CHAPTER VI

HUMAN EVOLUTION IN THE LIGHT OF RECENT DISCOVERIES

In this, the concluding Chapter, account is taken of the bearing of the foregoing discoveries and discussions, in relation with the light which they throw on the story of human development.

A. Up to a certain point, the evidence is strikingly favourable to the hypothesis of human evolution. By this is meant the gradual development of the modern type of skeleton found in association with a large and active brain, capable of manifesting its activity in a great variety of ways. Most of the oldest human skeletons just described, differ from this type. Although a difference cannot be demonstrated in respect of cranial capacity, yet those older skeletons are usually distinguished by the heavier jaw and by stout curved limb-bones of such length as to indicate an almost dwarf stature. Still these indications, even though marking a more primitive status, point undeniably to human beings. Passing beyond these, a few fragments remain to suggest a still earlier stage in evolution. And with these at least we find ourselves definitely on the neutral ground between the territories of man and ape, though even here on the human side of that zone.

In the same way, and again up to a certain point, the characters of human implements confirm the inferences drawn from the skeleton. For the older implements are re-gressively more and more crude, and an increasing amount of skill is needed to distinguish artefact from natural object.

Again, the associated animals seem to become less familiar, and the percentage of extinct species increases the further we peer into the stages of the past.

One of the most remarkable researches ever published upon these subjects is due to a group of scientists associated with Professor Berry of Melbourne University. In this place, only the most important of their memoirs (1910) can be called in evidence. In those particular publications, the initial objective was an attempt to measure the degree of resemblance between different types of skull. That endeavour may be roughly illustrated by reference to Fig. 26, in which tracings of various skull-outlines are adjusted to a conventional base-line. Should a vertical line be drawn from the mid-point of the base-line so as to cut the several contours, the vertical distances between the successive curves could be measured. The distance separating Pithecanthropus (_P.E._ of the figure) from that of the corresponding curve for the Spy skull No. 1 (Spy 1 of the figure) is clearly less than the distance between the curves for the second Spy skull (Spy 2) and the Papuan native.

But Mr Cross used a much more delicate method, and arrived at results embodied in the figure (27) reproduced from his memoir. A most graphic demonstration of those results is provided in this chart. Yet it must be added, that the Galley Hill skull, although shewn in an intermediate position, should almost certainly be nearer the upper limit. This criticism is based upon the conviction that many of the measurements upon which the results are dependent, assign to the Galley Hill skull a lowlier status than it originally possessed before it became distorted (posthumously). Again the Pithecanthropus is apparently nearer to the Anthropoid Apes than to Mankind of to-day. Let it be noticed however that this is not necessarily in contradiction with the opinion expressed above (p. 128 line 2). For Mr Cross' diagram is based upon cranial measurements, whereas the characters of the thigh-bone of Pithecanthropus tend to raise it in the general scale of appreciation. On the whole then, the evolutionary hypothesis seems to receive support from three independent sources of evidence.

B. But if in one of the very earliest of those stages, a human form is discovered wherein the characters of the modern higher type are almost if not completely realised, the story of evolution thus set forth receives a tremendous blow. Such has been the effect of the discovery of the Galley Hill skeleton. Time after time its position has been called 'abnormal' or 'isolated,' because it provides so many contrasts with the skeletons found in deposits regarded perhaps as leading towards but admittedly more recent than the Galley Hill gravel. And the juncture is long past at which its exact relation to that gravel could be so demonstrated as to satisfy the demands raised in a connection so vital to an important theory.

Some authors of great experience have refused to recognise in evidence any claim made on behalf of the Galley Hill skeleton. Yet it is at least pardonable to consider some of the aspects of the situation created by its acceptance.

(i) For instance, the argument is reasonable, which urges that if men of the Galley Hill type preceded in point of time the men of the lower Neanderthal type, the ancestry of the former (Galley Hill) must be sought at a far earlier period than that represented by the Galley Hill gravels. As to this, it may be noted that the extension of the 'human period,' suggested by eoliths for which Pliocene, Miocene, and even Oligocene antiquity is claimed, will provide more than this argument demands. The suggestion that a flint-chipping precursor of Man existed in Miocene time was made as long ago as 1878 by Gaudry[48].

