STUDIES
IN THE
PSYCHOLOGY OF SEX
VOLUME IV
SEXUAL SELECTION IN MAN
I. TOUCH. II. SMELL. III. HEARING. IV. VISION.
BY
HAVELOCK ELLIS
1927
PREFACE.
As in many other of these Studies, and perhaps more than in most, the task attempted in the present volume is mainly of a tentative and preliminary character. There is here little scope yet for the presentation of definite scientific results. However it may be in the physical universe, in the cosmos of science our knowledge must be nebulous before it constellates into definitely measurable shapes, and nothing is gained by attempting to anticipate the evolutionary process. Thus it is that here, for the most part, we have to content ourselves at present with the task of mapping out the field in broad and general outlines, bringing together the facts and considerations which indicate the direction in which more extended and precise results will in the future be probably found.
In his famous Descent of Man, wherein he first set forth the doctrine of sexual selection, Darwin injured an essentially sound principle by introducing into it a psychological confusion whereby the physiological sensory stimuli through which sexual selection operates were regarded as equivalent to æsthetic preferences. This confusion misled many, and it is only within recent years (as has been set forth in the "Analysis of the Sexual Impulse" in the previous volume of these Studies) that the investigations and criticisms of numerous workers have placed the doctrine of sexual selection on a firm basis by eliminating its hazardous æsthetic element. Love springs up as a response to a number of stimuli to tumescence, the object that most adequately arouses tumescence being that which evokes love; the question of æsthetic beauty, although it develops on this basis, is not itself fundamental and need not even be consciously present at all. When we look at these phenomena in their broadest biological aspects, love is only to a limited extent a response to beauty; to a greater extent beauty is simply a name for the complexus of stimuli which most adequately arouses love. If we analyze these stimuli to tumescence as they proceed from a person of the opposite sex we find that they are all appeals which must come through the channels of four senses: touch, smell, hearing, and, above all, vision. When a man or a woman experiences sexual love for one particular person from among the multitude by which he or she is surrounded, this is due to the influences of a group of stimuli coming through the channels of one or more of these senses. There has been a sexual selection conditioned by sensory stimuli. This is true even of the finer and more spiritual influences that proceed from one person to another, although, in order to grasp the phenomena adequately, it is best to insist on the more fundamental and less complex forms which they assume. In this sense sexual selection is no longer a hypothesis concerning the truth of which it is possible to dispute; it is a self-evident fact. The difficulty is not as to its existence, but as to the methods by which it may be most precisely measured. It is fundamentally a psychological process, and should be approached from the psychological side. This is the reason for dealing with it here. Obscure as the psychological aspects of sexual selection still remain, they are full of fascination, for they reveal to us the more intimate sides of human evolution, of the process whereby man is molded into the shapes we know.
HAVELOCK ELLIS.
Carbis Water,
Lelant, Cornwall, England.
CONTENTS.
PREFACE.
CONTENTS.
SEXUAL SELECTION IN MAN.
The External Sensory Stimuli Affecting Selection in Man. The Four Senses Involved.
TOUCH.
I.
The Primitive Character of the Skin. Its Qualities. Touch the Earliest Source of Sensory Pleasure. The Characteristics of Touch. As the Alpha and Omega of Affection. The Sexual Organs a Special Adaptation of Touch. Sexual Attraction as Originated by Touch. Sexual Hyperæsthesia to Touch. The Sexual Associations of Acne.
II.
Ticklishness. Its Origin and Significance. The Psychology of Tickling. Laughter. Laughter as a Kind of Detumescence. The Sexual Relationships of Itching. The Pleasure of Tickling. Its Decrease with Age and Sexual Activity.
III.
The Secondary Sexual Skin Centres. Orificial Contacts. Cunnilingus and Fellatio. The Kiss. The Nipples. The Sympathy of the Breasts with the Primary Sexual Centres. This Connection Operative both through the Nerves and through the Blood. The Influence of Lactation on the Sexual Centres. Suckling and Sexual Emotion. The Significance of the Association between Suckling and Sexual Emotion. The Association as a Cause of Sexual Perversity.
IV.
