a1 Department of Psychology, University of Konstanz, Germany
The daily activities observed in a Colombian village community of contemporary hunting and gathering people were analysed with respect to their time structure. Short term cycles of about 2 hours could be detected in both individual and common behavioural patterns. These behaviour cycles of individual group members appear to have been synchronised by social interaction. From temporal variations of individual activities a common ultradian time frame emerged.
(Received February 15 1993)