The Doctrine of Evolution Part 10

Before pa.s.sing to the next members of the series, which reveal additional principles more truly social in the human sense, let us pause to note that already we have found certain natural criteria that belong in the department of ethics. Even in the case of the biological unit like _Amoeba_, which is entirely solitary and unrelated to other individuals of its kind excepting in so far as it is a link in the chain of successive generations, any vital activity can be called good or bad, right or wrong.

Nature judges an act good and right if it tends to preserve the animal and the species; an act is wrong and evil if it is biologically destructive of the animal or if it interferes with the perpetuation of its kind. Again it must be pointed out that these terms are human words, employed for the complex conceptions that belong alone to retrospective and contemplative human consciousness to most of us they seem to imply the existence of some absolute standard or ideal by which a given act may be tested to see if it is right or the opposite.

If human ethics is truly unrelated to beginnings found in lower nature, something that has arisen by itself from supernature, then we must not use the terms in question except by way of a.n.a.logy. If, however, nature has been continuous in the working out of every department of human life and human thought through evolution, then the criteria of the righteousness of the acts performed even by an _Amoeba_ may be found to be basic and fundamental for ethical systems of whatever human race or time. This subject remains to be discussed in the final chapter, but it must be clear that we cannot survey the evolutionary process by which social systems have come into being without dealing at the same time with the origin and growth of ethical conduct as such.

Without leaving the group of one-celled animals typified by _Amoeba_, we find colonies of the most elementary biological nature, where other natural obligations are added to the two of greatest importance. Some species of the bell-animalcule, _Vorticella_, provide characteristic examples of these primitive compound protozoa. Here the a.s.semblage is made up of one-celled individuals essentially similar to one another in structure and in physiological activities; in the latter respect each one of them is like _Amoeba_ as well. They may remain together for a longer or shorter period, or during their whole existence until the time of reproduction. Like the solitary protozoon, each member leads a complete life in and by itself, equivalent to that of every biological unit. It obeys the two great laws already laid down, but in addition it seems to be required to remain with the others for some mutual good. The biological value of the a.s.sociation which imposes this additional obligation may be found perhaps in the fact that a large group is not so readily eaten by an enemy as an individual cell; but it is clearer that the process of reproduction, which consists of the fusion of small "gametes," or nucleated fragments produced by diverse or similar parents, must be greatly facilitated by the occurrence of gamete-forming individuals in one and the same colony. "_To remain together_" is the new duty imposed by nature for the good of all and for the welfare of each member of the group. Some biological advantage accrues to the several components, just as the banding of wolves enables the pack to accomplish something which the single wolf is unable to do, although in the latter case it is not so much a reproductive alliance that is formed as an offensive and defensive union.

One step higher in the scale stands the plant-form called _Volvox_, near the border-line between the one-celled and the many-celled organisms. This aquatic type, about the size of the head of an ordinary pin, is a hollow spherical colony, with a wall composed of closely set cellular components.

These elements are not all alike, as in the case of colonial protozoa like _Vorticella_, for they fall into two cla.s.ses which are distinguished by certain structural and functional characteristics. Most of them are simple feeding individuals which absorb nourishment for themselves primarily, but they pa.s.s on their surplus supplies to less favored neighbors if occasion demands. The other members begin life like the first-named, but later they become specialized to serve as reproductive individuals solely. Every member of the colony must obey the first precept of nature, otherwise it would be unable to play its part in the life of the whole community. But the discharge of the second natural obligation, namely to preserve the race, is here a.s.signed to some, and to some only, of the whole group of cell individuals. It follows therefore that the division of the tasks necessary for the maintenance of a complete biological individual, and the differentiation of the members of the group into two kinds, leads to the establishment of an individuality of a higher order than the cell. Neither the purely nutritive nor the reproducing member is complete in itself; the two kinds must be combined to make a perfect organism. The life of any member can be selfish no longer, for if it is to exist itself, it must help others for the mutual advantage of all. A clear social relation is thus established; and the reflex conduct of the units of a _Volvox_ colony can be justly denoted altruistic, even though in this case, as before, there can be no conscious recognition of the reasons why mutual interests are best served by what is actually done.

One of the most interesting and significant aspects of the life-history of _Volvox_ is the appearance for the first time of biological death. More elementary organisms are immortal potentially even if not actually, for every portion of the body is capable of pa.s.sing over into an animal of a succeeding generation. But in _Volvox_ a division of labor has been effected of such a nature that most of the components discharge the tasks of individual value, and with the performance of these they die. Only the reproductive members are immortal in the sense that _Amoeba_ is, for they only have a place in the chain of consecutive generations of _Volvox_ colonies. From the standpoint of the nutritive individual it is better to be relieved of the reproductive task in order that there may be no interruption of its specialized activities for the good of all, but the entailed mortality is certainly disadvantageous to it. It is the higher interest of the colony as a whole that supersedes the welfare of the parts taken singly, and this larger welfare is safeguarded by a differentiation worked out by natural evolution which results in the a.s.signment of personal and racial duties to different individuals, at the cost ultimately of the lives of the former.

