The singular arrangement of hair on the forearm of man is the subject of some curious statements by Darwin, Wallace and Romanes, and these suggested to me twenty years ago the following line of thought. To many minds the text will appear a humble one, but it opens many avenues of inquiry.
These three illustrious men are all more or less inaccurate and incomplete in their descriptions of the hair on man’s forearm, though Romanes42 gives a drawing which supplements his written account. They looked upon it as a vestige of the pattern of hair on the forearm of existing anthropoid apes, especially the orang, in whom its fully-developed form was an adapta-tion governed by Natural Selection. Of the three, Wallace is the most uncompromising on behalf of this view, Romanes rather accepts it en passant, and Darwin in a long passage43 adopts it with some reserve and his usual respect for the work of his great co-worker, as the most probable explana-tion of a fact which lay heavy on his scientific conscience. Indeed, for all these great men it was a crux, though Romanes, with his Lamarckian views, need not have found much difficulty with an alternative account of it.44
At the time when these statements were made, the lineal ancestors of man were much more definite personages than they are now, as Arthur, the legendary Celtic hero, was formerly held to be an historical personage more than is the case now. These ancestors were generally believed then to be found among the four existing anthropoid apes. The picture of our ancestor among
the apes, as given by Wallace, in connec-tion with this state of the hair on his forearm, represents him as spending much of his time like the gorilla, who, according to Livingstone, “sits in pelting rain with his hands over his head.” He would no doubt find the thatch-like arrangement of the hair a tolerably efficient umbrella, but one may doubt very much if so clever a denizen of the tropics would fail to find under the great branches of trees, in a tropical forest, a better covering and one more like the roofs of our houses. But when we cannot find a roof to our heads we—and the orang or gorilla—naturally employ a substitute, and not otherwise. Be that as it may, it is doubtful if the thatch of his forearms would supply him with that survival value on which the theory of Selection depends, to say nothing of the fact that in its incipient stage the reversal of the slope of hair, inherited from the lemur stock, would be trivial and useless.
But one must ask: “Did man’s Simian ancestor really loaf away so much of his time in this dull manner? and was the running-off of rain so frequent and imperative a need as to make him set to work to invent this special adapta-tion?”
After some millions of years have passed since his day we are not in a position to go beyond speculations, and this one seems barely credible, moreover, it is quite unnecessary, as certain following facts will show.
Steps of the Inquiry.
Having expounded the text and its context, I would mention that in 1897 I came across these views of biologists as to the very strange arrangement of hair on man’s forearm, and was struck with the inadequacy of the theory of Darwin, Wallace and Romanes to account for the state of things which every man can find, if he looks for it, on his own forearm. I examined a large number of apes and monkeys so as to test the theory, and the results were published in Nature, Vol. 55, under the title “Certain vestigial characters in Man.” Suffice it to say that from the evidence I brought forward one had to choose between two heresies: either to deny the Simian ancestry of man or to affirm the inheritance of some acquired characters; and I chose the latter. The choice of “evils” or heresies which had to be made then will serve as an introduc-tion to all that follows.
This article was followed by a paper at the Zoological Society of London on “The Hair-Slope in certain Typical Mammals,” and after this came a paper at the same Society, giving evidence and reason why certain patterns of hair in some mammals should rank
as specific characters. Various other papers at the Anatomical Society of Great Britain and Ireland were read and published and others at the Zoological Society, in which different regions of the hairy coat of man and lower mammals were dealt with. In 1903 the whole subject of the Direction of Hair in Animals and Man was treated in a book freely illustrated.
I then followed the advice of Horace and left the subject alone for nine years, during which time my further observations and reflections served but to confirm, except in two or three unimportant details, the results and conclusions in the book and papers of an earlier date. The connec-tion between the habits of an animal and the distribu-tion of its hairy coat were always cropping up, and I saw then and see now no possible explana-tion of the connec-tion than that the former is the efficient cause of the latter.
How the Hair is Arranged on the Forearm.
