Teguments: The Skin.—The human skin is essentially composed of two parts, the corium (Fig.3,D) and a superficial epidermis; the latter is formed in its turn of two cellular layers, the horny layers (Fig.3,c.c.), the quite shallow cells of which are freely exposed to the air, and Malpighi’s layer situated beneath it, with granules of pigment in more or less quantity in its lower range of cells (Fig.3,c.p.). In certain places the epidermis is modified so as to form either a mucousmembrane, as, for instance, on the lips, or a horny substance, sometimes transparent (as the cornea of the eye) and sometimes only translucent and more or less hard (the nails).
Skin and HairFIG.3.—Microscopic section (partly schematic) of skin and of hair: A, of a European; B, of a Negro.c.c.horny layer or cuticle andc.p.pigmented layer (rete Malpighii) of the epidermis;D.corium;g.su.sweat gland;c.e.excretory duct;pa.hair papilla, andfo.hair follicle;m.erector pili muscle;g.s.sebaceous gland;p.hair.
FIG.3.—Microscopic section (partly schematic) of skin and of hair: A, of a European; B, of a Negro.
c.c.horny layer or cuticle andc.p.pigmented layer (rete Malpighii) of the epidermis;D.corium;g.su.sweat gland;c.e.excretory duct;pa.hair papilla, andfo.hair follicle;m.erector pili muscle;g.s.sebaceous gland;p.hair.
There is little to say about the differences in the nature and structure of the skin according to race. Its colouring, of which I shall speak later on (seePigmentation), is more important. Attention has been drawn to the hardness of the corium and the velvety softness of the skin in the negro; the latter quality is probably due to the profusion and size of the sebaceous glands which accompany the hair. Bischoff has made an interesting observation on the relative rarity of the sweat glands (which are found in the thickness of thecorium, Fig.3,g.su.) among the Fuegians,[41]but comparative studies on this subject have not been pursued in regard to other races. The disposition of the papilla ridges on the tips of the fingers, so well studied by Galton,[42]is of great interest as regards the identification of the individual; but from this fact alone, that it is a good characteristic of the individual, it loses all its value as a characteristic of race.
Mohave IndiansFIG.4.—Mohave Indians of Arizona; smooth hair type.(Phot. Ten Kate.)
FIG.4.—Mohave Indians of Arizona; smooth hair type.(Phot. Ten Kate.)
Hair of the Head and Body.—The most important horny product of the skin, as regards the differentiation of races, isundoubtedly the hair of the head and body. The general structure and number of the hairs (about 260 to each square centimetre) hardly show any difference between race and race; on the other hand, the length of the hair of the head, the relation of this length in one sex to that in the other, the nature of the hair, its consistence, its transverse section, its form, its colour, vary much according to race.
Pure VeddahFIG.5.—Pure Veddah of Dangala Mountains of Ceylon; wavy hair type.(Phot. Brothers Sarasin.)
FIG.5.—Pure Veddah of Dangala Mountains of Ceylon; wavy hair type.(Phot. Brothers Sarasin.)
The body hair has its origin in a layer of the epidermis, deeply imbedded in the corium as though it were in a little sac or follicle (Fig.3,fo.); from the bottom of this sac, and covering by its root a little papilla (Fig.3,pa.) filled with vessels designed to nourish it, each hair rises and pushes its way to the outside; it is always accompanied by a little muscle which can move it (Fig.3,m.r.), and by a sebaceous gland (Fig.3,g.s.) designed to lubricate it.
Front ViewFIG.6.—Same subject as Fig.5, front view.(Phot. Brothers Sarasin.)
FIG.6.—Same subject as Fig.5, front view.(Phot. Brothers Sarasin.)
Four principal varieties of hair are usually distinguished in anthropology, according to their aspect and their nature—straight, wavy, frizzy, and woolly. It is easy to form a clear idea at first sight of the differences which are presented by these varieties, but the most careful examination shows that the differences are deeper, and can be pursued even into the microscopic structure of the hair.
Toda WomanFIG.7.—Toda woman (India); curly hair type.(Phot. Thurston.)
FIG.7.—Toda woman (India); curly hair type.(Phot. Thurston.)
