“The Relation of Darwin to Anthropology”: A Previously Unpublished Lecture by Franz Boas (1909)

In 1909 Columbia University celebrated both the fifty-year anniversary of The Origin of Species and the centenary of the birth of its author with a series of lectures titled “Charles Darwin and His Influence on Science.” The first talk in the series, “Darwin’s Life and Work,” was delivered by Henry Fairfield Osborn on February 12, one hundred years to the day after Darwin’s birth.  Another lecturer was John Dewey, whose talk, “Darwinism and Modern Philosophy,” became the title piece in his well-known volume The Influence of Darwin on Philosophy and Other Essays in Contemporary Thought.[i] Despite the publication and wide circulation of these other lectures in the series, the one given by Franz Boas, “The Relation of Darwin to Anthropology,” was never published. Strangely, it was also never archived with his other unpublished lectures in the American Philosophical Society (APS), nor, apparently, was it ever noted anywhere except in the announcement of the lecture series in Science.[ii]

In late June 1996, while waiting for delivery of files from the Boas archive at the APS, I passed the time flipping through the library card catalogue under “Boas, Franz” and came across a plain, typed card, with the words: “Boas, Franz– The Relation of Darwin to Anthropology.” Surprised and intrigued, I asked librarian Roy Goodman if he could locate it.  He returned a few minutes later with a 33-page typed manuscript, with Boas’s additions and corrections in pen. It had been hiding– not quite in plain sight– for many years.

Boas clearly did not intend this to be a popular piece for a general audience. Rather, it was a serious and technical evaluation of Charles Darwin’s work as it related to anthropology in both the physical and psychological (“mental faculties”) realms.  He found much to agree with in Darwin’s writings, but some ideas Boas considered unproven or questionable: in particular, Darwin’s idea that some races and languages were less developed than others and that there was a single line of human evolution upon which all races and systems of thought might be arranged.[iii]

The important point for the history of anthropology and our understanding of Franz Boas is that this document shows how seriously Boas knew, understood, and grappled with the works of Charles Darwin, a fact that was not apparent before this lecture was rediscovered. The definitive word on this subject had been Stocking’s 1968 claim, “But if Boas was not a committed Lamarckian, neither was he Darwinian, save perhaps in the broadest sense” — an understandable notion in the absence of evidence to the contrary.[iv] I do not suppose that Boas would have wanted to be labeled a “Darwinian,” but with this lecture we can see the extent to which Boas knew, appreciated, and tried to come to terms with Darwin’s ideas in The Descent of Man.[v]

Years later, in his 1974 evaluation of Darwin’s influence on Boas, Stocking wrote of Boas’s 1904 address, “The History of Anthropology,” as “Boas’ own myth-history of anthropology, with what was to become the typically Boasian overemphasis on the impact of Darwinism” (22; emphasis added). I see something different in Boas’ statement about the “powerful influence” of Darwin. In one section of his 1904 talk, Boas clearly associated himself with Darwin’s “historical” approach to “the phenomena of nature,” both physical and mental, which he saw as revolutionary. Boas wrote that “[t]he idea that the phenomena of the present have developed from previous forms with which they are genetically connected and which determine them, shook the foundations of the old principles of classification.” On the other hand, Boas criticized the tendency of those who wrongly claimed Darwin’s mantle, misunderstanding the master by combining evolutionism with “an ill-concealed teleological tinge” as well as “a subjective valuation of the various phases of development, the present serving as a standard of comparison.”[vi] Thus, in his careful evaluation of the merits and excesses of Darwinism, Boas showed himself to be truer to the foundations of Darwin’s thought, as we have now come to recognize them, than the Victorian evolutionists.[vii]

Boas’s previously unpublished lecture, “The Relation of Darwin to Anthropology,” is presented below, and the scanned manuscript may be viewed, through the APS’s site, here.

[i] John Dewey, The Influence of Darwin on Philosophy, and Other Essays in Contemporary Thought (New York: Henry Holt and Company, 1910).

[ii] If a note about Boas’s lecture was published anywhere before its (re)discovery in 1996 it has not come to the author’s attention.

