The Missing Link
E. Ray Lankester
Diversions of a Naturalist 1915
 Until the discovery of the wonderful fossil jaw in the gravel of Piltdown, near Lewes in Sussex, a favourite view as to the probable relationship of man and existing apes was, that if you could trace back the pedigree of man and of the chimpanzee into remote antiquity far back in the Tertiary periodprobably in the early Mioceneyou would arrive at a smallish creature with, proportionately to its size, larger jaws and teeth than any modern man, yet smaller than those of the living man-like apes, and with a brain not two-thirds the size of that of the least developed of modern savages, yet larger (in proportion to its general bulk) than that of the gorilla, chimpanzee, orang, and gibbons. This hypothetical creature would represent, it was held, the common ancestor of the two great "strains" or "stocks" one of which in the course of gradual modification gave rise to our living "humanity," and various non-surviving offshoots on the way; whilst the other gave rise to the company of great apes, with their tremendous jaws and dog-teeth, their small brains, and great bony skull-crests for the attachment of huge jaw muscles.
It was insisted that the obvious and immediate suggestion when once man's descent from animal ancestry was admitted, namely, that man has taken  his rise from the most man-like animals we knowthe great apes is erroneous. The public was warned that they must not jump to such a conclusion; it was too obvious, too facile The "celebrated ape of the Darwin shape" which popular songs made familiar to a wide public, was declared to be only a remote rustic, not to say brutalized, cousin of humanity, not in the direct line happily! Our real ancestors, it was declared, were mild, intelligent little creatures, animals, it is true, but animals which hastened to separate their mixed qualities in two divergent lines of descent(1) the intelligent, mild-mannered clan who ceased to climb trees, and walked uprightly on the soles of their feet, whilst their teeth grew smaller and smaller, and their brains grew bigger ant bigger; and (2) the violent tree-climbing members of the family, who refused to stand up, and acquired bigger and bigger jaws and teeth, whilst their brains remained small, their temper morose, and their conduct violent.
Old writers before the days of Darwin had talked and written about the "missing link," though I cannot say who first used the term in reference to a creature intermediate between man and apes. Sir Charles Lyell in 1851 made use of the term in regard to extinct animals which were intermediate in structure between two existing types. A learned and able writerthe Scotch judge, Lord Monboddoin the later half of the eighteenth century put forward a theory of the development of mankind from apes such as the orang, quite independently of any general theory of "transformism" or of the progressive development of the animal and vegetable worlds, from simple beginnings. Lord Monboddo, in the absence of any knowledge of a "missing link" or of animals intermediate between man and the
Fig. 23.Comparison of the right half of the lower jaw of A, Modern European; B., Eoanthropus from Piltdown; and C. Chimpanzee. The size of the drawings is two-thirds of the linear dimensions of the actual specimens. The dotted outline in B represents the part which was wanting in the original specimen and was thus re-constructed by Dr. Smith Woodward. X in A is the bony chin or "mental eminence"; in B and C it marks that part of the jaw which would become the mental protuberance were the palisade or line of teeth retracted as in A.
highest living apes, made reasonable speculations (based on wide study of anthropology and ancient philosophy) as to the passage from the monkey to man. He regarded man as of the same "species" as the orang-utan. He traced the gradual elevation of man to the social state as a natural process determined by "the necessities of human life." He looked on language (which he said is not "natural" to man in the sense of being necessary to his self-preservation) as a consequence of his social state. His views about the origin of society and language, and the faculties by which man is distinguishes from the brutes, are in some interesting ways similar to those of Darwin. He conceived man as gradually elevating himself from an animal condition in which his mind is immersed in matter to a state in which mind acts independent of body. He was ridiculed and declared to be half mad by his contemporaries (among them Samuel Johnson), although he was, philosophically, far in advance of those with whom he came into contact. Darwin's views on the "Descent of Man" were met in the same contemptuous spirit at first; but he held a much stronger position than Monboddo, having first of all established the general theory of organic evolution, and having, further, a well-established mass of evidence at his command in regard to the relationship of man and apes. Further, he had that wonderful champion, Huxley, to fight for him. Huxley's book, "Man's Place in Nature," originally given as lectures which I, then a boy, attended, placed the evidence of the close relationship of man and the higher apes in the clearest way before the public, and, indeed, established the identity of the structure of man with that of the ape, bone for bone, muscle for muscle, and nerve for nerve.
