Geological Evidences of the Antiquity of Man/Chapter 24
BEARING OF THE DOCTRINE OF TRANSMUTATION ON THE ORIGIN OF MAN, AND HIS PLACE IN THE CREATION.
WHETHER MAN CAN BE REGARDED AS AN EXCEPTION TO THE RULE IF THE DOCTRINE OF TRANSMUTATION BE EMBRACED FOR THE REST OF THE ANIMAL KINGDOM—ZOOLOGICAL RELATIONS OF MAN TO OTHER MAMMALIA—SYSTEMS OF CLASSIFICATION—TERM QUADRUMANOUS, WHY DECEPTIVE—WHETHER THE STRUCTURE OF THE HUMAN BRAIN ENTITLES MAN TO FORM A DISTINCT SUB-CLASS OF THE MAMMALIA—INTELLIGENCE OF THE LOWER ANIMALS COMPARED TO THE INTELLECT AND REASON OF MAN—GROUNDS ON WHICH MAN HAS BEEN REFERRED TO A DISTINCT KINGDOM OF NATURE—IMMATERIAL PRINCIPLE COMMON TO MAN AND ANIMALS—NON-DISCOVERY OF INTERMEDIATE LINKS AMONG FOSSIL ANTHROPOMORPHOUS SPECIES—HALLAM ON THE COMPOUND NATURE OF MAN, AND HIS PLACE IN THE CREATION—GREAT INEQUALITY OF MENTAL ENDOWMENT IN DIFFERENT HUMAN RACES AND INDIVIDUALS DEVELOPED BY VARIATION AND ORDINARY GENERATION—HOW FAR A CORRESPONDING DIVERGENCE IN PHYSICAL STRUCTURE MAY RESULT FROM THE WORKING OF THE SAME CAUSES—CONCLUDING REMARKS.
SOME of the opponents of transmutation, who are well versed in Natural History, admit that though that doctrine is untenable, it is not without its practical advantages as a 'useful working hypothesis,' often suggesting good experiments and observations, and aiding us to retain in the memory a multitude of facts respecting the geographical distribution of genera, and species, both of animals and plants, and the succession in time of organic remains, and many other phenomena which, but for such a theory, would be wholly without a common bond of relationship.
It is in fact conceded by many eminent zoologists and botanists, as before explained, that whatever may be the nature of the species-making power or law, its effects are of such a character as to imitate the results which variation, guided by natural selection, would produce, if only we could assume with certainty that there are no limits to the variability of species. But as the anti-transmutationists are persuaded that such limits do exist, they regard the hypothesis as simply a provisional one, and expect that it will one day be surperseded by another cognate theory, which will not require us to assume the former continuousness of the links which have connected the past and present states of the organic world, or the outgoing with the incoming species.
In like manner, many of those who hesitate to give in their full adhesion to the doctrine of progression, the other twin branch of the developement theory, and who even object to it, as frequently tending to retard the reception of new facts supposed to militate against opinions solely founded on negative evidence, are, nevertheless, agreed that on the whole it is of great service in guiding our speculations. Indeed, it cannot be denied that a theory which establishes a connection between the absence of all relics of vertebrata in the oldest fossiliferous rocks, and the presence of man's remains in the newest, which affords a more than plausible explanation of the successive appearance in strata of intermediate age of the fish, reptile, bird, and mammifer, has no ordinary claims to our favour as comprehending the largest number of positive and negative facts gathered from all parts of the globe, and extending over countless ages, that science has perhaps ever attempted to embrace in one grand generalisation.
But will not transmutation, if adopted, require us to include the human race in the same continuous series of developements, so that we must hold that man himself has been derived by an unbroken line of descent from some one of the inferior animals? We certainly cannot escape from such a conclusion without abandoning many of the weightiest arguments which have been urged in support of variation and natural selection, considered as the subordinate causes by which new types have been gradually introduced into the earth. Many of the gaps which separate the most nearly allied genera and orders of mammalia are, in a physical point of view, as wide as those which divide man from the mammalia most nearly akin to him, and the extent of his isolation, whether we regard his whole nature or simply his corporeal attributes, must be considered before we can discuss the bearing of transmutation upon his origin and place in the creation.
Systems of Classification.
In order to qualify ourselves to judge of the degree of affinity in physical organisation between Man and the lower animals, we cannot do better than study those systems of classification which have been proposed by the most eminent teachers of natural history. Of these an elaborate and faithful summary has recently been drawn up by the late Isidore Geoffrey St. Hilaire, which the reader will do well to consult.
He begins by passing in review numerous schemes of classification, each of them having some merit, and most of which have been invented with a view of assigning to Man a separate place in the system of Nature, as, for example, by dividing animals into rational and irrational, or the whole organic world into three kingdoms, the human, the animal, and the vegetable,—an arrangement defended on the ground that Man is raised as much by his intelligence above the animals as are these by their sensibility above plants. Admitting that these schemes are not unphilosophical, as duly recognising the double nature of Man (his moral and intellectual, as well as his physical attributes), Isidore G. St. Hilaire observes that little knowledge has been imparted by them. We have gained, he says, much more from those masters of the science who have not attempted any compromise between two distinct orders of ideas, the physical and psychological, and who have confined their attention strictly to Man's physical relation to the lower animals.
Linnæus led the way in this field of enquiry by comparing Man and the apes, in the same manner as he compared these last with the carnivores, ruminants, rodents, or any other division of warm-blooded quadrupeds. After several modifications of his original scheme, he ended by placing Man as one of the many genera in his order Primates, which embraced not only the apes and lemurs, but the bats also, as he found these last to be nearly allied to some of the lowest forms of the monkeys. But all modern naturalists, who retain the order Primates, agree to exclude from it the bats or cheiroptera; and most of them class Man as one of several families of the order Primates. In this, as in most systems of classification, the families of modern zoologists and botanists correspond with the genera of Linnæus.
Blumenbach, in 1779, proposed to deviate from this course, and to separate Man from the apes as an order apart, under the name of Bimana, or two-handed. In making this innovation he seems at first to have felt that it could not be justified without calling in psychological considerations to his aid, to strengthen those which were purely anatomical; for, in the earliest edition of his 'Manual of Natural History,' he defined Man to be 'animal rationale, loquens, erectum, bimanum,' whereas in later editions he restricted himself entirely to the two last characters, namely, the erect position and the two hands, or 'animal erectum, bimamun.'
The terms 'bimanous' and 'quadrumanous' had been already employed by Buffon, in 1766, but not applied in a strict zoological classification till so used by Blumenbach. Twelve years later, Cuvier adopted the same order Bimana for the human family, while the apes, monkeys, and lemurs constituted a separate order, called Quadrumana.
