Ethology of anxiety in phylogeny and ontogeny

Among animals, fear is a signal of an external danger which can be triggered without any learning. Fear is often mediated by the perception of another fear issued from a peer, allowing the contagion of the emotion. Ontogeny of animal fear can be observed in the natural environment, and it can be experimentally manipulated. This suggests the idea that animal fear is an internal signal of a danger, and that it develops by imprinting of external objects which categorizes the animal's world in a familiar tranquillizing world vs. a strange anxiogenic one. In humans, the child's development allows us to observe similar phenomena until such time as the child has access to the semantic world, and will experience emotions released by gestures and words issued from attachment figures or anxiogenic ones.