Still, there was always a gapa place unfilled between the large-brained, small-jawed man and the small-brained, large-jawed ape. The link was missing. It was hoped, when in 1859 the human workmanship of the flint axes found with the bones of extinct animals in our river gravels was recognized, that the bones of the men who made the flint axes would turn up alongside of them, and that they would show characters intermediate between those of modern man and the great apes. But no such human bones ever were found in the older gravels deposited as terraces along their beds by the rivers of Western Europe. Human bones, and more or less complete human skulls, of a highly-developed modern type (the Cromagnards) were found in caves associated with flint tools of a different character to those common in river gravels. Then we heard a good deal about the strangely flat skull-top, or calvaria, found in a cave near Dusseldorf on the Rhine, associated with the preaching of a certain hermit named "Neuman" ( = Neander). The valley was called "the Neanderthal," and the skull-top thus came to be called the "Neanderthal skull." Some authorities regarded the Neanderthal skull as that of an outcast idiot! Huxley studied it minutely, and compared it to that of Southern Australian black-fellows, and held that it took us no nearer to the apes than they did. Then an unsatisfactory small flat skull-top, together with a long, straight thigh-bone, was found in a gravel in Java, and the name "Pithecanthropus" was applied to these remains. Still we had got no nearer to any knowledge of the missing link.
Of late years we have, however, learnt a great deal more about the race or species of men of which the Neanderthal skull-top was the first indication. We now know that this species of man belonged to a period older than that of the other prehistoric cavementhe artistic Magdalenians and the bushman-like Aurignacians, which are races of Homo sapiens, not distinct species. The older period is called the Moustierian, or Middle Paleolithic, period, and is marked by a peculiar type of flint implement. It is later than the older river gravels, to which big tongue-shaped and almond-shaped flint implements are common. The two skulls and bones from the cave of Spey, in Belgium, the Gibraltar skull, and the skeletons and skulls of the cavern called the Chapelle aux Saints in the Correze (Central France), and of Ferassy, and some neighbouring localities, all belong to this Moustierian age (so named after the village "Le Moustier," in Perigord), and to the peculiar species Homo Neanderthalensis. 1 It is also necessary to include here the more ancient man indicated by the important lower jaw found by Schottensack near Heidelberg (see Fig. 25). The Neanderman or Neanderthal-man had a low forehead, with overhanging bony brow-ridges, and a depressed, flattened brain-case, which, nevertheless, was very long and broad and held an unusually large brain, measuring 1600 cubic centimetres, whereas the modern European averages 1450 only of such units. He had a powerful lower jaw, with a broad, upstanding piece or vertical "ramus," and no chin protuberance. Yet his teeth were identical with those of a modern man. His thigh-bones were much curved, and his arms a good deal longer in proportion to his legs than those of a modern man. He did not carry himself upright, but with a forward stoop.
Now that we know more of him, we may ask, Does this Neanderthal or Moustierian man fill the place of the missing link?" It appears that he does not. He seems to have died out without leaving any descendants. In so far as that his bony jaw sloped directly downwards and backwards from the margin of the sockets of his front teeth, as in the apes, without projecting below, to form a chin protuberanceas it does in all races of Homo sapiens, on account of the shrinking inwards of the gum-line or palisade of front teeth (incisors and canines)the Neanderman offers a certain approach to the condition of the apes; but in other details of shape of the lower jaw, and especially in regard to the narrowness of the lower surface of the chin and the large and deep attachments on its inner face, for the digastric muscle and certain muscles of the tongue, the bony remains of the Neanderman show that he is distinctly and altogether human, and not like the higher apes. Moreover, in the very large size of his brain (as much as 1600 units) the Neanderman shows no approach to the relatively small brain of the higher apes (which measures 500 units, possibly 800 by exception). There is in these structures some argument for the conclusion that the Neanderman could use articulate language, and inasmuch as the climate in which he flourished was extremely cold, there is ground for supposing that he could produce fire and clothe himself with skins. The flint implements which are definitely associated with him are of more skilful workmanship than the earlier, more elaborate, but less cleverly concaved, Chellean and Acheuillian implements. We cannot refuse to call him "man"not Homo sapiens, we agreebut of the "genus" HomoHomo Neanderthalensis.