We now reach the realm of the true many-celled animals, or Metazoa, where the biological units are combined to form an organic a.s.sociation displaying many more resemblances to a human society. The freshwater polyp _Hydra_, like the foregoing ill.u.s.trations, is one whose structure has already been discussed in the earlier chapters, but now we may use it for an a.n.a.lysis of another series of biological phenomena. Its sac-like body consists of two cell-layers; the outer one is concerned primarily with offense and defense, while the inner layer is made up of digesting or nutritive elements. The essential cells concerned solely with reproduction lie below the outer sheet. Comparing this animal with an a.s.sociation like _Volvox_, we discover the same differentiation into immortal germ-elements and mortal cells, concerned respectively with the _Hydra's_ racial existence and with its individual life; but far-reaching changes have come about in the biological relations.h.i.+ps of the second cla.s.s of cells. In describing the new phenomena it is absolutely necessary to employ the terms of human social organization, because the _Hydra's_ body is a true colony of diverse cells in exactly the same sense that a nation is a body of human beings with more or less dissimilar social functions.

To begin with the differentiation into ectoderm and endoderm, the organism is comparable to a human community made up of military and agricultural cla.s.ses. The cells of the former group protect themselves and the feeding elements also, while the units of the second defenseless type devote themselves to the task of provisioning the whole community, giving supplies of food to the defenders in exchange for the protection they afford; each kind needs the other, and each performs some distinctive task for the other as well as for itself. But the parallel thus drawn need not stop here. In the case of the outer layer, the cells are mostly flat covering elements that are the first to be torn off and injured when the animal is attacked. Scattered about among them are sense-cells standing like sentinels with delicate upright processes which receive stimuli from without the sense-cells transmit impulses to the network of nerve-cells below, which is a counterpart of the signal corps of an army, keeping all parts of the whole organization in communication with one another. Most wonderful of all are the stinging-cells of the outer layer; these produce a flask-shaped, poisoned bomb which is discharged by the convulsive contraction of the cell itself so as to stun and injure the enemy or prey.

The bomb-throwing cells die immediately after they have ejected their missiles; like soldiers partic.i.p.ating in a forlorn hope, they sacrifice their lives in one supreme effort of service to the cell-community of which they are members.

These and similar facts prove conclusively that _Hydra_ is a true community even in the human sense, and that the laws of biological a.s.sociation are established at a point far below the level of the insects.

The individuality of the unit is still maintained, and each cell must guard its own interests to a certain degree, but the original independence of the unit has become so altered by differentiation and division of labor that a close interdependent relation has come about. The complete individual is now the _whole_ aggregate; it is the entire _Hydra_ itself which must obey the primary commands of nature to live efficiently and to perpetuate its kind. True it is that the life of the higher individual is the sum total of the activities performed by its const.i.tuent cells, but no one of the varied specialized elements is biologically perfect by itself or equivalent to the whole. And, as we have seen, the welfare of the complete animal takes precedence over that of any one of its parts, just as the existence of a nation may be preserved only by the death of soldiers warring for its honor and life.

If, now, we should pa.s.s on to the more complex organisms like worms and insects and vertebrates, and should disregard the communal relations of some of these animals, each individual proves to be like _Hydra_ as regards the principles underlying its make-up and workings. A single bee, like a man, is a definitely const.i.tuted aggregate of cells, differing as a whole from _Hydra_ only in the _degree of differentiation_ exhibited by its const.i.tuent elements. Instead of a loose network of nerve-cells there is the far more complex nervous system whose evolution has been outlined in the sixth chapter. The blood-vascular and respiratory and excretory systems have become well organized, in response, so to speak, to the demands on the part of the nervous and alimentary organs that they may be relieved of the tasks of circulation and respiration and the discharge of ash-wastes. Therefore the cells which make up an insect and a man are more diverse, they have more varied interrelations.h.i.+ps, and they are far more interdependent then in the case of the components of _Hydra_. Yet all the many-celled organisms that we are so accustomed to regard as individuals are really communities, demonstrating the existence and partial ant.i.thesis of the great laws of egoism and altruism, which are traceable even down to _Amoeba_ and its like.

