Report on SAGA2/COE Symposium



The Apes and Us: Brain and Emergent Processes

Duane M. Rumbaugh

Departments of Psychology and Language Research Center
Georgia State University
Atlanta, Georgia USA 30303


     Within the order Primates, it is clear that the degree of both biological and psychological continuity is a function of genetic relatedness. We are more closely related to the chimpanzee/bonobo apes than they are, in turn, to any other primates, including the gorilla. Although biological continuity between animals and humans has been long recognized, psychological continuity has not * primarily because of the long-standing beliefs that animals cannot think or even feel and that human language results in a psychology that is quite different from that of animals. But now, at the dawn of a new millennium, we have solid evidence for significant psychological continuity between apes and humans. Apes are capable of complex learning, symbolic thought, speech comprehension, basic dimensions of language, basic numeric skills, and planning. Rhesus monkeys (Macaca) also have advanced skills and competencies, revealed by research with computers that requires of them facile use of a joystick that controls a cursor on a monitor. Although apparently not as adroit in symbolic processes, and probably with far less capacity to acquire language than the great apes, they nonetheless are impressive. They can predict events, estimate confidence in making choices, and learn equivalencies and ordinal relationships between arrays of items and Arabic numerals. Like us, they do significantly better when they can choose tasks on which to work, and they prefer to work at their computers rather than to get food "for free."
     Great apes and humans are noted for their large brains and protracted stages of development and maturation. Sensitive periods of early years have comparable effects, for better or worse, upon both infant ape and child. The effects can be extreme and life long.
     A comprehensive study with 12 primate species' (total N = 121) ability to transfer learning in relation to brain evolution yielded important insights that pertain to the evolution of humans. In an object-discrimination learning situation, transfer of learning was studied in relation to levels of mastery. A slight increment in the amount initially learned resulted in a remarkable decrease in transfer of learning proficiency in the prosimians and in some small bodied monkeys. By striking contrast, the larger monkeys and the great apes' transfer of learning increased. This shift, which is qualitative in its effect (i.e., from negative to positive transfer), is believed to reflect a shift from stimulus-response associative learning in the more primitive and small-bodied monkeys to a more rational/relational learning process, particularly in the great (but not lesser) apes.
     It is proposed that intelligence (e.g., facile learning and transfer of learning to an advantage rather than a disadvantage) increased fortuitously in its association with both brain size and body size. Such would have occurred if new primate species tended to be selected for having large bodies. (Large-bodied primates tend to have access rights over others.) But selection for intelligence based on body size, because of high metabolic demand, was surely constrained to the great apes. Selection of intelligence based upon brain enlargement apart from body size perhaps was contingent upon some early hominid becoming bipedal. An erect posture would have served to enhance use of the hands and facilitated manual interaction with objects of the environment. Inventions thus became more probable. Cumulatively, inventions would have served to enrich the rearing contexts for the offspring and to direct their cognitive development toward relational learning and facilitated applications of even small amounts of experience to meet new challenges. Offspring were thus prepared to make even greater gains in technological development than did their parents--and the rate of cultural development was accelerated.
     Here we will emphasize both the evolution and maturation of the primate brain as an information-sensitive structure that is particularly responsive to early rearing. The role of technology in research also will be emphasized.(HD-06016)


Rumbaugh, D. M., Savage-Rumbaugh, E. S., & Washburn, D. A. (1996). Toward a new outlook on primate learning and behavior: complex learning and emergent processes in comparative perspective. Japanese Psychological Research, 38(3), 113-125.

Rumbaugh, D. M., Washburn, D. A., & Hillix, W. A. (1996). Respondents, operants, and Emergents: toward an integrated perspective on behavior. In Learning as a Self-Organizing Process, K. Pribram & J. King (Eds.), pps. 57-73. Hillsdale, N.J.: Lawrence Erlbaum Associates.

Kilts, C. D., Rilling, J. K., Savage-Rumbaugh, E. S., Hoffman, J. M., Giroux, M., Rapoport, S., Williams, S. L., Beran, M. J., Rumbaugh, D. M. (submitted). Language-related brain activity in the chimpanzee.



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