So long as the Neanderman was the sole indication of a creature nearer in some features to the apes than are any living or extinct races of the species Homo
Description of Fig. 24
Fig. 24Diagrams of the lower surface of the lower jaw of A, man; B, the Eoanthropus of Piltdown (the left half reconstructed); and C, the Chimpanzee
The jaws are supposed to be immersed in sand, so as to conceal all but the lower surface. The narrowness of the actual inferior margin of the jaw in man, A, a, b, contrasts with the breadth and flatness of the same border in Eoanthropus, B, a, b, and the Chimpanzee, C, a, b.
In the human jaw A we see behind the narrow front border a the large semi-circular excavations for the attachment of the digastric muscles right and left. They pass from here to the hyoid bone. From the spine (double in origin) between the two digastric impressions passes a pair of muscular slips, called the genio-hyoid muscles, also to the hyoid bone, and from the pair of spines marked y a pair of muscles, called the genio-glossals, pass to the tongue. These inferior and superior mental spines and the digastric impressions, much smaller in size than in man, are seen in the chimpanzee's jaw, C, but are rubbed or partly broken and partly rubbed away in the Piltdown half-jaw, B. In the figures A and C the size of the digastric impressions and mental spines is exaggerated, but their relatively much greater size in man than in the chimpanzee is correctly given, and this greater size is connected with the greater control of the tongue and the floor of the mouth in man, possibly connected with speech.
Reference Letters.a, Broad, upward and forwardly sloping surface, reduced in man; b, lower border of the jaw-bone; x, front margin of the digastric "impression" of the right side. Dig, digastric impression; y, superior mental spine of the left side; Fr., fractured edge of the Piltdown jaw, and corresponding region in that of the chimpanzee.
sapiens, the view was possible that the two stocks which to-day blossom and display themselvesthe one as the human race, the other as the man-like apes (gorilla, chimpanzee, orang, and gibbons), became separated from one another in long past geologic ages, ant that they have underdone each an independent development from a creature so unlike both as seen to-day, that we cannot speak of it as a missing link or a link at all. That view must be considerably modified by the discovery of the Piltdown jawthe jaw of Eoanthropus Dawsoniwhich is not that of a "man," that is not of the genus Homo, but must, in my judgment, be considered as one of the family Hominidæ.a Hominid, as we may say a species assigned to a new genus Eoanthropus by Smith Woodward, which is grouped with the genus Homo and the ill-defined genus Pithecanthropus, to form the family Hominidæ; just as the genera Gorilla, Anthropopithecus (chimpanzee), Simia (orang), and Hylobates (gibbon) are grouped together to form the family Simiidæ. In Eoanthropus we have in our hands, at last, the much-talked-of "missing link"the link obviously connecting man, the genus Homo, with the apes.
The immense importance of the discovery of the jaw of Eoanthropus by Mr. Dawson, and of the clear perception of its distinctive features by Dr. Smith Woodward, is not, as yet, sufficiently recognized. The Piltdown jaw is the most startling and significant fossil bone that has ever been brought to light. The Neandermen and the Java skull-top are simply commonplace and insignificant in comparison with it. "What leads you to say that?" I may be asked. I say so because this jaw and the incomplete skull found with it (Fig. 29) really and in simple fact furnish a link a form intermediate between the man and the ape. Some fragments of the brain-case were found close to the jaw, indicating a fairly round, very thick-walled brain-case, holding a brain of about 1100 units capacityvery small for a man, very large for an ape. It is in the highest degree probable that the brain-case and the jaw belong to the same individual. If we were to put the brain-case aside as not certainly belonging to the same individual, we should guess that the owner of the jaw might have had a brain of about this size intermediate between that of the larger apes and the living races of men.2