Respecting this last innovation, Isidore G. St. Hilaire asks, 'How could such a division stand, repudiated as it was by the anthropologists in the name of the moral and intellectual supremacy of Man; and by the zoologists, on the ground of its incompatibility with natural affinities and with the true principles of classification? Separated as a group of ordinal value, placed at the same distance from the ape as the latter from the carnivore, Man is at once too near and too distant from the higher mammalia;—too near if we take into account those elevated faculties, which, raising Man above all other organised beings, accord to him not only the first, but a separate place in the creation,—too far if we merely consider the organic affinities which unite him with the quadrumana; with the apes especially, which, in a purely physical point of view, approach Man more nearly than they do the lemurs.
'What, then, is this order of Bimana of Blumenbach and Cuvier? An impracticable compromise between two opposite and irreconcilable systems—between two orders of ideas which are clearly expressed in the language of natural history by these two words: the human kingdom and the human family. It is one of those would-be via media propositions which, once seen through, satisfy no one, precisely because they are intended to please everybody; half-truths, perhaps, but also half-falsehoods; for what, in science, is a half-truth but an error?'
Isidore G. St. Hilaire then proceeds to show how, in spite of the great authority of Blumenbach and Cuvier, a large proportion of modern zoologists of note have rejected the order Bimana, and have regarded Man simply as a family of one and the same order, Primates.
Term 'Quadrumanous,' why deceptive.
Even the term 'Quadrumanous' has lately been shown by Professor Huxley, in a lecture delivered by him in the spring of 1860–61, which I had the good fortune to hear, to have proved a fertile source of popular delusion, conveying ideas which the great anatomists Blumenbach and Cuvier never entertained themselves, namely, that in the so-called Quadrumana the extremities of the hind-limbs bear a real resemblance to the human hands, instead of corresponding anatomically with the human feet.
As this subject bears very directly on the question, how far Man is entitled, in a purely zoological classification, to rank as an order apart, I shall proceed to cite, in an abridged form, the words of the lecturer above alluded to.
'To gain,' he observes, 'a precise conception of the resemblances and differences of the hand and foot, and of the distinctive characters of each, we must look below the skin, and compare the bony framework and its motor apparatus in each.
'The foot of Man is distinguished from his hand by—
'1. The arrangement of the tarsal bones.
'2. By having a short flexor and a short extensor muscle of the digits.
'3. By possessing the muscle termed peronæus longus.
And if we desire to ascertain whether the terminal division of a limb in other animals is to be called a foot or a hand, it is by the presence or absence of these characters that we must be guided, and not by the mere proportions, and greater or lesser mobility of the great toe, which may vary indefinitely without any fundamental alteration in the structure of the foot. Keeping these considerations in mind, let us now turn to the limbs of the Gorilla. The terminal division of the fore-limb presents no difficulty—bone for bone, and muscle for muscle, are found to be arranged precisely as in Man, or with such minute differences as are found as varieties in Man. The Gorilla's hand is clumsier, heavier, and has a thumb somewhat shorter in proportion than that of Man; but no one has ever doubted its being a true hand.
'At first sight, the termination of the hind-limb of the Gorilla looks very hand-like, and as it is still more so in the lower apes, it is not wonderful that the appellation "Quadrumana," or four-handed creatures, adopted from the older anatomists by Blumenbach, and unfortunately rendered current by Cuvier, should have gained such wide acceptance as a name for the ape order. But the most cursory anatomical investigation at once proves, that the resemblance of the so-called "hind-hand" to a true hand is only skin deep, and that, in all essential respects, the hind-limb of the Gorilla is as truly terminated by a foot as that of Man. The tarsal bones, in all important circumstances of number, disposition, and form, resemble those of Man. The metatarsals and digits, on the other hand, are proportionally longer and more slender, while the great toe is not only proportionally shorter and weaker, but its metatarsal bone is united by a far more movable joint with the tarsus. At the same time, the foot is set more obliquely upon the leg than in Man.
'As to the muscles, there is a short flexor, a short extensor, and a peronæus longus, while the tendons of the long flexors of the great toe and of the other toes are united together and into an accessory fleshy bundle.
'The hind-limb of the Gorilla, therefore, ends in a true foot with a very movable great toe. It is a prehensile foot, if you will, but is in no sense a hand: it is a foot which differs from that of Man in no fundamental character, but in mere proportions—degree of mobility—and secondary arrangement of its parts.
'It must not be supposed, however, that because I speak of these differences as not fundamental, that I wish to underrate their value. They are important enough in their way, the structure of the foot being in strict correlation with that of the rest of the organism; but after all, regarded anatomically, the resemblances between the foot of Man and the foot of the Gorilla are far more striking and important than the differences.'
After dwelling on some points of anatomical detail, highly important, but for which I have not space here, the Professor continues:—'Throughout all these modifications, it must be recollected that the foot loses no one of its essential characters. Every monkey and lemur exhibits the characteristic arrangement of tarsal bones, possesses a short flexor and short extensor muscle, and a peronæus longus. Varied as the proportions and appearance of the organ may be, the terminal division of the hind-limb remains in plan and principle of construction a foot, and never in the least degree approaches a hand.' For these reasons, Professor Huxley rejects the term 'Quadrumana,' as leading to serious misconception, and regards Man as one of the families of the Primates. This method of classification he shows to be equally borne out by an appeal to another character on which so much reliance has always been placed in classification, as affording in the mammalia the most trustworthy indications of affinity, namely, the dentition.
'The number of teeth in the Gorilla and all the Old World monkeys except the lemurs is thirty-two, the same as in Man, and the general pattern of their crowns the same. But besides other distinctions, the canines in all but Man project in the upper or lower jaws almost like tusks. But all the American apes have four more teeth in their permanent set, or thirty-eight in all, so that they differ in this respect more from the Old World apes than do these last from Man.
If therefore, by reference to this character, we place Man in a separate order, we must make several orders for the apes, monkeys, and lemurs, and so, in regard to the structure of the hands and feet before alluded to, 'the Gorilla differs far more from some of the quadrumana than he differs from Man.' Indeed, Professor Huxley contends that there is more difference between the hand and foot of the Gorilla and those of the Orang, one of the anthropomorphous apes, than between those of the Gorilla and Man, for 'the thumb of the Orang differs by its shortness and by the absence of any special long flexor muscle from that of the Gorilla more than it differs from that of Man.' The carpus also of the Orang, like that of most lower apes, contains nine bones, while in the Gorilla, as in Man and the Chimpanzee, there are only eight.' Other characters are also given to show that the Orang's foot separates it more widely from the Gorilla than that of the Gorilla separates that ape from Man. In some of the lower apes, the divergence from the human type of hand and foot, as well as from those of the Gorilla, is still greater, as, for example, in the spider-monkey and marmoset.