So much has been made of the lower kinds of cell-a.s.sociations because the mind of the layman is unconsciously imbued with the idea that human society is a new thing,--an idea which we now see it is necessary to discard at the outset. Indeed, the cell-a.s.sociation of the _Hydra_ and insect type is a more compact and a more stable kind of community than any group of human individuals worked out by nature toward the present end of the whole scheme of evolution. That is to say, the subordination of cell-interest to cell-group welfare, while it must not go so far as to render the unit incapable of doing its work, is sufficiently advanced to make uncontrolled individualism impossible. Let any cla.s.s of _Hydra's_ cells, such as the nerve or muscle network, a.s.sume to exercise a selfish preeminence or to conduct a "strike," the other cla.s.ses, like the feeding cells, would not be properly served and they would be unable in consequence to work efficiently for the strikers. The immediate result would be suicidal, for the selfish nerve-cla.s.s would inevitably suffer through the downfall of the whole social fabric. It is a nicely adjusted equilibrium that is established, where the "equal rights" of all the diverse cells consist in freedom to play a special part in the life of the group, serving other individuals in return for their service. The Golden Rule is a natural law as old as nature; for even in _Hydra's_ life, unconscious discharge of duties to the race, and hence to others, is obligatory. And all these low types of organic a.s.sociations evolved ages before the rules of human social order were vaguely recognized by the reflective self-consciousness of man, to be formulated as the science of ethics.

The evolution of the wonderfully varied societies found among insects begins with the solitary insect itself, just as this, viewed as a cell-community, originates from one-celled beginnings like _Amoeba_ through progressive evolution in time. The similarity between social insects and human a.s.sociations is clearer than in the case of a comparison between an example from either group and a cell-community, because the higher forms lack the organic contact of the components which is so prominent a feature in the lower instance. The social bonds are looser and they allow a freer play of the const.i.tuents; but nevertheless the same laws that control the activities of the cells making up what we now take as the individual element, command obedience on the part of the interrelated members of an insect community with equal strictness.

A b.u.t.terfly or a moth is primarily egoistic and unsocial in the ordinary sense during its entire life-history, until the final reproductive act which has a value to the species. The caterpillar larva devotes all of its energies to feeding and growing, unconcerned with the final duties of the moth with which it is connected just as the indifferent unit of a young _Volvox_ colony is related to a reproducing member of the full-grown organism. Now and then, it is true, species like the so-called tent caterpillar are met with where numerous larvae spin silken communal nests to which they retire at night and in which they remain to molt. The pupa, like the larva, is individualistic and employs its time in producing the final adult form. The mature individual, however, is constructed almost solely for the greater purpose of perpetuating the species. Indeed the larger silkworm moths do not and cannot feed, and their value is only that of a device for keeping the race established. Adult may-flies live only a few minutes, just long enough to provide for the fertilization and deposition of the eggs, although to prepare for these acts the young individuals must have toiled for months; the preparatory time may amount to many years in such a case as the seventeen-year locust. But nature is satisfied, as long as the organic mechanisms obey her double commandment, "Live and grow so as to multiply." Like an _Amoeba_, the solitary insect must be egoistic at first, in order to be altruistic in a racial sense in its last days.

Wasps, bees, and ants provide many familiar examples of colonial organizations that become all the more marvelous on closer acquaintance, on account of their resemblances to human a.s.sociations on the one hand, and to cell-a.s.sociations on the other. Their ill.u.s.trative beauty is enhanced by their wide variety, for they grade from counterparts of highly civilized men down to a savage among insects, such as the strictly solitary digger-wasp, whose instincts served to exemplify the insect type of "mentality" in the discussions of the preceding chapter.

The true communities founded by wasps and hornets must be a.s.signed to a low grade in the scale because they originate during a single season and break up at its end; for this very reason the wasp community is intensely interesting to the student of comparative social evolution. In the spring a solitary female emerges from the crevice where she has hibernated and resumes active life; she feeds for a time to renew her strength and then she constructs a simple nest of mud or masticated wood-pulp. In the first few cells of this nest she deposits her eggs, and when they hatch she herself provides the larvae with food, but still continues to enlarge the house and to produce more eggs. Thus during the first few weeks of the colony's existence this single individual performs a variety of tasks of racial as well as of purely egoistic value; but as time goes on, a profound change comes about in her activities and in the life of the whole community. The members of the first brood do not grow into counterparts of their mother; they are all s.e.xless "workers" who progressively relieve their parent of the tasks of nest-building and foraging and nursing, so that their mother becomes a "queen" who devotes her entire time to the special reproductive task which she only can perform. We may justly compare the queen to the reproductive organ of _Hydra_, for the values to the life of the species are identical in the two cases, while the various cla.s.ses of workers are counterparts of such units as the muscle and nerve and nutritive components of the _Hydra_ or any other cell-community individual. Another resemblance between the two is found in the death of all the s.e.xless individuals at the end of the season, when reproducing males and females are finally formed, of whom the fertile queens only survive in their winter hiding places; and again we can discover the cause for biological death in that division of labor which calls upon certain members of the whole community to perform tasks that have no value when once provision has been made for perpetuating the species. Finally the mode by which the colony grows and amplifies is in all respects like the embryonic development of an egg into a _Hydra_, so that we may add the phrase "social embryology" to our vocabulary. The original female is an undifferentiated master of all trades; the small tribe she first establishes is little better off than a horde of savages; but during its seasonal existence the community increases in numbers and complexity until it advances well toward the civilized condition, when each cla.s.s performs its special task for the good of all.