[iii] Gregory Radick, The Simian Tongue: The Long Debate about Animal Language (Chicago: University of Chicago Press, 2007).  In his conclusion, Radick discusses “The Relation of Darwin to Anthropology” (pp. 371-73), linking Boas’s stance to positions he soon staked out in The Mind of Primitive Man (New York: Macmillan, 1911) and to his ambivalence towards Galton– his opposition to eugenics, as well as his appreciation of statistical biometrics.

[iv] George W. Stocking, Race, Culture, and Evolution: Essays in the History of Anthropology (New York: Free Press, 1968), 184-185.

[v] Charles Darwin, The Descent of Man and Selection in Relation to Sex (London: John Murray, 1871). For a more sophisticated view of Boas and evolution see Alexander Lesser, “Franz Boas,” in Totems and Teachers: Perspectives on the History of Anthropology, ed. Sydel Silverman (New York: Columbia University Press, 1981), 1–23ff. Herbert S. Lewis, “Boas, Darwin, Science and Anthropology,” Current Anthropology 42, no. 03 (2001): 381–406 offers a fuller assessment of Boas’s connection to Darwinian thought, not wholly dependent on the finding of his 1909 lecture.

[vi] Franz Boas, “The History of Anthropology,” Science, New Series, Vol. 20, No. 512 (Oct. 21, 1904): 515.

[vii] Douglas, Cole, Franz Boas: The Early Years, 1858-1906 (Seattle: University of Washington Press, 1999): 125ff.

 

The Relation of Darwin to Anthropology

Lecture delivered in 1909 at Columbia University to commemorate the 50^th anniversary of the publication of The Origin of Species.

by Franz Boas

 

Modern anthropology has developed so recently that its beginnings may be said to have been laid during the end of the first half of the nineteenth century. Before this period anthropology was understood to deal with the metaphysical question of the relation of the mental life of man to the outer world. The great descriptive works of Prichard, Klemm, Waitz, not to mention others, may be said to mark the beginnings of anthropological science.

It is true that before this time much attention had been paid to the anatomical characteristics of the races of man and to their mutual relations, but the attempt to correlate all these phenomena under one general point of view had not been made before the year 1859.

Before the promulgation of Darwin’s theory, the biological discussion of the diversity of the human races was devoted almost entirely to the question of their monogenetic or polygenetic origin; in other words, to the question whether mankind consists of several species or of a single species; whether it may be derived from a single ancestral type and spread from a single centre, or whether a number of distinct ancestral types must be assumed which may have originated in a number of distinct centres. I mention only the extended monographs of Prichard, of Morton, and later those of Nott and Gliddon, which led their authors to diametrically opposed results. In these attempts at a zoological classification of mankind, the influence of Cuvier was felt no less than in the general development of zoology. Cuvier assumed that the human species developed after the last geological revolution, and expressed himself repeatedly to the effect that while possibly human remains antedating the last revolution might be found in some remote part of the world, they had not been found at the time when he wrote, and he consistently tried to explain away such finds as were brought to his notice. Thus it happened that the finds of Quaternary remains of man made between 1823 and 1834, and their elaborate description by Semmering had at the time no influence whatever upon the further development of anthropology.

The question of monogenetic and polygenetic origin was discussed with equal zeal in the psychological field; and I will mention here only the great work by Waitz, which appeared in 1859, and which was designed to establish the psychic unity of mankind. On the other side we find the extended investigations by Gobineau, who tried to prove the mental disparity of the races of man.

It will be seen, therefore, that the ideas propounded by Lamarck had had no influence upon the development of anthropology during the first half of the nineteenth century; but it may be well to quote here his ideas relating to the origin of man: “The characteristics which we use for defining man with his varieties as a family by itself are all the product of former changes, of his actions, and of the habits which he has developed, and which belong now only to the individuals of his species. Let us imagine the most perfect race of Quadrumana. If, compelled by circumstances or for some other reason, they should have lost the habit of climbing trees and of holding to the branches with their feet in the same way as with their hands, and if the individuals of this race through a series of generations had been forced to use their feet only for walking, and if they had ceased to use their hands like feet, there is no doubt that these Quadrumana would finally have been transformed into Bimana, and that the thumbs of their feet would have ceased to be separated from the fingers, since their feet would have served only for walking.”

