Although organization, on the whole, may have advanced and may be still advancing throughout the world, yet the scale will always present many degrees of perfection; for the high advancement of certain whole cla.s.ses, or of certain members of each cla.s.s, does not at all necessarily lead to the extinction of those groups with which they do not enter into close compet.i.tion. In some cases, lowly organized forms appear to have been preserved to the present day from inhabiting confined or peculiar stations, where they have been subjected to less severe compet.i.tion and where their scanty numbers have r.e.t.a.r.ded the chance of favorable variations arising.

Finally, I believe that many lowly organized forms now exist throughout the world from various causes. In some cases variations or individual differences of a favorable nature may never have arisen for natural selection to act on and acc.u.mulate. In no case, probably, has time sufficed for the utmost possible amount of development. In some few cases there has been what we must call retrogression of organization.

But the main cause lies in the fact that under very simple conditions of life a high organization would be of no service--possibly would be of actual disservice, as being of a more delicate nature and more liable to be put out of order and injured.

4. Man: An Adaptive Mechanism[187]

Everything in nature, living or not living, exists and develops at the expense of some other thing, living or not living. The plant borrows from the soil; the soil from the rocks and the atmosphere; men and animals take from the plants and from each other the elements which they in death return to the soil, the atmosphere, and the plants. Year after year, century after century, eon after eon, the mighty, immeasurable, ceaseless round of elements goes on, in the stupendous process of chemical change, which marks the eternal life of matter.

To the superficial observer, nature in all her parts seems imbued with a spirit of profound peace and harmony; to the scientist it is obvious that every infinitesimal particle of the immense concourse is in a state of desperate and ceaseless struggle to obtain such share of the available supply of matter and energy as will suffice to maintain its present ephemeral form in a state of equilibrium with its surroundings.

Not only is this struggle manifest among living forms, among birds and beasts and insects in their compet.i.tion for food and habitat, but--if we may believe the revelations of the science of radio-activity--a process of trans.m.u.tation, of disintegration of the atoms of one element with simultaneous formation of another element, is taking place in every fragment of inanimate matter, a process which parallels in character the more transitory processes of life and death in organisms and is probably a representation of the primary steps in that great process of evolution by which all terrestrial forms, organic and inorganic, have been evolved from the original ether by an action inconceivably slow, continuous, and admitting of no break in the series from inanimate to animate forms.

From colloidal slime to man is a long road, the conception of which taxes our imaginations to the utmost, but it is an ascent which is now fairly well demonstrated. Indeed, the problems of the missing links are not so difficult as is the problem of the origin of the organs and functions which man has acquired as products of adaptation. For whether we look upon the component parts of our present bodies as useful or useless mechanisms, we must regard them as the result of age-long conflicts between environmental forces and organisms.

Everywhere something is pursuing and something is escaping another creature. It is a constant drama of getting food and of seeking to escape being made food, evolving in the conflict structures fitted to accomplish both reactions. Everywhere the strong prey upon the weak, the swift upon the slow, the clever upon the stupid; and the weak, the slow, the stupid, retaliate by evolving mechanisms of defense, which more or less adequately repel or render futile the oppressor's attack. For each must live, and those already living have proved their right to existence by a more or less complete adaptation to their environment. The result of this twofold conflict between living beings is to evolve the manifold structures and functions--teeth, claws, skin, color, fur, feathers, horns, tusks, wily instincts, strength, stealth, deceit, and humility--which make up character in the animal world. According to the nature and number of each being's enemies has its own special mechanism been evolved, distinguishing it from its fellows and enabling it to get a living in its particular environment.

In every case the fate of each creature seems to have been staked upon one mechanism. The tiger by its teeth and claws, the elephant and the rhinoceros by their strength, the bird by its wings, the deer by its fleetness, the turtle by its carapace--all are enabled to counter the attacks of enemies and to procreate. Where there is a negative defense, such as a sh.e.l.l or quills, there is little need and no evidence of intelligence: where a rank odor, no need and no presence of claws or carapace; where sting or venom, no need and no possession of odor, claws, sh.e.l.l, extraordinary strength, or sagacity. Where the struggle is most bitter, there exist the most complex and most numerous contrivances for living.