The bees take us higher in the scale, although many solitary species occur, as well as social forms like the b.u.mblebees where colonies are formed in a single season only to break up with the advent of cold weather. The honeybees, however, establish permanent communities from which swarms may set out during the warm months to become new colonies elsewhere. Many hundreds of bees make up a hive, and they belong to three cla.s.ses or castes, which differ in structure and social function. The queen is a fertile female, the drones are males, and the workers are stunted and infertile females which take no part in reproduction. In this case the queen never discharges any menial duties, for these are attended to by the workers; she devotes her entire time to laying eggs, which are cared for by her subjects, who act as nurses and guards for the monarch as well. The young workers serve at first as doorkeepers, and only later do they take the field in the search for nectar and pollen, and work as house-builders. Each individual performs its special task for its own benefit and for the weal of all; each possesses an equal right to share in the prosperity of the whole community so long as it acts altruistically as well as egoistically. And just as the welfare of _Hydra_ is superior to that of any one of its const.i.tuent cells, so the well-being of a hive of bees may be safeguarded only by the actual sacrifice of some of its members. Should food supplies be inadequate, the superfluous drones are stung to death,--the victims of legalized murder. But more marvelous still is the provision that is said to be made by certain individuals for their own destruction should this become desirable. As every one knows, a reigning queen may leave the hive with many of her subjects and "swarm" in a new locality. When she does this, during the warm months, the workers of the original hive feed some of the female larvae with richer food, and place these potential queens or princesses in special roomy cells apart from the ordinary brood chambers; one of them soon emerges to become a new sovereign. Let us note in pa.s.sing how similar this is to the production of new egg-cells in a _Hydra_, when the mature germs of an earlier generation are prepared and discharged. When, now, the colder weather sets in, and the possibility of subsequent swarming is set aside, the reigning queen is allowed by her attendant guards to visit the royal cells, whose occupants she stings to death, thus destroying any possible claimant to her place.

And when the royal princess constructs her part of the pupal case, she leaves an aperture so that if and when it should become necessary for the queen to kill her, the sovereign would not injure her sting and be unable to kill the other individuals who might become aspirants for the throne and so precipitate a civil war! As in the case of the self-destructive act on the part of a stinging cell in _Hydra_, altruistic subservience to the interests of the colony can go no farther.

The ants form stable colonies of still higher grades, where the workers are not all alike in general structure, but become more rigidly specialized for the performance of restricted tasks. As before, there is the fundamental differentiation into the s.e.xual "queens" and males, and the sterile workers concerned with the immediate material life of the community. In some species the workers serve as herdsmen, caring for the ant-cattle or aphids, from which they receive minute drops of a sweet juice for food. The aphids are tended on the leaves of various plants during the summer, and are carefully reared and stabled and fed below ground during the winter months. In other species seeds are procured and stored in underground granaries. The leaf-cutters are forms which grow food supplies of fungi in subterranean mushroom gardens; the compost consists of cuttings brought from the leaves of bushes by myriads of workers, whose processions are guarded by larger-headed soldiers of several ranks. In the honey-ants of Colorado and tropical America certain individuals pa.s.s their time suspended from the roof of a large nest-chamber, where they receive the sweet juice brought in by the workers.

They serve as animated preserve jars, distended sometimes to the size of a grape with the communal stores of food, which they return to the workers when external sources of food may fail. Finally there are the slaveholding species which conduct forays upon the nests of other forms, to procure the young of the latter, which grow up in their captors' nests and serve them as nurses and masons and foragers. So long has this custom been established that some slaveholders are entirely unable to feed themselves, and would die out if their slaves failed to support them.

Let us pause at this point to summarize the results of the foregoing a.n.a.lysis, in order that we may approach the biological study of human a.s.sociations with definite and clear conceptions of the fundamental laws controlling living communities of all grades.