While the attention of the early anthropologists was still directed to the attempt of differentiating and properly classifying the races of man, a number of discoveries were made which prepared the way for the new era which dates from the acceptance of the Darwinian theory. I have referred before to the finds made in France, Belgium, and western Germany, which seemed to prove the existence of man during the Quaternary period. It was, however, not until these investigations were taken up systematically and with great energy by Boucher de Perthes, and later on by Prestwich and Lyell, that their true significance was understood. The finds in the valley of the Somme and those made in Kent, the geological significance of which was fully discussed by Prestwich and Lyell, show conclusively that man, or at least a being using artificially-shaped tools, had existed in western Europe in the Quaternary period. Thus the time of existence of the human races was enormously extended.

At the same time the discussion of the development of the mental characteristics of man received a new stimulus by the publication of Spencer’s work in 1855, in which the first systematic attempt was made to consider the development of human civilization and of human institutions from a general evolutionary point of view.

Such were the conditions when Darwin published his “Origin of Species,” and although twelve more years elapsed before he published his work on “The Descent of Man,” the influence of his teachings began at once with the publication of his first great work. Nevertheless it was left to him to be the first to formulate clearly and succinctly the biological problem relating to the evolution of the human species. His book “The Descent of Man” created a sensation, and still it was merely a consistent application of his theories to the anatomical and mental characteristics of man. In a calm and succinct discussion of the homologous structures in man and the lower animals, the main points of their correspondence, the occurrence of rudimentary structures in man which are more fully developed in the animal series, and the data furnished by human embryology, were brought forward to show that man must have developed from some lower form.

Darwin summarizes his opinions regarding the manner of development of man in the following way: [“]As man at the present day is liable, like every other animal, to multiform individual differences or slight variations, so, no doubt, were the early progenitors of man, the variations being formerly induced by the same general causes and governed by the same general and complex laws as at present. As all animals tend to multiply beyond their means of subsistence, so it must have been with the progenitors of man; and this would inevitably lead to a struggle for existence and to natural selection. The latter process would be greatly aided by the inherited effects of the increased use of parts, and these two processes would incessantly re-act on each other. It appears also that various unimportant characters have been acquired by man through sexual selection. An unexplained residuum of change must be left to the assumed uniform action of those unknown agencies which occasionally induce strongly marked and abrupt deviations of structure in our domestic productions.” In other words, Darwin assumed natural selection, adaptation, sexual selection, and influences bringing about sudden variations or mutations, to be the main causes which brought about the development of man from a lower form.

Darwin anticipated the storm of indignation that the publication of his book was to release, and he wrote at the end of his book as follows: “The main conclusion arrived at in this work, namely, that man is descended from some lowly organized form will, I regret to think, be highly distasteful to many; but there can hardly be a doubt that we are descended from Barbarians. He who has seen a savage in his native land will not feel much shame if forced to acknowledge that the blood of some more humble creature flows in his veins. Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen instead of having been aboriginally placed there may give him hope for a still higher destiny in the distant future; but we are not here concerned with hopes or fears, only with the truth as far as our reason permits us to discover it, and I have given the evidence to the best of my ability. We must, however, acknowledge, as it seems to me, that man, with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men, but to the humblest living creature, with his God-like intellect, which has penetrated into the movements and constitution of the solar system,  with all these exalted powers, man still bears in his bodily frame the indelible stamp of his lowly origin.”

And again, at another place: “I am aware that the conclusions arrived at in this work will be denounced by some as highly irreligious; but he who denounces them is bound to show why it is more irreligious to explain the origin of man as a distinct species by a descent from some lower form through the laws of variation and natural selection, than to explain the birth of the individual through the laws of ordinary reproduction. The birth both of the species and of the individual are equally parts of that grand sequence of events which our minds refuse to accept as the result of blind chance. The understanding revolts at such a conclusion, whether or not we are able to believe that very slight variation of structure, the union of each pair in marriage, the dissemination of each seed, and other such events, have all been ordained for some special purpose.”