The Bath. Antagonism of Primitive Christianity to the Cult of the Skin. Its Cult of Personal Filth. The Reasons which Justified this Attitude. The World-wide Tendency to Association between Extreme Cleanliness and Sexual Licentiousness. The Immorality Associated with Public Baths in Europe down to Modern Times.
V.
Summary. Fundamental Importance of Touch. The Skin the Mother of All the Other Senses.
SMELL.
I.
The Primitiveness of Smell. The Anatomical Seat of the Olfactory Centres. Predominance of Smell among the Lower Mammals. Its Diminished Importance in Man. The Attention Paid to Odors by Savages.
Rise of the Study of Olfaction. Cloquet. Zwaardemaker. The Theory of Smell. The Classification of Odors. The Special Characteristics of Olfactory Sensation in Man. Smell as the Sense of Imagination. Odors as Nervous Stimulants. Vasomotor and Muscular Effects. Odorous Substances as Drugs.
III.
The Specific Body Odors of Various Peoples. The Negro, etc. The European. The Ability to Distinguish Individuals by Smell. The Odor of Sanctity. The Odor of Death. The Odors of Different Parts of the Body. The Appearance of Specific Odors at Puberty. The Odors of Sexual Excitement. The Odors of Menstruation. Body Odors as a Secondary Sexual Character. The Custom of Salutation by Smell. The Kiss. Sexual Selection by Smell. The Alleged Association between Size of Nose and Sexual Vigor. The Probably Intimate Relationship between the Olfactory and Genital Spheres. Reflex Influences from the Nose. Reflex Influences from the Genital Sphere. Olfactory Hallucinations in Insanity as Related to Sexual States. The Olfactive Type. The Sense of Smell in Neurasthenic and Allied States. In Certain Poets and Novelists. Olfactory Fetichism. The Part Played by Olfaction in Normal Sexual Attraction. In the East, etc. In Modern Europe. The Odor of the Armpit and its Variations. As a Sexual and General Stimulant. Body Odors in Civilization Tend to Cause Sexual Antipathy unless some Degree of Tumescence is Already Present. The Question whether Men or Women are more Liable to Feel Olfactory Influences. Women Usually more Attentive to Odors. The Special Interest in Odors Felt by Sexual Inverts.
IV.
The Influence of Perfumes. Their Aboriginal Relationship to Sexual Body Odors. This True even of the Fragrance of Flowers. The Synthetic Manufacture of Perfumes. The Sexual Effects of Perfumes. Perfumes perhaps Originally Used to Heighten the Body Odors. The Special Significance of the Musk Odor. Its Wide Natural Diffusion in Plants and Animals and Man. Musk a Powerful Stimulant. Its Widespread Use as a Perfume. Peau d'Espagne. The Smell of Leather and its Occasional Sexual Effects. The Sexual Influence of the Odors of Flowers. The Identity of many Plant Odors with Certain Normal and Abnormal Body Odors. The Smell of Semen in this Connection.
V.
The Evil Effects of Excessive Olfactory Stimulation. The Symptoms of Vanillism. The Occasional Dangerous Results of the Odors of Flowers. Effects of Flowers on the Voice.
VI.
The Place of Smell in Human Sexual Selections. It has given Place to the Predominance of Vision largely because in Civilized Man it Fails to Act at a Distance. It still Plays a Part by Contributing to the Sympathies or the Antipathies of Intimate Contact.
HEARING.
I.
The Physiological Basis of Rhythm. Rhythm as a Physiological Stimulus. The Intimate Relation of Rhythm to Movement. The Physiological Influence of Music on Muscular Action, Circulation, Respiration, etc. The Place of Music in Sexual Selection among the Lower Animals. Its Comparatively Small Place in Courtship among Mammals. The Larynx and Voice in Man. The Significance of the Pubertal Changes. Ancient Beliefs Concerning the Influence of Music in Morals, Education and Medicine. Its Therapeutic Uses. Significance of the Romantic Interest in Music at Puberty. Men Comparatively Insusceptible to the Specifically Sexual Influence of Music. Rarity of Sexual Perversions on the Basis of the Sense of Hearing. The Part of Music in Primitive Human Courtship. Women Notably Susceptible to the Specifically Sexual Influence of Music and the Voice.
II.
