Please compare
He shrugged.
and
He shrugged his shoulders.
Is there anything else that can be shrugged, besides shoulders? To me it sounds like duplication when used in this way. I'm aware of constructs like "He shrugged it off." but that's not what I'm interested in, and it also implies the use of shoulders, doesn't it?
So why the need to specify the shoulders as an object?
[edit: I also find "he shrugged his eyebrows" but that's rather rare.]
Best Answer
Browsing through COHA and Google Books, I can’t find any body parts that can be shrugged apart from shoulders. In any case, the intransitive use — she shrugged etc. — is certainly always understood as the shoulder-gesture — it is, as you say, essentially redundant.
So shrugged is very nearly a stormy petrel. The only other thing you can do with it (that I can think of or find in the dictionary) is to shrug something off.
(If anyone at a subscribed university or library is reading, by the way, the OED online would be my best bet to look for other usages — their historical quotations will hopefully show how it came to be used this way. Unfortunately I’m currently travelling and so without access. Also, a clever COHA search would probably be able to automatically look there for instances of anything non-shouldery being shrugged, more thoroughly than I could browse.)