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A less-known example of such an association is the flatworm Convoluta roscoffensis, which lives on the beaches of Normandy, rising to the surface while the tide is low to permit the algae in its tissues to carry on photosynthesis in the sunshine, then retiring into the sand to avoid being washed away by the rising tide. The colorless newly hatched Convoluta eats with its mouth like other flatworms; but soon motile green algae invade its body; its mouth closes; its excretory organs degenerate; it becomes wholly dependent for nutrition upon its algal associates, which in turn appear to use its waste products as a source of nitrates. However, these plant-animals are not self-perpetuating organisms; the algae lose the ability to reproduce, with the result that each new generation of worms is infected by algae that have hitherto remained independent.

On the wider view, the chief interest of carnivorous plants is as examples of life's versatility, its improbable or paradoxical developments. The compromise of nutritional self-sufficiency to become partly dependent upon animal food has contributed little to the success of plants. The carnivorous species are a very minor component of the vegetable kingdom; their disappearance from Earth would hardly be noticed by anyone except a few botanists with special interests. Not by (so to speak) imitating one another but by stubbornly retaining the outstanding attribute of eachthe synthetic capacity of green plants, the mobility of animalsdo these two major branches of the living world enter into the most fruitful associations. By pollinating their flowers or dispersing their seeds, animals recompense plants for foods that sustain them. To this interchange of benefits we owe not only a large part of nature's beauty, including the loveliness of flowers and the brilliance of many birds and butterflies, but the integrity of biotic communities.

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7

Three Biological Heresies

A science, like a religion, develops an orthodoxy, and those whose thought diverges from it become heretics. Although in the present age they are not likely to be burned at the stake or forced by torture to recant, they can be penalized in various ways. Editors of scientific journals may reject their contributions; reviewers censure their books; universities are reluctant to give them professorships. Nevertheless, the scientific heretics of one age may become the revered pioneers of a later age. When astronomical orthodoxy favored a geocentric universe, Copernicus was a heretic whose book was not published until he lay dying. When biological orthodoxy supported the fixity of species, Darwin was a heretic who hesitated to promulgate his theory of evolution until prompted to do so by receipt of a paper, expounding similar ideas, that Alfred Russel Wallace sent to him from the East Indies. Among the biological heresies of our day are anthropomorphism, teleology, and intergroup selection. Anthropomorphism makes unproved assumptions about the psychic life of animals. Teleology, the doctrine that nature strives toward predetermined ends or goals, is rejected because mutations are random and the agents of selection, chiefly predation, disease, starvation, and climatic extremes, care not at all for the welfare of a species. Intergroup selection is in disfavor because individuals, rather than families or groups, are primarily screened by natural selection.

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Anthropomorphism

Anthropomorphic means humanlike in form. Most of humankind's gods have been more or less anthropomorphic, often revoltingly so. In zoology, anthropomorphism is the ascription of human characteristics to animals. The literal meaning of the word, derived from the Greek nouns anthropos (human being, man) and morphe (form) would lead one to conclude that it refers to the physical configuration of nonhuman animals rather than to their psychic qualities. To point out that the bones of a bird's wing correspond closely to those of a human arm and hand