Straight and smooth hair(droitorlissein French,strafforschlichtin German) is ordinarily rectilinear, and falls heavily in bands on the sides of the head; such is the hair of the Chinese, the Mongols, and of American Indians (Fig.4). Straight hair is ordinarily stiff and coarse, but it is sometimes found tolerably fine; for example, among the western Finns. It is true that in this case it has a tendency to become wavy.Wavy hair(ondéin French,welligin German) forms a long curve or imperfect spiral from one end to the other (Figs.5and6). It is called curly when it is rolled up at the extremity (Fig.7). The whole head of hair when wavy produces a very pleasing effect; I will merely cite as examples certain fair Scotchwomen. The type is very widespread among Europeans, whether dark or fair. The frizzy type (friséin French,lockigin German) is that in which the hair is rolled spirally,forming a succession of rings a centimetre or more in diameter (Fig.8). Such is the hair of the Australians (Figs.21and22), the Nubians, of certain Mulattos, etc. Lastly, the type of woolly hair (crépuin French,krausin German) is characterised by spiral curves exceedingly narrow (from 1 millimetre to 9 millimetres as the maximum); the rings of the spiral are very near together, numerous, well rolled, and often catch hold of each other, forming tufts and balls, the whole result recalling in appearance sheep’s wool (Fig.9). The type admits of two varieties. When the hair is relatively long and the spirals sufficiently broad, the whole head looks like a continuous fleece, as with certain Melanesians (Fig.153), or the majorityof Negroes (Figs.9and47). In his classification of the human races, Haeckel[43]has taken this type as characteristic of the group oferiocomes. But when the hair is short, consisting ofvery small spirals, it has a tendency, when tangled, to form little tufts, the dimensions of which vary from the size of a pea to that of a pepper-corn; these tufts are separated by spaces which appear bald (pepper-corn hair). This type (calledlophocomeby Haeckel) is very widespread among Hottentots and Bushmen, but the majority of Negroes have it in their infancy, and even at adult age, especially towards the temples, on the forehead—briefly, in all the places where the hair remains very short (Fig.9). We must not think that the disposition of which I have just spoken is due to the hair being stuck in the skin of the head like the bristles of a brush, for the mode of insertion is the same in all races, with Bushmen as with Europeans or Mongols. At the most it may be noted that the rows of hair in Negroes are more irregular, and are closer together in certain places, leaving in other rows intervals between them of two or three millimetres. Only, as a consequence of the shortness andthe excessive twisting, the hair gets entangled and the spirals catch hold of each other, so forming glomerules or tufts.
Kurumba ManFIG.8.—Kurumba man of Nilgiri Hills; frizzy hair type.(Phot. Thurston.)
FIG.8.—Kurumba man of Nilgiri Hills; frizzy hair type.(Phot. Thurston.)
Does there exist any difference of form between straight, waved, frizzy, or woolly hair? The microscopical examination of transverse sections of the hair allows us to reply affirmatively to this question. This examination, already applied to the hair in 1822 by Heusinger, then successively by Blower (of Philadelphia), Kölliker, Pruner-Bey, Latteux, and Waldeyer,[44]has yielded results which have been vigorously discussed, and are still debatable if we cling to the individual and absolute figures, comparing sections made according to defective methods, or carried out on different levels of the hair. But if we calculate theindex—that is to say, the relation of the breadth to the length (= 100) of the section (and that in a great number of individual cases)—we obtain satisfactory results, as Topinard and Ranke[45]have shown in general, as also Baelz in the case of the Japanese, and Montano in the case of the races of the Malay Archipelago.[46]
AgniFIG.9.—Agni Negro of Krinjabo, Western Africa; woolly hair type.(Photo. Thoman, lent by Collignon.)
FIG.9.—Agni Negro of Krinjabo, Western Africa; woolly hair type.(Photo. Thoman, lent by Collignon.)
