In almost all other species, especially primates, baring one's teeth is a threat or a show of potential force. Are there any cultures in which smiling is not considered friendly?
Before the smartphone or even Morse code, some rural peoples “spoke” long distance by whistling. Linguists are racing to study the dying languages
Analyzing how stories change in the retelling down through the generations sheds light on the history of human migration going as far back as the Paleolithic period