Part VI — Some Points in the History of Social Animals
I The Individual and the Race
Problem of the species in the human race—Loss of individuality in the associations of lower animals—Myxomycetes and Siphonophora—Individuality in Ascidians—Progress in the development of the individual living in a society
In the following pages I shall try to reply to the criticism on The Nature of Man that in that book I only considered the individual without thinking of the interests of society or of the race. I have been reproached for having lost sight of the truth that in the general course of evolution the interests of the individual must yield to the higher interests of the community. It was asserted, in fact, that by advising orthobiosis, that is to say, the most complete cycle of human life, ending in extreme old age, I was suggesting something to the detriment of humanity as a whole.
This objection rests on a misunderstanding which it will be interesting to clear up. I think that the complete development of the individual not only would not injure the community but would be of great advantage to it. Moreover, we must not lose sight of the fact that the individual has rights which must not be ignored.
In the attack on my theory many facts were brought forward which show that in the animal and vegetable kingdoms the individual is always sacrificed to the advantage of the race. There is no doubt as to this, and in the course of this book I have given exact facts bearing on it. I instanced plants such as the Agave and some Cryptogams which die as soon as they have reproduced; I have also spoken of the small female round worms (Nematoda) which are brutally torn in pieces and devoured by their progeny. It would be difficult to find better cases of the sacrifice of the individual to the species. The rule, however, does not apply to man, who, in this respect, stands in a special position.
Since the arrival of man, several species of animals have disappeared from the earth. Man has played a large part in the destruction of the Moa (Aepyornis) of Madagascar, the largest member of the class of birds. He destroyed the Dodo of the Island of Mauritius and Steller’s sea cow (Rhytina stelleri), a harmless relative of the Manatee, from the shores of the Aleutian Archipelago. Man is about to cause the extinction of several species of harmful carnivorous animals, such as the wolf and the bear, and possibly it will not be long before automobiles have replaced the horse, which would then become extremely rare. However, although he has destroyed so many other species, man has taken good care of himself. The progress already made by civilisation has considerably reduced our mortality. Every year, a large number of young infants are kept alive by the aid of hygiene and medicine. The decrease of war and of assassination has also played a part in maintaining the race. The position which man has acquired in the world makes it more likely that what we have to fear is too great an increase of population, and although the theory of Malthus has not been verified in all its details, it is still true that man could multiply on the face of the earth too abundantly. It is already clear that almost in the proportion that humanity stops the effusion of its blood in war, it tends to limit the propagation of the race.
As the future of the species seems to be safe, it is natural to consider in the first place that of the individual. In this respect the facts of general biology are of special interest.
Man is not the only social animal on the earth. Long before his appearance other living beings existed in organised societies. The splendid colonies of Siphonophora float on the surface of the seas, whilst in the ocean depths there are societies of corals of extraordinary variability, whilst again, on land, many kinds of insects live in highly organised societies.
This social life has been developed without external assistance, and without any code to regulate the conduct of the individuals united for a common purpose.
It will be interesting to give a slight survey of the fundamental principles of such societies; I intend to draw special attention to one of the essential points in the societies of animals, hoping to elucidate the relations between the individuals and society.
In the organisation of human society the most difficult points are the extent to which the society may encroach on the individual and the degree to which the individual may preserve his rights and his independence. Disputes on these have been interminable, and I do not propose to discuss the theories according to which an individual must be sacrificed for the good of the community to which he belongs. I shall limit myself to reviewing the fate of the individuals in societies of beings much inferior to man.
There are examples of societies composed of many individuals, even amongst living things on the borderland between the animal and vegetable kingdoms.
| Fig. 21.—Isolated individuals of a Myxomycete. (After Zopff.) a, spore; b-f, escape of the zoospores. | Fig. 22.—Myxomycete individuals united to form a plasmodium. (After Zopff.) |
There may be found in woods, on dead leaves or on decaying timber, minute plants resembling tiny mushrooms. These are Myxomycetes, and the visible portions are minute sacs filled with microscopical rounded bodies, known as spores. When one of the spores is moistened, there emerges a minute organism with a mobile appendage by which it can be impelled through water. A drop of water on a leaf or on a fragment of timber may be filled with numbers of these tiny swimming bodies (Fig. 21). Their free life as individuals, however, is of brief duration. When they come into contact, their bodies fuse, forming a gelatinous mass which may be quite large (Fig. 22). This mass is called a plasmodium, and is composed of a living substance which can move slowly over leaves and which exhibits streaming movements in the interior, so that the whole resembles in some respects the lava from a volcano.