If we consider a great number of microscopical sections, all obtained from the same level of the hair, we note that straight hair gives a circular section, whilst woolly hair gives one in the form of a lengthened ellipse. This ellipse is less extended, a little more filled out, in the sections of wavy hair. If the major axis of the ellipse be supposed to equal 100, the minor axis will be represented by figures varying from 40 to 50 for the woolly hair of the Bushmen and the Hottentots, from 50to 60 for that of the Negroes, while the straight hair of the Eskimo will have this axis = 77, that of the Thibetans = 80, that of the Japanese = 85, etc. The hair of Europeans represents an elliptical section in which the major axis being = 100, the minor axis will be represented by figures varying from 62 to 72 (Topinard). It can be said to-day with certainty, after the work of Unna,[47]that the woolly hair of Negroes rolls up into a compact spiral precisely because of the flattened shape of this elliptical section, and of the special form of the follicle and papilla. In fact, in the Negro the follicle, instead of being straight, as in the European (Fig.3, A), is curved inward in the form of a sabre, or even of the arc of a quarter of a circle (Fig.3, B); further, the papilla is flattened instead of being round. One would say that the hair has encountered in its development so much resistance on the part of the dermis (which is so hard, in fact, among the Negroes), that it would be twisted, as it were, from the first. Emerging from an incurvated mould, it can only continue to roll up outside, given especially its flattened shape; it rolls up into a spiral, the plane of which, at the beginning, is perpendicular to the surface of the skin.[48]As to the thickness of the hair, it appears that in general it is greater in straight hair than in woolly; however, the hair of the western Finns is straight and fine at the same time.
A certain correlation appears to exist between the nature of the hair and its absolute and relative length. Thus straight hair is at the same time the longest—Chinese, Americans, Indians (Fig.4), while woolly hair is shortest, from 5 to 15 centimetres (Fig.9); wavy hair occupies an intermediate position. Moreover, the difference between the length of the hair of men and women is almost inappreciable in the two extreme divisions. In certain straight-haired races the hair of the head is as long with men as with women; one need but tocall to mind the plaits of the Chinese, or the beautiful heads of hair of the Red Indians, which may attain in certain cases a length of even two metres (Catlin). In frizzy-haired races the hair of the head, on the contrary, is equally short in the two sexes; the hair of the head of women among the Bushmen, Hottentots, and even Negroes, is not appreciably longer than among the men. It is only in the categories of wavy and in part of frizzy hair, that the differences are appreciable. With European men the length of the hair rarely exceeds 30 or 40 centimetres, while with the women it averages 65 to 75 centimetres, and may attain in exceptional cases to 2 metres (as in the case of an Englishwoman, according to Dr. D. Watson).
Another fact to be noted is that the general development of the pilose system on the face, as on the rest of the body, seems also to be in relation to the nature of the hair of the head.
Straight-haired races are ordinarily very glabrous, the men have hardly a rudimentary tuft of beard—American Indians (Fig.4), Mongols (Fig.20), Malays; while in the wavy or frizzy-haired races, the development of the pilose system is considerable—Australians, Dravidians, Iranians (Fig.22), Ainus (Fig.117), etc. The woolly-haired races are not, however, included in this rule; glabrous types (Bushmen, western Negroes) are found side by side with rather hairy types (Melanesians, Akka, Ashanti). There appears to be a certain likeness between the abundance of hair on the head and on the body. Thus, according to Hilgendorf, the Japanese who are glabrous have from 252 to 286 hairs to each square centimetre on the head, whilst the hairy Ainus have only 214. Negroes and white men do not appear, however, to present the same differences (Gould). Even baldness results largely from the nature of the hair. According to Gould, baldness is ten times less frequent among Negroes than among Whites, between 33 years and 44 years, and thirty times less so between 21 and 32. Among Mulattos it is more frequent than among the Negroes, but less than among Whites.Lastly, among Red Indians it seems to be still more rare than among Negroes. White hair follows almost the same rule.[49]
In the mass, the human races may be divided according to the character of their hair as follows:—
Woolly Hair.—Bushmen, Negro, and Melanesian races.
Frizzy Hair.—Australian, Ethiopian, Beja, Fulbé, etc., and Dravidian.
Wavy Hair.—The white races of Europe, of Northern Africa, and Asia (Melanochroi or the dark-complexioned Whites, and Xanthochroi or pale Whites).
Fine, straight, or lightly-waved Hair.—Turco-Tatars, Finns, Ainus, and Indonesians (Dyaks, Nagas, etc.); lastly,
Coarse straight Hair.—Mongolians and American races, with some exceptions. It must be noted that, in the manifold blendings of races, characteristics of the hair amalgamate. Thus the half-breeds between Negroes and American Indians have, most frequently, the hair frizzy or wavy. But there are also frequent reversions to the primitive type, almost always, however, a little weakened.