At the time when Darwin wrote, the evidence bearing upon the various points here quoted was very fragmentary; but the unceasing endeavors to find evidence supporting or invalidating his theories have led to a much better understanding of the problem.

The number of finds of human remains undoubtedly belonging to the early Quaternary were very small at the time when Darwin wrote; but extended investigations in the caves and river deposits of Europe and of other parts of the world have added considerably to our knowledge of the subject. We are now in a position to say that at the end of the last Glacial period a type of man existed in Europe, occupying the area of what is now France, Belgium, central Germany, and Bohemia, that differed considerably in appearance from any known race of the present. Man of this type was characterized by a low, receding forehead, although his skull was capacious, and his brain presumably nearly as large, if not quite as large, as that of the present races. The skull was low and long. His eyes were overshadowed by excessively heavy brows, such as do not occur in any modern race. His face was heavy, his jaws large, but his chin was undeveloped. The condition of the leg-bones indicates that his gait, while erect, was slouchy. This is suggested by the position of the surfaces of the knee-joints. It is excessively doubtful whether this type survives among the present races of man; but its biological relationship to the human species is so evident, that we must recognize in it an early representative of mankind.

Quite recently a new link has been added to the chain of types representing the human species. The famous remains of the Pithecanthropus erectus found in Java carry us back to very early Quaternary times, and seem to present a type resembling in certain respects the Quaternary type just described, but still lower in the scale. Intermediate between these two is a human jaw which has been found recently in southern Germany, the geological age of which is placed in the second Interglacial period before our present period.

The candid observer must therefore admit that one of the fundamental demands of Darwin has been substantiated; that types have been found in recent geological strata immediately preceding our own period which are closely related to modern man, but which have a number of characteristics that suggest a lower type of development. The evidence that has been accumulated during the last thirty years is so encouraging, that it seems fair to express the expectation that new forms which will fill missing gaps will be found in the future.

It is worth remarking that all the undoubted finds of this character have been made in the Old World, while the search for human remains of equal antiquity in North America has not produced any evidence which has withstood geological and anatomical criticism. The evidence in regard to the South American finds does not seem to be conclusive, and it would seem safest to suspend judgment in regard to the alleged occurrence of a predecessor of man in South America until more evidence is available.

Although no human remains have been found in the early Quaternary, we have ample evidence that a being using artificial tools existed at this period. The caves of Europe, the river-gravels of Europe and of some parts of Africa, are full of artificially-shaped stones, which can only be explained as objects used by a man-like being for striking, breaking, and cutting. It is also noticeable that the perfection of form of these implements increases as we ascend the geological horizons. The evidence is perfectly satisfactory that implements of this kind have been in use since the earliest Quaternary; that is to say, beginning at a time since when the fauna and flora of Europe have undergone several material changes, so that very few only of the animals contemporaneous with the implement using beings of those times have survived. During recent years the attempt has been made to prove that stones were used by a being living in the late Tertiary, in the Pliocene as well as in the Miocene; and some of the specimens thus interpreted give a considerable amount of plausibility to this theory. The inference therefore seems quite safe that a form resembling man, and presumably a predecessor of the later Quaternary man, must have existed at this time, although his bodily form is not known at present.

It is necessary to point out here that the advancement of culture at the close of the last Glacial period was considerable. The remains deposited during this time, and generally designated as “Magdalenian,” are characterized by the occurrence of remarkably well executed etchings representing the mammoth, the reindeer, and the horse, by paintings on the walls of caves, and by carefully executed carvings in ivory and bone. It is therefore obvious that the culture of this period is comparable to that of the more primitive tribes of later times.

