people around. Certainly, in this case, the dolpin and whale had to be "aware" of the ongoing events surrounding them, which enabled them to monitor when individuals were present and when they were absent.
Dolphins also have been reported to use "tools" on several occasions. Brown and Norris ( 1956) reported two dolphins trying to persuade a moray eel to play with them. When the eel retreated to a crevice to hide while one of the dolphins went and killed a scorpionfish, which has sharp dorsal spines, and returned with it in its mouth and began to poke at the eel, finally forcing the eel into the open. Similar tool usage has been well documented in the laboratory ( Yerkes & Yerkes, 1929) and field ( Goodall, 1964; Pitman, 1931) for the great apes. Herman and Tavolga ( 1980) have shown that dolphins are capable of receptively comprehending strings of sentences using an artificial language.
In order to better understand the cognitive capacities of dolphins, and to determine whether or not they are capable of complex intentional communications, we must continue to investigate their receptive capacities ( Herman, this volume), and to attempt to provide them with a communication system that would tap their productive capacities.
The study of those communicative behaviors that reflect higher order intelligence is of special interest in the dolphin because of its great evolutionary diversity from ourselves. Ape and man separated only 4.5 million years ago, while we divergenced from dolphins at least 60 million years ago. Should dolphins prove to have some capacities for intentional communicative behavior, we would have strong support for the idea that intelligence is an entity whose existence transcends the anatomy of the bearer. Similarities between the intelligence of apes and that of dolphins, if they are found to exist, will help us to better understand the evolution of mind in our own species. The use of a productive communication system with dolphins would also allow us to explore avenues of dolphine intelligence not presently open to us; do they for example, have a sense of time, of math, of music, of ethics? These questions are only just now being posed with apes, they should also prove fascinating if addressed to dolphins.
This research supported by grants from the National Institute of Child Health and Human Development (HD-06016) and from the Division of Research Resources, National Institutes of Health (RR-00165). Research for reprints may be sent to E. Sue Savage- Rumbaugh, Yerkes Regional Primate Center, Emory University, Atlanta, GA. 30322.
Breland K., & Breland M. ( 1966). Animal behavior. New York: Macmillan.
Brown D. H., & Norris K. S. ( 1956). Observations of captive and wild cetaceans. Journal of Mammalology, 37, 311-326.