国際シンポジウムThe Cognitive Triangle: Primates, Cetaceans, and Corvids

話題提供要旨  

Thomas Bugnyar (The Konrad Lorenz Research Station Grünau and Depertment for Behaviour, Neurobiology and Cognition, University of Vienna)

   Tactical maneouvres and sophisticated social cognition in ravens

Human social behavior is influenced by attributing mental states to others. It is debated whether such skills play a role in the behavior of non-human animals. We here used the mutually antagonistic interactions occurring between food-storing ravens and conspecific pilferers to test for the possibility of knowledge attribution in birds. Ravens’ pilfer success depends on memory for observed caches. We thus manipulated the view of birds at caching, thereby designing competitors who were knowledgeable or ignorant of cache locations, and then tested the responses of focal subjects to those competitors at recovery. In a series of experiments, we show that ravens modify their cache protection and pilfer tactics not simply in response to the behavior of competitors but on the recognition of individuals that could or could not see the caching. Our results indicate that ravens know that obstacles can obstruct the view of others and that this affects pilfering.

Satoshi Hirata (Great Ape Research Institute, Hayashibara Biochemical Laboratories, Inc.)

   Social intelligence in chimpanzees

Many primate species live in groups with specific social structures. Much attention has been paid to the social intelligence hypothesis, which claims that higher cognitive ability is required to survive in a complex social world, and this is the reason for the evolution of intelligence. I conducted five sets of studies to investigate social intelligence in captive chimpanzees. The aspects investigated in these studies included tactical interactions in a food competition situation, learning tool use in a social situation, trading food for mating, mothers assisting their infants, and cooperative problem-solving behavior in an experimental situation. The results illustrate similarities and differences between humans and chimpanzees, but the emphasis is that chimpanzees share much social intelligence with humans.

Tadamichi Morisaka (Research Fellow at Ethology Laboratory, Graduate School of Science, Kyoto University)

   Psychology and behavior of odontocetes

Odontocetes, or toothed whales, are living in an aquatic environment, which is totally different from terrestrial environments. Although they have come along a different evolutionary path from primates for more than 50 million years, they exhibit some of the same cognitive abilities as primates, including “mirror self-recognition” and “tool-use”. They also have the capacity for “vocal learning”, which is reported for a few mammals and some birds. Male bottlenose dolphins in Shark Bay, Australia are known to form some types of alliance, which indicate that dolphins may have complex social cognitive abilities. Bottlenose dolphins at other sites, however, do not exhibit such complex alliances. “Mirror self-recognition” and “tool-use” are also reported for bottlenose dolphins, but studies have failed to show such abilities in other odontocete species or at other locations. Cetologists now consider that ecological factors may strongly influence whether cetaceans acquire such abilities. In my talk, I will introduce some of the basic studies of dolphin cognition and behavior, and after that, I will show some behavioral work concerning rubbing behavior and acoustics.