June 1, 1900.] 



SCIENCE. 



853 



In his classic treatise on emotional ex- 

 pression Darwin gives the results of his 

 numerous inquiries of persons in all parts 

 of the earth as to laughter among savage 

 races, and these vrere invariably to the 

 effect that the phenomena is identical among 

 them all : the seemingly wretched dweller 

 in Terra del Fuego or the pigmy in the dark 

 forest of the heart of Africa smiles pre- 

 cisely as does the newly made peer of Britain 

 when he is alone, and for a precisely similar 

 reason — because he is at that moment un- 

 usually happy. The cannibal may laugh at 

 the contortions of his victim roasting in the 

 fire before him, and the pampered infant in 

 his nurse's arms may be wreathed in smiles 

 at the prospect of another sugared ' cookie,' 

 but the process in the two cases is not dif- 

 ferent and the physiologic cause is the 

 same — pleasure, or the prospect of pleasure 

 in itself pleasant. Dogs and monkeys are 

 not infrequently seen to smile, and there 

 are many who consider certain joyous mani- 

 festations in other animals as properly 

 laughter. The nearly continuous state of 

 smiling or laughter often seen in the case of 

 imbeciles may obviously be taken as the 

 reflex organic co-ordinate of that constant 

 tone of pleasantness which these persons 

 doubtless usually experience. The limita- 

 tion of intelligence in these subjects makes 

 it impossible for them to realize the serious 

 burdens of life, while the somatic process, 

 to an awareness of which their conscious- 

 ness is often reduced, certainly gives as its 

 psychic tone a complex sense of pleasant- 

 ness or even of pleasure. It is on this ac- 

 count that in very young children, savages, 

 and imbeciles the smile is to be obsei'ved at 

 its purest, physiologically speaking. 



Aside from innumerable references and 

 descriptions, throughout general literature, 

 of the phenomena we are discussing, the 

 technical treatises on their physiology have 

 been relatively numerous in all ages, al- 

 though many of the books which pretend to 



explain laughter are really treatises on wit 

 or on humor or on both, and contain little 

 or nothing physiological, while the riddle 

 why humor causes laughter and what the 

 former is withal, is still as far as ever, ap- 

 parently, from its interesting solution. It 

 is sufficient for us that we ignore wit and 

 humor, and begin with the ^ileasantness 

 which these, together with innumerable 

 other causes, produce in the soul. "With 

 this we may start with entire confidence', 

 for, save perhaps in rare abnormal cases, the 

 smile and laugh are everywhere the natural 

 'expression,' or, better, correlates, of pleas- 

 antness or joy in the individual. What, 

 then, are the bodily accompaniments of 

 general pleasantness in the human animal ? 

 The more conspicuous of the reactions may 

 be suggested as follows, which later on we 

 shall endeavor to explain and to account for. 

 There occur in laughter and more or less 

 in smiling, clonic spasms of the diaphragm 

 in number ordinarily about eighteen per- 

 haps, and contraction of most of the muscles 

 of the face. The upper side of the mouth 

 and its corners are drawn upward. The 

 upper eyelid is elevated, as are also, to some 

 extent, the brows, the skin over the gla- 

 bella, and the upper lip, while the skin at 

 the outer canthi of the eyes is character- 

 istically puckered. The nostrils are mod- 

 erately dilated and drawn upward, the 

 tongue slightly extended, and the cheeks 

 distended and drawn somewhat upward ; 

 in persons with the pinnal muscles largely 

 developed, the pinnae tend to incline for- 

 wards. The lower jaw vibrates or is some- 

 what withdrawn (doubtless to afford all 

 possible air to the distending lungs), and 

 the head, in extreme laughter, is thrown 

 backward ; the trunk is straightened even 

 to the beginning of bending backward, until 

 (and this usually happens soon), fatigue- 

 pain in the diaphragm and accessory ab- 

 dominal muscles causes a marked proper 

 flexion of the trunk for its relief. The 