Summary. Why the Influence of Music in Human Sexual Selection is Comparatively Small.
VISION
I.
Primacy of Vision in Man. Beauty as a Sexual Allurement. The Objective Element in Beauty. Ideals of Feminine Beauty in Various Parts of the World. Savage Women sometimes Beautiful from European Point of View. Savages often Admire European Beauty. The Appeal of Beauty to some Extent Common even to Animals and Man.
II.
Beauty to Some Extent Consists Primitively in an Exaggeration of the Sexual Characters. The Sexual Organs. Mutilations, Adornments, and Garments. Sexual Allurement the Original Object of Such Devices. The Religious Element. Unæsthetic Character of the Sexual Organs. Importance of the Secondary Sexual Characters. The Pelvis and Hips. Steatopygia. Obesity. Gait. The Pregnant Woman as a Mediæval Type of Beauty. The Ideals of the Renaissance. The Breasts. The Corset. Its Object. Its History. Hair. The Beard. The Element of National or Racial Type in Beauty. The Relative Beauty of Blondes and Brunettes. The General European Admiration for Blondes. The Individual Factors in the Constitution of the Idea of Beauty. The Love of the Exotic.
III.
Beauty Not the Sole Element in the Sexual Appeal of Vision. Movement. The Mirror. Narcissism. Pygmalionism. Mixoscopy. The Indifference of Women to Male Beauty. The Significance of Woman's Admiration of Strength. The Spectacle of Strength is a Tactile Quality made Visible.
IV.
The Alleged Charm of Disparity in Sexual Attraction. The Admiration for High Stature. The Admiration for Dark Pigmentation. The Charm of Parity. Conjugal Mating. The Statistical Results of Observation as Regards General Appearance, Stature, and Pigmentation of Married Couples. Preferential Mating and Assortative Mating. The Nature of the Advantage Attained by the Fair in Sexual Selection. The Abhorrence of Incest and the Theories of its Cause. The Explanation in Reality Simple. The Abhorrence of Incest in Relation to Sexual Selection. The Limits to the Charm of Parity in Conjugal Mating. The Charm of Disparity in Secondary Sexual Characters.
Summary of the Conclusions at Present Attainable in Regard to the Nature of Beauty and its Relation to Sexual Selection.
APPENDIX A.
APPENDIX B.
INDEX OF AUTHORS.
INDEX OF SUBJECTS.
SEXUAL SELECTION IN MAN.
The External Sensory Stimuli Affecting Selection in Man—The Four Senses Involved.
Tumescence—the process by which the organism is brought into the physical and psychic state necessary to insure conjugation and detumescence—to some extent comes about through the spontaneous action of internal forces. To that extent it is analogous to the physical and psychic changes which accompany the gradual filling of the bladder and precede its evacuation. But even among animals who are by no means high in the zoölogical scale the process is more complicated than this. External stimuli act at every stage, arousing or heightening the process of tumescence, and in normal human beings it may be said that the process is never completed without the aid of such stimuli, for even in the auto-erotic sphere external stimuli are still active, either actually or in imagination.
The chief stimuli which influence tumescence and thus direct sexual choice come chiefly—indeed, exclusively—through the four senses of touch, smell, hearing, and sight. All the phenomena of sexual selection, so far as they are based externally, act through these four senses.[1] The reality of the influence thus exerted may be demonstrated statistically even in civilized man, and it has been shown that, as regards, for instance, eye-color, conjugal partners differ sensibly from the unmarried persons by whom they are surrounded. When, therefore, we are exploring the nature of the influence which stimuli, acting through the sensory channels, exert on the strength and direction of the sexual impulse, we are intimately concerned with the process by which the actual form and color, not alone of living things generally, but of our own species, have been shaped and are still being shaped. At the same time, it is probable, we are exploring the mystery which underlies all the subtle appreciations, all the emotional undertones, which are woven in the web of the whole world as it appeals to us through those sensory passages by which alone it can reach us. We are here approaching, therefore, a fundamental subject of unsurpassable importance, a subject which has not yet been accurately explored save at a few isolated points and one which it is therefore impossible to deal with fully and adequately. Yet it cannot be passed over, for it enters into the whole psychology of the sexual instinct.
