Wingback, or just wing chairs originated in the late 17th century as a way to protect sitters from drafts. The "wings" (or ears, as they call them in French) partially enclose a sitter and help to keep heat in when seated by a fire. The form has evolved slightly over time as it morphed under various styles like Charles II (first photo below), Queen Anne, Georgian, Chippendale, and Hepplewhite.
A version of the wingback chair is the porter chair. Its original purpose was similar to the wingback: to protect the sitter, keeping them enclosed and warm by a fire. But for servants in grand old estate houses whose job it was to sit up all night in the hall in case the Lord or Lady awoke and needed anything, they sat in a porter chair, protecting them from drafts and chill. Whereas a wingback chair's protection comes from the sides, a porter chair's protection is like a bubble... in fact, the chair is also referred to as a balloon chair (since it resembles an 18th century hot air balloon with a gondola). Kelly Wearstler put the mandarin-colored beauties below in her Beverly Hills home, seen in her magnificent coffee table book DOMICILIUM DECORATUS.