It is remarkable how readily and instantly retching or actual vomiting is induced in some persons by the mere idea of having partaken of any unusual food, as of an animal which is not commonly eaten;although there is nothing in such food to cause the stomach to reject it.
When vomiting results, as a reflex action, from some real cause--as from too rich food, or tainted meat, or from an emetic--it does not ensue immediately, but generally after a considerable interval of time.
Therefore, to account for retching or vomiting being so quickly and easily excited by a mere idea, the suspicion arises that our progenitors must formerly have had the power (like that possessed by ruminants and some other animals) of voluntarily rejecting food which disagreed with them, or which they thought would disagree with them; and now, though this power has been lost, as far as the will is concerned, it is called into involuntary action, through the force of a formerly well-established habit, whenever the mind revolts at the idea of having partaken of any kind of food, or at anything disgusting.
This suspicion receives support from the fact, of which I am assured by Mr. Sutton, that the monkeys in the Zoological Gardens often vomit whilst in perfect health, which looks as if the act were voluntary.
We can see that as man is able to communicate by language to his children and others, the knowledge of the kinds of food to be avoided, he would have little occasion to use the faculty of voluntary rejection;so that this power would tend to be lost through disuse.
[8] Duchenne believes that in the eversion of the lower lip, the corners are drawn downwards by the _depressores anguli oris_.
Henle (Handbuch d. Anat. des Menschen, 1858, B. i. s. 151) concludes that this is effected by the _musculus quadratus menti_.
As the sense of smell is so intimately connected with that of taste, it is not surprising that an excessively bad odour should excite retching or vomiting in some persons, quite as readily as the thought of revolting food does; and that, as a further consequence, a moderately offensive odour should cause the various expressive movements of disgust.
The tendency to retch from a fetid odour is immediately strengthened in a curious manner by some degree of habit, though soon lost by longer familiarity with the cause of offence and by voluntary restraint.
For instance, I wished to clean the skeleton of a bird, which had not been sufficiently macerated, and the smell made my servant and myself (we not having had much experience in such work) retch so violently, that we were compelled to desist. During the previous days I had examined some other skeletons, which smelt slightly; yet the odour did not in the least affect me, but, subsequently for several days, whenever I handled these same skeletons, they made me retch.
From the answers received from my correspondents it appears that the various movements, which have now been described as expressing contempt and disgust, prevail throughout a large part of the world.
Dr. Rothrock, for instance, answers with a decided affirmative with respect to certain wild Indian tribes of North America. Crantz says that when a Greenlander denies anything with contempt or horror he turns up his nose, and gives a slight sound through it.[9] Mr. Scott has sent me a graphic description of the face of a young Hindoo at the sight of castor-oil, which he was compelled occasionally to take.
Mr. Scott has also seen the same expression on the faces of high-caste natives who have approached close to some defiling object.
Mr. Bridges says that the Fuegians "express contempt by shooting out the lips and hissing through them, and by turning up the nose."
The tendency either to snort through the nose, or to make a noise expressed by _ugh_ or _ach_, is noticed by several of my correspondents.
[9] As quoted by Tylor, `Primitive Culture,' 1871, vol. i. p. 169.
Spitting seems an almost universal sign of contempt or disgust;and spitting obviously represents the rejection of anything offensive from the mouth. Shakspeare makes the Duke of Norfolk say, "I spit at him--call him a slanderous coward and a villain." So, again, Falstaff says, "Tell thee what, Hal,--if I tell thee a lie, spit in my face."