Evolution of the Chemical Communication and Olfactory System in Animal Kingdom

Chemical signals transmit a large amount of information about the environment, enabling animals to identify desirable elements (such as food) or dangers to avoid (such as predators) and to locate mating partners. Considering the wide range of different chemicals, it is not surprising that organisms, living in different contexts, use an important repertoire of receptors and signaling pathways to probe their environment. The aim of this work was to describe the major stages in the development of the olfactory organ during the course of evolution. The few cells on the body surface of primitive organisms gave way to an individualised organ, at first rudimentary and then increasingly complex and efficient. Keywords: chemicals, sense organs, olfactory system, vertebrates, invertebrates