We have dealt mainly with _Amoeba_, _Hydra_, and the ant-community which exemplify three somewhat distinct types of organic individuality.

Some of the transitional forms have been specified to show how the second kind originates from the first, and how in its turn this grows in time into the third and most complex a.s.sociation; thus _Vorticella_ and _Volvox_ connect _Amoeba_ with the cell-community individual like _Hydra_ and a solitary wasp, while the annually established colonies of social wasps and of b.u.mblebees lead to the permanent colony-individual.

Restricting attention to the three primary examples, and remembering that the criterion of completeness is the ability to discharge satisfactorily all of the eight biological tasks, it is clear that the entire _Hydra_ and the whole ant-community correspond _physiologically_ with _Amoeba_, although the first-named is _structurally_ a cell-community equivalent to many protozoa, and the insect colony is composed of many such cell-communities as elements. In the third type, neither a single queen nor a single worker is able to carry on all of the biological tasks any more than a muscle-cell or an unformed egg of _Hydra_ can maintain itself capably in isolation. Therefore the ant-society as a whole and the _Hydra_ in its entirety are organic individuals on the same physiological plane with _Amoeba_, and they are equally subject to the same great laws of nature demanding selfish maintenance and racial perpetuation.

But we must not lose sight of the fundamental value of the unit during the evolution of a higher from a lower type. The tissue-cell of _Hydra_ must still obey the mandate to live an efficient personal life, because this is necessary for the welfare of other cells and of the whole complex. The original egoistic tasks are not abolished, but new duties are added to them in ways we have learned to distinguish. In _Vorticella_ the products of fission do not separate, and certain advantages accrue from the organic continuity thus maintained. The success of _Hydra_ in its ceaseless struggle to live depends wholly upon the cooperation of its differentiated cell-units, now no longer equivalent in function to the all-powerful _Amoeba_, although each one must be kept alive until its task is done, or the whole a.s.sociation would have no place in nature. Similarly in the higher insect community, the superadded duties to fellow-components are even clearer, for in the compet.i.tion of colony with colony, involving terrific battles whose casualties may be numbered by thousands, the stronger wins; and strength depends upon the concerted efforts of all the members of the kingdom, that only collectively const.i.tute a complete biological whole. Mere self-protection demands altruistic conduct: if the worker ceased to bring in food when its own hunger was satisfied, there would be no tribal stores for the stay-at-home queens and nurses; and if the soldier fled from the field of battle to save its own life, its act would be suicidal ultimately, for to the degree of one unit the defense of its non-military supporters would be weakened and they would be so much the less unprotected during their service for the soldiers and all others.

Furthermore, we must admit the reality of natural criteria of ethical values, established far below mankind in the scale of life. In an ant-republic, laws are instinctively obeyed quite as implicitly as though they were intelligibly proclaimed to all of the emmet citizens. Right is might when community battles with community, for right is that which is biologically favorable. And what may be correct conduct on the part of the members of one species may be naturally wrong and evil in another case. To kill the princesses in order to obviate the possibility of civil war seems advantageous and therefore right when the queen remains in the persistent colony of honeybees, ready to do her part the following spring; but it might result in disaster and evil in the case of the social wasps, where the community dies as such in the fall, and the continuity of the species from one year to another requires the production of many queens lest the severe conditions of the winter's hibernation should kill all fertile females if only one or two were available. The standards of conduct are simple indeed; and whether or not it may seem best to separate the processes of social and ethical evolution culminating in human phenomena, the fact remains that these processes begin with elements discovered by the biologist among organisms of the lower levels in the scale.

We come at length to the biological interpretation of human social evolution, in so far as this may be expounded in a simple and concise form. The comparative method must be employed in order to discover the fundamental attributes of savage, barbarous, and civilized communities which seem to differ so considerably in their complexity of social structure, and in order also to show that such basic elements are like those of communities formed by lower animals, and are equally the products of natural evolution. This whole subject seems to be exceedingly complex, because in our daily contact with others of our kind and in our occasional views of foreign races like our own, the smaller details occupy our attention, diverting it from the great basic principles according to which every society is organized and operates. But when once the major elements have been discovered in civilized and more primitive nations, the secondary and less essential phenomena fall into their proper relations, and a statement of the whole process of development becomes relatively simple. So much s.p.a.ce has been devoted to lower types of communal organisms in order to learn what the fundamentals are, and not merely to provide a.n.a.logies that may be useful hereafter. It now remains to arrange the evidences of social progress during the history of mankind itself, and to bring such human facts into relation with what has been discovered in lower nature. It is helpful to begin this part of the subject by asking ourselves what is already part of common knowledge about human history. Do we know of any civilized nation that is absolutely stable and unvarying in social structure, or one that has remained unchanged throughout historic time? The answer must be negative, for in no case does the past disclose an example of permanence in social or in any other respect; monarchies and republics are plastic like the human frame itself. The American Commonwealth is a relatively young social organism, and it is an easy task to trace its growth from beginnings in the diffuse and uncorrelated colonies of pre-Revolutionary years. Those colonies that were formed by English settlers were transplanted outgrowths from a civilized social parent which in its turn had clearly evolved from the state of King John's time and the still cruder form it had under King Alfred.

