Okay, they probably didn't mean it that way. But the interest of this book is indeed the cross-cultural variety of meanings of various gestures. It certainly isn't the surprising amount of material which is blindingly obvious to anyone who's ever participated in an actual conversation in the USA. "Sadness is generally betrayed by the mouth, which tends to droop at the corners, so emphasizing the generally slack and unanimated appearance of the face. The lips may quiver if you are on the verge of tears." Who is this book for, anyway? Escaped androids from an MIT lab?
There's also a fair amount of what strikes me as dime-store evo-psych just-so stories. "A domineering speaker raises a forefinger and beats it up and down in an action that is symbolic of a stick (or an ape's overarm blows) pummeling an opponent into submission." Beating, okay, but why the ape? Or this one: a female courting signal is that "the woman might [look] at the man over a raised shoulder for longer than people normally look at each other," which does indeed sound seductive (imagine Keira Knightley doing it, for example), but here's the explanation: "Self-mimicry; the shoulder resembles the breast and so is sexually inviting" – which, well, I dunno.
Back to ambiguous cross-cultural gestures. The one in which the head is "jerked sharply backwards" (I think I've seen this one in the movies – "ehh!") is negative in southern Italy, as I would have expected, but it means "yes" in Ethiopia. No wonder those two countries couldn't get along! Also, the authors acknowledge that some gestures are inherently ambiguous. Under "male courtship signals," one such gesture is indicated, followed by a few "possible alternative meanings" in parentheses:
Straightening the tie (nervousness; habit; tie might need straightening).You think??