There are no races ofhairy men. Everything that has been said of different “hairy savages” in the interior of Africa or Indo-China resolves itself into the presence of a light down (probably the remains of embryonic lanugo) in the case of the Akkas of the Upper Nile, or to the fortuitous existence of one or two families of hairy men and women from Burma exhibited some years ago in Europe and America. Other “phenomena” have been shown, like the famous Julia Pastrana or the “Dog-men” of Russia. All these subjects are only particular cases of atavism, or of a reversion to the probable primordial condition of man or of his precursor at the period when he was as hairy as, for instance, the anthropoid apes of to-day; they are by no means the representatives of a hairy race.
The beard is, as we know, one of the sexual characteristics of man, although many fine ones are found among certain women, notably among the Europeans of the south, and especially among Spanish women. The more hairy the body, the thicker as arule is the beard. In the glabrous races (Mongols, Malays, Americans) a few straggling hairs are all that can be seen at the corners of the mouth and on the chin (Figs.20and168); in the very hairy races, like the Ainus, the Iranians, certain Semites, the Todas, the Australians, the Melanesians, the beard is strong and abundant on the lips, the chin, and the cheeks, where it reaches sometimes to the cheek-bones (Fig.22); in the Negro and Bushmen races neither the moustache nor the beard can attain to great dimensions, because of the curly nature of the hair (Figs.140and143). The eyelashes and the eyebrows are likewise much developed in races having an abundant beard, and this is the case in both sexes; we have only to recall the thick and joined eyebrows of the Persian women. On the other hand, among the Mongolians we note the small development of the eyelashes in relation to the particular structure of their eye (see p.77).
Pigmentation.—The distribution of the pigment which gives the colouring to the skin, to the hair, to the iris, varies much according to race, and forms, along with the nature of the hair, a good distinctive characteristic. As I have already stated above, the pigment is accumulated principally in the lowest layers of the rete Malpighii (Fig.3,c.p.), but it is also met with in small quantities in the horny layer, and even in the dermis.[50]According to race, the microscopic granules of pigment of a uniform brown are very unequally distributed around the nuclei of the cells, to which they give the most varied tones from pale yellow to dark brown, almost black. As the pigment exists in all races, and in all parts of the body, it is to its more or less plentiful accumulation in the cells that the colouring of the skin and its derivatives is due. Further, there must be added, for certain races at least, the combination with the tint of the blood of the vessels, as seen through the skin.
Every one knows that our white races become tanned in the sun; the cause of this is the pigment, developing abundantlyand being deposited in the cells under the combined action of air, heat, and light; the congestion of the vessels has also something to do with it. In the same way, persons living a long time in dense forests or in dark though airy places end by becoming paler, in consequence of the loss of the pigment, but recover colour immediately on re-exposure to the sun. But the modifications produced by the action of air and sun vary even among Europeans according to the colouring peculiar to their race.
Thus among the fair races of Northern Europe the skin, burnt by the sun, becomes red, as if swollen; on the other hand, among the dark-coloured peoples of the Mediterranean, it takes a bronze tint. There are thus between these two races notable differences, if not in the chemical nature of the pigment, which is scarcely likely, at least in regard to its quantity. It is the same with other races generally, and ten principal shades of colour at least can easily be distinguished. In the first place, among Whites, three shades: 1st, pale white; 2nd, florid, or rosy, peculiar to the Scandinavians, English, Dutch, etc.; 3rd, brownish-white, peculiar to Spaniards, Italians, etc. In the races called Yellow, three varieties of colour can likewise be distinguished: 4th, yellowish-white, a sickly hue the colour of wheat, as, for example, among certain Chinese; 5th, olive-yellow, the colour of new portmanteau leather, as among the majority of South American Indians, Polynesians, and Indonesians; 6th, dark yellow-brown, dark olive, or the colour of dead leaves, as among certain Americans, Malays, etc. In the dark-skinned races, four shades at least must be distinguished: 7th, red, copper-coloured, as, for example, among the Bejas, Niam-Niam, Fulbé; 8th, reddish-brown, chocolate, as among the Dravidians, the Australians, certain Negroes and Melanesians; lastly, 9th, sooty black, and 10th, coal-black, for example, among the different Negro populations.