Of the four senses—touch, smell, hearing, and sight—with which we are here concerned, touch is the most primitive, and it may be said to be the most important, though it is usually the last to make its appeal felt. Smell, which occupies the chief place among many animals, is of comparatively less importance, though of considerable interest, in man; it is only less intimate and final than touch. Sight occupies an intermediate position, and on this account, and also on account of the very great part played by vision in life generally as well as in art, it is the most important of all the senses from the human sexual point of view. Hearing, from the same point of view, is the most remote of all the senses in its appeal to the sexual impulse, and on that account it is, when it intervenes, among the first to make its influence felt.
[1]
Taste must, I believe, be excluded, for if we abstract the parts of touch and smell, even in those abnormal sexual acts in which it may seem to be affected, taste could scarcely have any influence. Most of our "tasting," as Waller puts it, is done by the nose, which, in man, is in specially close relationship, posteriorly, with the mouth. There are at most four taste sensations—sweet, bitter, salt, and sour—if even all of these are simple tastes. What commonly pass for taste sensations, as shown by some experiments of G. T. W. Patrick (Psychological Review, 1898, p. 160), are the composite results of the mingling of sensations of smell, touch, temperature, sight, and taste.
TOUCH.
I.
The Primitive Character of the Skin—Its Qualities—Touch the Earliest Source of Sensory Pleasure—The Characteristics of Touch—As the Alpha and Omega of Affection—The Sexual Organs a Special Adaptation of Touch—Sexual Attraction as Originated by Touch—Sexual Hyperæsthesia to Touch—The Sexual Associations of Acne.
We are accustomed to regard the skin as mainly owing its existence to the need for the protection of the delicate vessels, nerves, viscera, and muscles underneath. Undoubtedly it performs, and by its tough and elastic texture is well fitted to perform, this extremely important service. But the skin is not merely a method of protection against the external world; it is also a method of bringing us into sensitive contact with the external world. It is thus, as the organ of touch, the seat of the most widely diffused sense we possess, and, moreover, the sense which is the most ancient and fundamental of all—the mother of the other senses.
It is scarcely necessary to insist that the primitive nature of the sensory function of the skin with the derivative nature of the other senses, is a well ascertained and demonstrable fact. The lower we descend in the animal scale, the more varied we find the functions of the skin to be, and if in the higher animals much of the complexity has disappeared, that is only because the specialization of the various skin regions into distinct organs has rendered this complexity unnecessary. Even yet, however, in man himself the skin still retains, in a more or less latent condition, much of its varied and primary power, and the analysis of pathological and even normal phenomena serves to bring these old powers into clear light.
Woods Hutchinson (Studies in Human and Comparative Pathology, 1901, Chapters VII and VIII) has admirably set forth the immense importance of the skin, as in the first place "a tissue which is silk to the touch, the most exquisitely beautiful surface in the universe to the eye, and yet a wall of adamant against hostile
It may be added that the extreme beauty of the skin as a surface is very clearly brought out by the inadequacy of the comparisons commonly used in order to express its beauty. Snow, marble, alabaster, ivory, milk, cream, silk, velvet, and all the other conventional similes furnish surfaces which from any point of view are incomparably inferior to the skin itself. (Cf. Stratz, Die Schönheit des Weiblichen Körpers, Chapter XII.)
With reference to the extraordinary vitality of the skin, emphasized by Woods Hutchinson, it may be added that, when experimenting on the skin with the electric current, Waller found that healthy skin showed signs of life ten days or more after excision. It has been found also that fragments of skin which have been preserved in sterile fluid for even as long as nine months may still be successfully transplanted on to the body. (British Medical Journal, July 19, 1902.)
Everything indicates, remark Stanley Hall and Donaldson ("Motor Sensations in the Skin," Mind, 1885), that the skin is "not only the primeval and most reliable source of our knowledge of the external world or the archæological field of psychology," but a field in which work may shed light on some of the most fundamental problems of psychic action. Groos (Spiele der Menschen, pp. 8-16) also deals with the primitive character of touch sensations.
