The Origin and Nature of Emotions [31]
improbable that a single general principle underlies all. Before presenting a hypothesis which harmonizes most of the facts, and which mayoffer an explanation of the origin and purpose of laughter, let us return for a moment to some previous considerations-- that man is essentially a motor being; that all his responses to the physical forces of his environment are motor; {illust. caption = FIG. 26.--LAUGHING CHIMPANZEE. "Mike," the clever chimpanzee in the London Zoo, evidently enjoys a joke as well as any one else. (Photo by Underwood and Underwood, N. Y.)}
that thoughts and words even are symbolic of motor acts; that in the emotions of fear, of anger, and of sexual love the whole body is integrated for acts which are not performed. These integrations stimulate the brain-cells, the ductless glands, and other parts, and the energizing secretions, among which are epinephrin, thyroid and hypophyseal secretions, are thrown into the blood-stream, while that most available fuel, glycogen, is also mobilized in the blood. This body-wide preparation for action may be designated kinetic reaction. The fact that emotion is more injurious to the body than is muscular action is well known, the difference being probably caused by the fact that when there is action the above-mentioned products of stimulation are consumed, while in stimulation without action they are not consumed and must be eliminated as waste products. Now these activating substances and the fuel glycogen may be consumed by any muscular action as well as by the particular muscular action for which the integration and consequent stimulation were made; that is, if one were provoked to such anger that he felt impelled to attack the object of his anger, one of three things might happen: First, he might perform no physical act but give expression to the emotion of anger; second, he might engage in a physical struggle and completely satisfy his anger; third, he might immediately engage in violent gymnastic exercises and thus consume all the motor-producing elements mobilized by the anger and thus clarify his body.
In these premises we find our explanation of the origin and purpose of laughter and crying, for since they consist almost wholly of muscular exertion, they serve precisely such clarifying purposes as would be served by the gymnastic exercises of an angry man. As it seems to me, the muscular action of laughter clears the system of the energizing substances which have been mobilized in various parts of the body for the performance of other actions (Figs. 27 to 29). If this be true, the first question that presents itself is, Why is the respiratory system utilized for such a clarifying purpose? Why do we not laugh with our feet and hands as well? Were laughter expressed with the hands, the monkey might fall from the tree and, if by the feet, man might fall to the ground. He would at least be ataxic. In fact, laughter has the great advantage of utilizing a group of powerful muscles which can be readily spared without seriously interfering with the maintenance of posture. Laughter, however, is only one form of muscular action which may consume the fuel thrown into the blood by excitation. That these products of excitation are often consumed by other motor acts than laughter is frequently seen in public meetings when the stamping of feet and the clapping of hands in applause gives relief to the excitation (Fig. 30). Why the noise of laughter? In order that the products of excitation may be quickly and completely consumed, the powerful group of expiratory muscles must have some resistance against which they can exert themselves strongly and at the same time provide for adequate respiratory exchange. The intermittent closure of the epiglottis serves this purpose admirably, just as the horizontal bars afford the resistance against which muscles may be exercised. The facial muscles are not in use for other purposes, hence their contractions will consume a little of the fuel. An audience excited by the words of an impassioned speaker undergoes a body-wide stimulation
that thoughts and words even are symbolic of motor acts; that in the emotions of fear, of anger, and of sexual love the whole body is integrated for acts which are not performed. These integrations stimulate the brain-cells, the ductless glands, and other parts, and the energizing secretions, among which are epinephrin, thyroid and hypophyseal secretions, are thrown into the blood-stream, while that most available fuel, glycogen, is also mobilized in the blood. This body-wide preparation for action may be designated kinetic reaction. The fact that emotion is more injurious to the body than is muscular action is well known, the difference being probably caused by the fact that when there is action the above-mentioned products of stimulation are consumed, while in stimulation without action they are not consumed and must be eliminated as waste products. Now these activating substances and the fuel glycogen may be consumed by any muscular action as well as by the particular muscular action for which the integration and consequent stimulation were made; that is, if one were provoked to such anger that he felt impelled to attack the object of his anger, one of three things might happen: First, he might perform no physical act but give expression to the emotion of anger; second, he might engage in a physical struggle and completely satisfy his anger; third, he might immediately engage in violent gymnastic exercises and thus consume all the motor-producing elements mobilized by the anger and thus clarify his body.
In these premises we find our explanation of the origin and purpose of laughter and crying, for since they consist almost wholly of muscular exertion, they serve precisely such clarifying purposes as would be served by the gymnastic exercises of an angry man. As it seems to me, the muscular action of laughter clears the system of the energizing substances which have been mobilized in various parts of the body for the performance of other actions (Figs. 27 to 29). If this be true, the first question that presents itself is, Why is the respiratory system utilized for such a clarifying purpose? Why do we not laugh with our feet and hands as well? Were laughter expressed with the hands, the monkey might fall from the tree and, if by the feet, man might fall to the ground. He would at least be ataxic. In fact, laughter has the great advantage of utilizing a group of powerful muscles which can be readily spared without seriously interfering with the maintenance of posture. Laughter, however, is only one form of muscular action which may consume the fuel thrown into the blood by excitation. That these products of excitation are often consumed by other motor acts than laughter is frequently seen in public meetings when the stamping of feet and the clapping of hands in applause gives relief to the excitation (Fig. 30). Why the noise of laughter? In order that the products of excitation may be quickly and completely consumed, the powerful group of expiratory muscles must have some resistance against which they can exert themselves strongly and at the same time provide for adequate respiratory exchange. The intermittent closure of the epiglottis serves this purpose admirably, just as the horizontal bars afford the resistance against which muscles may be exercised. The facial muscles are not in use for other purposes, hence their contractions will consume a little of the fuel. An audience excited by the words of an impassioned speaker undergoes a body-wide stimulation