Should we follow back the recorded history of any people now civilized, we would always find evidence of ceaseless change; and the writings of ancient historians like Herodotus and Caesar and Tacitus give a great deal of information about the barbarous conditions from which civilization evolved.

But much more is known that materially amplifies the account of human progress based upon doc.u.ments alone. The student of existing human races early learns that social structure is a very varied thing. The natives of northern Africa now live in a semi-civilized state which is very like that of medieval England. In Siberia and the American Southwest are tribes that correspond socially with the barbarians of Europe described by Greek and Roman writers. The American Indians discovered by the earliest colonists, the Polynesians of a century ago, and the Fuegians of recent decades provide counterparts of the ancient stone-wielding people who were the savage ancestors of European barbarians. Hence the comparative study and cla.s.sification of modern races establishes a scale of social grades which corresponds with the order of their historic succession, just as in a larger way the complete series of comparative anatomy from _Amoeba_ to man displays the order of evolution from unicellular beginnings to the present culminating types. Savagery, barbarism, and civilization are the three major terms of this social scale, but by no means are they discontinuous, for many intermediate forms of organization occur which are transitional from one major type to a higher one.

In human social evolution the starting point is not so simple as the solitary unit from which insect societies evolved,--that is, an organism which lives alone and is a.s.sociated with another of its species only at the time of mating. The lowest human beings now existing have some form of family organization, traceable to the more or less continuous unions formed among certain of the apes and even among many lower animals, and not a characteristic that belongs to mankind alone. The savage and his mate const.i.tute the social unit out of which all else is built up; the man and the woman must perform all of the vital tasks demanded by nature.

Fruits and vegetables must be secured from the wild forest or by cultivation; the flesh of game animals or of a human victim is no less essential for food. The savage is his own weapon maker and warrior; he himself builds the rude shelter for his family and fas.h.i.+ons the canoe if such is required. He is also his own judge, recognizing no control save the dictates of his wishes and needs, for he does not consciously realize that he must obey the primal commands of nature to preserve himself and his family so that the species shall persist. In brief, the elementary family unit carries on all of the individual biological tasks of foraging, righting, home-building, and the like, and it also discharges the racial task of multiplying, quite as instinctively as it provides for its own maintenance.

By the union of several families, a primitive a.s.sociation arises, like that of the Veddahs in Ceylon. The primal duties of each family are unchanged, and their biological activities are identical, as in the protozoon colony of _Vorticella_ or in a pack of wolves; but certain new relations are established. A member of such an inchoate tribe must not treat his confreres as he might a man of another group; robbery and murder within the limits of the small a.s.sociation are detrimental to communal interests, though they may remain unchecked if the victims are strangers.

Cooperation for mutual offense and defense makes the group stronger than its const.i.tuent family units taken singly, and every man of such a tribe gains something by looking out for others as well as for himself. By natural selection alone the bonds of union would be strengthened in direct proportion to the subordination of individual interest to group welfare, and to the amount of altruistic action that in a true sense grows out of purely selfish conduct.

But when such a primitive biological a.s.sociation forms and grows, an opportunity arises for increasing the effectiveness of the whole group by differentiation. Some of the men are stronger in battle and they soon become the chief warriors; others prove to be more skilful in the hunt or in the construction of canoes and weapons. Just as among the insects, the hunter seeks food not only for himself but for the warriors, who in their turn defend themselves, but do not cease fighting when they have disposed of their own enemies if foes of their comrades still survive. The barbarous state of society thus arises, and the division of labor brought about during its origin makes it possible and indeed essential for many family units to remain together for mutual good. The union is stable and efficient, however, only if the individual suppresses his own selfish inclinations, suspending private quarrels when public wars are toward, and acting at all times in concert with his fellows. Self-control increases necessarily, and lines of conduct deemed right by a solitary savage unit come more and more under the sway of social inhibition, for although the primitive savages must inhibit individualistic action to some degree, the barbarian must suppress much more of his purely personal wishes for the purpose of social solidarity. Thus it comes about that a barbarous community can number thousands, while a tribe of savages with a higher degree of individualism and less altruism cannot cohere if it comprises more than hundreds or scores.