Touch sensations are without doubt the first of all the sensory impressions to prove pleasurable. We should, indeed, expect this from the fact that the skin reflexes have already appeared before birth, while a pleasurable sensitiveness of the lips is doubtless a factor in the child's response to the contact of the maternal nipple. Very early memories of sensory pleasure seem to be frequently, perhaps most frequently, tactile in character, though this fact is often disguised in recollection, owing to tactile impression being vague and diffused; there is thus in Elizabeth Potwin's "Study of Early Memories" (Psychological Review, November, 1901) no separate group of tactile memories, and the more elaborate investigation by Colegrove ("Individual Memories," American Journal of Psychology, January, 1899) yields no decisive results under this head. See, however, Stanley Hall's valuable study, "Some Aspects of the Early Sense of Self," American Journal of Psychology, April, 1898. Külpe has a discussion of the psychology of cutaneous sensations (Outlines of Psychology [English translation], pp. 87 et seq.)
Harriet Martineau, at the beginning of her Autobiography, referring to the vivid character of tactile sensations in early childhood, remarks, concerning an early memory of touching a velvet button, that "the rapture of the sensation was really monstrous." And a lady tells me that one of her earliest memories at the age of 3 is of the exquisite sensation of the casual contact of a cool stone with the vulva in the act of urinating. Such sensations, of course, cannot be termed specifically sexual, though they help to furnish the tactile basis on which the specifically sexual sensations develop.
The elementary sensitiveness of the skin is shown by the fact that moderate excitation suffices to raise the temperature, while Heidenhain and others have shown that in animals cutaneous stimuli modify the sensibility of the brain cortex, slight stimulus increasing excitability and strong stimulus diminishing it. Féré has shown that the slight stimulus to the skin furnished by placing a piece of metal on the arm or elsewhere suffices to increase the output of work with the ergograph. (Féré, Comptes Rendus Société de Biologie, July 12, 1902; id., Pathologic des Emotions, pp. 40 et seq.)
Féré found that the application of a mustard plaster to the skin, or an icebag, or a hot-water bottle, or even a light touch with a painter's brush, all exerted a powerful effect in increasing muscular work with the ergograph. "The tonic effect of cutaneous excitation," he remarks, "throws light on the psychology of the caress. It is always the most sensitive parts of the body which seek to give or to receive caresses. Many animals rub or lick each other. The mucous surfaces share in this irritability of the skin. The kiss is not only an expression of feeling; it is a means of provoking it. Cataglottism is by no means confined to pigeons. The tonic value of cutaneous stimulation is indeed a commonly accepted idea. Wrestlers rub their hands or limbs, and the hand-shake also is not without its physiological basis.
"Cutaneous excitations may cause painful sensations to cease. Many massage practices which favor work act chiefly as sensorial stimulants; on this account many nervous persons cannot abandon them, and the Greeks and Romans found in massage not only health, but pleasure. Lauder Brunton regards many common manœuvres, like scratching the head and pulling the mustache, as methods of dilating the bloodvessels of the brain by stimulating the facial nerve. The motor reactions of cutaneous excitations favor this hypothesis." (Féré, Travail et Plaisir, Chapter XV, "Influence des Excitations du Toucher sur le Travail.")
The main characteristics of the primitive sense of touch are its wide diffusion over the whole body and the massive vagueness and imprecision of the messages it sends to the brain. This is the reason, why it is, of all the senses, the least intellectual and the least æsthetic; it is also the reason why it is, of all the senses, the most-profoundly emotional. "Touch," wrote Bain in his Emotions and Will, "is both the alpha and the omega of affection," and he insisted on the special significance in this connection of "tenderness"—a characteristic emotional quality of affection which is directly founded on sensations of touch. If tenderness is the alpha of affection, even between the sexes, its omega is to be found in the sexual embrace, which may be said to be a method of obtaining, through a specialized organization of the skin, the most exquisite and intense sensations of touch.
"We believe nothing is so exciting to the instinct or mere passions as the presence of the hand or those tactile caresses which mark affection," states the anonymous author of an article on "Woman in her Psychological Relations," in the Journal of Psychological Medicine, 1851. "They are the most general stimuli in lower animals. The first recourse in difficulty or danger, and the primary solace in anguish, for woman is the bosom of her husband or her lover. She seeks solace and protection and repose on that part of the body where she herself places the objects of her own affection. Woman appears to have the same instinctive impulse in this respect all over the world."