In order to avoid an arbitrary designation of colours, anthropologists make use of chromatic tables, in which examples of the chief variations of colour are marked by numbers. The best table, almost universally adopted, is thatof Broca, of thirty-four shades.[51]The Anthropological Institute of Great Britain and Ireland has published a very practical and simplified edition of it,[52]which contains only the ten numbers of principal shades proposed by Topinard, namely, those I have just enumerated.
The pigment is not uniformly distributed, as I have said, through the whole body, and this is so with the Whites as well as with the darkest races. In all of them the parts of the body most deeply coloured are the nape of the neck, the back (as with animals), the back part of the limbs, the arm-pits, the scrotum, and the breasts; the belly (as with animals), the insides of the hands, the soles of the feet, are among the most lightly coloured. The parts covered by garments are less coloured among white and yellow races than the parts uncovered; it is affirmed, but without reliable proofs, that the contrary takes place among the dark and black populations.
In the iris, the pigmentation assumes a particular character. As we know, this perforated diaphragm of the eye is composed, histologically, of three layers: an anterior epithelial one; a middle one, the “stroma,” with muscular fibres, designed to enlarge or reduce the pupil; and lastly, a posterior layer, called the pigmental layer. But it must not be thought that this layer is the only repository of the pigment of the iris. It is also found accumulated in the thickness of the stroma, and between the muscular fibres. In both places the granules of the pigment have the same brown colour as in the rest of the body, but the pigment of the posterior or pigmental layer is only seen through the stroma and appears blue or grey, more or less light or dark, according to its quantity, just as the black veins of the blood appear to us blue through the skin. On the contrary, the pigment accumulated in the stroma or between the muscular fibres of the iris exhibits its natural yellow, brown, or almost black colouring, according to the quantity of it, under the form of a trail radiating very clearly from the pupil towards the periphery of the eye occupying one-third, two-thirds, or even the whole of the iris.
Seen at a certain distance, irises without pigment in their stroma appear blue or grey; those having the whole or the greater part of this charged with pigment appear brown, dark brown, or almost black, according to the quantity of this pigment. But irises having a blue or grey foundation strewn with yellowish spots of pigment appear green, yellow, yellowish-grey, greenish-grey, etc.
There are thus distinguishable only three fundamental shades of the iris, or, as is commonly said, of the colour of the eyes: light (blue or grey); dark (bright or dull brown or black); and intermediate shades (green, yellow, yellowish-grey, greenish-grey, etc.). This classification is entirely based on the quantity of pigment in the iris.
It is only in fair European races that blue or grey eyes are found, perhaps also in the Turco-Ugrian races; light-brown eyes are met with among some Mongolians. In all the other populations of the earth the eyes are dark-brown or black. It is the same with the colouring of the hair. It varies appreciably among the wavy-haired races, much less so among the straight and frizzy-haired races, and remains always black among the woolly-haired races. Four principal shades can be distinguished in the hair—black, dark-brown, chestnut-brown (châtainin French), and fair. In this last shade, golden must be separated from flaxen and dull grey-reddish hair. Red hair of all shades is only an individual anomaly, accompanied besides, almost always, by freckles (ephelides) on the face and neck. There are no red-haired races, but light and chestnut hair may have a reddish reflection in it. Red hair is very common in countries where several white-coloured races (brown or fair) are intermixed. In these crossed races there are found heads of hair of all colours—black, brown, fair, reddish-brown, dull-grey, chestnut, etc. This is the natural result of the intermixture of blood. Among adark-haired people, which has remained free from intermixture, or has only intermingled with dark-haired races, an exceptional red-haired individual constitutes a pathological condition, called “erythrism” by Broca. Erythrism can only manifest itself in certain races; at least, until now no example has been instanced among the Negroes; on the other hand, erythrism is somewhat common among the Jews of Europe, and among such Jews it is most frequently associated with frizzy hair.[53]
The colouring of the hair depends not only on the pigment, but on the more or less quantity of air in the medulla of the hair, which blends the white and grey tones with the general tint given by the pigment. In the air, the hair fades, becomes less highly coloured, duller. Certain acids of the perspiration render the hair reddish-brown, as for instance, under the arm-pit.