Throughout its whole course the process of evolution, where it is visible in the struggle of organisms, has been marked by a progressive victory of brain over brawn. And this, in turn, may be regarded as but a manifestation of the process of survival by _lability_ rather than by _stability_. Everywhere the organism that exhibits the qualities of quick response, of extreme sensibility to stimuli, of capacity to change, is the individual that survives, "conquers," "advances." The quality most useful in nature, from the point of view of the domination of a wider environment, is the quality of _changeableness_, _plasticity_, _mobility_, or _versatility_. Man's particular means of adaptation to his environment is this quality of versatility. By means of this quality expressed through the manifold reactions of his highly organized central nervous system, man has been able to dominate the beasts and to maintain himself in an environment many times more extensive than theirs. Like the defensive mechanisms of sh.e.l.ls, poisons, and odors, man's particular defensive mechanism--his versatility of nervous response (mind)--was acquired automatically as a result of a particular combination of circ.u.mstances in his environment.

In the Tertiary era--some twenty millions of years ago--the earth, basking in the warmth of a tropical climate, had produced a luxuriant vegetation and a swarming progeny of gigantic small-brained animals for which the exuberant vegetation provided abundant and easily acquired sustenance. They were a breed of huge, clumsy, and grotesque monsters, vast in bulk and strength, but of little intelligence, that wandered heavily on the land and gorged lazily on the abundant food at hand. With the advance of the carnivora, the primitive forerunners of our tigers, wolves, hyenas, and foxes, came a period of stress, comparable to a seven years of famine following a seven years of plenty, which subjected the stolid herbivorous monsters to a severe selective struggle.

Before the active onslaught of lighter, lither, more intelligent foes, the clumsy, inelastic types succ.u.mbed, those only surviving which, through the fortunate possession of more varied reactions, were able to evolve modes of defense equal to the modes of attack possessed by their enemies. Many, unable to evolve the acute senses and the fleet limbs necessary for the combat on the ground, shrank from the fray and acquired more negative and pa.s.sive means of defense. Some, like the bat, escaped into the air. Others, such as the squirrel and the ape, took refuge in the trees.

It was in this concourse of weak creatures which fled to the trees because they lacked adequate means of offense, defense, or escape on the ground that the lineaments of man's ancient ancestor might have been discerned. One can imagine what must have been the pressure from the carnivora that forced a selective transformation of the feet of the progenitor of the anthropoids into grasping hands. Coincidentally with the tree life, man's special line of adaptation--_versatility_--was undoubtedly rapidly evolved. Increased versatility and the evolution of hands enabled man to come down from the trees millions of years thereafter, to conquer the world by the further evolution and exercise of his organ of strategy--the brain. Thus we may suppose have arisen the intricate reactions we now call mind, reason, foresight, invention, etc.

Man's claim to a superior place among animals depends less upon _different_ reactions than upon a _greater number_ of reactions as compared with the reactions of "lower" animals. Ability to respond adaptively to more elements in the environment gives a larger dominion, that is all.

The same measure applies within the human species--the number of nervous reactions of the artist, the financier, the statesman, the scientist, being invariably greater than the reactions of the stolid savage. That man alone of all animals should have achieved the degree of versatility sufficient for such advance is no more remarkable than that the elephant should have evolved a larger trunk and tusks than the boar; that the legs of the deer should be fleeter than those of the ox; that the wings of the swallow should outfly those of the bat. Each organism, in evolving the combination of characters commensurate with safety in its particular environment, has touched the limit of both its necessity and its power to "advance." There exists abundant and reliable evidence of the fact that wherever man has been subjected to the stunting influences of an unchanging environment fairly favorable to life, he has shown no more disposition to progress than the most stolid animals. Indeed, he has usually retrograded. The need to fight for food and home has been the spur that has ever driven man forward to establish the manifold forms of physical and mental life which make up human existence today.

Like the simple adaptive mechanisms of the plant by which it gets air, and of the animal by which it overcomes its rivals in battle, the supremely differentiated functions of thought and human relations are the outcome of the necessity of the organism to become adapted to ent.i.ties in its environment.

