I love this blog. It is everything I have been looking for. However I have reached the post that says "21 pages" and am giving up. Just consider, aliens with minimal body language or some telepathy being perplexed but sign language. "Sure, maybe with your lack of thought share it is a way to communicate without making your presence known, but why do some humans use it as primary? There is nothing wrong with speach
But! The cool thing about American Sign Language (the one I know most about, albeit still very little) is that it’s an actual language unto itself, not just a mimed version of English! It has its own grammar, and is a “complex language that employs signs made by moving the hands combined with facial expressions and postures of the body.” And ASL is distinct from other sign languages–British Sign Language is not the same and (from my knowledge) is not mutually intelligible to ASL-speakers [signers?] and vice-versa, even though British English and American English are.
What I think is more likely would be aliens having the same confusion a lot of humans have: not understanding ASL/other sign languages as a separate language and not understanding the importance of gesture, facial expression, and other body language in the language itself (rather than as a sort-of secondary way to emphasize/modify spoken language).
Edit:// As some have pointed out, ASL is related to/descended from French Sign Language, although they’re not the same language. I meant to explain that the different sign languages are not all the same and not all mutually intelligible–there is no one worldwide sign language, just as there is no one worldwide spoken language.