If the muscles, viscera, or any other part of the animal fabric, including the brain, be compared, the results are declared to be similar.
Whether the Structure of the Human Brain entitles Man to Form a distinct Sub-class of the Mammalia.
When, in consequence of these and many other zoological considerations, the order Bimana had already been declared in 1856, by Isidore G. St. Hilaire, in his history of the science above quoted (p. 473), 'to have become obsolete,' even though sanctioned by the great names of Blumenbach and Cuvier, the reader may imagine the surprise excited in the scientific world when Professor Owen announced, in the year following the publication of G. St. Hilaire's work, that he had been led by purely anatomical considerations to separate Man from the other Primates and from the mammalia generally as a distinct sub-class, thus departing farther from the classification of Blumenbach and Cuvier than they had ventured to do from that of Linnæus.
The proposed innovation was based chiefly on three cerebral characters belonging, it was alleged, exclusively to Man, and thus described in the following passages of a memoir communicated to the Linnæan Society in 1857, in which all the mammalia were divided, according to the structure of the brain, into four sub-classes, represented by the kangaroo, the beaver, the ape, and Man, respectively:—
'In Man, the brain presents an ascensive step in developement, higher and more strongly marked than that by which the preceding sub-class was distinguished from the one below it. Not only do the cerebral hemispheres overlap the olfactory lobes and cerebellum, but they extend in advance of the one and farther back than the other. Their posterior developement is so marked, that anatomists have assigned to that part the character of a third lobe; it is peculiar to the genus Homo, and equally peculiar is the "posterior horn of the lateral ventricle" and the "hippocampus minor" which characterises the hind-lobe of each hemisphere. The superficial grey matter of the cerebrum, through the number and depth of its convolutions, attains its maximum of extent in Man.
'Peculiar mental powers are associated with this highest form of brain, and their consequences wonderfully illustrate the value of the cerebral character; according to my estimate of which, I am led to regard the genus Homo as not merely a representative of a distinct order, but of a distinct sub-class of the mammalia, for which I propose the name of "Archencephala."'
The above definition is accompanied in the same memoir by the following note:—'Not being able to appreciate, or conceive, of the distinction between the psychical phenomena of a chimpanzee and of a Boschisman, or of an Aztec with arrested brain-growth, as being of a nature so essential as to preclude a comparison between them, or as being other than a difference of degree, I cannot shut my eyes to the significance of that all-pervading similitude of structure—every tooth, every bone, strictly homologous—which makes the determination of the difference between Homo and Pithecus the anatomist's difficulty; and therefore, with every respect for the author of the "Records of Creation," I follow Linnæus and Cuvier in regarding mankind as a legitimate subject of zoological comparison and classification.'
To illustrate the difference between the human and Simian brain, Professor Owen gave figures of the negro's brain as represented by Tiedemann, an original one of a South American monkey, Midas rufimanus, and one of the chimpanzee, fig. 54, p. 482, from a memoir published in 1849 by MM. Schroeder van der Kolk and M. Vrolik.
Upper surface of brain of Chimpanzee, distorted (from Schroeder van der Kolk and Vrolik).
a. Left cerebral hemisphere.
Side view of same (from Schroeder van der Kolk and Vrolik), showing at e the extension of the displaced cerebellum beyond the cerebrum at d.
Correct side view of Chimpanzee's brain (from Gratiolet), showing the backward extension of the cerebrum at d, beyond the cerebellum at e.
f f. Fissure of Sylvius.
Correct view of upper surface of Chimpanzee's brain (from Gratiolet), in which the cerebrum covers and conceals the cerebellum.
Side view of human brain (from Gratiolet), namely, that of the bush-woman called the Hottentot Venus.
a. Left cerebral hemisphere.
Scale of the five figures, from 54 to 58, half the diameter of the natural size.
The selection of the last-mentioned figure was most unfortunate, for three years before, M. Gratiolet, the highest authority in cerebral anatomy of our age, had, in his splendid work on 'The Convolutions of the Brain in Man and the Primates' (Paris, 1854), pointed out that, though this engraving faithfully expressed the cerebral foldings as seen on the surface, it gave a very false idea of the relative position of the several parts of the brain, which, as very commonly happens in such preparations, had shrunk and greatly sunk down by their own weight.
Anticipating the serious mistakes which would arise from this inaccurate representation of the brain of the ape, published under the auspices of men so deserving of trust as the two above-named Dutch anatomists, M. Gratiolet thought it expedient, by way of warning to his readers, to repeat their incorrect figures (figs. 54 and 55, p. 482), and to place by the side of them two correct views (57, p. 483, and 56, p. 482) of the brain of the same ape. By reference to these illustrations, as well as to fig. 58, p. 483, the reader will see not only the contrast of the relative position of the cerebrum and cerebellum, as delineated in the natural as well as in the distorted state, but also the remarkable general correspondence between the chimpanzee brain and that of the human subject in everything save in size. The human brain (fig. 58) here given, by Gratiolet, is that of an African bushwoman, called the Hottentot Venus, who was exhibited formerly in London, and who died in Paris.
Respecting this striking analogy of cerebral structure in Man and the apes, Gratiolet says, in the work above cited: 'The convoluted brain of Man and the smooth brain of the marmoset resemble each other by the quadruple character of a rudimentary olfactory lobe, a posterior lobe completely covering the cerebellum, a well-defined fissure of Sylvius, (ff, fig. 56,) and lastly, a posterior horn in the lateral ventricle. These characters are not met with together, except in Man and the apes.'
In reference to the other figure of a monkey given by Professor Owen, namely, that of the Midas, one of the Marmosets, he states, in 1857 as he had done in 1837, that the posterior part of the cerebral hemispheres 'extends, as in most of the quadrumana, over the greater part of the cerebellum.' In 1859, in his Reade Lecture, delivered to the University of Cambridge, the only illustration which he gave of an ape's brain was a reproduction of that distorted one of the Dutch anatomists already cited (fig. 54, p. 482).
