American poet and scientist Loren Eiseley (1907-1977) followed in a rich tradition of natural-history writers, including Gilbert White, Ralph Waldo Emerson, Henry David Thoreau, John Burroughs, and John Muir. As Andrew Angyal writes in the Encyclopedia of the Essay, "What Eiseley accomplished through his popular essays was to create an imaginative synthesis of literature and science--one that enlarged the power and range of the personal essay."
In this excerpt from "The Dream Animal," an informal study of human evolution, Eiseley relies on patterns of cause and effect to explore the mystery of the rapid emergence of the human brain.
from "The Dream Animal"*
by Loren Eiseley
Somewhere in the glacial mists that shroud the past, Nature found a way of speeding the proliferation of brain cells and did it by the ruthless elimination of everything not needed to that end. We lost our hairy covering, our jaws and teeth were reduced in size, our sex life was postponed, our infancy became among the most helpless of any of the animals because everything had to wait upon the development of that fast-growing mushroom which had sprung up in our heads.
Now in man, above all creatures, brain is the really important specialization. As Gavin de Beer, Director of the British Museum of Natural History, has suggested, it appears that if infancy is lengthened, there is a correspondingly lengthier retention of embryonic tissues capable of undergoing change.† Here, apparently, is a possible means of stepping up brain growth. The anthropoid ape, because of its shorter life cycle and slow brain growth, does not make use of nearly the amount of primitive neuroblasts--the embryonic and migrating nerve cells--possible in the lengthier, and at the same time paradoxically accelerated development of the human child. The clock in the body, in other words, has placed a limit upon the pace at which the ape brain grows--a limit which, as we have seen, the human ancestors in some manner escaped. This is a simplification of a complicated problem, but it hints at the answer to Wallace's question of long ago as to why man shows such a strange, rich mental life, many of whose artistic aspects can have had little direct value measured in the old utilitarian terms of the selection of all qualities in the struggle for existence.
When these related potentialities for brain growth began, they carried man into a new world where the old laws no longer totally held. With every advance in language, in symbolic thought, the brain paths multiplied. Significantly enough, those which are most heavily involved in the life processes, and are most ancient, mature first. The most recently acquired and less specialized regions of the brain, the "silent areas," mature last. Some neurologists, not without reason, suspect that here may lie other potentialities which only the future of the race may reveal.
†Embryos and Ancestors, rev. ed. (New York, Oxford, 1951), p. 93.
Selected Works of Nonfiction by Loren Eiseley
- The Immense Journey (1957)
- Darwin's Century (1958)
- The Firmament of Time (1960)
- The Unexpected Universe (1969)
- The Brown Wasps: A Collection of Three Essays in Autobiography (1969)
- The Night Country: Reflections of a Bone-Hunting Man (1971)
- All The Strange Hours: The Excavation of a Life (1975)
- The Star Thrower (1978)
*"The Dream Animal" by Loren Eiseley appeared in The Immense Journey, published in 1957 by Random House and currently available in a paperback edition published by Vintage Books.