The plasmodia may be regarded as societies in the constitution of which the individuality of the members has been completely sacrificed. The ideal of those philosophers who have urged that man should renounce his individuality and merge himself in the community has been realised in the fullest way at the lower end of the scale of life, at an epoch inconceivably remote from the appearance of the human race.
Amongst animals, even the most lowly, there are no societies in which the members are sacrificed so completely to the whole. Individuality is always preserved to a greater or lesser extent. Consider the polyps, colonies of which form reefs in the sea and may even become islands. These creatures live in aggregations, the members of which are incapable of living an independent life. They are united by living substance and resemble double monsters, such as Doodica and Radica, who were so much talked of some years ago when M. Doyen operated upon them. The peritoneal cavities of these twins were in free communication, and the blood-vessels were united so that the blood of the one passed freely into the body of the other. In another double monster, the two Tscheck girls, Rosa and Josepha, the intestinal tracts communicate, both leading to a common rectum. In these, who are still alive, the peritoneum is joined and there is a single urethra.
In the case of the coral polyps, the fusion of the individuals of the colony is nearly always much more complete. Each individual has its own mouth and stomach, whilst the other organs cannot be assigned to individuals but must be regarded as common to the whole.
In the swimming polyps or Siphonophora, the loss of individuality is still more remarkable. These graceful and transparent creatures, sometimes large in size, live in the sea and may appear on its surface in great numbers. They possess many whip-like filaments provided with tentacles, swimming bells and stomachs. There can be no doubt as to their colonial nature (Fig. 23), but it is difficult to decide as to whether each piece of the colony, each swimming bell, stomach and so forth, is to be regarded as an individual or an organ, different zoologists having taken different views on the question. One interpretation is that colonial life has brought with it such modifications that of each individual there remains only a single organ. Some individuals have been reduced to simple stomachs, attached to the central stem, whilst others have lost all organs except that of locomotion which has become one of the swimming bells of the colony. Other zoologists, and I myself amongst them, think that the Siphonophora are colonies of organs in which there has been as yet practically no development of individuality. A living chain of Siphonophora is simply a number of organs such as stomachs, tentacles, swimming bells and so forth, united on a common stem. I need not discuss the disputed point further, for the only matter pertinent to my argument is that in the Siphonophora the loss of individuality, the sacrifice of the parts to the whole, is not so great as in the Myxomycetes.
In support of my view, I must recall the small forms of Siphonophora known as Eudoxia. These are detached pieces of the common trunk which swim freely in the sea and have a remarkable structure (Fig. 24). Their mobility is due to a bell provided with strong muscular fibres. The bell is a portion of an individual which possesses organs of reproduction but which is devoid of the means to capture or digest food. These two functions are performed by a second individual which is closely united with the first. The nutrient individual has a long tentacle by which the prey is captured, and a capacious stomach in which it is digested. The products of digestion pass by channels into the reproductive individual, carrying as it were a ready-made blood. Eudoxia in fact is a double being composed of an individual incapable of locomotion or of reproduction, but adapted for prehension and digestion, and of a second individual which can reproduce and which is mobile. Eudoxia is an association resembling that of the blind man and the paralytic, in Florian’s fable.
| Fig. 24.—Eudoxia. (After Chun.) | Fig. 25.—Botryllus colonies. o, mouth; A, common cloaca. |
Advance in the organisation of social animals is plainly incompatible with complete loss of individuality, and this becomes the more apparent the higher we reach in the scale of life. In the social Ascidians, each member retains all the organs necessary to life. Animals of the genus Botryllus (Fig. 25), perhaps the most interesting of these Ascidians, occur in the form of circular colonies. The individuals which compose the colony are grouped radially around a common centre which is occupied by the cloaca. Each individual has its own mouth and digestive tube, but the latter opens into a cloaca, common to all the individuals, by which the excreta are voided. There is, in fact, a single anus, as in the case of Rosa and Josepha which I have just mentioned.