Two years later, Professor Huxley, in a memoir 'On the Zoological Relations of Man with the Lower Animals,' took occasion to refer to Gratiolet's warning, and to cite his criticism on the Dutch plates; but this reminder appears to have been overlooked by Professor Owen, who six months later came out with a new paper on 'The Cerebral Character of Man and the Ape,' in which he repeated the incorrect representation of Schroeder van der Kolk and Vrolik, associating it with Tiedemann's figure of a negro's brain, expressly to show the relative and different extent to which the cerebellum is overlapped by the cerebrum in the two cases respectively. In the ape's brain as thus depicted, the portion of the cerebellum left uncovered is greater than in the lemurs, the lowest type of Primates, and almost as large as in the rodentia, or some of the lowest grades of the mammalia.
When the Dutch naturalists above mentioned found their figures so often appealed to as authority, by one the weight of whose opinion on such matters they well knew how to appreciate, they resolved to do their best towards preventing the public from being misled. Accordingly, they addressed to the Royal Academy of Amsterdam a memoir 'On the brain of an Orang-outang' which had just died in the Zoological Gardens of that city. The dissection of this ape, in 1861, fully bore out the general conclusions at which they had previously arrived in 1849, as to the existence both in the human and the simian brain of the three characters, which Professor Owen had represented as exclusively appertaining to Man, namely, the occipital or posterior lobe, the hippocampus minor, and the posterior cornu. These last two features consist of certain cavities and furrows in the posterior lobes, which are caused by the foldings of the brain, and are only visible when it is dissected. MM. Schroeder van der Kolk and Vrolik took this opportunity of candidly confessing, that M. Grratiolet's comments on the defects of their two figures (figs. 54 and 55) were perfectly just, and they expressed regret that Professor Owen should have overstated the differences existing between the brain of Man and the Quadrumana, 'led astray, as they supposed, by his zeal to combat the Darwinian theory respecting the transformation of species,' a doctrine against which they themselves protested strongly, saying that it belongs to a class of speculations which are sure to be revived from time to time, and are always 'peculiarly seductive to young and sanguine minds.'
As the two memoirs before alluded to by us (p. 408), the one by Mr. Darwin on 'Natural Selection,' and the other by Mr. Wallace 'On the Tendency of Varieties to depart indefinitely from the original Type,' did not appear till 1858, a year after Professor Owen's classification of the mammalia, and as Darwin's 'Origin of Species' was not published till another year had elapsed, we cannot accept the explanation above offered to us of the causes which led the founder of the sub-class Archencephala to seek for new points of distinction between the human and simian brains; but the Dutch anatomists may have fallen into this anachronism by having just read, in the paper by Professor Owen in the Annals, some prefatory allusions to 'the Vestiges of Creation, Natural Selection, and the question whether man be or be not a descendant of the ape.'
The number of original and important memoirs to which this discussion on the cerebral relations of Man to the Primates has already given rise in less than five years, must render the controversy for ever memorable in the history of Comparative Anatomy.
In England alone, no less than fifteen genera of the Primates (the subjects having been almost all furnished by that admirable institution, the Zoological Gardens of London) have been anatomically examined, and they include nearly all the leading types of structure of the Old and New World apes and monkeys, from the most anthropoid form to that farthest removed from Man; in other words, from the Chimpanzee to the Lemur. These are—
Ateles (Spider Monkey).
Cebus (Capuchin Monkey).
In July, 1861, Mr. Marshall, in a paper on the brain of a young Chimpanzee, which he had dissected immediately after its death, gave a series of photographic drawings, showing that when the parts are all in a fresh state, the posterior lobe of the cerebrum, instead of simply covering the cerebellum, is prolonged backwards beyond it even to a greater extent than in Gratiolet's figure, 56, p. 482, and, what is more in point, in a greater degree relatively speaking (at least in the young state of the animal) than in Man. In fact, 'the projection is to the extent of about one-ninth of the total length of the cerebrum, whereas the average excess of overlapping is only one-eleventh in the human brain.'
The same author gives an instructive account of the manner in which displacement and distortion take place when such brains are preserved in spirits as in the ordinary preparations of the anatomist.
Mr. Flower, in a recent paper on the posterior lobe of the cerebrum in the Quadrumana, remarks, that although Tiedemann had declared himself unable in 1821 to detect the hippocampus minor or the posterior cornu of the lateral ventricle in the brain of a Macacus dissected by him, Cuvier, nevertheless, mentions the latter as characteristic of Man and the apes, and M. Serres, in his well-known work on the brain in 1826, has shown in at least four species of apes the presence of both the hippocampus minor and the posterior cornu.
Tiedemann had expressly stated that 'the third or hinder lobe in the ape covered the cerebellum as in Man,' and as to his negative evidence in respect to the internal structure of that lobe, it can have no weight whatever against the positive proofs obtained to the contrary by a host of able observers. Even before Tiedemann's work was published, Kuhl had dissected, in 1820, the brain of the spider-monkey (Ateles beelzebuth), and had given a figure of a long posterior cornu to the lateral ventricle, which he had described as such.
The general results arrived at by the English anatomists already cited, and by Professor Rolleston in various papers on the same subject, have thus been briefly stated by Professor Huxley:—
'Every lemur which has yet been examined has its cerebellum partially uncovered, its posterior lobe with the contained posterior cornu and hippocampus minor more or less rudimentary. Every marmoset, American monkey, Old World monkey, baboon or man-like ape, on the contrary, has its cerebellum entirely covered, a large posterior cornu, and a well-developed hippocampus minor.
'In many of these creatures, such as the Saimiri (Chrysothrix), the cerebral lobes overlap and extend much farther behind the cerebellum in proportion than they do in Man.'
It is by no means pretended that these conclusions of British observers as to the affinity in cerebral structure of Man and the Primates, are new, but, on the contrary, that they confirm the inductions previously made by the principal continental teachers of the last and present generations, such as Tiedemann, Cuvier, Serres, Leuret, Wagner, Schroeder van der Kolk, Vrolik, Gratiolet, and others.
At a late meeting of the British Association (1862), Professor Owen read a paper 'On the brain and limb characters of the Gorilla as contrasted with those of Man,' in which, without alluding to the disclaimer by the Dutch anatomists of their defective plates, now so widely circulated in England, he observes, that in the gorilla the cerebrum 'extends over the cerebellum, not beyond it.' This statement, although slightly at variance with one published the year before (1861) by Professor Huxley, who maintains that it does project beyond, is interesting as correcting the description of the same brain given by Professor Owen in that year, in a lecture to the Royal Institution, in which a considerable part of the cerebellum of the gorilla was represented as uncovered. In the same memoir, it is remarked, that in the Maimon Baboon the cerebrum not only covers but 'extends backwards even beyond the cerebellum.' This baboon, therefore, possesses a posterior lobe, according to every description yet given of such a lobe, including a new definition of the same lately proposed by Professor Owen. For the posterior lobe was formerly considered to be that part of the cerebrum which covers the cerebellum, whereas Professor Owen defines it as that part which covers the posterior third of the cerebellum, and extends beyond it.