At birth pigment is found in the body in less quantity than in the adult state. Every one knows that the hair of children, often light-coloured at birth and in early years, becomes darker as they grow up. Almost all our European children are born with blue eyes, and the pigment only begins to increase in the iris, transforming the eyes into grey, brown, or black at the end of some weeks, or even months after birth. New-born Chinese, Botocudos, Malays, Kalmuks, are much less yellow than the adults of these people, and, lastly, Negroes at birth are of a reddish-chocolate or copper colour, which only becomes darker at the end of three or four days, beginning in certain places, such as the nape, nipples, scrotum, etc.
The presence of temporary spots of pigment noticed among new-born Japanese by Grimm and Baelz, among the Chinese by Matignon, among the Tagals of the Philippines by Collignon, and among the Eskimo by Sören-Hansen,[54]is more puzzling. These are somewhat large blue, grey, or black spots, situated in the sacro-lumbar region and on the buttocks, which disappear about the age of two, three, or five years. The existence of these spots, like that of the ephelides in the European child, would prove rather the migration of pigmental granules to the places selected than a general increase of them. In most races women appear to have clearer skin than men; in that respect, as in many other characters, they have a closer resemblance to children. It is thought by some that the hair of women is lighter than that of men among European races.[55]
Among Negroes the pigment is visible not only on the skin, in the hair, and the iris, but also in the sclerotic, in the mucous membrane of the lips, the mouth, the genital organs, etc.; the internal organs, even, are not free from it; the suprarenal capsules, the mesentery, the liver, the spleen, are often coloured with black spots of pigment, and even the brain contains numerous pigmented points in its envelopes and in its grey matter. Such an abundance of pigment would become a danger to the White, as is proved by certain diseases, melanism, for example, in which the pigment especially invades the viscera, or Addison’s disease, in which, on the contrary, there is an over-production of pigment in the skin and the mucous membranes.
The total absence of pigment, which may occur with the Negro as with the White, is termed albinism. This may be accompanied, if complete (that is to say, when, besides the white skin and hair, the iris is also deprived of pigment, and appears red), by somewhat serious affections of the eyesight.But, in every respect, albinos are weakly, and probably not fertile amongst themselves.
In considering from all points of view the nature of hair and pigmentation in general, we cannot help noticing a certain correlation between these two characters. In fact, to the white colouring of the skin corresponds, in a general fashion, wavy hair, the colouring of which varies often in accord with the colour of the eyes and the shades of the skin (white, fair, brown races); to the yellow colouring corresponds straight, smooth hair; to the reddish-brown skin, frizzy hair; and to the black, woolly hair.
Cranium or Skull: Cranial measurements—Orbits and orbital index—Nasal bone and nasal index—Prognathism—Head of the living subject: Cephalic index—Face—Eyes—Nose and nasal index in the living subject—Lips—Trunk and Limbs: The Skeleton—Pelvis and its indices—Shoulder blade—Thoracic limb—Abdominal limb—Proportions of the body in the living subject: Trunk and neck—Curve of the back—Steatopygy—Various Organs: Genital organs—Brain—Its weight—Convolutions—The neuron—Its importance from the psychical point of view.
HAVINGtreated of the body in its general aspect, we shall now examine from the morphological point of view its different parts: the head, trunk, limbs, etc., as well as their relations to each other and their reciprocal dimensions, both in the skeleton and the living subject.
Cranium or Skull.—This part of the skeleton forms the object of investigation of a very extended branch of anthropology called craniology.
Craniology must not be confounded with the cranioscopy of the phrenologists, a sham science founded by Gall, who wished to establish a connection between certain bumps or irregularities of the surface of the skull and the parts of the brain in which, as was pretended, were localised the different intellectual functions. It is now demonstrated that the inequalities of the external table of the cranium walls have no relation whatever with the irregularities of the internal table, and still less have they anything in common with the conformation of the various parts of the brain. But if there beno such direct connection as this between the cranium and the brain, there is nevertheless a certain remote relation between them, and the brain has attained such a development in man that the study of everything which concerns it, immediately or remotely, possesses great interest. This would alone suffice to explain the pre-eminent position assigned to craniology in the natural history of man. But there exist still other reasons why the study of the skull is one of the most cultivated branches of anthropology. As in the case of all the other mammals, the skull in man is one of the parts of the skeleton, and even of the entire body, which exhibits the greatest number of well-marked variations. The differences in the form and the dimensions of the skull in correlation with those of the brain and the masticatory organs, serve to distinguish races and species, both in man and other vertebrata. Besides, the teeth, which characterise not only genera but even families and orders of the mammifera, are always attached to the skull, though not forming part of the bony system. We may also observe that the skull, with the other bones of the skeleton, constitutes the only anatomical document of prehistoric man which has come down to us; it is only in studying it that we can connect and compare, from the point of view of physical type, existing with extinct races of mankind.
