Junk 1, 1900.] 



SCIENCE. 



851 



noted, have the plumose and curved forms 



occurring in the rosettes of the caverns 



mentioned. 



Geoege p. Merrill. 



TSE NATURE OF THE S3IILE AND LAUGH. 



A DEFINITION of the Smile and laugh is 

 not needed by any one, for to every human 

 being it is a self-evident birth-right, an 

 axiomatic fact. Nor in general does this 

 phenomenon (we shall consider in this essay 

 the smile as only a lesser degree of the 

 laugh) need description, and for the same 

 reason. But the nature of the smile and 

 laugh psychophysiologically does need ex- 

 planation, why it is as it is and not other- 

 wise. We shall try then here to look a 

 little at the biological character of this in- 

 cident of our common experience. 



Herbert Spencer in his famous essay on 

 ' The Physiology of Laughter' (1S60), sug- 

 gests as the occasions of the laugh, these : 

 The ludicrous, joy, sardonic stimuli, hys- 

 terical states, mental distress, tickling, 

 cold, and some acute pains. It seems, 

 however, that pure or typical smiling and 

 laughter comes from what is best termed 

 joy, alone. It is only by inaccuracy of ob- 

 servation and a deficient consideration of 

 certain facts that that smile-like expression 

 of the face occasioned by ' sardonic stimuli,' 

 mental distress, and acute pains is termed 

 a smile, for while it is obvious, indeed, 

 that the facial ' expression' of this tone of 

 feeling is somewhat like that of unalloyed 

 pleasantness, yet there are differences. 

 These differences are chiefly in the mouth 

 in the way of a greater uncovering of the 

 upper teeth, with a different look about the 

 eyes, the total appearance being harsher, in 

 a way hard to particularize but very easy 

 to feel. The so-called laughter of really 

 painful states, at best only rarely observed, 

 seems to depend on the well-established 

 affective principle that the extremes of 

 contraries tend to produce like effects, 



probably through the occurrence of wide 

 radiation in the cortex, as would be ex- 

 pected when the stimulus is on the verge 

 of abnormality of strength. Again, it must 

 be remembered that so perfect and sensi- 

 tive is the neuromuscular mechanism in 

 question that even in an experience which 

 is chiefly unpleasant or painful, even a 

 momentary idea of any sort, or a brief ces- 

 sation of the pain (in itself a pleasantness), 

 would serve as the occasion of a true smile 

 and so complicate the expression, giving it 

 more the look of a properly occasioned 

 smile. Tickling, on the other hand, is es- 

 sentially pleasant if not too long continued ; 

 and it is characteristic of hysteria in a 

 marked degree that it simulates arbitrarily 

 every known emotion to perfection, or rather 

 is in itself a versatile emotional state. It 

 seems proper then to consider the laugh and 

 smile as concomitant properly only to pleas- 

 antness or to pleasure, whether this affec- 

 tive tone be derived from purely conceptual 

 relations, as in humor, or from stimulation 

 of whatever bodily organs are in their action 

 concomitant to pleasure. 



One may observe even within the first 

 week of the post-natal life of the infant that 

 the eyes and especially the mouth display 

 at times an incipient smile, the purely re- 

 flex or mechanical accompaniment of a true 

 sensational pleasantness, arising usually 

 from the normal functioning of the digestive 

 process. A very few weeks later (two, as 

 I have observed in one infant), the con- 

 sciousness has become so far familiar, so to 

 say, with its organism, as to bring out 

 nearly if not quite in all its adult details 

 the action of the inborn intricate mechanism 

 of nerve and muscle. The ' hearty laugh ' 

 does not seem to occur until a somewhat 

 later period, aloud and briefly perhaps by 

 the end of the eighth week, but as a general 

 bodily process not before two or three years 

 of life have passed ; this is not, probably, 

 because of any incompleteness in the ap- 