We may, therefore, consider the attempt to distinguish the brain of Man from that of the ape on the ground of newly-discovered cerebral characters, presenting differences in kind, as virtually abandoned by its originator, and if the sub-class Archencephala is to be retained, it must depend on differences in degree, as, for example, the vast increase of the brain in Man, as compared with that of the highest ape, 'in absolute size, and the still greater superiority in relative size to the bulk and weight of the body.'
If we ask why this character, though well known to Cuvier and other great anatomists before our time, was not considered by them to entitle Man, physically considered, to claim a more distinct place in the group called Primates, than that of a separate order, or, according to others, a separate genus or family only, we shall find the answer thus concisely stated by Professor Huxley in his new work, before cited:—
'So far as I am aware, no human cranium belonging to an adult man has yet been observed with a less cubical capacity than 62 cubic inches, the smallest cranium observed in any race of men, by Morton, measuring 63 cubic inches; while on the other hand, the most capacious gorilla skull yet measured has a content of not more than 341 cubic inches. Let us assume, for simplicity's sake, that the lowest man's skull has twice the capacity of the highest gorilla's. No doubt this is a very striking difference, but it loses much of its apparent, systematic value, when viewed by the light of certain other equally indubitable facts respecting cranial capacities.
'The first of these is, that the difference in the volume of the cranial cavity of different races of mankind is far greater, absolutely, than that between the lowest man and the highest ape while, relatively, it is about the same; for the largest human skull measured by Morton contained 114 cubic inches, that is to say, had very nearly double the capacity of the smallest, while its absolute preponderance of over 50 cubic inches is far greater than that by which the lowest adult male human cranium surpasses the largest of the gorillas (62 – 321 = 271). Secondly, the adult crania of gorillas which have as yet been measured, differ among themselves by nearly one-third, the maximum capacity being 34·5 cubic inches, the minimum 24 cubic inches; and, thirdly, after making all due allowance for difference of size, the cranial capacities of some of the lower apes fall nearly as much, relatively, below those of the higher apes, as the latter fall below man.'
Are we then to conclude, that differences in mental power have no intimate connection with the comparative volume of the brain? We cannot draw such an inference, because the highest and most civilised races of Man exceed in the average of their cranial capacity the lowest races, the European brain, for example, being larger than that of the negro, and somewhat more convoluted and less symmetrical, and those apes, on the other hand, which approach nearest to Man in the form and volume of their brain being more intelligent than the Lemurs, or still lower divisions of the mammalia, such as the Rodents and Marsupials, which have smaller brains. But the extraordinary intelligence of the elephant and dog, so far exceeding that of the larger part of the Quadrumana, although their brains are of a type much more remote from the human, may serve to convince us how far we are as yet from understanding the real nature of the dependence of intellectual superiority on cerebral structure.
Professor Rolleston, in reference to this subject, remarks, that 'even if it were to be proved that the differences between Man's brain and that of the ape's are differences entirely of quantity, there is no reason, in the nature of things, why so many and such weighty differences in degree should not amount to a difference in kind.
'Differences of degree and differences of kind are, it is true, mutually exclusive terms in the language of the schools; but whether they are so also in the laboratory of Nature, we may very well doubt.'
The same physiologist suggests, that as there is considerable plasticity in the human frame, not only in youth and during growth, but even in the adult, we ought not always to take for granted, as some advocates of the developement theory seem to do, that each advance in psychical power depends on an improvement in bodily structure, for why may not the soul, or the higher intellectual and moral faculties, play the first instead of the second part in a progressive scheme?
Intelligence of the lower Animals compared to that of Man.
Ever since the days of Leibnitz, metaphysicians who have attempted to draw a line of demarcation between the intelligence of the lower animals and that of Man, or between instinct and reason, have experienced difficulties analogous to those which the modern anatomist encounters when he tries to distinguish the brain of an ape from that of Man by some characters more marked than those of mere size and weight, which vary so much in individuals of the same species, whether simian or human.
Professor Agassiz, after declaring that as yet we scarcely possess the most elementary information requisite for a scientific comparison of the instincts and faculties of animals with those of Man, confesses that he cannot say in what the mental faculties of a child differ from those of a young chimpanzee. He also observes, that 'the range of the passions of animals is as extensive as that of the human mind, and I am at a loss to perceive a difference of kind between them, however much they may differ in degree, and in the manner in which they are expressed. The gradations of the moral faculties among the higher animals and Man are, moreover, so imperceptible, that to deny to the first a certain sense of responsibility and consciousness, would certainly be an exaggeration of the difference between animals and Man. There exists, besides, as much individuality within their respective capabilities among animals as among Man, as every sportsman, or every keeper of menageries, or every farmer and shepherd can testify, who has had a large experience with wild, or tamed, or domesticated animals. This argues strongly in favour of the existence in every animal of an immaterial principle, similar to that which, by its excellence and superior endowments, places Man so much above animals. Yet the principle exists unquestionably, and whether it be called soul, reason, or instinct, it presents, in the whole range of organised beings, a series of phenomena closely linked together, and upon it are based not only the higher manifestations of the mind, but the very permanence of the specific differences which characterise every organ. Most of the arguments of philosophy in favour of the immortality of Man apply equally to the permanency of this principle in other living beings.'
Professor Huxley, when commenting on a passage in Professor Owen's memoir, above cited (p. 481), argues that there is a unity in psychical as in physical plan among animated beings, and adds, that although he cannot go so far as to say that 'the determination of the difference between Homo and Pithecus is the anatomist's difficulty,' yet no impartial judge can doubt that the roots, as it were, of those great faculties which confer on Man his immeasurable superiority above all other animate things are traceable far down into the animate world. The dog, the cat, and the parrot, return love for our love, and hatred for our hatred. They are capable of shame and of sorrow, and, though they may have no logic nor conscious ratiocination, no one who has watched their ways can doubt that they possess that power of rational cerebration which evolves reasonable acts from the premises furnished by the senses—a process which takes fully as large a share as conscious reason in human activity.
Grounds for referring Man to a distinct Kingdom of Nature.