(ii) But if this be so, the significance of the Neanderthal type of skeleton is profoundly altered. It is no longer possible to claim only an 'ancestral' position for that type in its relation to modern men. It may be regarded as a degenerate form. Should it be regarded as such, a probability exists that it ultimately became extinct, so that we should not expect to identify its descendants through many succeeding stages. That it did become extinct is a view to which the present writer inclines. Attempts have been made to associate with it the aborigines of Australia. But an examination of the evidence will lead (it is believed) to the inference that the appeal to the characters of those aborigines is of an illustrative nature only. Difficulties of a similar kind prevent its recognition either in the Eskimo, or in certain European types, although advocates of such claims are neither absent nor obscure.

Again, it is well to enquire whether any other evidence of degeneration exists in association with the men of the Neanderthal type. The only other possible source is that provided by the implements. This is dangerous ground, but the opinion must be expressed that there is some reason to believe that Mousterian implements (which rather than any other mark the presence of the Neanderthal type of skeleton) do present forms breaking the sequence of implement-evolution. One has but to examine the material, to become impressed with the inferiority of workmanship displayed in some Mousterian implements to that of the earlier Acheulean types. In any case, a line of evidence is indicated here, which is not to be overlooked in such discussions.

(iii) The Galley Hill skeleton has been described as comparatively isolated. Yet if it be accepted as a genuine representative of Man in the age of the gravel-deposits of the high-level terrace, it helps towards an understanding of the characters of some other examples. Thus a number of specimens (rejected by many authors as lacking adequate evidence of such vast antiquity as is here postulated) appear now, in this new light, as so many sign-posts pointing to a greater antiquity of that higher type of human skeleton than is usually recognised. Above all (to mention but a few examples), the cranium of Engis, with those from S. Acheul (discovered in 1861 by Mr H. Duckworth), and Tilbury, the fragment of a human skull from gravel at Bury St Edmunds, and a skeleton discovered near Ipswich beneath the boulder-clay in October 1911, seem to find their claims enhanced by the admission of those proffered on behalf of the Galley Hill specimen. And since Huxley wrote his memoir on the skulls from Engis and the Neanderthal, the significance of the former (Engis), fortified by the characters of the Galley Hill skeleton, has been greatly increased. Consequently it is not surprising to find confident appeals to the characters of a Galley Hill Race or Stock, near associates being the specimens mentioned in a preceding chapter as Brünn (1891) and the Aurignac man next to be considered. The relations of these to the well-known Cro-Magnon type will be mentioned in the next paragraph.

C. The appearance of the higher type of humanity in the period next following the Mousterian, viz. that distinguished by the Aurignacian type of implement, has now to be discussed. As already remarked, the man of Aurignac, as compared with him of the Neanderthal, has less protruding jaws, the lower jaw in particular being provided with the rudiment of a chin, while the limb bones are slender and altogether of the modern type. Upon such contrasts a remarkable theory has been based by Professor Klaatsch[49]. He made a comparison between the anthropoid apes on the one hand, and the two human types on the other (Fig. 28). As a result, he pointed out that the Orang-utan differs from the Gorilla much as the Aurignac does from the Neanderthal man. Assuming this statement to be correct, a hypothesis is elaborated to the effect that two lines of human descent are here in evidence. Of these one includes an ancestor common to the Orang-utan (an Asiatic anthropoid ape) and the Aurignac man; the other is supposed to contain an ancestor common to the Gorilla (of African habitat), and the Neanderthal man.

The further development of the story includes the following propositions. The more primitive and Gorilla-like Neanderthal type is introduced into Europe as an invader from Africa. Then (at a subsequent epoch probably) an Asiatic invasion followed. The new-comers owning descent from an Orang-utan-like forerunner are represented by the Aurignac skeleton and its congeners. In various respects they represented a higher type not only in conformation but in other directions. Having mingled with the Neanderthal tribes, whether by way of conquest or pacific penetration, a hybrid type resulted. Such was the origin of the Cro-magnon race.

The hypothesis has been severely handled, by none more trenchantly than by Professor Keith[50]. A notable weakness is exposed in the attribution to the ancestors of the Orang-utan so close an association to any human ancestral forms, as Professor Klaatsch demands. To those familiar with the general anatomy of the Orang-utan (_i.e._ the anatomy of parts other than the skeleton) the difficulties are very apparent.

