Nature

Classical science assumed that objectivity depended upon the separation of the knowing observer from the world of nature. Charles Darwin's (1809–1882) theory of evolution upset that assumed separation forever, reinserting humankind into a cognizable view of nature. Darwin's penetrating insights into the nature of our own humanity—and the importance of language—are effectively a Copernican revolution in our self-understanding of the idea of nature itself. Humankind can no longer be thought of as separate from the cognizable world picture. The status of humankind as something apart from, rather than a part of, nature becomes, after Darwin, increasingly incomprehensible (consider, for example, Werner Heisenberg [1901–1976], who makes clear that not only are humans embedded within biophysical systems but that our observations themselves profoundly color what can be known).

As with Newton, so with Darwin's precursors, who framed the stage upon which he stood. First, the work of scientists in disparate disciplines, such as geology and paleontology, combined with Darwin's work in natural history, led to what can be termed the discovery of time in four crucial dimensions, beginning with geological time. Irish Archbishop James Ussher (1581–1656) had calculated the age of the Earth, based on biblical interpretation, as no more than 6,000 years. Charles Lyell (1797–1875) heralded the arrival of a scientifically informed grasp of the enormity of geological time. Lyell's theory of very slow but uniform change in the Earth upset the dominant theory of catastrophism—the notion of a ruined Earth as God's punishment for sin. Geological inquiry expanded the notion of time over almost unimaginably large temporal scales: Ussher's estimate was off by nearly six magnitudes.

Second, paleontology disclosed through the discovery of successive layers of the fossil record a continual transformation of the forms of life. The natural world could no longer be rationally understood as frozen into eternal forms, but only as a ceaseless flux. The work of Georges Cuvier (1769–1832) drew in part from the geological law of superposition. Fossilized life forms found in lower strata were necessarily older than those lying above. Cuvier also observed that the various strata themselves had characteristic life forms, suggesting a coming and going of great epochs of life.

Third, Darwin's own studies made clear that the process of natural selection had not only shaped but continued to shape the flora and fauna. His five-year voyage on the HMS Beagle provided the data that were soon interpreted as evidence for natural selection over biological time. The adaptive radiation manifest in his famous finches, whose beaks illustrated the evolutionary diversification of forms through adaptation, became an exemplary case study. While Darwin lacked any knowledge of the genetic basis for inheritance of advantageous characteristics, discovered by Gregor Mendel (1822–1882), he clearly understood that natural selection was governed by the principle of survival of the fittest—an idea that the economist Thomas Malthus (1766–1834) had developed in relation to human populations.

Finally, near the end of the century, archeologists discovered the Paleolithic strata, a clear record of cultural transformation as successive generations of humans adapted their lives to the natural world. However dimly, these discoveries coalesced in a dawning awareness that humankind is a naturally evolved species that has moved into culture—a symbolically mediated space from where nature is increasingly and continuously theorized. The ongoing inquiries of prehistoric archeology and paleoanthropology have fundamentally changed both the ways we think of ourselves and our ideas of nature.