Civilization is a product of evolution by precisely the same natural mode of development, that is, through further subordination of individual to communal interests and through progressive dividing up of the tasks necessary for the life of the group. The final result is so obvious and familiar that we take it for granted, accepting it as self-sufficient without realizing how it has come about and how modern is the present state of affairs. Let us compare the life of an Indian savage living on Manhattan Island four centuries ago with that of a New Yorker to-day, as regards so simple a matter as the procuring of fish food. The Indian emerged from his tepee, built by himself, and walking to the sh.o.r.e, stepped into a canoe which also he had made with his own hands. Paddling to the fis.h.i.+ng ground, he patiently cast his line until the desired fish were caught. Does any one of us do all of these things for himself? We live in houses constructed for us by others who devote their lives to building; we are very apt to go about the city in conveyances that demand special and peculiar skill for their invention, manufacture, and operation. Arriving at a market-place, we obtain such an article of food as a fish without having to go out upon the water ourselves, for many other workers have built vessels that we do not know how to make and may not know how to handle, and hundreds of fishermen devote their lives to their special task, not for themselves, but for us and all others, such as the builder, the subway operator, the boat maker, and the manufacturers who supply their clothing and apparatus.

What has come about then is a higher degree of specialization in the performance of the fundamental biological tasks, resulting in the formation of coherent and efficient groups comprising millions as compared with the thousands of barbarism and the hundreds of savagery. Just so the communities of insects with the greatest degree of altruism and division of labor far exceed in numbers the small colonies of the social wasps with lower social differentiation.

But the great biological functions of an entire complex civilized society remain the same as those of a primitive savage family unit, of an insect community, of _Hydra_, and of _Amoeba_. Let any nation fail to maintain itself in material individual respects, it must inevitably die out; in the islands of the South Seas many a tragic death-struggle of a people can be witnessed. If in the second place a nation should concern itself too greatly with the material benefits of human life without obeying the natural mandate to propagate itself, its place in the scheme of things becomes insecure, as in the case of the French Republic. Natural social laws that go back to _Amoeba_ must be observed, consciously or unconsciously, or else even the civilized community must fall, like scores and hundreds of others that lie along the road of historic progress--a road strewn with the remains of the unfit thrown out by natural selection.

What now are the lessons of social evolution and what guidance does science give for human endeavor? Although it may seem that the biologist leaves his field when he considers these questions, his duty would be unfulfilled if he neglected an opportunity to give his results their highest utility through their use for the betterment of human life.

The first lesson is that the history of human social organization is far from unique, and that it is identical with the process by which insect communities and cell-aggregates have evolved; in a word, the laws of biological a.s.sociation are uniform throughout the entire organic scale. In some respects evolution in mankind has yet to equal the heights attained by some insects, inasmuch as no human society has accomplished so rigid a specialization of its members that a given individual is foreordained by its inherited structure to be a particular kind of worker and nothing else. Furthermore, evolution in human society is still far short of a state where some and some only are reproductive members of the group while the others are necessarily sterile; social insects with stable colonies are so organized that the queens and drones are solely reproductive while the workers are destined to care for the material wants of the colony. It is true that the birth-rate is by no means the same in all cla.s.ses of society, but the social and other advent.i.tious restrictions that bring this about are not on the same plane with the hereditary determining factors which operate among insects. Therefore the scale of human communities proves to be only a part of the wider range of organic a.s.sociations in general--a part which can be definitely placed in such a wider scheme and so become more intelligible in itself.

In all departments of social evolution, progress is made by the twofold process of combination and differentiation. We have dealt with detailed instances, and now it is profitable to treat the process in a larger way, with a view toward the possibilities of the future. The Thirteen Colonies, somewhat similar in their earlier economic activities, united for mutual support much as wolves combine to form a pack. Later, as circ.u.mstances directed, they differentiated into farming or manufacturing or commercial organs of the body politic, each to some degree freeing itself of the functions undertaken by others, and becoming thereby more dependent than before upon those that specialized in different ways. As in the history of the insects in a growing wasp community and of savages evolving into barbarians, the original condition of relative independence pa.s.sed into a state of interdependence and cooperation. In like manner, if nature remains the same, as there is every reason to believe it will, nations now separate will unite to make more complex combinations that will be veritable empires of world-wide scope. Countries on opposite sides of an ocean are now more closely connected by lines of communication and means of travel than were the Carolinas and New England a century ago.

