Emblems are substitute of words. They are body movements that have rather specific translations, such as nonverbal signs of OK.
Emblems are as arbitrary as any words in any language. Consequently, your present culture’s emblems are not necessarily the same as your culture’s emblems of 300 years ago or the same as the emblems of other cultures.
Just as the English language is spreading throughout the world, so too is the nonverbal language.