No less powerful than the stimulus to archaeological investigation exerted by Darwin was his influence upon the discussion of the anatomical evidence of the development of man from lower forms. I will mention here the bold attempt made by Haeckel to reconstruct the whole phylogeny of man, and the more careful and painstaking investigations on rudimentary organs, on the variations in the occurrence of forms of muscles, bones, and other parts of the body and of their distribution among different races, and of the general question of the occurrence of theromorphic characteristics. Much new evidence has been accumulated, and there are at least one or two points which deserve particular mention because they have an immediate bearing upon Darwin’s own investigations.

One of the problems that concern us in the development of man relates to the changes which man undergoes owing to the change of the horizontal position of the vertebral column to the erect posture. In the quadrupeds the body is entirely supported by the extremities, and the vertebral column does not carry the weight of the whole body. In man, on the other hand, the weight of the whole trunk and head rests on the vertebral column, and consequently the weight supported by the lower vertebrae is much greater than that supported by the upper vertebrae. We find correspondingly that in man the size of the lower vertebrae is much greater than that of the upper vertebrae, while in the quadrupeds this difference is not so marked. We may therefore conclude that the increase of the size of the lower vertebrae is correlated to the development of the erect posture. Investigations of the various races of man have shown that the Australians show a much lesser differentiation in size of vertebrae than do the other races, and the inference has been drawn from this that the Australians represent an earlier type of man. This conclusion is supported by a number of other characteristics in the skeleton of that race. Thus the low nose and the small size of the brain are characteristics  which place the Australian lower in the scale than the Mongoloid or the European race.

Similar conditions are found in the foot of the Australian. The bones of the foot are shorter and more slender, and the relation of the big toe to the other toes resembles slightly more the relation of the thumb to the fingers than it does in other races. The ankle-joint and the bones of the leg below the knee are also of such character as may be explained by assuming the Australians to be less removed from the condition of a being which has just begun to walk in erect posture than those of other races.

These observations, however, cannot be directly interpreted as indicating a considerably lower position in the human series, because there are other traits in regard to which the Australians seem to deviate more from the higher animals than other races do. Thus, for instance, the length of the lower extremities, and the proportions of the body, differ more in the Australians from conditions found in the higher apes than these proportions do in any other human race.

On the whole, the principle of discussion which has been applied in recent years has been to assume that that race which shows the most generalized traits characteristic of mankind, and which has the greatest variability in those directions represented at the present time by the various races of man, is considered the oldest. In man, as well as in higher animals the most generalized traits are found in the female sex, and even more markedly in children; and consequently the assumption is made that form and proportions of the infantile body give the best clew relating to the early form of man.

It seems, however, necessary to observe that the results of this method of inquiry are not as satisfactory as might be desired, and misinterpretations based on these assumptions are difficult to avoid. For instance, it has been observed that in the Australian, Negro, and some of the Mongoloid types, and also in the earliest stages of development of all races, the human nose is very slightly developed, and that in the European it diverges most strongly from this type. From this observation the inference has been drawn that the nose of the European is most highly developed, while that of the Negro and of the Asiatic Mongols represents a lower type. On the other hand, the face during the early stages of life is exceedingly small. It develops most markedly among the Negro types, and to a much less extent among the Mongols, still less among the whites. Nevertheless we do not claim that the development of the Negro face represents a higher type, or even a more specialized type, for the reason that it has this strong facial development in common with the higher apes. Similar are the conditions of the brain-case. In the infant of all races the forehead is high and large as compared to the body. This condition is preserved most markedly among the Europeans, while among the Negroes and among the Australians the forehead becomes very much flatter, and the brain does not grow in the same proportion as among other races. The European, therefore, represents the earlier form. Nevertheless we are not tempted to characterize his traits as earlier in the animal scale, because the failure of the other parts of the body to grow in proportion to the brain is a characteristic of the higher types of animals. It is therefore obvious that in the discussion of the form of the nose and in that of the development of face and brain quite different principles of interpretation have been applied. Similar caution is necessary in the interpretation of other theromorphic traits. Thus we find that in certain groups of man the upper part of the occipital bone tends to form a separate bone, a feature which occurs commonly among certain lower mammals. Still it is doubtful in how far this may be considered as a reversion in an atavistic sense, or in how far it may be considered as due to local disturbing causes.