Another effect of the hypothesis is that the so-called Neanderthaloid resemblances of the aborigines of Australia are very largely if not entirely subverted. This would not matter so much, but for the very decided stress laid by Professor Klaatsch upon the significance of those resemblances (cf. Klaatsch, 1909, p. 579, 'Die Neanderthalrasse besitzt zahlreiche australoide Anklänge'). Again in earlier days, Professor Klaatsch supported a view whereby the Australian continent was claimed as the scene of initial stages in Man's evolution. Finally, up to the year 1908, Professor Klaatsch was amongst the foremost of those who demand absolute exclusion of the Orang-utan and the Gorilla from any participation in the scheme of human ancestry.

Having regard to such facts and to such oscillations of opinion, it is not surprising that this recent attempt to demonstrate a 'diphyletic' or 'polyphyletic' mode of human descent should fail to convince most of those competent to pronounce upon its merits.

Yet with all its defects, this attempt must not be ignored. Crude as the present demonstration may be, the possibility of its survival in a modified form should be taken into account. These reflections (but not necessarily the theory) may be supported in various ways. By a curious coincidence, Professor Keith, in rebutting the whole hypothesis, makes a statement not irrelevant in this connexion. For he opines that 'the characters which separate these two types of men (viz. the Aurignac and Neanderthal types) are exactly of the same character and of the same degree as separate a blood-horse from a shire-stallion.' Now some zoologists have paid special attention to such differences, when engaged in attempts to elucidate the ancestry of the modern types of horse. As a result of their studies, Professors Cossar Ewart and Osborn (and Professor Ridgeway's name should be added to theirs) agree that proofs have been obtained of the 'multiple nature of horse evolution' (Osborn). If we pass to other but allied animals, we may notice that coarser and finer types of Hipparion (_H. crassum_ and _H. gracile)_ have been contrasted with each other. A step further brings us to the Peat-hog problem (_Torf-Schwein Frage_ of German writers), and in the discussion of this the more leggy types of swine are contrasted with the more stocky forms. Owen (in 1846) relied on similar points for distinguishing the extinct species of Bovidae (Oxen) from one another. The contrast maybe extended even to the Proboscidea, for Dr Leith Adams believed that the surest test of the limb bones of _E. antiquus_ was their stoutness in comparison with those of _E. primigenius_. This is the very character relied upon by Professor Klaatsch in contrasting the corresponding parts of the human and ape skeletons concerned. But such analogies must not be pressed too far. They have been adduced only with a view to justifying the contention that the diphyletic scheme of Professor Klaatsch may yet be modified to such an extent as to receive support denied to it in its present form.

D. In commenting upon the hypothesis expounded by Professor Klaatsch, mention was made of its bearing upon the status of the Cro-Magnon race. This is but part of a wide subject, viz. the attempt to trace in descent certain modern European types. It is necessary to mention the elaborate series of memoirs now proceeding from the pen of Dr Schliz[51], who postulates four stocks at least as the parent forms of the mass of European populations of to-day. Of these four, the Neanderthal type is regarded as the most ancient. But it is not believed to have been extirpated. On the contrary its impress in modern Europe is still recognisable, veiled though it may be in combination with any of the remaining three. The latter are designated the Cro-Magnon, Engis, and Truchère-Grenelle types, the last-mentioned being broad-headed as contrasted with all the rest. Of Professor Schliz' work it is hard to express a final opinion, save that while its comprehensive scope (without excessive regard to craniometry as such) is a feature of great value, yet it appears to lack the force of criticism based upon extensive anatomical, _i.e._ osteological study.

E. The remarkable change in Professor Klaatsch's views on the part played by the anthropoid apes in human ancestral history has been already mentioned. In earlier days the Simiidae were literally set aside by Professor Klaatsch. But although the anthropoid monkeys have gained an adherent, they still find their claim to distinction most energetically combated by Professor Giuffrida-Ruggeri[52]. The latter declares that though he now (1911) repeats his views, it is but a repetition of such as he, following De Quatrefages, has long maintained. In this matter also, the last word will not be said for some time to come.

F. The significance of the peculiar characters of massiveness and cranial flattening as presented by the Neanderthal type of skeleton continues to stimulate research. In addition to the scattered remarks already made on these subjects, two recently-published views demand special notice.