 The astonishing thing about this half-jaw from Piltdown is that it is definitely and obviously more like that of a chimpanzeeespecially a young chimpanzee than it is like that of a man (see Fig. 23, A, B, and C and their explanation). If it had been found under other circumstances it might quite well have been described as the jaw of a simiida large ape allied to the chimpanzeewith some unimportant resemblance to a human one. The front part of the bony jaw of Piltdown, instead of forming a narrow ridge below the protruding bony chin as in man, is wide and flat; there is no protruding chin. This very important fact is shown in our Fig. 24, in which the lower margin of the lower jaw of modern man, of the chimpanzee and of the Piltdown specimen are compared. The jaw ended in front in a wall of bone sloping forward and upward continuously from the flat and broad lower surface of the jaw. In this the great incisor teeth were set, as in all Simiids. In man, on the contrary, the front group of teeth is much smaller than in the apes, and the semicircle formed by the line of the gums is much smaller than the semicircular lower margin of the jaw. The semicircle of teeth in man retreats (as it were) behind the front part of the bony jaw which is left projecting far in advance of the line of teeth, forming the "chin" or "chin protuberance." The Piltdown jaw when found had only two of the cheek-teeth in place, as shown in Fig. 25. They were certainly very human in pattern and in the smoothness of their worn surfaces. But it was found impossible to fill the front part of the bony jaw with the missing teeth if they also were fashioned according to human pattern. They would in that case only reach along the jaw to a distance of an inch and three fifths from the first molar tooth, whereas to fill the space from that tooth up to the front end of the bone in which the teeth are socketed they must be big enough to occupy a length of two inches and two-fifths (consult Fig. 25 and its explanation). Dr. Smith Woodward did not hesitate, in view of the shape of the jaw. so closely like that of a chimpanzee, to postulate the former existence in it of big front teethcanines and incisorslike those of a chimpanzee, and unlike those of man, although there was no trace of them left in the specimen. He restored the jaw, giving it very much the shape and the teeth of a chimpanzee's jaw (Fig. 23, B). That this was a correct interpretation was proved a year
FIG. 25.The Piltdown Jaw (shaded) and the Heidelberg Jaw (outline only) super-imposed and compared by placing the first and second molar teeth (1 and 2) of the two specimens in exact coincidence on the horizontal line A, B. The linear dimensions of the drawings are reduced to two-thirds of those of the specimens. It is obvious that when the front bony part of the Piltdown jaw is completed with an outline like that of the Heidelberg and Neander jaws, as shown by the dotted line m , the space between its molars and the sockets of its front teeth cannot be filled by teeth of the normal human dimension, as it is in the Heidelberg jaw. As the figure shows, they would stop short half an inch from the front of the jaw. Hence Dr. Smith Woodward inferred that larger teeth like those of a chimpanzee were present in this region in the Piltdown jaw (Eoanthropus).
 later, in a startling, almost romantic way, by the discovery by Mr. Dawson and a young French naturalist who were resifting and searching the gravel at the exact spot where the jaw was found, of one of the great canine teeth, twice as big as that of any man and resembling that of a chimpanzee (see Fig. 26 and its explanation). There was a good deal of hesitation about the admission of the correctness of Dr. Smith Woodward's presentation of the jaw of Eoanthropus, with so close a resemblance to that of a chimpanzee. But the careful consideration of the specimen, and above all the welcome discovery of the great ape-like canine, has now convinced every anatomist of the truth of Dr. Woodward's restoration. The jaw itself and the recovered canine tooth, as well as the completely restored model of the two sides of the lower jaw and of the brain-case, may now be seen and studied by visitors to the Natural History Museum. They are placed in the Geological Gallery. I have visited with Mr. Dawson and the gravel at Piltdown where the jaw and skull were found, and have picked
Fig. 26 Fig. 27
Fig. 26.The canine tooth of the right side Fig. 27.Canine tooth of the right side of the
of the lower jaw of Eoanthropus Dawsoni, lower jaw of a European child, milk dentition.
found at Piltdown a year after the discovery This "first" tooth is drawn of twice its actual
and description of the lower jaw, to which length and breadth, which brings it very nearly
it belongs. Drawn of the natural size. To to the same size as the canine of Eoanthropus. It
the left a back view, to the right a side is more closely similar in shape to the canine of
view, showing the wearing away of the of the Piltdown jaw than is the canine of the
surface of the tooth. second or permanent dentition of modern man.
 up there humanly worked flints of very primitive workmanship. I have also followed with Dr. Smith Woodward the development and confirmation of his interpretation of the jaw.
