THE MISSING LINK
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 period--probably in the early Miocene--you 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 know--the 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 and 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.
[Illustration: 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 protuberance"; 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.]
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 writer--the Scotch judge, Lord Monboddo--in 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 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 distinguished 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 co-temporaries (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 gap--a 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 cavemen--the 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,
in 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 Corrèze (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.[10] 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.
[10] For figures of the skulls and flint implements of these ancient
men, see my volume, "Science from an Easy Chair," First Series.
Methuen, 1910.
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 protuberance--as 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
conceived, Chellean and Acheuillian implements. We cannot refuse
to call him "man"--not Homo sapiens, we agree--but of the "genus"
Homo--Homo Neanderthalensis.
[Illustration: FIG. 24.--Diagrams 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 this
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
semicircular 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, upwardly 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.]
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 sapiens, the view was possible that the two stocks
which to-day blossom and display themselves--the 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,
and that they have undergone 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 jaw--the jaw of Eoanthropus
Dawsoni--which 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 capacity--very 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.[11]
[11] 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.
[Illustration: 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 dimensions,
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).]
The astonishing thing about this half-jaw from Piltdown is that it is
definitely and obviously more like that of a chimpanzee--especially
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
simiid--a large ape allied to the chimpanzee--with 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 teeth--canines and incisors--like
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 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 the gravel at Piltdown where the jaw
and skull were found, and have picked 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.
[Illustration: FIG. 26.--The canine tooth of the right side of the
lower jaw of Eoanthropus Dawsoni, found at Piltdown a year after the
discovery and description of the lower jaw, to which it belongs. Drawn
of the natural size. To the left a back view, to the right a side view,
showing the wearing away of the surface of the tooth.]
[Illustration: FIG. 27.--Canine tooth of the right side of the lower
jaw of a European child, milk dentition. This "first" tooth is drawn
of twice its actual length and breadth, which brings it very nearly to
the same size as the canine of Eoanthropus. It is more closely similar
in shape to the canine of the Piltdown jaw than is the canine of the
second or permanent dentition of modern man.]
[Illustration: 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.[12]
[12] 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.
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 floor--an immense lapse
of time, amounting probably to millions of years! 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 latest or as early 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 series--derived from a common ancestry--is 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.[13]
[13] But see foot-note on p. 284.
[Illustration: 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 at
Piltdown.]
[Illustration: 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.]