None of the authors above cited, while they admit so fully the analogy which exists between the faculties of Man and the inferior animals, are disposed to underrate the enormous gap which separates Man from the brutes, and if they scarcely allow him to be referable to a distinct order, and much less to a separate sub-class, on purely physical grounds, it does not follow that they would object to the reasoning of M. Quatrefages, who says, in his work on the Unity of the Human Species, that Man must form a kingdom by himself if once we permit his moral and intellectual endowments to have their due weight in classification.
As to his organisation, he observes, 'We find in the mammalia nearly absolute identity of anatomical structure, bone for bone, muscle for muscle, nerve for nerve—similar organs performing like functions. It is not by a vertical position on his feet, the os sublime of Ovid, which he shares with the penguin, nor by his mental faculties, which, though more developed, are fundamentally the same as those of animals, nor by his powers of perception, will, memory, and a certain amount of reason, nor by articulate speech, which he shares with birds and some mammalia, and by which they express ideas comprehended not only by individuals of their own species but often by Man, nor is it by the faculties of the heart, such as love and hatred, which are also shared by quadrupeds and birds, but it is by something completely foreign to the mere animal, and belonging exclusively to Man, that we must establish a separate kingdom for him (p. 21). distinguishing characters,' he goes on to say, 'are the abstract notion of good and evil, right and wrong, virtue and vice, or the moral faculty, and a belief in a world beyond ours, and in certain mysterious beings, or a Being of a higher nature than ours, whom we ought to fear or revere; in other words, the religious faculty.'—P. 23.
By these two attributes, the moral and the religious, not common to man and the brutes, M. Quatrefages proposes to distinguish the human from the animal kingdom.
But he omits to notice one essential character, which Dr. Sumner, the late Archbishop of Canterbury, brought out in strong relief fifty years ago in his 'Records of Creation.' 'There are writers,' he observes, 'who have taken an extraordinary pleasure in levelling the broad distinction which separates Man from the Brute Creation. Misled to a false conclusion by the infinite variety of Nature's productions, they have described a chain of existence connecting the vegetable with the animal world, and the different orders of animals one with another, so as to rise by an almost imperceptible gradation from the tribe of Simiæ to the lowest of the human race, and from these upwards to the most refined. But if a comparison were to be drawn, it should be taken, not from the upright form, which is by no means confined to mankind, nor even from the vague term reason, which cannot always be accurately separated from instinct, but from that power of progressive and improvable reason, which is Man's peculiar and exclusive endowment.
'It has been sometimes alleged, and may be founded on fact, that there is less difference between the highest brute animal and the lowest savage than between the savage and the most improved Man. But, in order to warrant the pretended analogy, it ought to be also true that this lowest savage is no more capable of improvement than the Chimpanzee or Orang-outang.
'Animals,' he adds, 'are born what they are intended to remain. Nature has bestowed upon them a certain rank, and limited the extent of their capacity by an impassible decree. Man she has empowered and obliged to become the artificer of his own rank in the scale of beings by the peculiar gift of improvable reason.'
We have seen that Professor Agassiz, in his Essay on Classification, above cited (p. 494), speaks of the existence in every animal of 'an immaterial principle similar to that which, by its excellence and superior endowments, places man so much above animals;' and he remarks, 'that most of the arguments of philosophy in favour of the immortality of man, apply equally to the permanency of this principle in other living beings.'
Although the author has no intention by this remark to impugn the truth of the great doctrine alluded to, it may be well to observe, that if some of the arguments in favour of a future state are applicable in common to man and the lower animals, they are by no means those which are the weightiest and most relied on. It is no doubt true that, in both, the identity of the individual outlasts many changes of form and structure which take place during the passage from the infant to the adult state, and from that to old age, and the loss again and again of every particle of matter which had entered previously into the composition of the body during its growth, and the substitution of new elements in their place, while the individual remains always the same, carries the analogy a step farther. But beyond this we cannot push the comparison. We cannot imagine this world to be a place of trial and moral discipline for any of the inferior animals, nor can any of them derive comfort and happiness from faith in a hereafter. To man alone is given this belief, so consonant to his reason, and so congenial to the religious sentiments implanted by nature in his soul, a doctrine which tends to raise him morally and intellectually in the scale of being, and the fruits of which are, therefore, most opposite in character to those which grow out of error and delusion.
The opponents of the theory of transmutation sometimes argue that, if there had been a passage by variation from the lower Primates to Man, the geologist ought ere this to have detected some fossil remains of the intermediate links of the chain. But what we have said respecting the absence of gradational forms between the recent and pliocene mammalia (p. 436), may serve to show the weakness in the present state of science of any argument based on such negative evidence, especially in the case of man, since we have not yet searched those pages of the great book of nature, in which alone we have any right to expect to find records of the missing links alluded to. The countries of the anthropomorphous apes are the tropical regions of Africa, and the islands of Borneo and Sumatra, lands which may be said to be quite unknown in reference to their pliocene and post-pliocene mammalia. Man is an old world type, and it is not in Brazil, the only equatorial region where ossiferous caverns have yet been explored, that the discovery, in a fossil state, of extinct forms allied to the human, could be looked for. Lund, a Danish naturalist, found in Brazil, not only extinct sloths and armadilloes, but extinct genera of fossil monkeys, but all of the American type, and, therefore, widely departing in their dentition and some other characters from the Primates of the old world.
At some future day, when many hundred species of extinct quadrumana may have been brought to light, the naturalist may speculate with advantage on this subject; at present we must be content to wait patiently, and not to allow our judgement respecting transmutation to be influenced by the want of evidence, which it would be contrary to analogy to look for in post-pliocene deposits in any districts, which as yet we have carefully examined. For, as we meet with extinct kangaroos and wombats in Australia, extinct llamas and sloths in South America, so in equatorial Africa, and in certain islands of the East Indian Archipelago, may we hope to meet hereafter with lost types of the anthropoid Primates, allied to the gorilla, chimpanzee, and orang-outang.
Europe, during the pliocene period, seems not to have enjoyed a climate fitting it to be the habitation of the quadrumanous mammalia; but we no sooner carry back our researches into miocene times, where plants and insects, like those of Oeninghen, and shells, like those of the faluns of the Loire, would imply a warmer temperature both of sea and land, than we begin to discover fossil apes and monkeys north of the Alps and Pyrenees. Among the few species already detected, two at least belong to the anthropomorphous class. One of these, the Dryopithecus of Lartet, a gibbon or long-armed ape, about equal to man in stature, was obtained in the year 1856 in the upper miocene strata at Sansan, near the foot of the Pyrenees in the South of France, and one bone of the same ape is reported to have been since procured from a deposit of corresponding age at Eppelsheim near Darmstadt, in a latitude answering to that of the southern counties of England. But according to the doctrine of progression it is not in these miocene strata, but in those of pliocene and post-pliocene date, in more equatorial regions, that there will be the greatest chance of discovering hereafter some species more highly organised than the gorilla and chimpanzee.
