よ。
(ア) As a result, humans can break up an *exhalation and *modulate it to
produce language and laughter.
(イ) It's this back-and-forth between breath cycle and *yocalization that makes
w it impossible for most primates to speak or laugh.
(ウ) This difference has its roots going back millions of years, deep in the story of
human evolution.
(エ) When humans began walking upright, it , the upper bódy from *weight-
freed
bearing functions and allowed better breath control.
