18. Joy and sadness are experienced by people in all cultures around the world, but how can we tellwhen other people are happy or unhappy? It turns out that the expression of many emotions maybe universal. Smiling is apparently a universal sign of friendliness and approval. Baring theteeth in a hostile way, as noted by Charles Darwin in the nineteenth century, may be a universalsign of anger. As the originator of the theory of evolution, Darwin believed that the universalrecognition of facial expressions would have survival value. _______________
(A) In fact, various emotional states give rise to certain patterns of electrical activity in the facialmuscles and in the brain.
(B) Moreover, people in diverse cultures recognize the emotions manifested by the facial expressions.
(C) For example, facial expressions could signal the approach of enemies (or friends) in the absenceof language.
(D) Obviously, different emotions that are conveyed through facial expressions could bridge thecommunication breakdowns.¯