The only reputed fossil monkey of eocene date, namely, that found in 1840 at Kyson, in Suffolk, and so determined by Professor Owen, has recently been pronounced by the same anatomist, after reexamination, and when he had ampler materials at his command, to be a pachyderm.
M. Rütimeyer, however, an able osteologist, referred to in the earlier chapters of this work, has just announced the discovery in eocene strata, in the Swiss Jura, of a monkey allied to the lemurs, but as he has only obtained as yet a small fragment of a jaw with three molar teeth, we must wait for fuller information before we confidently rely on the claims of his Cœnopithecus lemuroides to take rank as one of the Primates.
Hallam on Man's place in the Creation.
Hallam, in his 'Literature of Europe,' after indulging in some profound reflections on 'the thoughts of Pascal,' and the theological dogmas of his school respecting the fallen nature of Man, thus speaks of Man's place in the creation:—'It might be wandering from the proper subject of these volumes if we were to pause, even shortly, to inquire whether, while the creation of a world so full of evil must ever remain the most inscrutable of mysteries, we might not be led some way in tracing the connexion of moral and physical evil in mankind, with his place in that creation, and especially, whether the law of continuity, which it has not pleased his Maker to break with respect to his bodily structure, and which binds that, in the unity of one great type, to the lower forms of animal life by the common conditions of nourishment, reproduction, and self-defence, has not rendered necessary both the physical appetites and the propensities which terminate in self; whether again, the superior endowments of his intellectual nature, his susceptibility of moral emotion, and of those disinterested affections which, if not exclusively, he far more intensely possesses than an inferior being—above all, the gifts of conscience and a capacity to know God, might not be expected, even beforehand, by their conflict with the animal passions, to produce some partial inconsistencies, some anomalies at least, which he could not himself explain in so compound a being. Every link in the long chain of creation does not pass by easy transition into the next. There are necessary chasms, and, as it were, leaps from one creature to another, which, though not exceptions to the law of continuity, are accommodations of it to a new series of being. If man was made in the image of God, he was also made in the image of an ape. The framework of the body of him who has weighed the stars and made the lightning his slave, approaches to that of a speechless brute, who wanders in the forests of Sumatra. Thus standing on the frontier land between animal and angelic natures, what wonder that he should partake of both!'
The law of continuity here spoken of, as not being violated by occasional exceptions, or by leaps from one creature to an other, is not the law of variation and natural selection above explained (Chap. XXI.), but that unity of plan supposed to exist in the Divine Mind, whether realised or not materially and in the visible creation, of which the 'links do not pass by an easy transition' the one into the other, at least as beheld by us.
Dr. Asa Gray, an eminent American botanist, to whom we are indebted for a philosophical essay of great merit on the Origin of Species by Variation and Natural Selection, has well observed, when speaking of the axiom of Leibnitz, 'Natura non agit saltatim,' that nature secures her ends, and makes her distinctions, on the whole, manifest and real, but without any important breaks or long leaps. 'We need not wonder that gradations between species and varieties should occur, or that genera and other groups should not be absolutely limited, though they are represented to be so in our systems. The classifications of the naturalist define abruptly where nature more or less blends. Our systems are nothing if not definite.'
The same writer reminds us that 'plants and animals are so different, that the difficulty of the ordinary observer would be to find points of comparison, whereas, with the naturalist, it is all the other way. All the broad differences vanish one by one as we approach the lower confines of the animal and vegetable kingdoms, and no absolute distinction whatever is now known between them.'
The author of an elaborate review of Darwin's 'Origin of Species,' himself an accomplished geologist, declares that if we embrace the doctrine of the 'continuous variation of all organic forms from the lowest to the highest, including man as the last link in the chain of being, there must have been a transition from the instinct of the brute to the noble mind of man; and in that case, 'where,' he 'asks,' are the missing links, and at what point of his progressive improvement did man acquire the spiritual part of his being, and become endowed with the awful attribute of immortality?'
Before we raise objections of this kind to a scientific hypothesis, it would be well to pause and enquire whether there are no analogous enigmas in the constitution of the world around us, some of which present even greater difficulties than that here stated. When we contemplate, for example, the many hundred millions of human beings who now people the earth, we behold thousands who are doomed to helpless imbecility, and we may trace an insensible gradation between them and the half-witted, and from these again to individuals of perfect understanding, so that tens of thousands must have existed in the course of ages, who in their moral and intellectual condition, have exhibited a passage from the irrational to the rational, or from the irresponsible to the responsible. Moreover it has recently been ascertained by the statistics of our metropolis, a city falling by no means below the average standard in regard to health, that one fourth of all the infants which are born, die before they are a month old; so that we may safely affirm that millions perish on the earth in every century, in the first few hours of their existence. To assign to such individuals their appropriate psychological place in the creation, is one of the unprofitable themes on which theologians and metaphysicians have expended much ingenious speculation.
The philosopher, without ignoring these difficulties, does not allow them to disturb his conviction that 'whatever is, is right,' nor do they check his hopes and aspirations in regard to the high destiny of his species; but he also feels that it is not for one who is so often confounded by the painful realities of the present, to test the probability of theories respecting the past, by their agreement or want of agreement with some ideal of a perfect universe which those who are opposed to his opinions may have pictured to themselves.
We may also demur to the assumption that the hypothesis of variation and natural selection obliges us to assume that there was an absolutely insensible passage from the highest intelligence of the inferior animals to the improvable reason of man. The birth of an individual of transcendent genius, of parents who have never displayed any intellectual capacity above the average standard of their age or race, is a phenomenon not to be lost sight of, when we are conjecturing whether the successive steps in advance, by which a progressive scheme has been developed, may not admit of occasional strides, constituting breaks in an otherwise continuous series of psychical changes.
The inventors of useful arts, the poets and prophets of the early stages of a nation's growth, the promulgators of new systems of religion, ethics, and philosophy, or of new codes of laws, have often been looked upon as messengers from Heaven, and after their death have had divine honours paid to them, while fabulous tales have been told of the prodigies which accompanied their birth. Nor can we wonder that such notions have prevailed when we consider what important revolutions in the moral and intellectual world such leading spirits have brought about; and when we reflect that mental as well as physical attributes are transmissible by inheritance, so that we may possibly discern in such leaps the origin of the superiority of certain races of mankind. In our own time the occasional appearance of such extraordinary mental powers may be attributed to atavism; but there must have been a beginning to the series of such rare and anomalous events. If, in conformity with the theory of progression, we believe mankind to have risen slowly from a rude and humble starting point, such leaps may have successively introduced not only higher and higher forms and grades of intellect, but at a much remoter period may have cleared at one bound the space which separated the highest stage of the unprogressive intelligence of the inferior animals from the first and lowest form of improvable reason manifested by man.
