Ekman isolated the wink, you see.
In 1976 the Facial Actions Coding System [FACS] was developed by Paul Ekman and colleague Wallace V. Friesen. It featured in their paper for the inaugural issue of Environmental Psychology and Nonverbal Behavior, 1(1), pp. 56-75, which was entitled ‘Measuring Facial Movement’. The Facial Action Code was derived from an analysis of the anatomical basis of facial movement – and described a comprehensive set of ‘Action Units’ which can, it’s said, be used to describe any facial movement in humans.
Here, for example, is Action Unit 46 – The Wink (video here in .mpg format)
But, in the last 37 years or so, the concept has been taken several steps forward – in that it’s no longer restricted to humans. See (for example):
• GibbonFACS and
• MaqFACS from which the picture above is taken.
BONUS: Quite a few of Professor Ekman’s peers are less than enthralled with the professor’s work.
BONUS: Video of Ekman’s code M59, the nod:
BONUS (possibly unrelated): Huh?