The characters that may be observed in the skull are very numerous, and may be divided intodescriptivecharacters, which give an account of the conformation of the bony structure of the head and its parts, andcraniometricalcharacters, which give the dimensions of these parts by exact measurements taken by means of special apparatus or instruments. These two orders of characters are complementary to each other. The cranial characters vary according to race, but within the limits of each race there are other lesser variations according to age and sex.
The general form of the cranium, as also the number, the consistence, and structure of the different parts which compose it are modified as the individual develops and growsolder. Formed of a single cartilaginous and membranous substance at the beginning of embryonic life, the cranium is composed in the last fœtal state of a great number ofpoints of ossification of various texture. At birth the number of these points has considerably diminished; they have united for the most part to form the different parts of thebones of the craniumorbrain caseand thebones of the face; as the child grows, these points grow and end by being contiguous; about the age of eighteen or twenty years they form bones separated bysutures. There are twenty-one separated bones described in classic treatises on anatomy. Later on these bones begin to unite, thesutureswhich separate them disappear, and in extreme old age the cranium is formed of a bony mass almost as continuous and homogeneous as was the cranial cartilaginous and membranous mass in the embryo. According to the number of the pieces composing the cranium, and also according to their position, structure, and conformation, according to the degree of obliteration of the sutures and the order in which the obliteration of each suture takes place, according to the general form of the forehead, the angle of the lower jaw, according to the volume and dimensions of the skull, and lastly, according to the state of the dentition, etc., the nearly exact age of the individual to whom the skull had belonged may easily be discovered in this cycle of development. Other characters serve to distinguish the sex: the forehead is straight and rounded in woman, retreating in man; the cranial cavity is less in woman than in man in any given race; the orbital edges are sharper in woman, the impress of the muscles less marked, the weight of the skull in general less than that of the masculine skull, etc.[56]Lastly, the characters of race arenumerous and special. I shall proceed briefly to enumerate some of them. First in order of importance comescranial capacity, or the volume of the cavity of the brain-case, which gives an idea of the volume of the brain, and approximately of its weight.
Dolichocephalic SkullFIG.10.—Dolichocephalic skullof an islander of Torres Straits. Cephalic index, 61.9.(After O. Thomas.)
FIG.10.—Dolichocephalic skullof an islander of Torres Straits. Cephalic index, 61.9.(After O. Thomas.)
Cranial capacity may vary to the extent of double the minimum figure (from 1100 cubic centimetres to 2200 cubic centimetres) among normal individuals in the human race. The average capacity for the races of Europe is from 1500 to 1600 cubic centimetres; that of the skulls of Asiatic races appears to be very nearly the same; that of the Negro races and Oceanians a little smaller, perhaps from 1400 to 1500 cubic centimetres on an average. That of the Australians, the Bushmen, and the Andamanese is still less, from 1250 to 1350 cubic centimetres. But it must not be forgotten that the volume of the head, as with its other dimensions, has a certain relation to the height of the individual, and, as a matter of fact, Bushmen and Andamanese are very short in stature; Australians, however, are of average height. Partly, too, to their disproportion of height must, probably, be attributed the difference between the volume of the cranium in man and in woman. According to the series examined, this sexual difference may extend from 100 to 200 cubic centimetres, and even beyond, in favour of man. The cranial capacity of woman represents from eighty-five to ninety-five of the cranial capacity of man.[57]The cranial capacity of lunatics, of certain criminals, and especially of celebrated or distinguished men, scholars, artists, statesmen, etc., appears to be slightly superior to the average of their race. We shall revert later to the question of cranial capacity in connection with weight of brain.
Dolichocephalic SkullFIG.11.—Brachycephalic skullof a Ladin of Pufels (Tyrol). (After Holl.)