B. COMPEt.i.tION AND SEGREGATION

1. Plant Migration, Compet.i.tion, and Segregation[188]

Invasion is the complete or complex process of which migration, ecesis (the adjustment of a plant to a new home), and compet.i.tion are the essential parts. It embraces the whole movement of a plant or group of plants from one area into another and their colonization in the latter.

From the very nature of migration, invasion is going on at all times and in all directions.

Effective invasion is predominantly local. It operates in ma.s.s only between bare areas and adjacent communities which contain species capable of pioneering, or between contiguous communities which offer somewhat similar conditions or contain species of wide range of adjustment. Invasion into a remote region rarely has any successional effect (effect tending to transform the character of a plant community), as the invaders are too few to make headway against the plants in possession or against those much nearer a new area. Invasion into a new area or a plant community begins with migration when this is followed by ecesis. In new areas, ecesis produces reaction (the effect which a plant or a community exerts upon its habitat) at once, and this is followed by aggregation and compet.i.tion, with increasing reaction. In an area already occupied by plants, ecesis and compet.i.tion are concomitant and quickly produce reactions. Throughout the development migrants are entering and leaving, and the interactions of the various processes come to be complex in the highest degree.

Local invasion in force is essentially _continuous_ or _recurrent_.

Between contiguous communities it is _mutual_, unless they are too dissimilar. The result is a transition area or ecotone which epitomizes the next stage in development. By far the greater amount of invasion into existing vegetation is of this sort. The movement into a bare area is likewise continuous, though it is necessarily not mutual, and hence there is no ecotone during the earlier stages. The significant feature of continuous invasion is that an outpost may be repeatedly reinforced, permitting rapid aggregation and ecesis, and the production of new centers from which the species may be extended over a wide area.

Contrasted with continuous invasion is intermittent or periodic movement into distant regions, but this is rarely concerned in succession. When the movement of invaders into a community is so great that the original occupants are driven out, the invasion is _complete_.

A topographic feature or a physical or a biological agency that restricts or prevents invasions is a barrier. Topographic features are usually permanent and produce permanent barriers. Biological ones are often temporary and exist for a few years or even a single season.

Temporary barriers are often recurrent, however. Barriers are complete or incomplete with respect to the thoroughness of their action. They may affect invasion either by limiting migration or by preventing ecesis.

Biological barriers comprise plant communities, man and animals, and parasitic plants. The limiting effect of a plant community is exhibited in two ways. In the first place, an a.s.sociation acts as a barrier to the ecesis of species invading it from a.s.sociations of another type, on account of the physical differences of the habitats. Whether such a barrier be complete or partial will depend upon the relative unlikeness of the two areas. Shade plants are unable to invade a prairie, though the species of open thickets or woodland may do so to a certain degree.

Closed communities (one in which all the soil is occupied) likewise exert a marked influence in decreasing invasion by reason of the intense and successful compet.i.tion which all invaders must meet. Closed a.s.sociations usually act as complete barriers, while more open ones restrict invasion in direct proportion to the degree of occupation. To this fact may be traced the fundamental law of succession (the law by which one type of community or formation is succeeded by another) that the number of stages is determined largely by the increasing difficulty of invasion as the area becomes stabilized. Man and animals affect invasion by the destruction of germules. Both in bare areas and in seral stages the action of rodents and birds is often decisive to the extent of altering the whole course of development. Man and animals operate as marked barriers to ecesis wherever they alter conditions unfavorably to invaders or where they turn the scale in compet.i.tion by cultivating, grazing, camping, parasitism, etc. The absence of pollinating insects is sometimes a curious barrier to the complete ecesis of species far out of their usual habitat or region. Parasitic fungi decrease migration in so far as they affect seed production. They restrict or prevent ecesis either by the destruction of invaders or by placing them at a disadvantage with respect to the occupants.

By the term _reaction_ is understood the effect which a plant or a community exerts upon its habitat. In connection with succession, the term is restricted to this special sense alone. It is entirely distinct from the response of the plant or group, i.e., its adjustment and adaptation to the habitat. In short, the habitat causes the plant to function and grow, and the plant then reacts upon the habitat, changing one or more of its factors in decisive or appreciable degree. The two processes are mutually complementary and often interact in most complex fashion.

