Woodhead has suggested the term complementary association to denote a community of species that live together in harmony, because their rhizomes occupy different depths in the soil; for example, he described an "association" in which Holcus mollis is the "surface plant," Pteris aquilina has deeper-seated rhizomes, and Scilla festalis buries its bulbs at the greatest depth. The photophilous parts of these plants are "seasonably complementary." The opposite extreme is provided by competitive associations, composed of species that are battling with each other.
2. Ant Society[85]
There is certainly a striking parallelism between the development of human and ant societies. Some anthropologists, like Topinard, distinguish in the development of human societies six different types or stages, designated as the hunting, pastoral, agricultural, commercial, industrial, and intellectual. The ants show stages corresponding to the first three of these, as Lubbock has remarked.
Some species, such as Formica fusca, live principally on the produce of the chase; for though they feed partially on the honey-dew of aphids, they have not domesticated these insects. These ants probably retain the habits once common to all ants. They resemble the lower races of men, who subsist mainly by hunting. Like them they frequent woods and wilds, live in comparatively small communities, as the instincts of collective action are but little developed among them. They hunt singly, and their battles are single combats, like those of Homeric heroes. Such species as Lasius flavus represent a distinctly higher type of social life; they show more skill in architecture, may literally be said to have domesticated certain species of aphids, and may be compared to the pastoral stage of human progress—to the races which live on the products of their flocks and herds. Their communities are more numerous; they act much more in concert; their battles are not mere single combats, but they know how to act in combination. I am disposed to hazard the conjecture that they will gradually exterminate the mere hunting species, just as savages disappear before more advanced races. Lastly, the agricultural nations may be compared with the harvesting ants.
Granting the resemblances above mentioned between ant and human societies, there are nevertheless three far-reaching differences between insect and human organization and development to be constantly borne in mind:
a) Ant societies are societies of females. The males really take no part in the colonial activities, and in most species are present in the nest only for the brief period requisite to secure the impregnation of the young queens. The males take no part in building, provisioning, or guarding the nest or in feeding the workers or the brood. They are in every sense the sexus sequior. Hence the ants resemble certain mythical human societies like the Amazons, but unlike these, all their activities center in the multiplication and care of the coming generations.
b) In human society, apart from the functions depending on sexual dimorphism, and barring individual differences and deficiencies which can be partially or wholly suppressed, equalized, or augmented by an elaborate system of education, all individuals have the same natural endowment. Each normal individual retains its various physiological and psychological needs and powers intact, not necessarily sacrificing any of them for the good of the community. In ants, however, the female individuals, of which the society properly consists, are not all alike but often very different, both in their structure (polymorphism) and in their activities (physiological division of labor). Each member is visibly predestined to certain social activities to the exclusion of others, not as a man through the education of some endowment common to all the members of the society, but through the exigencies of structure, fixed at the time of hatching, i.e., the moment the individual enters on its life as an active member of the community.
c) Owing to this pre-established structure and the specialized functions which it implies, ants are able to live in a condition of anarchistic socialism, each individual instinctively fulfilling the demands of social life without "guide, overseer, or ruler," as Solomon correctly observed, but not without the imitation and suggestion involved in an appreciation of the activities of its fellows.
An ant society, therefore, may be regarded as little more than an expanded family, the members of which co-operate for the purpose of still further expanding the family and detaching portions of itself to found other families of the same kind. There is thus a striking analogy, which has not escaped the philosophical biologist, between the ant colony and the cell colony which constitutes the body of a Metazoan animal; and many of the laws that control the cellular origin, development, growth, reproduction, and decay of the individual Metazoan, are seen to hold good also of the ant society regarded as an individual of a higher order. As in the case of the individual animal, no further purpose of the colony can be detected than that of maintaining itself in the face of a constantly changing environment till it is able to reproduce other colonies of a like constitution. The queen-mother of the ant colony displays the generalized potentialities of all the individuals, just as the Metazoan egg contains in potentia all the other cells of the body. And, continuing the analogy, we may say that since the different castes of the ant colony are morphologically specialized for the performance of different functions, they are truly comparable with the differentiated tissues of the Metazoan body.