A Brief History of Biology: Before 1900

Origins of Biological Thought

Biology begins in practical medical intervention, the knowledge of which was already pursued and handed down orally in prehistoric societies in many different places and times. The pharmacopoeia (“ethnobotany”) compiled by untold generations of shamans and healers, both male and female, is without a doubt the best-known form of such traditional medical knowledge. However, the early forms of surgical intervention apparent from the archaeological record—from the setting of bone fractures to tooth extraction to trepanning—are also of interest.

With the advent of settled life and ultimately the invention of writing, the kinds of medical knowledge possessed by different cultures became more diversified, while at the same time the potential for the cross-fertilization of geographically and linguistically distinct cultures by each other’s knowledge and practices was vastly increased. Thus, one can trace a more or less steady development of Western medical thought and practice stretching from ancient Egypt, to the Mesopotamian civilization, to the fifth-century Greek body of writings known as the Hippocratic Corpus, where the systematic observation of the characteristic course of various diseases—and their response to diverse remedies—first achieves a recognizably scientific status. (It should be noted that the ancient Indian and Chinese medical traditions are also of considerable interest, though we have no space to explore them here.)

With the advent of the Greek “nature philosophers” (physiologoi) in the sixth century BC, empirical medicine and theoretical reflection upon the nature of living things began to go their separate ways, although a considerable amount of interaction between the two traditions always continued to occur. On the one hand, ancient Greek medicine gradually developed its own distinctive theoretical perspective on health and disease based on the concept of a necessary balance among the four “humors” of the body, while, on the other, some philosophers—notably, Aristotle of Stagira (384–322 BC)—also engaged in detailed empirical observation.

Later important milestones in the Western medical tradition include the anatomists Herophilos and Erasistratus (third century BC); the Greek physician Galen (second century AD); the great Persian philosopher-physician Avicenna (eleventh century AD); the Flemish anatomist Andreas Vesalius (sixteenth century); and the famed English physician William Harvey , whose discovery of the circulation of the blood was published in 1628, on the threshold of the Scientific Revolution. After Harvey, the medical discoveries come thick and fast, and are too numerous to mention here individually.

Aristotle and Teleology

At this point, the empirical-medical and the theoretical-philosophical traditions rejoin to a significant extent. For this reason, there is little need to examine the separate tradition of philosophical reflection upon the subject of life during Antiquity and the Middle Ages—except with respect to one individual. No account of the history of biology would be complete without acknowledgment of the preeminent role played by Aristotle’s theoretical work in biology, particularly his notion that living things are characterized by “final” causes (from the Latin for “end,” in the sense of “object” or “aim”)—that is, that organisms are purposively, or “teleologically,” organized such that the parts act for the sake of the whole. The locus classicus of this claim is the passage (Parts of Animals I.1; 641a6–14) where he shows the absurdity of supposing even a sculpted hand could be created by random blows from an adze, much less a living hand by any similarly random means.

The historical importance of the problem of teleology for all subsequent biological inquiry—even up until the present day—can scarcely be exaggerated. Many (though not all) of the seventeenth-century founders of the Scientific Revolution wished to extirpate final causes from philosophy and science, replacing them with “material” and “efficient” (that is, mechanical) causes alone. A good example is René Descartes (1596–1650), who described animals, including man, as pneumatic mechanisms similar in their operation to the elaborate mechanical clocks and toys of his day. On the other hand, a little later Francesco Redi (1626–1697) showed conclusively that all living things derive from other living things, thus disproving the theory of “spontaneous generation”—the idea that lower organisms can spring directly from inorganic matter—thus demonstrating that life has a special status not yet understood.

The Mechanistic Philosophy

In the long run, however, Redi’s experiments did little to stem the mechanistic tide, which soon rose to heights unimagined by Descartes himself. As is well known, in his own writings the French father of modern philosophy retained the hypothesis of a human soul entirely separate from the mechanical body. However, a century later this sort of half-measure would be utterly rejected by the philosophes of the French Enlightenment. One of the most aggressive of these was Julien Offray de La Mettrie (1709–1751), whose principal work—L’Homme-Machine [Machine-Man], published in 1747—announced its materialistic philosophy in its title.

During the nineteenth century, a school of “scientific materialists” arose in Germany, whose members—notably, Carl Vogt (1817–1895), Ludwig Büchner (1824–1899), and Jacob Moleschott (1822–1893)—were physiologists-turned-philosophers. Their central doctrine may be summarized by their notorious maxim: “the brain secretes thought like the liver secretes bile and the kidneys secrete urine.”