(i) Professor Keith has (1911) been much impressed with the exuberance of bone-formation, and the parts it affects in the disease known as Acromegaly. The disease seems dependent upon an excessive activity of processes regulated by a glandular body in the floor of the brain-case (the pituitary gland). The suggestion is now advanced that a comparatively slight increase in activity might result in the production of such 'Neanderthaloid' characters as massive brow-ridges and limb bones. (Of existing races, some of the aborigines of Australia would appear to exemplify this process, but to a lesser degree than the extinct type, since the aboriginal limb bones are exempt.) Professor Keith adopts the view that the Neanderthal type is ancestral to the modern types. And his argument seems to run further to the following effect: that the evolution of the modern from the Neanderthal type of man was consequent on a change in the activity of the pituitary gland.

It is quite possible that the agency to be considered in the next paragraph, viz. climatic environment, may play a part in influencing pituitary and other secretions. But heavy-browed skulls (and heavy brows are distinctive tests of the glandular activity under discussion) are not confined to particular latitudes, so that there are preliminary difficulties to be overcome in the further investigation of this point. It is possible that the glandular activity occasionally assumed pathological intensity even in prehistoric times. Thus a human skull with Leontiasis ossea was discovered near Rheims at a depth of fifteen feet below the level of the surrounding surface.

(ii) Dr Sera[53] (1910) has been led to pay particular attention to the remarkably flattened cranial vaulting so often mentioned in the preceding paragraphs. As a rule, this flattening has been regarded as representative of a stage in the evolution of a highly-developed type of human skull from a more lowly, in fact a more simian one. This conclusion is challenged by Dr Sera. The position adopted is that a flattened skull need not in every case owe its presence to such a condition as an early stage in evolution assigns to it. Environment, for which we may here read climatic conditions, is a possible and alternative influence.

If sufficient evidence can be adduced to shew that the flattened cranial arc in the Neanderthal skull does actually owe its origin to physiological factors through which environment acts, the status of that type of skull in the evolutionary sequence will be materially affected. A successful issue of the investigation will necessitate a thorough revision of all the results of Professor Schwalbe's work[54], which established the Neanderthal type as a distinct species (_Homo primigenius_) followed closely and not preceded by a type represented by the Gibraltar skull. Dr Sera commenced with a very minute examination of the Gibraltar (Forbes Quarry) skull. In particular, the characters of the face and the basal parts of the cranium were subjected to numerous and well-considered tests. As a first result of the comparison of the parts common to both crania, Dr Sera believes that he is in a position to draw correct inferences for the Neanderthal skull-cap in regard to portions absent from it but present in the Forbes Quarry skull.

But in the second place, Dr Sera concludes that the characters in question reveal the fact that of the two, the Gibraltar skull is quite distinctly the lowlier form. And the very important opinion is expressed that the Gibraltar skull offers the real characters of a human being caught as it were in a lowly stage of evolution beyond which the Neanderthal skull together with all others of its class have already passed. The final extension of these arguments is also of remarkable import. The Gibraltar skull is flattened owing to its low place in evolution. But as regards the flatness of the brain-case (called the platycephalic character) of the Neanderthal calvaria and its congeners (as contrasted with the Gibraltar specimen), Dr Sera suggests dependence upon the particular environment created by glacial conditions. The effect is almost pathological, at least the boundary-line between such physiological flattening and that due to pathological processes is hard to draw. Upon this account therefore, Dr Sera's researches have been considered here in close association with the doctrines of Professor Keith.

Dr Sera supports his argument by an appeal to existing conditions: he claims demonstration of the association (regarded by him as one of cause and effect) between arctic latitudes or climate on the one hand, and the flattening of the cranial vault on the other. Passing lightly over the Eskimo, although they stand in glaring contradiction to his view, he instances above all the Ostiak tribe of hyperborean Asia. The platycephalic character has a geographical distribution. Thus the skull is well arched in Northern Australia, but towards the south, in South Australia and Tasmania, the aboriginal skull is much less arched. It is thus shewn to become more distinctly platycephalic towards the antarctic regions, or at least in the regions of the Australian Continent considered by Professor Penck to have been glaciated. So too among the Bush natives of South Africa as contrasted with less southern types.