The reaction of a community is usually more than the sum of the reactions of the component species and individuals. It is the individual plant which produces the reaction, though the latter usually becomes recognizable through the combined action of the group. In most cases the action of the group acc.u.mulates or emphasizes an effect which would otherwise be insignificant or temporary. A community of trees casts less shade than the same number of isolated individuals, but the shade is constant and continuous, and hence controlling. The significance of the community reaction is especially well shown in the case of leaf mold and duff. The leaf litter is again only the total of the fallen leaves of all the individuals but its formation is completely dependent upon the community. The reaction of plants upon wind-borne sand and silt-laden waters ill.u.s.trates the same fact.

2. Migration and Segregation[189]

All prehistoric investigation, as far as it relates to the phenomena of the animate world, necessarily rests upon the hypothesis of migration.

The distribution of plants, of the lower animals, and of men over the surface of the earth; the relationships existing between the different languages, religious conceptions, myths and legends, customs and social inst.i.tutions--all these seem in this one a.s.sumption to find their common explanation.

Each fresh advance in culture commences, so to speak, with a new period of wandering. The most primitive agriculture is nomadic, with a yearly abandonment of the cultivated area; the earliest trade is migratory trade; the first industries that free themselves from the household husbandry and become the special occupations of separate individuals are carried on itinerantly. The great founders of religion, the earliest poets and philosophers, the musicians and actors of past epochs, are all great wanderers. Even today, do not the inventor, the preacher of a new doctrine, and the virtuoso travel from place to place in search of adherents and admirers--notwithstanding the immense recent development in the means of communicating information?

As civilization grows older, settlement becomes more permanent. The Greek was more settled than the Phoenician, the Roman than the Greek, because one was always the inheritor of the culture of the other.

Conditions have not changed. The German is more migratory than the Latin, the Slav than the German. The Frenchman cleaves to his native soil; the Russian leaves it with a light heart to seek in other parts of his broad fatherland more favorable conditions of living. Even the factory workman is but a periodically wandering peasant.

To all that can be adduced from experience in support of the statement that in the course of history mankind has been ever growing more settled, there comes a general consideration of a twofold nature. In the first place, the extent of fixed capital grows with advancing culture; the producer becomes stationary with his means of production. The itinerant smith of the southern Slav countries and the Westphalian iron works, the pack-horses of the Middle Ages and the great warehouses of our cities, the Thespian carts and the resident theater mark the starting and the terminal points of this evolution. In the second place, the modern machinery of transportation has in a far higher degree facilitated the transport of goods than of persons. The distribution of labor determined by locality thereby attains greater importance than the natural distribution of the means of production; the latter in many cases draws the former after it, where previously the reverse occurred.

The migrations occurring at the opening of the history of European peoples are migrations of whole tribes, a pushing and pressing of collective units from east to west, which lasted for centuries. The migrations of the Middle Ages ever affect individual cla.s.ses alone; the knights in the crusades, the merchants, the wage-craftsmen, the journeymen hand-workers, the jugglers and minstrels, the villeins seeking protection within the walls of a town. Modern migrations, on the contrary, are generally a matter of private concern, the individuals being led by the most varied motives. They are almost invariably without organization. The process repeating itself daily a thousand times is united only through the one characteristic, that it is everywhere a question of change of locality by persons seeking more favorable conditions of life.

Among all the phenomena of ma.s.ses in social life suited to statistical treatment, there is without doubt scarcely one that appears to fall of itself so completely under the general law of causality as migrations; and likewise hardly one concerning whose real cause such misty conceptions prevail.

The whole department of migrations has never yet undergone systematic statistical observation; exclusive attention has. .h.i.therto been centered upon remarkable individual occurrences of such phenomena. Even a rational cla.s.sification of migrations in accord with the demand of social science is at the present moment lacking.

Such a cla.s.sification would have to take as its starting-point the result of migrations from the point of view of population. On this basis they would fall into these groups: (1) migrations with continuous change of locality; (2) migrations with temporary change of settlement; (3) migrations with permanent settlement.

