Man in the Landscape: A Historic View of the Esthetics of Nature

CHAPTER ONE: THE EYE

Chapter One THE HUMAN—the vertebrate—eye originated in the sea. Its basic structure is the same for all vertebrates, the most primitive of which are aquatic. When it is compared to eyes invented in the air, such as those of the insects, the differences are enormous; compared to eyes independently invented in the sea, such as those of the squids, the similarities are astonishing . An important difference between the sea eye and the land eye is the number of chambers, being multiple in the latter and single in the former. The single-chambered eye is apparently more effective in the murky, homogeneous, threedimensional world of the sea. The flicker effect, which seems to be the advantage of the multiple ommatidia of the insect eye, is unnecessary in the sea, where, even on the bottom, light and dark are blurred in a universal penumbra, a gentle uniformity where total light gathering rather than flickering contrast is important. With some slight additions and modifications, especially in the external protective structures and the size and shape of the lens, the vertebrates carried this eye onto the land. It was a very good eye, and was further perfected by terrestrial quadrupeds, probably both the amphibian labyrinthodonts and reptilian therapsids, before it came to the first of the mammals. But it was debased by the early mammals as The Eye ( 4 ) MAN IN THE LANDSCAPE excess baggage in their nocturnal lives and underground ways. Then certain of these insectivore-like creatures shifted back to daylight activity. Tree shrews have sharp eyes and may be very similar to the ancestors of the Primate order, to which lemurs, monkeys, apes, and man belong. One, the Philippine tree shrew, is diurnal, nervous, fussy, intelligent, inquisitive, omnivorous, clean, and nimble of forefoot. It has binocular vision, a round pupil, color vision, expressive eyes, and even humanlike ears. Some authorities think it is actually a primate, and it is indeed disconcerting to see these humanlike traits in a creature so much more primitive than a monkey. Of all the mammals—some eighteen orders—the primates are almost alone in their seventy-million-year struggle to re-establish the primacy of vision. They have returned it to the daylight and built their lives around it, reinvented color vision, and made other improvements. Could this have happened with a compound eye and could it have been carried into the trees? To it the world is a mosaic with sharp partitions like the glue between hexagonal ceramic tiles. Then could it have provided the flexibility to be coordinated with the use of hands? Our thoughts are teased by the consequences of a rebuilt sea eye on the delicate ego of a grounded primate, or, more exactly, the role of a salvaged reptilianamphibian -ichthyoform eye in making the man. It is impossible to say whether good eyes or arboreality came first. What the "bottleneck" mammals, scrounging a living at night through the mid-Mesozoic, bequeathed to the primate ancestors was probably not much better than the dim little brown orbs of the modern ground shrews, the wasted remains of the elegant structures of the reptilian forerunners. Night eyes need not be degenerate if the animal remains eye-minded, as did the cat, owl, and tarsier; but near the ground or under it, where food is but fat grubs and crunchy roaches, there is no visual imperative. The smallness of the eye is itself a weakness, as it contains fewer sensory cells. And in the night eye these are entirely rods, the type of receptor functioning in dim light, their communication to the The Eye ( 5 ) brain pooled by neural connections so that the message is "summated" and the ultimate picture coarse and colorless. The first arboreal pre-primate forms may have clambered up trees at night as though following vertical trails. If so, these were "nosy" animals who rediscovered the use of vision only after electing to remain in trees. An animal heavily dependent on the sense of smell is a good candidate for the progenitor of a brainy one relying on sight, as a "braininess" specifically means elaboration of the cerebrum of the forebrain , whose enlargement was begun for the receiving, mixing , analyzing, and storing of information from the nose. The combination of ground and tree life, or even of traveling on the vertical and horizontal trails of tree trunks and branches, is a kind of re-entry of the...