It is because the sexual orgasm is
The following observations were written by a lady (aged 30) who has never had sexual relationships: "I am only conscious of a very sweet and pleasurable emotion when coming in contact with honorable men, and consider that a comparison can be made between the idealism of such emotions and those of music, of beauties of Nature, and of productions of art. While studying and writing articles upon a new subject I came in contact with a specialist, who rendered me considerable aid, and, one day, while jointly correcting a piece of work, he touched my hand. This produced a sweet and pure sensation of thrill through the whole system. I said nothing; in fact, was too thrilled for speech; and never to this day have shown any responsive action, but for months at certain periods, generally twice a month, I have experienced the most pleasurable emotions. I have seen this friend twice since, and have a curious feeling that I stand on one side of a hedge, while he is on the other, and, as neither makes an approach, pleasure of the highest kind is experienced, but not allowed to go beyond reasonable and health-giving bounds. In some moments I feel overcome by a sense of mastery by this man, and yet, feeling that any approach would be undignified, some pleasure is experienced in restraining and keeping within proper bounds this passional emotion. All these thrills of pleasurable emotion possess a psychic value, and, so long as the nervous system is kept in perfect health, they do not seem to have the power to injure, but rather one is able to utilize the passionate emotions as weapons for pleasure and work."
Various parts of the skin surface appear to have special sexual sensitiveness, peculiarly marked in many individuals, especially women; so that, as Féré remarks (L'Instinct Sexuel, second edition, 1902, p. 130), contact stimulation of the lips, lobe of ear, nape of neck, little finger, knee, etc., may suffice even to produce the orgasm. Some sexually hyperæsthetic women, as has already been noted, experience this when shaking hands with a man who is attractive to them. In some neurotic persons this sensibility, as Féré shows, may exist in so morbid a degree that even the contact of the sensitive spot with unattractive persons or inanimate objects may produce the orgasm. In this connection reference may be made to the well-known fact that in some hysterical subjects there are so-called "erogenous zones" simple pressure on which suffices to evoke the complete orgasm. There is, perhaps, some significance, from our present point of view, in the fact that, as emphasized by Savill ("Hysterical Skin Symptoms," Lancet, January 30, 1904), the skin is one of the very best places to study hysteria.
The intimate connection between the skin and the sexual sphere is also shown in pathological conditions of the skin, especially in acne as well as simple pimples on the face. The sexual development of puberty involves a development of hair in various regions of the body which previously were hairless. As, however, the sebaceous glands on the face and elsewhere are the vestiges of former hairs and survive from a period when the whole body was hairy, they also tend to experience in an abortive manner this same impulse. Thus, we may say that, with the development of the sexual organs at puberty, there is correlated excitement of the whole pilo-sebaceous apparatus. In the regions where this apparatus is vestigial, and notably in the face, this abortive attempt of the hair-follicles and their sebaceous appendages to produce hairs tends only to disorganization, and simple comedones or pustular acne pimples are liable to occur. As a rule, acne appears
The influence of menstruation in exacerbating acne has been called in question, but it seems to be well established. Thus, Bulkley ("Relation between Certain Diseases of the Skin and the Menstrual Function," Transactions of the Medical Society of New York, 1901, p. 328) found that, in 510 cases of acne in women, 145, or nearly one-third, were worse about the monthly period. Sometimes it only appeared during menstruation. The exacerbation occurred much more frequently just before than just after the period. There was usually some disturbance of menstruation. Various other disorders of the skin show a similar relationship to menstruation.
It has been asserted that masturbation is a frequent or constant cause of acne at puberty. (See, e.g., discussion in British Medical Journal, July, 1882.) This cannot be accepted. Acne very frequently occurs without masturbation, and masturbation is very frequently practiced without producing acne. At the same time we may well believe that at the period of puberty, when the pilo-sebaceous system is already in sensitive touch with the sexual system, the shock of frequently repeated masturbation may (in the same way as disordered menstruation) have its repercussion on the skin. Thus, a lady has informed me that at about the age of 18 she found that frequently repeated masturbation was followed by the appearance of comedones.
