Until the advent of modern times, a State of Nature was conceived, in Hobbes' famous words, as "a condition of war of everyone against everyone'. Individuals fought for food, land and sexual partners. As society developed, social relations came to be governed by ethical principles, typified by the Golden Rule: "Do as you would be done by'. Modern human societies have steadily expanded the scope of ethics. In Ancient Greece, slaves could be treated like farm animals:
When the God-like Odysseus returned from the wars in Troy, he hanged all on one rope a dozen slave-girls of his household whom he suspected of misbehaviour during his absence. (Leopold, 1970)
They were his property, to be disposed of as he wished. Until the mid-twentieth century, the progress of civilization had been marked by the taming of nature. The above quotation comes from a forester, Aldo Leopold, who argued that just as ethical principles were extended to women and slaves, the time had come for ethics to be extended to plants and animals. The principle became known as the Land Ethic, on the ground that land is no longer a type of property that can be maltreated at will. Proponents hold that we have no more right to kill songbirds than we do slaves; no more right to destroy wildlife habitats than we do nations. Carried to an extreme, this principle would prevent agriculture, gardening and human life. In moderation, it commands ever-wider support.
In areas of natural or semi-natural habitat, application of the Land Ethic is straightforward: new plant communities should be similar or identical to pre-development habitats. This applies, for example, when a new road is built through the mountains. Road embankments are made to resemble existing slopes; road verges, which used to be mown like private gardens, are now managed like wildlife habitats.
In agricultural areas, a policy of similarity or identity is less applicable. If a road embankment is to be made where the pre-development condition was a potato field, there are two choices. New embankments could be treated as potato fields; or they could be returned to a pre-agricultural condition. The latter policy would be implemented by leaving the land bare of vegetable soil. In time, the subsoil would become colonized and a new habitat would develop without human intervention. This would result in a road verge that is entirely different from its present surroundings, though similar to its "uncivilized' condition.
In urban areas, the contextual problem takes another form. Staying with the above example, there are many places where new roads with vegetated embankments have been driven through existing towns. As the old habitat was garden, Similarity and Identity policies, which are so obviously right in the mountains, would lead to embankments being treated as garden space. This is often done, but the policy is increasingly unpopular. Town dwellers feel isolated from nature and yearn for contact with the wild flowers and animals that they see on TV programmes and read about in nature books. To satisfy this desire, and to comply with the Land Ethic, a good case can be made for a large-scale habitat re-creation policy in towns. Information on pre-urbanization habitats can be obtained from several sources: pollen analysis; study of vestigial habitats; historical records; analysis of soil and water conditions; comparisons with similar environments outside towns. This information makes possible the production of Habitat Potential Maps, which can show, for example: heathland, oak--birch wood; acid grass, marsh (Figure 9d). When a new road is pushed through the town, or new public open space is created, landscape architects can consult these maps and set about re-creating pre-urban habitat conditions.