On the other hand, natural philosophers, experimental biologists, and practicing physicians, who had serious reservations about, or rejected, the purely mechanical view of life, were never wholly banished from the scene. Indeed, some of the most distinguished biologists of the eighteenth and nineteenth centuries—for example, Albrecht von Haller (1708–1777), who did pathbreaking research on the innervation of the muscles and organs; Xavier Bichat (1771–1802), a pioneering histologist; Karl Ernst von Baer (1792–1896), who first described the mammalian ovum; and Gustav Fechner (1801–1887), one of the founders of psychophysics—all believed that efficient causes had to be supplemented by something like final causation if living things were to be properly understood. (The controversy between mainstream materialistic-mechanistic biologists and those who sought to retain some place for final causes continued into the 20th and 21st centuries, creating controversies that will be discussed in the appropriate places.)

The Microscope and the Cell Theory

There are limits to the knowledge that can be gleaned about living things through naked-eye observations and experiments. For this reason, the advance of experimental biology was greatly promoted by the invention and improvement of the microscope—notably, by Antonie van Leeuwenhoek (1632–1723), who first revealed an entire, hitherto-unsuspected world of living beings invisible to the naked eye (“animalcules”).

Another outstanding breakthrough made possible by the microscope is the “cell theory of life”—that is, the discovery, principally by Matthias Jakob Schleiden (1804–1881) and Theodor Schwann (1810–1882), that all living things are composed of cells. In 1858 Rudolf Virchow (1821–1902) supplemented the Schleiden-Schwann cell theory with the principle “omnis cellula e cellula” [every cell from a cell], thus confirming through careful observations at the microscopic level Francesco Redi’s refutation of spontaneous generation two centuries earlier (see above). Among the many other remarkable advances during the nineteenth century made possible by better microscopes, the science of microbiology was placed at last upon a firm scientific foundation by Louis Pasteur (1822–1895), Robert Koch (1843–1901), and others.

During this same period, general advances in the knowledge of chemistry, as well as new methods of chemical analysis, proved to be of capital importance, as well, contributing to the explosion of knowledge in such fields as anatomy and physiology. The German-speaking lands took the lead here. For example, in 1828 Friedrich Wöhler (1800–1882) synthesized the organic molecule urea by purely abiotic means, a feat which contributed greatly to the growing materialistic interpretation of life.

Other important advances in the understanding of physiology during the nineteenth century were made by Johannes Peter Müller (1801–1858), Justus von Liebig (1803–1873), Ernst Wilhelm von Brücke (1819–1892), Emil du Bois-Reymond (1818–1896), and many others. In France, the great experimental physiologist, Claude Bernard (1813–1878), established the doctrine of the “internal environment” of the organism (later called “homeostasis”).

The Rise of Evolutionary Thinking

In addition to the question of the material composition and operation of myriad kinds of living things, there remained the question of their origin, affiliations, and transformation. With respect to origins, there was little that could be said. Charles Darwin (1809–1882) himself was reduced to speculating that life may have begun in “a warm little pond” somewhere—an idea that would be dubbed the “primordial soup” theory in 1929 by the British biologist J. B. S. Haldane (1892–1964).

Regarding affiliation, much light was thrown on this question by the great Swedish botanist and zoologist, Carl Linnaeus (1707–1778), who invented the binomial classification system we still use today.

As for the question of transformation—or what we now call evolution—the Greek nature philosopher Empedocles of Akragas (fifth century BC) already speculated about the possibility of random recombinations of phenotypic features giving rise to new types of animals. The idea of biological transformation was revived in modern times during the eighteenth century by a number of authors, notably the Georges-Louis Leclerc, Comte de Buffon (1708–1788), whose theory took the form of “decadence” (i.e., regressive, not progressive, change). Inverting Buffon’s conception was the obvious next step, and it was taken by several thinkers, including Erasmus Darwin (1731–1801; Charles’s grandfather), Jean-Baptiste Robinet (1735–1820), Jean-Baptiste Lamarck (1744–1829), and Étienne Geoffroy Saint-Hilaire (1772–1844), not to mention the Scottish publisher, Robert Chambers (1802–1871), whose sensationally written Vestiges of the Natural History of Creation, published anonymously in 1844, became the talk of polite society in England.

When Charles Darwin published his own ideas in 1859 in his Origin of Species, then, his original contribution consisted not so much in the idea of transformation (evolution) itself, as in his proposed mechanism of natural selection by which to explain it—a crucial distinction that is too-often lost sight-of even in contemporary debates surrounding evolution. Moreover, Darwin knew nothing of genetics. Therefore, his speculations about the means by which novel traits might be introduced into populations were just that—idle speculations.

The two main laws of inheritance in sexually reproducing organisms (“segregation” and “independent assortment”) were established by the Austrian monk Gregor Mendel (1822–1884) through his rigorous experiments on garden peas. An uncut complimentary copy of the 1866 journal article announcing his historic discoveries was found among Darwin’s effects after his death.