Setting aside these minor points, we find that much evidence has been accumulated which proves with a fair degree of certainty the close relationship between man and the higher apes of the Old World. Perhaps the most important point that has recently been brought forward is the establishment of the similarity of constitution of the blood of man and of the blood of the higher apes. The test to which I refer is based on the chemical relation of the blood of one animal to the blood of another animal closely related to it by descent, which is shown by chemical changes that take place when the serum of its blood is injected into the blood of the other animal. It is stated that these re-actions occur when the blood of man is made to re-act on the blood of the higher apes. It has even been claimed that by this and similar methods the degree of relationship between the various races of man can be established; but the experiments in question are so few in number, and so delicate, that I presume it will be safer to await further evidence.

While there is not by any means unanimity of opinion in regard to the actual line of descent of man, most anthropologists adhere to the opinion that the higher apes and man are direct descendants of an earlier form of ape, the specialized representatives of which in the present time are the modern apes and man. This supposed ancestral form, however, has not been found up to the present time. Other investigators are more inclined to assume that the common ancestor of the apes and man must be looked for on a much lower stage; but the similarities between the higher anthropoids and man are so great, that their descent from a form more nearly related to both seems to be more plausible.

During the last thirty years much evidence has been accumulated regard[ing] all these points, resulting in a firm establishment of the views relating to the line of descent of man, first expressed by Darwin, and in a considerable elaboration of the evidence on which his far-seeing conclusions were based.

The anatomical study of man, and archaeological investigation, have, however, failed to furnish any material that could be utilized to prove or disprove Darwin’s opinions relating to the manner in which man has developed from lower forms, and in which the different types of man originated from the same ancestral forms. In fact, so far as our knowledge of the distribution of human types during the last ten thousand years goes, the races of man, as well as his numerous sub-types, appear stable; and we are not in a position to show a single case of the transition of one type into another, however closely they are related. Neither can we give any proof that the civilization which had existed in Europe and in China at least for several thousand years has had any cumulative effect upon the organization of the human body. This stability of the recent human types seems particularly remarkable when we consider that, from a biological point of view, man must be considered in the same way we consider domesticated animals, the extreme degree of variability of which has been so elaborately discussed by Darwin.

The theories propounded by Darwin in his “Descent of Man” have led, however, to detailed studies of the effects of natural and sexual selection in other directions. It has been known, as early as 1860, that the physical proportions of different social strata of the same population show minute differences which can be discovered by metrical studies. These observations seemed likely to be the result of selection or adaptation, and thus it happened that under the impetus given by Darwin’s theory their study was taken up in detail. We are particularly indebted to Darwin’s eminent cousin, Francis Galton, for the development of this subject, the metrical study of man.

In this case also the beginnings of a new method of scientific inquiry were laid at an earlier time. The Belgian astronomer Quetelet was the first to describe the varieties of man by means of measurements, and to apply the metrical method of description to living beings. His whole object, however, was entirely distinct from the objects that Galton had in view in his investigation of the effects of selection in man and of the laws of heredity. Quetelet endeavored to establish, by the measurement of very large numbers of individuals, the ideal type to which man approached. He believed that the variations from this type were indications of imperfections due to unfavorable social causes. He expected that with the improvement of social conditions the variations would become less and less, and that the ideal type would be more and more clearly represented. Galton, on the other hand, took up Darwin’s idea of the necessary existence of variants, and tried to determine the influence of heredity in perpetuating variant types, and of selection in eliminating variants. He and his successors also took up the important question of sexual selection which was put forward by Darwin, and they endeavored to establish the tendency to assortive mating in man. The methods which have been developed by Galton, and under his influence by Karl Pearson and others, are so highly technical, and so intricate, that I must forego the attempt to outline this new development, which in recent years has been successfully extended over the whole domain of biology. The endeavor of the biometricians is to prove by quantitative methods the relative effects of heredity, of adaptation, of natural selection, and of sexual selection, with a view of determining the role that each of these processes plays in the history of life. It is perhaps too early to foretell the results of the statistical study of variation in man and animals, the methods of which are only beginning to be developed, and which, in combination with experimental, geographical, and sociological studies, seem to promise the most important results. We can, however, see even now that the statistical methods provide us with a most powerful means of proving or disproving biological theories. We must, however, not expect too much of these methods. The statistical treatment of biological phenomena must not be expected to furnish biological explanations. All we can do by its means is to formulate the biological problem clearly and concisely, and to formulate the conclusions to which a certain theory will lead.

