A method and apparatus is provided for creating and recognizing a USN (Unique Signature Number) from an analysis of living entity's (e.g. person, animal or other multi-cellular being having neural activity) emitted electrical or electromagnetic signal in a given, normalized or calm state. This USN may then be used at a later date, in a comparison function of a number of stored USN's, in ascertaining the identity of an entity recently detected as being in proximity to an antenna of the apparatus. A further analysis process can also detect neural activity that is abnormal to that indicated by the USN of a given entity in a calm state and which neural activity may be indicative of excessive aggression, stress or even ill health said given entity.