To say that such leaps constitute no interruption to the ordinary course of nature, is more than we are warranted in affirming. In the case of the occasional birth of an individual of superior genius, there is certainly no break in the regular genealogical succession; and when all the mists of mythological fiction are dispelled by historical criticism, when it is acknowledged that the earth did not tremble at the nativity of the gifted infant, and that the face of heaven was not full of fiery shapes, still a mighty mystery remains unexplained, and it is the order of the phenomena, and not their cause, which we are able to refer to the usual course of nature.
Dr. Asa Gray, in the excellent essay already cited (p. 502), has pointed out that there is no tendency in the doctrine of Variation and Natural Selection to weaken the foundations of Natural Theology; for, consistently with the derivative hypothesis of species, we may hold any of the popular views respecting the manner in which the changes of the natural world are brought about. We may imagine 'that events and operations in general go on in virtue simply of forces communicated at the first, and without any subsequent interference, or we may hold that now and then, and only now and then, there is a direct interposition of the Deity; or, lastly, we may suppose that all the changes are carried on by the immediate orderly and constant, however infinitely diversified, action of the intelligent, efficient Cause.' They who maintain that the origin of an individual, as well as the origin of a species or a genus, can be explained only by the direct action of the creative cause, may retain their favourite theory compatibly with the doctrine of transmutation.
Professor Agassiz, having observed that, 'while human thought is consecutive, divine thought is simultaneous,' Dr. Asa Gray has replied that, 'if divine thought is simultaneous, we have no right to affirm the same of divine action.'
The whole course of nature may be the material embodiment of a preconcerted arrangement; and if the succession of events be explained by transmutation, the perpetual adaptation of the organic world to new conditions leaves the argument in favour of design, and therefore of a designer, as valid as ever; 'for to do any work by an instrument must require, and therefore presuppose, the exertion rather of more than of less power, than to do it directly.'
As to the charge of materialism brought against all forms of the developement theory, Dr. Gray has done well to remind us that 'of the two great minds of the seventeenth century, Newton and Leibnitz, both profoundly religious as well as philosophical, one produced the theory of gravitation, the other objected to that theory, that it was subversive of natural religion.'
It may be said that, so far from having a materialistic tendency, the supposed introduction into the earth at successive geological periods of life,—sensation,—instinct,—the intelligence of the higher mammalia bordering on reason,—and lastly the improvable reason of Man himself, presents us with a picture of the ever-increasing dominion of mind over matter.
- Histoire Naturale Générale des Règnes organiques. Paris, vol. ii. 1856.
- Professor Huxley's third lecture 'On the Motor Organs of Man compared with those of other Animals,' delivered in the Royal School of Mines, in Jermyn Street (March 1861), has been embodied with the rest of the course in his forthcoming work, entitled, 'Evidence as to Man's Place in Nature.' Williams & Norgate, London.
- Professor Huxley, ibid.
- Huxley, ibid. p. 29.
- Owen, Proceedings of the Linnæan Society, London, vol. viii. p. 20.
- The late Archbishop of Canterbury, Dr. Sumner.
- Comptes rendus de l'Académie Royale des Sciences, vol. xiii. Amsterdam.
- Gratiolet's words are: 'Les plis cérébraux du chimpanzé y sont fort bien étudiés, malheureusement le cerveau qui leur a servi de modèle était profondément affaissé, aussi la forme générale du cerveau est-elle rendue, dans leurs planches, d'une manière tout-à-fait fausse.' Ibid. p. 18.
- Gratiolet, ibid. Avant-propos, p. 2, 1854.
- Proceedings of the Linnæan Society, 1857, p. 18, and Philosophical Transactions, 1837, p. 93.
- Huxley, Natural History Review, January 7, 1861, p. 76.
- Annals and Magazine of Natural History, vol. vii. p. 456, and Pl. XX., June 1861.
- This paper is reprinted in the original French, in the Natural History Review for January 1862, vol. ii. p. 111.
- Ibid. p. 114.
- Rolleston, Natural History Review, April 1861. Huxley, on Brain of Ateles, Zoological Proceedings, June 1861. Flower, Posterior Lobe in Quadrumana, &c. (Philosophical Transactions, 1862.) Id. on Javan Loris (Proceedings of the Zoological Society, 1862). Id. on Anatomy of Pithecia (ibid. December 1862).
- Natural History Review, July 1861, by John Marshall, F.R.S., Surgeon to University College Hospital. See also on this subject Professor Rolleston on the slight degree of backward extension of the cerebrum in some races of Man. Medical Times, October 1862, p. 419.
- Philosophical Transactions, 1862, p. 185.
- Tiedemann, Icones cerebri Simiarum, &c., p. 48.
- Beiträge zur Zoologie, &c., Frankfurt am Main, 1820.
- Medical Times and Gazette, October 1862, p. 373.
- Athenæum Journal Report of Royal Institution, Lecture, March 23, 1861, and reference to it by Professor Owen as to Gorilla, ibid. March 30, p. 434.
- For Report of Professor Owen's Cambridge British Association Paper, see Medical Times, October 11, 1862, p. 373.
- Annals, ibid. p. 457.
- Owen, ibid. p. 373.
- Huxley, On the Relation of Man to the rest of the Animal Kingdom. London, 1863.
- Report of a Lecture delivered at the Royal Institution, by Professor George Rolleston, On the Brain of Man and Animals. Medical Gazette, March 15, 1862, p. 262.
- Contributions to the Natural History of the United States of North America, vol. i. part i. pp. 60, 64.
- Natural History Review, No. 1, p. 68, January 1861.
- Records of Creation, vol. ii. chap. ii. 2nd ed. 1816.
- See above, p. 479.
- Owen, 'Geologist,' November 1862.
- Rütimeyer, 'Eocene Säugethiere,' &c. Zurich, 1862.
- Hallam, Introduction to the Literature of Europe, &c., vol. iv. p. 162.
- Natural Selection not inconsistent with Natural Theology, p. 55, by Dr. Asa Gray. Trübner & Co., London, 1861.
- Physical Theories of the Phenomena of Life, Frazer's Magazine, July 1860, p. 88.
- Asa Gray, ibid. p. 55.
- Ibid, p 31.