Fig. 28.The Piltdown Jaw (Eoanthropus) with dotted lines showing the parts as now "re-constructed" or "imagined" by Dr. Smith Woodward, together with the late-found or recovered canine in its natural position.
I now desire to insist upon the legitimate conclusion to be drawn from this wonderful specimen. That conclusion is that the creature, indicated by it, is not (or was not when it was alive) an eccentric cousin either of the Simiid or of the Hominid stock, but represents a real "missing link," an animal intermediate in great and obvious features between the two stocks, and either to be described as an ape which had become man-like or as a man who still retained characteristic ape-like features a truly connecting or linking form. Nothing like it, nothing occupying such a position, has hitherto been discovered. It brings the focus of interest in the  knowledge of primitive man away from the caves of France to the thin patch of iron-stained gravel in the meadow-land of the River Ouse as it flows through the Sussex weald. These remains are the first remains of a man-like creature found in a Pleistocene river gravel, and they exceed in interest any human remains as yet known. There is now reason to hope that more such remains will be discovered in similar gravels.3
It would be highly important were we able to arrive at a satisfactory conclusion as to what age must be attributed to the Piltdown jaw and skull. Did we know their age their true significance as a link between man and ape would be more easily estimated. The gravel in which they were found contains a handful, as it were, of the sweepings of the land surface of the great Weald valley of Sussex of all ages and periods since the emergence of the chalk from the ocean flooran immense lapse of time, amounting probably to millions of years!
Fig. 29.Complete Skull and Jaw of Eoanthropus
Dawsoni. One-third the natural diameter. The
parts indicated by dotted lines are re-constructed,
The rest is drawn from the actual bones discovered
Fig. 30.The complete Skull and Jaw of
a young chimpanzee. Drawn of one-half
the natural diameter in order to compare
with Fig. 29, representing the adult skull
of Eoanthropus, reduced to about the same size.
In this sparse and inconspicuous patch of gravel we find fragments of teeth of mastodon and elephant and rhinoceros of Miocene and Pliocene age; we also find bones of quite late kinds of mammals of the Pleistocene period; we also find two kinds of roughly chipped flint instruments belonging the one to an earlier and the other to a later age. All are mixed up together in the gravel. When we come to the question as to  which of these remains are of animals which were the contemporaries of Eoanthropus, all we can say is that Eoanthropus, the creature whose jaw was found at Piltdown, may have lived as late as the earliest of the animals whose remains are associated with it. The Eoanthropus remains are not so heavily mineralized, it seems to me, as are the fragments of teeth of Miocene age found with them. At the same time, we have no ground for assuming that this creature made either the earlier or the later type of flint implements found with it, or was capable of such manufacture. I see no reason for supposing, whatever may be the age which we may have to attribute to Eoanthropus, that that creature was capable of flaking flints to a desired shape or of making fire or had developed the use of articulate speech. Nor is there any evidence to show that the humanly cut elephant-bone recently found at Piltdown by Mr. Dawson was cut by Eoanthropus. It is more probable that this was done by a more highly developed creature of the genus Homo. In fact, the only ground which at present justifies the association of Eoanthropus with the Hominidæ, or human series rather than with the Simiidæ or ape seriesderived from a common ancestryis the man-like rather than ape-like size of the brain, which we must attribute to Eoanthropus on the assumption, which is at present a reasonable one, that the half-jaw and the incomplete skull found near each other at Piltdown are parts of the same individual.4
1 For figures of the skulls and flint implements of these ancient men, see my volume, "Science
from an Easy Chair," First Series. Methuen, 1910.
2 The recent discovery by Mr. Dawson of fragments of a second skull of the same character as the first and at the same spot justifies a certain amount of hesitation in concluding that the lower jaw and the fragments of the first found skull belong to one individual.
3 The human lower jaw found at Moulin-Quignon fifty years ago by workmen who brought it to M. Boucher de Perthes, was dismissed after much study and examination by the most competent anatomists at the time as being a comparatively recent specimen. I do not know whether it has been preserved. I have a flint implement found with it which was given to me in 1862 by M. de Perthes as genuine. It is a forgery, and the jaw was fraudulently buried with it and others in order to deceive M. de Perthes and earn a pecuniary reward for the forgers.
4 But see foot-note on p. 284.