The function of biometry in the study of biological problems may be compared to the function of mathematical physics in the study of physical phenomena. Experiment or observation gives the material on which a theory may be based. The theory, when carefully thought out and developed according to mathematical and statistical methods, will lead us to expect certain results, which may be verified by observation or experiment. An example may make this clearer. It is assumed by some authors that heredity acts in such a way that the descendants of a couple will tend to stand halfway between the two parents. On the other hand, a theory has been propounded according to which the descendants do not form an intermediate type, but resemble either father or mother. Each of these theories would of necessity lead to certain characteristic distributions of measurements among the offspring, and the theories may be verified by observation. In our particular case the biometric study has led to the conclusion that the one theory is correct in regard to certain traits, the other in regard to other traits.

The biometrical studies of man which have been carried on so far have proved that a slight amount of sexual selection occurs in each community. It has been shown that city life and country life exert an appreciable selective influence, which results in a differentiation of city population and country population. The occurrence of adaptive changes according to occupation have been proved to exist; in short, every one of the factors recognized by Darwin as influencing the development of the human species has been established as a potent factor in the modifications of the human forms. Whether or not the changes that have been observed are progressive and cumulative, cannot be stated at the present time.

It is not the object of my discussions to-day to take up in detail Darwin’s influence upon the development of psychology and of sociology; but it seems impossible to forego entirely a discussion of this subject in a presentation of Darwin’s influence upon the development of anthropology. Much of his book on “The Descent of Man” is devoted to the discussion of the development of the mental powers of man from those of animals; and he pays considerable attention to the difference between the mental capacity of the lower and that of the higher races of man. It seems to my mind exceedingly difficult to separate, in the development of these investigations, the influence of Darwin from that of Spencer, although Darwin’s attempt to apply his theory of natural selection to the development of the mental faculties sets off his attempts clearly from the general evolutionary scheme developed by Spencer.

It is not surprising that in the beginning, the argument for natural selection as a cause of evolution did not meet with as ready a response in the field of mental science as it did in the field of natural science. The prime endeavor of the naturalist must be the explanation of nature by giving sufficient reasons for the occurrence of observed phenomena. The great stumbling-block in the development of a consistent view of the world, based on causality alone, had been up to Darwin’s time the apparent purposeful form of organisms; and the convincing power of his argument, as has often been stated, lies in the fact that he was the first to show a satisfactory way by means of which forms [which] apparently are destined to serve a purpose may be explained as the resultants of purely causal action. In the domain of mental activity, where our inner consciousness makes us cognizant of purposeful action, an attempt to explain phenomena by purely causal relations is not so readily appreciated. Although the idea does not appear quite definitely expressed in Darwin’s discussion of the development of mental powers, it seems quite clear that his main object has been to express his conviction that the mental faculties developed essentially without a purposive end, but that they originated as variations, and were continued by natural selection. This idea was also brought out very clearly by Wallace, who emphasized that apparently reasonable activities of man might very well have developed without an actual application of reasoning. I think the difficulty of abstracting from the purposeful action of the human mind has brought it about that for a considerable time after the appearance of Darwin’s “Descent of Man” the attempts to explain the beliefs and customs of people have been more or less distinctly of a rationalistic character. We have to except from this the discussions of the development of ethics, which, ever since the publication of Darwin’s book, have taken the form of theories based on the survival of utilitarian activities and ideas. It is only lately that we recognize more and more clearly how little purposive reasoning has to do with the development of mental activities; that we begin to see how thoughts and customs develop without ever rising into the consciousness of man, and receive only later a purposive or rationalistic interpretation.