Diplomatic activities give many signs of a growing appreciation of the value of reciprocal agreements for mutual advantage, and the Hague Conference is a concrete manifestation of a continuing process of social evolution that finds its beginnings and its interpretation far below human history in lower organic nature.

But perhaps the most important result of this whole discussion is the lesson of social service that it teaches. We are members of a vast community whose complex total life seems far removed from anything going on in an ant-colony, and our daily tasks vary greatly in specific character and degree when compared with those of lower communal organisms.

It seems scarcely credible that any principles of social relations.h.i.+p, however general, can hold true for us and for them. But when the rock-bottom foundations are reached, they are simple and instructive indeed. Being here, we cannot escape our personal obligations as living things or our equally clear duties as members of our community. These facts being as they are, what must we do? Self-interest is rightly to be served, otherwise we would be incapable of discharging our secondary tasks, namely, those of service to others in ways that are determined by hereditary endowment and conditional circ.u.mstances. The difficulty is to find the right compromise between the two sets of obligations; but the right balance must be found, or else the health of the community is impaired. Should any cla.s.s demand more than its just dues, others must suffer through the diversion of what they require, and the well-being of the selfish cla.s.s is jeopardized to some degree, so closely interwoven are the interests of all. Freedom of opportunity within the limits of ability and efficiency is the right of every one, but freedom of conduct must never result in trespa.s.s upon the equal rights of others to make the most of their abilities and opportunities.

To summarize, then, social evolution is a continuous process accomplished through differentiation and division of labor among the components of biological a.s.sociations. Although the total form remains the same everywhere, progress has been made in content through the further subordination of selfish to altruistic conduct; only by this means does an individual gain liberty to pursue the social task for which he is best fitted by nature.

VIII

EVOLUTION AND THE HIGHER HUMAN LIFE

We have now reached the last division of the large subject that has occupied our thoughts for so long. The present t.i.tle has been chosen because the questions now before us relate to the highest human ideas belonging to the departments of ethics, religion, theology, science, and philosophy. These matters may seem at first sight to be far removed from the territory of the naturalist as such, and quite exempt from the control of laws which determine the nature and history of the human individual in physical, mental, and social respects. Yet one reason alone would impel us onward: we cannot close the present examination into the basic facts of evolution and into the scope of the doctrine without asking to what extent a belief in its truth may affect our earlier formed conceptions of nature and supernature. Heretofore these possible effects upon what may be dearly cherished intellectual possessions have received no attention, so that we might learn how evolution works in the lower fields of organic life in general and human life in particular without being disturbed by them. No doubt, however, the conviction has grown with each step in our progress that the principles we have learned must cause us to readjust our views of the highest elements in human thought to a degree that must be inversely proportional to our previous acquaintance with the laws and processes of nature. But the seeker after truth is fearless of consequences. He knows that truth cannot contradict itself; and if those to whom he looks for authority give him conflicting accounts of nature's history, he knows that one of these must be less surely grounded than the other. The investigator soon learns to withhold final judgment, realizing that the primary conditions for intellectual development are the plasticity and openness of mind that dogmatism and finality destroy. He knows that while his researches may be, and indeed must be, iconoclastic, they provide him with better icons in place of the old.

Let us recall the steps in our progress through one and another field of knowledge, from which representative facts have been chosen for cla.s.sification and summary. We began with the basic principles of organic structure and workings, and then we examined serially the larger categories of the evidences relating to evolution as a fact, and to the mode of its accomplishment by natural factors. Proceeding to the special case of our own species, we learned that human beings are inevitably a part of nature and not outside it; in structure, development, and palaeontological history, mankind is subject to the control of the uniform laws which operate throughout the entire range of living things. Finally, the mental characters and the social relations of human organisms were derived from beginnings lower down in the scale, and were proved to be no more exceptional than the physical const.i.tution of a single human being.

Are we to forget all of these things when we try to put in order our ideas belonging to the categories of higher thought? Can we hope to find the truth if we fail to employ the methods of scientific common-sense which only yield sure results? It is no more justifiable to discard our hard-earned knowledge than it would be for an advocate to undertake the conduct of a case in deliberate disregard of what he had learned of the law, or for a surgeon to leave his knowledge at the door when he entered the operating room. Too often we are bidden to view the larger conceptions of nature and supernature as something outside the realm of ordered knowledge too frequently we are given statements upon authority that takes no account of reason, and we are asked to accept these views whether or not they accord with the demonstrated facts of common-sense. But those who have followed the present description of evolution can readily recognize their obligation to use for the further a.n.a.lysis of higher human life the means which have given in that doctrine the most reasonable explanation of the natural phenomena already investigated.