Precursors of morality in the use of the symbols "good" and "bad" in two bonobos (Pan paniscus) and a chimpanzee (Pan troglodytes)

Morality is a concept that is based on value judgments of "right" or "wrong" and "good" and "bad". Three language-competent apes (two bonobos and a chimpanzee) are shown to use the symbols "good" and "bad" in appropriate contexts and to co-construct these values with the humans in their environment, indicating that the specific expression of value judgments is cultural. Their developmental use of these symbols parallels studies in children which suggest that conceptual simplicity and internal development may affect the development of moral precursors. These findings support recent research that has found moral precursors in several species of nonhuman primates. (C) 2008 Elsevier Ltd. All rights reserved.