Returning now to the text, the remarkable arrangement of hair on man’s forearm, attention may be directed to the accompanying figure of the forearm of a lemur, an ape and man, in which the extensor or back view of this limb-segment is shown, the heavy “war-arrows” being employed to direct the attention of the reader to the main lines in which the hair-streams flow. The front or flexor surfaces in the lemur and ape are not shown because they are precisely like the corresponding back surfaces, and the flexor surface in man is shown in the figure. The figures are so much like diagrams that a very little detailed descrip-tion will suffice. For the examina-tion of the hair on man’s forearm the best subject is a dark-haired youth, and it is easily traced, though in any hairy subject it can be shown up well by placing the forearm in water for a minute and allowing the water to drain off. The normal and congenital hair-slope on the forearm is then well displayed.
On the front surface of man’s forearm the hairs point away from the elbow and divide in the middle of the surface into two streams, one passing to the outer and the other to the inner border in a downward gentle curve, and they join the streams of hair on the back surface. In this pattern there is nothing very peculiar, for it is shared by many monkeys.
When the back surface is examined it is found to present an arrangement of the hair which is unique among hairy mammals. The figure shows the eccentric course taken by the hair on the back surface. In the centre, exactly along the extensor border of the ulna, from the wrist to the point of the elbow, the hair-stream
has been bold enough to turn straight upwards in a narrow line, and it was here that our three great leaders saw their chance of claiming for Selection a tiny bit of territory, a kind of Duchy of Luxembourg between two great States, though, as I proceed to show, the claim is disallowed and untenable.
Fig 1.—Arrangement of Hair on the Forearm.
In the ape the hairs of the forearm are much longer and thicker than those of man, and both on the front and back all point from the wrist to the elbow.
In the lemur all the hairs point from the elbow to the wrist.
In the products of Nature there are no freaks, or impish tricks performed, and it is not for nothing she does her work. Every one of them asks for and should receive an explana-tion consistent with fact and reason, and here comes in the need for studying, as one may, the broad outlines of man’s ancestry. His ancestor being now sought in an earlier and more generalized stock than that of the four genera of anthropoid apes known to us, the most instructive and safest line to take is to trace him back to the stock lemur, who remains to-day among the most Chinese or unchanging of known mammals. In his illuminating work, Prehistoric Man and History, Professor Scott Elliott adopts an excellent term, “lemur-monkey-man,” to sum up, without missing links, the long ancestry of man. I take the liberty of adapting this term more closely to the present inquiry and use that of lemur-ape-man instead, for whatever may be the relation of man to present apes some ape-like ancestors enter into his genealogical tree.45 For my purpose the monkey is less useful because his hair-slope differs so little from that of lemurs, whereas apes have made for themselves a very remarkable position as regards the hair of their forearms. Our series of animals for study is then well represented by the lemur-ape-man—hypothetical, necessary and serviceable. Through all the immense stretch of time occupied in this process of descent there has been ample opportunity for the lemur to change his fashion to that of the ape, and the latter to change to the present fashion of man.
This simple arrangement of the lemur’s hair is common to that of all the more primitive long-bodied mammals, of which an otter is a good example, and I venture, greatly daring, to call this the normal slope of hair. Somewhere and somehow in the human tree there has appeared a total reversal of the lemur-type; the stock of apes acquired a new fashion, and gradually discarded
altogether their ancient inheritance, beginning their innova-tion perhaps, with Dryopithecus fontani in the Miocene Age.
The Dynamics of Hair-Pattern.
There are a few well-known facts which it is necessary to bear in mind if one is endeavouring to understand the mode of origin and order of the events before us. The hairy coat of a mammal is composed of individual hairs of varying length, colour and thickness, each being rooted in a tiny pit in the skin and growing from a papilla at its base. As the hair grows, its free end is pushed away from the papilla at the rate of one inch in two months. This is the rate in man’s hair, and it is probably greater in the case of lower mammals on account of the greater importance and physiological activity of their hairy coat than in man’s. But one inch in two months is a close enough calcula-tion. Here, then, is a structure which grows throughout the whole life of the animal, and has to dispose itself somehow on the surface of the skin. It does this in the line of least resistance, and to trace this line is the Alpha and Omega of the present inquiry.