[2]
A. Franklin, Les Soins de Toilette, p. 81.
[3]
W. James, Principles of Psychology, vol. ii. p. 347.
[4]
Numerous passages from the theologians bearing on this point are brought together in Mœchialogia, pp. 221-220.
II.
Ticklishness—Its Origin and Significance—The Psychology of Tickling—Laughter—Laughter as a Kind of Detumescence—The Sexual Relationships of Itching—The Pleasure of Tickling—Its Decrease with Age and Sexual Activity.
Touch, as has already been remarked, is the least intellectual of the senses. There is, however, one form of touch sensation—that is to say, ticklishness—which is of so special and peculiar a nature that it has sometimes been put aside in a class apart from all other touch sensations. Scaliger proposed to class titillation as a sixth, or separate, sense. Alrutz, of Upsala, regards tickling as a milder degree of itching, and considers that the two together constitute a sensation of distinct quality with distinct end-organs, for the mediation of that quality.[5] However we may regard this extreme view, tickling is certainly a specialized modification of touch and it is at the same time the most intellectual mode of touch sensation and that with the closest connection with the sexual sphere. To regard tickling as an intellectual manifestation may cause surprise, more especially when it is remembered that ticklishness is a form of sensation which reaches full development very early in life, and it has to be admitted that, as compared even with the messages that may be sent through smell and taste, the intellectual element in ticklishness remains small. But its presence here has been independently recognized by various investigators. Groos points out the psychic factor in tickling as evidenced by the impossibility of self-tickling.[6] Louis Robinson considers that ticklishness "appears to be one of the simplest developments of mechanical and automatic nervous processes in the direction of the complex functioning of the higher centres which comes within the scope of psychology,"[7] Stanley Hall and Allin remark that "these minimal touch excitations represent the very oldest stratum of psychic life in the soul."[8] Hirman Stanley, in a somewhat similar manner, pushes the intellectual element in ticklishness very far back and associates it with "tentacular experience." "By temporary self-extension," he remarks, "even low amœboid organisms have slight, but suggestive, touch experiences that stimulate very general and violent reactions, and in higher organisms extended touch-organs, as tentacles, antennæ, hair, etc., become permanent and very delicately sensitive organs, where minimal contacts have very distinct and powerful reactions." Thus ticklishness would be the survival of long passed ancestral tentacular experience, which, originally a stimulation producing intense agitation and alarm, has now become merely a play activity and a source of keen pleasure.[9]
We need not, however, go so far back in the zoölogical series to explain the origin and significance of tickling in the human species. Sir J. Y. Simpson suggested, in an elaborate study of the position of the child in the womb, that the extreme excitomotory sensibility of the skin in various regions, such as the sole of the foot, the knee, the sides, which already exists before birth, has for its object the excitation and preservation of the muscular movements necessary to keep the fœtus in the most favorable position in the womb.[10] It is, in fact, certainly the case that the stimulation of all the ticklish regions in the body tends to produce exactly that curled up position of extreme muscular flexion and general ovoid shape which is the normal position of the fœtus in the womb. We may well believe that in this early developed reflex activity we have the basis of that somewhat more
The mental element in tickling is indicated by the fact that even a child, in whom ticklishness is highly developed, cannot tickle himself; so that tickling is not a simple reflex. This fact was long ago pointed out by Erasmus Darwin, and he accounted for it by supposing that voluntary exertion diminishes the energy of sensation.[11] This explanation is, however, inadmissible, for, although we cannot easily tickle ourselves by the contact of the skin with our own fingers, we can do so with the aid of a foreign body, like a feather. We may perhaps suppose that, as ticklishness has probably developed under the influence of natural selection as a method of protection against attack and a warning of the approach of foreign bodies, its end would be defeated if it involved a simple reaction to the contact of the organism with itself. This need of protection it is which involves the necessity of a minimal excitation producing a maximal effect, though the mechanism whereby this takes place has caused considerable discussion. We may, it is probable, best account for it by invoking the summation-irradiation theory of pain-pleasure, the summation of the stimuli in their course through the nerves, aided by capillary congestion, leading to irradiation due to anastomoses between the tactile corpuscles, not to speak of the much wider irradiation which is possible by means of central nervous connections.