cases where the question lies between instinct and reflex action. And the explanation of this is, as already observed, that instinct passes into reason by imperceptible degrees; so that actions in the main instinctive are very commonly tempered with what Pierre Huber calls “a little dose of judgment or reason,” and vice versa. But here, again, the difficulty which attaches to the classification of particular actions has no reference to the validity of the distinctions between the two classes of actions; these are definite and precise.

– Romanes (1886, p. 16)

Given that recent investigators have labeled a variety of behaviors in various birds and mammals as tool use (e.g., Alcock, 1972; Beck, 1980; Hall, 1963; Kortlandt & Kooij, 1962; van Lawick-Goodall, 1970), it is appropriate to establish our definition of “tool use.” We require that to qualify as a tool user, the animal must move a detached object for the purpose of changing the state and/or position of another object or a behavior (Beck, 1980; Parker & Gibson, 1977; van Lawick-Goodall, 1970). Furthermore, we require that to qualify as an intelligent tool user, the animal must understand that the detached object acts as a detached intermediary capable of displacing the goal object, and the animal must understand how to manipulate the object in relation to the physical constraints of the situation, as described later.