PSYCHOLOGY 283 



animals in the loud, joyous bark of the dog, the whinny of the 

 horse, the screech of the parrot and other birds. 



Another characteristic expression of delight is " laughter," 

 consisting of forcible expiratory shocks of sound with shaking of 

 the thorax and abdomen. The mouth is pulled upwards and 

 backwards so that its opening is transversely widened, while 

 the lower eyelids are wrinkled up (Figs. 127 and 128). Haller 

 made the observation that the note on which an adult man 

 laughs has the character of the vowel A or O, women and 

 children sound an E or I. The latter is always the case in apes 

 when laughing or chuckling, even as the result of tickling. The 

 chimpanzee makes a half-barking, half-chuckling noise ; the 

 small capuchin ape Nellie, the subject of Garner's observations, 



FIG. 127. Girl laughing. FIG. 128. Black baboon grinning. 



was so amused by the sudden appearances of a boy who played 

 hide-and-seek with her that she burst into loud laughter which 

 could be heard all over the house. The rhesus ape Dolly had 

 an almost human, but somewhat softer laugh. Dogs and horses, 

 although they do not laugh, certainly grin with delight, the 

 former sniffing with retracted upper lip, the latter drawing back 

 the upper lip and exposing the upper teeth. Laughter is then 

 no specific human characteristic of expression. 



Dancing too is not peculiar to man. Mankind, especially 

 during youth, dances round in a circle in ecstasies of joy, and 

 takes great delight in the social dance. When the dog is told 

 to come out with his master he rushes round and round madly, 

 and there are birds which give expression to their joy by 