There is a concep-tion of much value in understanding the dynamics of the distribu-tion of hair, and that is to view the hair of mammals as composed of certain streams. As in every illustra-tion, this concep-tion may be challenged because of some difference the critic may find between these streams and a stream of fluid. It certainly does not leave its bed as do the component parts of a river, a glacier or molten lava, for the base of the hair is fixed. But it will serve, and is at least not more open to objection than certain useful metaphors in biology as when the genealogy of man and animals is pictured as a tree, or the living things of the earth as a “web of life.” It is, then, as streams moving at the rate of one inch in two months in the lines of least resistance that I propose to discuss the animal hair and its diverse patterns and offer no further apology for doing so. Just as in the cases of a stream of water with varying banks and rocks in its course, or a glacier with its mountain-sides and sinuous valleys, or a stream of lava with small projecting surfaces of a mountain, our stream of hair flows on, hindered only by adequate obstructions.
Yet another concep-tion from the region of metaphor must be mentioned. It is one which will commend itself to every mind which has been steeped in thoughts of warfare for five years. We are all soldiers now; we think in terms of military affairs. In the case of our hair-streams there are in many regions two forces directly opposed to one another, others in which no struggle has
yet occurred, as, in the Great War, Italy was not at one period at open war with Germany.
Between the opposing forces in our small battle-field of the hairy coat there have been waged battles to which those of Mukden, Verdun, the Somme and Arras, are not to be compared in point of time. They are but as one day to a thousand years. On one side of the conflict in our present chosen field the ancient primitive type of the lemur has remained entrenched for some millions of years, until there arose new forces in its descendants on the other side and this changed the war of positions into one of movement. It was indeed “a contemptible little army” which came forward to oppose the ancient barbarian forces of the lemur, long prepared and organised, and these new armies fought under the banner, Habit. In the slowly-formed patterns in many types of mammals we have records of the treaties made after these long struggles and the rectifications of frontier which became necessary. The critic may call these “battles of kites and crows,” and ask What war correspondents were allowed to describe them; but a battle, whether great or small, long or short, is important to the parties concerned, and it is open to us to “reconstruct” the facts of the battle as do the historians on their part, for example, Sir James Ramsay the battle of Agincourt—with tolerable verisimilitude. But in science, especially geological science, the process of reconstruc-tion is much more ambitious and bold than any that is here attempted. Who has not been fascinated, if he has read Sir E. Ray Lankester’s work on Extinct Animals, by the skill and daring with which he conveys to us a vivid idea of the form and mode of life, with scanty data, of the extinct Moa of New Zealand, the great Pterodactyle, Pteranodon, or the Diprotodon of Owen—“the probable appearance in life” of these uncanny but very real inhabitants of the earth in days long past. How skilfully did Owen from a piece of bone seven inches long, sent to him by a gentleman in New Zealand sixty years ago, pronounce it to be a part of the thigh-bone of a bird like an ostrich, and then after a few years had passed, confirmed it by more bones of the skeleton, till the large Moa, extinguished 600 or 700 years ago by the Maoris, lived again before us—an historical personage; or how by the examina-tion of the skull and most of its skeleton the giant marsupial from Australia, Diprotodon, was resuscitated and admired; or again, how from the bones of the arms, shoulder-girdle and fingers was built up the strange body of Pteranodon, the great flying dragon. All of which is the legitimate and approved business of biologists and pal?ontologists, and this digression is made here to show that my line of
treatment of a little subject agrees with that in a greater one; nay, it even proceeds in its explanations of events on the ever valuable principle of Lyell in a still greater one without which to-day geology would be a thing of naught, that is, the principle of explaining changes in the surface of the earth by reference to causes now in action. The objection that one subject is very great and the other very small is not valid; for one as much as the other there are millions of years to be had for the asking. Who in these days hesitates to talk and try to think in millions?—tens of millions of men, millions of soldiers, millions upon millions of money, millions of bacteria in vaccines and millions of money belonging to other people disposed of by the new spendthrift Minister?
From Lemur to Ape.
