Short-Term Activity Cycles in Leptothorax Ants

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A fundamental problem in the study of behavior is the emergence of complexity of social behavior from the behavior of individuals within the social unit. If the characteristics of a social group can be accounted for by the summed actions of individuals, then social behavior is a resultant of individual behavior. If the characteristics of a group are not simply due to the summed actions of individuals, then social behavior has an emergent property. Social insects are well known to have attributes of the colony that are not present among the individuals comprising the colony. The activity of a colony is basic to all its other behavior. Dr. Cole has discovered that activity within nests of a species of ant, Leptothorax allardycei, has short-term cycles, with pulses of activity occurring at intervals of approximately 20 minutes. Individual, isolated ants do not show this regularity of activity, but the periodicity emerges as more and more ants are added to the aggregate. The purpose of this research project is to analyze the production of periodicity in colonies from the behavior and movement patterns of individual ants. Dr. Cole will develop a computer model of the movement patterns of individual ants, including their velocity of movement, turning angles, and position within the nest that they occupy. This information will be combined with information on their response to encounters with other ants, the effect of an encounter on the probability of subsequent activity by an individual ant, and mutual synchronization of activity to produce a computer model of the activity of a colony. This model will be tested by direct manipulation of the activity of colonies through the use of alarm pheromones. Dr. Cole's research is an important step toward gaining an understanding of the mechanisms by which the individuals within a social unit produce social phenomena. Until we understand the mechanisms of social interaction, it will remain impossible to predict the consequences of group living and the effects of natural selection on social behavior.