FACS is the Facial Action Coding System developed by Paul Eckman. I studied this in my undergraduate work when I was writing about Sculpting the Deceased. I wanted to know how I capture emotion in my art, or why I “feel” some things from my deceased subjects. FACS is some of the science behind what I do and feel with sculpting the deceased. It is used in animation and is mentioned here in this video about how they did the face of Benjamin Button. I think this is fascinating.