Returning now to our Eocene lemur we must remind ourselves of the problem before his simple mind and those of his Simian descendants. How was he to change so greatly the direction of the hair on his forearm (Fig. 1) till it should turn right about face and imitate those great German “victories” of Hindenburg, well called Marshal Rückwarts? The problem lies open in the Figure and receiving no aid from Selection or survival of the fittest, in this little effort, he had to fall back on the eternal and tedious force of habit and use. I am afraid if here I were interrupted by some critic, more learned than wise, by a summary demand on the part of Selection for its share in the result, I should be tempted to reply with the word Φλυαρια employed by George Borrow, forbearing to give the transla-tion of the reply as he gives it. Anyhow, it is a case in which to “listen politely and change the subject.”
Here comes in the aspect of strife between primitive and new obstructing forces in a little hair-stream. The lemur lives in trees and carries on a stealthy nocturnal business, moving on all fours in quest of his daily bread, and no external force or new habit avails to modify the hair-slope on his forearms, and so it remains until some primitive form of monkey, gradually evolving into a primitive ape, brings into the family new habits and customs. Other men and other manners appear in the Miocene Age. Our supposed Dryopithecus fontani becomes more upright in his bodily, and perhaps his moral habits, and spends an increasing amount of his leisure time in the sitting posture; his hands are frequently grasping a bough as he sits and reflects, it may be in a man-ward direction, or, as is more likely, on his last meal of nuts and fruits. But he did not spend quite so much time as Wallace and others think in this futile attitude, for he knew in his way as much as the modern
bachelor does, of making his posture comfortable and restful when he was not out at work, and he varied his plans by resting his forearms on his thigh, crouched up and cosy, and doubtless slept much in this attitude. All these bold departures from his lemur-ancestor’s habits had the necessary result of altering the slope of his hair on the forearms, which was now growing as long and coarse as we see it to-day in the orang. In course of milleniums the ancient forces yielded to those of the new armies, and the once normal slope became reversed in a way which shocked the conservative lemurs of his day. It requires little imagina-tion to see how the lengthening thickening hairs on this limb-segment became changed in their direction by friction against the opposing surfaces of the thighs, by gravita-tion, and the frequent dripping of rain when they were held up to grasp a bough. Here then we see at work new forces of friction, pressure, gravita-tion and dripping of rain, turning endlessly and slowly the lemur-fashion into the ape-fashion, with unlimited time for their effectual action. In this stock of Man’s ancestry Selection was taking care of the individual and Habit of the details of his making—two truly harmonious partners.
From Ape to Man.
Another step, and a long one, has still to be taken from the ape-fashion to that of man. Bearing in mind that the lemur-fashion has been totally reversed by the ape it startles one to find that man in his modern fashion has largely reverted to that of the lemur on the front and sides of his forearm. This is clearly shown in Figure 1. There also you see graphically recorded in the hair of the extensor border of the ulna, a little backward streak, a poor little legacy of fifty pounds from the fortunes of many thousands once possessed by the ape. From the present limited point of view, man is a veritable pauper, and his possessions in this limb-segment may with some irony well be called a “vestige.”
Professor Scott-Elliott in his book, Prehistoric Man and His Story, p. 60, goes rather wide of the mark here in his graphic picture of our rude ancestor and his hard life. He gives too strongly the idea of him sitting asleep in raging gales, in driving rain which is neatly conducted by the thatch of his hair off his skin. As far as it goes this need not be questioned, as a matter of probability, but he states far too broadly “The hair on the arm, even of those civilised men who retain sufficient to trace the arrangement, turns down both upper and forearm to the elbow”46—true as to the
upper arm, but only true of the forearm in a very narrow streak of hair over the extensor surface of the ulna. The fact is that in every human being, not too old, its course can be traced with a lens. He overlooks also from this protective point of view the fact that the ape or early man, in the position of rest he describes, would have very much the reverse of protec-tion from the “lie” of the hair on his thighs, for this is towards the knee and is well calculated to catch the rain and conduct it carefully, or let it run, into his groins. So the protec-tion theory (under the empire of Selection) is again in straits. But I must not forget my self-denying ordinance alluded to in the Preface, but will show how the ape fashion began to be modified into its present and probably final form in man. Still further changes in the simple habits of the earliest men became frequent, and fresh forces were organised in our mimic battlefield. Gravita-tion gradually ceased to act as the hairs became thinner and shorter. Friction and pressure changed their lines of incidence with the increasing tendency of man to assume the upright posture, for the surfaces exposed to pressure and friction were only affected when the extensor surface or back of the forearm rested on some supporting object, an attitude extremely common in man as we know him now. Then came the opportunity of the primitive barbarian host, the lemur fashion, by a prolonged counter-attack to recover on the greater part of the forearm the ground lost millions of years before by the ape, and then was engraved on the forearm of man the permanent treaty which we have before us to-day.