The correctness of the view that mental phenomena apparently based upon careful reasoning developed entirely automatically is nowhere as apparent as in human language. There is no language in the world the grammar of which does not show an elaborate system of logical classification of human experience. The distinction between abstract terms and concrete terms, between denominating terms and predicative terms, between self and not self, are at the foundation of all human speech. Still it is quite obvious that these notions, although they are in constant use, and although they determine the form in which thought finds expression, have never risen into the consciousness of the speakers, and consequently their origin cannot be explained by any conscious reasoning. They are there, and their development can be understood only in a manner analogous to the development of the functions of the human body. The same consideration may be made in regard to the gradual differentiation of human languages. The processes by which differentiation takes place are obviously entirely unconscious. The shifting of sounds, which is such an important feature in the growth of new dialects and in the modification of older forms,  where it is not due to outer influences, can be understood only either on the basis of the assumption of a considerable variability of sound and the survival of selected groups, or by assuming various types of assimilation of sounds.

While in the development of human action the unconsciousness of the processes is perfectly self-evident, it is not so in the development of other human activities and beliefs, which are almost always rationalistically explained. Nevertheless, much evidence has been gathered which tends to show that the religious beliefs and the customs of the peoples of the whole world originate unconsciously, but are later on given rationalistic interpretations. An example of ideas developing in this manner are most of the actions which are considered proper and becoming, in any particular social group, and which, on the whole, cannot be explained in their origin by any reason, for which, however, we are in the habit of giving explanations that, although invented to justify the acts, appear to us entirely adequate.

This whole domain of customs and beliefs had never been successfully investigated until the stimulus given by Darwin and Spencer made themselves felt.

The theories developed by Tylor and Lubbock are clearly due to the stimulus given by these two men. In the introduction to his work on primitive culture, Tylor apologizes in a way for not specifically mentioning Darwin and Spencer in the detailed discussion that follows, expressing, however, his feeling of obligation to the thoughts engendered by the far-reaching theories of these two men.

The important applications of Darwinian thought made by Lubbock and Tylor were contained in the proof that certain groups of customs occurring in all forms of society are analogous to the rudimentary organs occurring in organisms. A certain form of activity which has developed in a certain society does not disappear suddenly, but continues to exist. When, however, it is no longer in accordance with other activities and with the general form of life that develops in the community, it may become more and more formal, and lose many of those features which characterized it when it was more fully developed. These survivals are in the same way proofs of early stages through which society passed as rudimentary organs are evidences of the descent of life forms.

It is curious to note that the influence of Darwin and of Spencer led naturally to what might be called a monogenetic treatment of the development of mental activities. Unconsciously the line of thought underlying the theory of the development of animal forms was transferred to the development of types of culture. In the same way as the body of man must have developed from a lower form by gradual stages, and in the same way as the races of man must have differentiated from a primitive form, so the mental life of man was treated as having its germ in a very primitive social life, from which, by gradual stages, the present forms have developed. This led to the assumption that in all the modern and historically known forms of life, survivals may be found of the same primitive conditions, and that all human culture has passed through the same stages. This idea has taken such firm hold of the anthropological investigation of human culture, that certain peculiar traits in the mental life of man have long been overlooked. The significance of parallel developments in different groups, which is of importance for a clear understanding of the history of the animal series, is of infinitely greater importance in the mental life of man, and many of the traits that are apparently adequately interpreted by the theory of a single line of mental development for the whole human family may be better interpreted as due to parallel but independent mental development. Furthermore, it must be borne in mind that the conditions of mental life bring it about that forms of mental activity do not only become more surely differentiate[d], but that diverse forms may often combine. There is not only a divergent or parallel development, as in the animal world, but there is also a convergent development, which results in new currents, in which two lines may unite that have originally been widely separated.

But I must not allow myself to enter in detail into these subjects, which will be more fully and adequately dealt with by later speakers in this course. I hope I may have succeeded in presenting to you, however imperfectly, the currents of thought due to the work of the immortal Darwin which have helped to make anthropology what it is at the present time.