The demonstration of a latitudinal distribution in the New World is complicated by the presence of the great Cordillera of the Rocky Mountains and Andes. Great altitudes are held by Dr Sera to possess close analogy with arctic or antarctic latitudes. Therefore the presence of flat heads (artificial deformation being excluded) in equatorial Venezuela is not surprising.

It is felt that the foregoing statement, though made with every endeavour to secure accuracy, gives but an imperfect idea of the extent of Dr Sera's work. Yet in this place, nothing beyond the briefest summary is permissible. By way of criticism, it cannot be too strongly urged that the Eskimo provide a head-form exactly the converse of that postulated by Dr Sera as the outcome of 'glacial conditions.' Not that Dr Sera ignores this difficulty, but he brushes it aside with treatment which is inadequate. Moreover, the presence of the Aurignac man with a comparatively well-arched skull, following him of the Mousterian period, is also a difficulty. For the climate did not become suddenly cold at the end of the Mousterian period, and so far as evidence of arctic human surroundings goes, the fauna did not become less arctic in the Aurignac phase.

_Conclusion._

In section A of this chapter, an outline was given of the mode in which the evolution of the human form appears to be traceable backwards through the Neanderthal type to still earlier stages in which the human characters are so elementary as to be recognisable only with difficulty.

Then (B) the considerations militating against unquestioning acquiescence in that view were grouped in sequence, commencing with the difficulties introduced by the acceptance (in all its significance) of the Galley Hill skeleton. From an entirely different point of view (C), it was shewn that many difficulties may be solved by the recognition of more than one primordial stock of human ancestors. Lastly (F) came the modifications of theory necessitated by appeals to the powerful influence of physiological factors, acting in some cases quite obscurely, in others having relation to climate and food.

The impossibility of summing up in favour of one comprehensive scheme will be acknowledged. More research is needed; the flatness of a cranial arc is but one of many characters awaiting research. At the present time a commencement is being made with regard to the shape and proportions of the cavity bounded by the skull. From such characters we may aspire to learn something of the brain which was once active within those walls. Yet to-day the researches of Professors Keith and Anthony provide little more than the outlines of a sketch to which the necessary details can only be added after protracted investigation.

It is tempting to look back to the time of the publication of Sir Charles Lyell's 'Antiquity of Man.' There we may find the author's vindication of his claims (made fifty years ago) for the greater antiquity of man. In comparison with that antiquity, Lyell believed the historical period 'would appear quite insignificant in duration.' As to the course of human evolution, it was possible even at that early date to quote Huxley's opinion 'that the primordial stock whence man has proceeded need no longer be sought ... in the newer tertiaries, but that they may be looked for in an epoch more distant from the age of the Elephas primigenius than that is from us.'

The human fossils at the disposal of those authors included the Neanderthal, the Engis, and the Denise bones. With the Neanderthal specimen we have (as already seen) to associate now a continually increasing number of examples. And (to mention the most recent discovery only) the Ipswich skeleton (p. 151) provides in its early surroundings a problem as hard to solve as those of the Engis skull and the 'fossil man of Denise.' But we have far more valuable evidence than Lyell and Huxley possessed, since the incomparable remains from Mauer and Trinil provide an interest as superior on the anatomical side as that claimed in Archaeology by the Sub-crag implements.

Turning once more to the subject of human remains, the evolution of educated opinion and the oscillations of the latter deserve a word of notice. For instance, in 1863, the Engis skull received its full and due share of attention. Then in a period marked by the discoveries at Spy and Trinil, the claims of the Engis fossil fell somewhat into abeyance. To-day we see them again and even more in evidence. So it has been with regard to details. At one period, the amount of brain contained within the skull of the Neanderthal man was underestimated. Then that opinion was exchanged for wonder at the disproportionately large amount of space provided for the brain in the man of La Chapelle. The tableau is changed again, and we think less of the Neanderthal type and of its lowly position (in evolutionary history). Our thoughts are turned to a much more extended period to be allotted to the evolution of the higher types. Adaptations to climatic influences, the possibilities of degeneracy, of varying degrees of physiological activity, of successful (though at first aberrant) mutations all demand attention in the present state of knowledge.

If progress since the foundations were laid by the giant workers of half a century ago appears slow and the advance negligible, let the extension of our recognition of such influences and possibilities be taken into account. The extraordinarily fruitful results of excavations during the last ten years may challenge comparison with those of any other period of similar duration.

