▁reflected ▁through ▁a ▁variety ▁of ▁ne uro - dynamic ▁lim b ic ▁emot ional ▁action ▁systems , ▁including ▁seeking , ▁fear , ▁ra ge , ▁l ust , ▁care , ▁pan ic ▁and ▁play . ▁Through ▁brain ▁stim ulation ▁and ▁ph arm ac ological ▁challeng es , ▁such ▁emot ional ▁responses ▁can ▁be ▁effectively ▁monitor ed . ▁ ▁Em otion ▁has ▁been ▁observed ▁and ▁further ▁research ed ▁through ▁multiple ▁different ▁approaches ▁including ▁that ▁of ▁behaviour ism , ▁compar ative , ▁an ec dot al , ▁specifically ▁Dar win ' s ▁approach ▁and ▁what ▁is ▁most ▁widely ▁used ▁today ▁the ▁scientific ▁approach ▁which ▁has ▁a ▁number ▁of ▁sub fields ▁including ▁functional , ▁mechan istic , ▁cogn itive ▁bias ▁tests , ▁self - med ic ating , ▁sp ind le ▁neur ons , ▁vocal izations ▁and ▁ne uro log y . ▁ ▁While ▁emot ions ▁in ▁animals ▁is ▁still ▁quite ▁a ▁controvers ial ▁topic ▁it ▁has ▁been ▁studied ▁in ▁an ▁extensive ▁array ▁of ▁species ▁both ▁large ▁and ▁small ▁including ▁prim ates , ▁rod ents , ▁ele ph ants , ▁horses , ▁birds , ▁dogs , ▁c ats , ▁h oney be es ▁and ▁c ray fish . ▁ ▁Et ym ology , ▁definitions , ▁and ▁different iation ▁The ▁word ▁" em otion " ▁dates ▁back ▁to ▁ 1 5 7 9 , ▁when ▁it ▁was ▁adapted ▁from ▁the ▁French ▁word ▁é m ou voir , ▁which ▁means ▁" to ▁stir ▁up ". ▁However , ▁the ▁earliest ▁prec urs ors ▁of ▁the ▁word ▁likely ▁date ▁back