To the _first_ group belong gypsy life, peddling, the carrying on of itinerant trades, tramp life; to the _second_, the wandering of journeymen craftsmen, domestic servants, tradesmen seeking the most favorable spots for temporary undertakings, officials to whom a definite office is for a time entrusted, scholars attending foreign inst.i.tutions of learning; to the _third_, migration from place to place within the same country or province and to foreign parts, especially across the ocean.

An intermediate stage between the first and second group is found in the _periodical migrations_. To this stage belong the migrations of farm laborers at harvest time, of the sugar laborers at the time of the _campagne_, of the masons of Upper Italy and the Ticino district, common day-laborers, potters, chimney-sweeps, chestnut-roasters, etc., which occur at definite seasons.

In this division the influence of the natural and political insulation of the different countries is, it is true, neglected. It must not, however, be overlooked that in the era of nationalism and protection of national labor political allegiance has a certain importance in connection with the objective point of the migrations. It would, therefore, in our opinion, be more just to make another division, taking as a basis the politico-geographical extent of the migrations. From this point of view migrations would fall into _internal_ and _foreign_ types.

Internal migrations are those whose points of departure and destination lie within the same national limits; foreign, those extending beyond these. The foreign may again be divided into _continental_ and _extra-European_ (generally transmaritime) emigration. One can, however, in a larger sense designate all migrations that do not leave the limits of the Continent as internal, and contrast with them real emigration, or transfer of domicile to other parts of the globe.

Of all these manifold kinds of migration, the transmaritime alone has regularly been the subject of official statistics; and even it has been but imperfectly treated, as every student of this subject knows. The periodic emigrations of labor and the peddling trade have occasionally been also subjected to statistical investigation--mostly with the secondary aim of legislative restriction. Yet these migrations from place to place within the same country are vastly more numerous and in their consequences vastly more important than all other kinds of migration put together.

Of the total population of the kingdom of Belgium there were, according to the results of the census of December 31, 1880, not less than 32.8 per cent who were born outside the munic.i.p.ality in which they had their temporary domicile; of the population of Austria (1890), 34.8 per cent.

In Prussia, of 27,279,111 persons, 11,552,033, or 42.4 per cent, were born outside the munic.i.p.ality where they were domiciled. More than two-fifths of the population had changed their munic.i.p.ality at least once.

If we call the total population born in a given place and domiciled anywhere within the borders of the country that locality's _native_ population, then according to the conditions of interchange of population just presented the native population of the country places is greater than their actual population; that of the cities, smaller.

A balancing of the account of the internal migrations in the grand duchy of Oldenburg gives the cities a surplus, and country munic.i.p.alities a deficit, of 15,162 persons. In the economy of population one is the complement of the other, just as in the case of two brothers of different temperament, one of whom regularly spends what the other has laboriously saved. To this extent, then, we are quite justified from the point of view of population in designating the cities man-consuming and the country munic.i.p.alities man-producing social organisms.

There is a very natural explanation for this condition of affairs in the country. Where the peasant, on account of the small population of his place of residence, is much restricted in his local choice of help, adjoining communities must supplement one another. In like manner the inhabitants of small places will intermarry more frequently than the inhabitants of larger places where there is a greater choice among the native population. Here we have the occasion for very numerous migrations to places not far removed. Such migrations, however, only mean a local exchange of socially allied elements.

This absorption of the surplus of emigration over immigration is the characteristic of modern cities. If in our consideration of this problem we pay particular attention to this urban characteristic and to a like feature of the factory districts--where the conditions as to internal migrations are almost similar--we shall be amply repaid by the discovery that in such settlements the result of internal shiftings of population receives its clearest expression. Here, where the immigrant elements are most numerous, there develops between them and the native population a social struggle--a struggle for the best conditions of earning a livelihood or, if you will, for existence, which ends with the adaptation of one part to the other, or perhaps with the final subjugation of the one by the other. Thus, according to Schliemann, the city of Smyrna had in the year 1846 a population of 80,000 Turks and 8,000 Greeks; in the year 1881, on the contrary, there were 23,000 Turks and 76,000 Greeks. The Turkish portion of the population had thus in thirty-five years decreased by 71 per cent, while the Greeks had increased ninefold.