The problem of the emergence of ethical conduct is considered in the perspective of the neo-darwinian scheme and thus of the survival value of actions complying to this definition. After a brief recall of basic ethological principles, the applications of the cultural character to certain behaviour patterns of primates is analysed and introduces the concept of value. The emergence of symbolic and reflexible language in the course of the evolution of the ancestors of Homo sapiens is discussed. The ethical order is defined as a code liable to qualify actions which were originally programmed. The consequences of this duality of codes governing a same action are discussed.