FIG.11.—Brachycephalic skullof a Ladin of Pufels (Tyrol). (After Holl.)
The general form of the brain-case is an oval, but this oval may be more or less rounded, quite globular (Fig.11), or more or less elongated to resemble an ellipse, the major axis of whichis almost double the minor (Fig.10). The numerical expression of the cranial form is given in anthropology by what is called thecephalic index—that is to say, by the relation of the length of the cranium (ordinarily measured from the glabella to the most prominent point of the occiput (Figs.10and13,A B) to its greatest breadth (Fig.10,C D, Fig.12,M N)). Reducing uniformly the first of these measurements to 100, we obtain the different figures for the breadth, which expresses the cranial form; thus very round skulls (Fig.11) have 85, 90, and even 100 (extreme individual limit) for index, while elongated skulls (Fig.10) may have an index of 70, of 65, and even of 58 (extreme individual limit). According to Broca’s nomenclature, skulls having indices between 77.7 and 80 are mesaticephalic or mesocephalic; those having the indices below this figure are sub-dolichocephalic (up to 75), or dolichocephalic (beyond 75, Fig.10); those which have theindex above 80 are sub-brachycephalic (up to 83.3), or brachycephalic (above 83.3, Fig.11).[58]Peoples or ethnic groups being formed of various elements, it is in most cases impossible to determine, after the examination of an isolated skull, to which population it belongs; all that can be said is that the skull is brachy- or dolicho-cephalic, orthognathous or prognathous, etc. We must have a certain number of skulls (from ten to thirty at least, according to the homogeneity of the population) to be able to discern the constituent elements of this population as far as they are manifested in the cranial characteristics. Theaveragemeasurements are then deduced from a given number of skulls, by adding the individual measurements and dividing them by the number of skulls examined. But the average of any measurement whatever only gives a very general and somewhat vague idea of the actual dimensions of skulls. To determine it we mustco-ordinateandseriatethese skulls—that is to say, arrange them, for example, in an ascending order of figures expressing their cephalic index. In this manner we can discover one or several indices around which the skulls are grouped in the largest number. It is thus that we can often discern two or three cranial elements in the same population.[59]
If we apply these methods to the study of the cephalic index, we see that generally the crania of Negroes, Melanesians, Eskimo, Ainus, Berbers, the races of Northern Europe, etc., are dolichocephalic, while those of the Turkish peoples, the Malays, certain Slavs, Tyrolese, etc., are brachycephalic; that the dolichocephalic predominate in Great Britain, while the brachycephalic are in a majority in France, etc. (See p.75, andAppendix II.)
The relation of the height to the breadth or to the length of the skull gives likewise an idea of its general form. It is thus that we recognise low skulls (platycephalic), medium (orthocephalic or metriocephalic), or high (hypsicephalic).
In order more correctly to describe the different peculiarities of the cranium, and to be able to refer the measurements to fixed co-ordinates, it is desirable to place the skull, when being studied, on a horizontal plane. Unfortunately, anthropologists are far from being agreed as to this initial plane. In France, in England, and in many other countries, that adopted is the alveolocondylean plane of Broca (Fig.13,L K), which passes through the condyles and the alveolar border of the upper jaw; it is nearly parallel to the horizontal plane passing through the visual axes of the two eyes in the living subject; whilst in Germany the plane still in favour is one passing through the inferior border of the orbit and the centre or top of the contour of the auditory meatus[60](Fig.13,N M). The skull once conveniently placed in position according to a horizontal plane, the different views of it are the following: seen from above (norma verticalisof Blumenbach, Figs.10and11), from below (norma basilaris), from the side or in profile (norma lateralis, Fig.13), from the full face (norma facialis, Fig.12), or from behind (norma occipitalis).
In regard to the face, different measurements express its general form; thus the relation of the bi-zigomatic length (Fig.12,I G) to the total height of the bony structure of the head (Fig.12,K L), or to its partial height from the glabella to the alveolar border of the upper jaw-bone (Fig.12,F H), serves to separate skulls into brachy-or dolicho-facial, or, as they are also called,chamæprosopesandleptoprosopes. Other characters, such as the excessive development of the supraciliary ridges (Fig.13,A), also give a special physiognomy to the bony structure of the face.