APPENDIX

The forecast, made when the manuscript of the first impression of this little book was completed, and in reference to the rapid accumulation of evidence, has been justified.

While it would be impossible to provide a review of all the additional literature of the last few months, it is thought reasonable to append notes on two subjects mentioned previously only in the preface.

(A) A short account of the 'La Quina' skeleton has now appeared (in 'L'Anthropologie,' 1911, No. 6, p. 730).

The skull is of the form described so often above, as distinctive of the Neanderthaloid type, but the brow-ridges seem even more massive than in the other examples of that race. The cranial sutures are unclosed, so that the individual is shewn to be of mature age, or at any rate, not senile. The teeth are, however, much worn down. Nearly all the teeth have been preserved in situ, and they present certain features which have been observed in the teeth found in Jersey (S. Brélade's Cave).

The skeleton lay in a horizontal position, but no evidence of an interment has been adduced. The bones were less than a metre below the present surface, and in a fine mud-like deposit, apparently ancient, and of a river-bed type. Implements were also found, and are referred unhesitatingly to the same horizon as the bones. The Mousterian period is thus indicated, but no absolutely distinctive implements were found. The general stratigraphical conditions are considered to assign the deposit to the base of what is termed the 'inferior Mousterian' level.

(B) The 'sub-boulder-clay' skeleton, discovered near Ipswich in 1911, was in an extraordinarily contracted attitude. Many parts are absent or imperfect, owing to the solvent action of the surroundings, but what remains is sufficient to reveal several features of importance (cf. fig. 29).

Save in one respect, the skeleton is not essentially different from those of the existing representatives of humanity. The exception is provided by the shin-bone. That of the right limb has been preserved, and it presents an anomaly unique in degree, if not in kind, viz.: the substitution of a rounded for a sharp or keel-like edge to the front of the bone. It can hardly be other than an individual peculiarity, though the Spy tibia (No. 1) suggests (by its sectional contour) the same conformation.

So far as the skeleton is concerned, even having regard to the anomaly just mentioned, there is no good reason for assigning the Ipswich specimen to a separate racial type.

Its interest depends largely upon the circumstances of its surroundings. It was placed beneath about four feet of 'boulder-clay,' embedded partly in this and, to a much smaller extent, in the underlying middle-glacial sand which the bones just entered.

There is some evidence that the surface on which the bones lay was at one time exposed as an old 'land-surface.' A thin band of carbonised vegetable matter (not far beneath the bones) contains the remains of land plants. On this surface the individual whose remains have been preserved is supposed to have met with his end, and to have been overwhelmed in a sand drift. The latter it must be supposed was then removed, to be replaced by the boulder-clay.

Several alternatives to this rather problematical interpretation could be suggested. The most obvious of these is that we have to deal here with a neolithic interment, in a grave of which the floor just reached the middle-glacial sand of the locality. If we enquire what assumptions are requisite for the adoption of this particular alternative, we shall find, I think, that they are not very different in degree from those which are entailed by the supposition that the skeleton is really that of 'sub-boulder-clay' man.

The contracted attitude of the skeleton, and our familiarity of this as a feature of neolithic interments, taken together with the fact that the skeleton does not differ essentially from such as occur in interments of that antiquity, are points in favour of the neolithic age of the specimen. On the other hand, Mr Moir would urge that man certainly existed in an age previous to the deposition of the boulder-clay; that the implements discovered in that stratum support this claim; that the recent discovery of the bones of a mammoth on the same horizon (though not in the immediate vicinity) provides further support; that the state of mineralisation of the bones was the same in both cases, and that it is at least significant that they should be found on strata shewn (by other evidence) to have once formed a 'land-surface.'

On the whole then, the view adopted here is, that the onus of proof rests at present rather with those who, rejecting these claims to the greater antiquity of this skeleton, assign it to a far later date than that to which even the overlying Boulder-clay is referred. And, so far as the literature is at present available, the rejection does not seem to have been achieved with a convincing amount of certainty.

It is to be remarked, finally, that this discovery is entirely distinct from those made previously by Mr Moir in the deposits beneath the Red Crag of Suffolk, with which his name has become associated.

REFERENCES TO LITERATURE