This small and apparently trivial battle-ground has been described at what may seem undue length, but it is a miniature of the rise and fall of little empires such as here engage our attention, and I make no apology for this to the reader who has gone thus far with me, for, on the principle of ex uno disce omnes, all that follows in other areas of the hairy coat of mammals will be the clearer, and little repeti-tion will be needed.
Note.—Two terms have been used somewhat freely in this Introduc-tion, “vestige” and “normal,” and a few remarks upon them are not out of place, for they are both somewhat ambiguous and apt to be carelessly employed.
A vestige in biological writings is almost the exclusive property of the Pan-Selectionists, and no one can doubt that on the one hand it is a far more correct term than that of rudiment which Darwin employed so freely, on the other that they have a perfectly legitimate claim to it in a large number of obsolete structures of animal forms. But vestiges, footsteps, footprints, have another and equally correct meaning, even if less often thus employed, in the fact that a vestige or footprint may just as well be a relic of what the race and individuals have done, as a relic of what they have retained in the way of possession, and I submit that the facts and arguments I have here advanced afford a valid claim to the term “vestige” in the results of certain doings on the part of animals—as will appear later still more clearly.
The term “normal” is a fine field for dialectics, but neither ordinary men nor scientific students can do their work without its use, and yet it would have been an intellectual treat to have heard how Huxley, for example, would have turned inside out any opponent who chose to employ it to his dissatisfac-tion. In a strictly-conducted tournament no evolutionary biologist would allow its use—to his adversary. A norm for him exists only as one of Professor Karl Pearson’s “conceptual counters,” a piece of mental shorthand or hardly more than a pis aller. Among the fundamental conceptions of organic evolution there is one which is almost a truism, the doctrine of Heraclitus, π?ντα ρε?ι, the everlasting flux and change of Nature and her products. In strict logic, according to what we all now believe, there is no possible norm. All that one may do is to take stock at a certain epoch of evolution and label, for our own convenience, some group, or organism or structure as “normal”—and go on with our business, collecting some specimens, calling them type-specimens, and putting them in books or cases in the Natural History Museum—and then proceed to business.
The biological teacher in his class room says he must live, he must have his tools for his work, to which the idle student replies under his breath, “I do not see the necessity,” but then few students are now idle, and this jibe does not sting any one! The examiner must have his normal human anatomy, and would ruthlessly plough any daring examinee who tried to sophisticate the meaning of the term “normal.” I have often been struck with what I must call the intellectual audacity of a most eminent leader in physical science and mathematics, who is not unlike a certain great Church, which grants nothing to her adversaries but is not averse from taking. In his Grammar of Science, written with a pen dipped in hydrochloric acid, Professor Karl Pearson four times over, and perhaps more, has the courage to call the human brain in this twentieth century “normal.” Has he never heard of the coming Superman of Mr. Bernard Shaw and other prophets? Thinking sub specie aeternitatis has he here in the West, and at a certain small epoch of time, any right to call the human brain “normal”? I can only long that there may be more normal brains such as Professor Karl Pearson’s, and am almost inclined to echo the prayer of Moses, “Would God all the Lord’s people were [such] prophets”! These comments on the term “normal” imply no complaint against its use, indeed are a claim for it, and I deprecate very much that form of criticism known in boys’ schools, domestic circles, and among politicians as the tu quoque reply, and I hope the few ambiguous terms used in this book will pass the censor, and help the reader.