Before Darwin
Would it be too bold to imagine, that in the great length of time since the earth began
to exist, perhaps millions of ages before the commencement of the history of man-
kind, . . . that all warm-blooded animals have arisen from one living filament, which
THE GREAT FIRST CAUSE endued with animality, with the power of acquiring new
parts, attended with new propensities, directed by irritations, sensations, volitions
and associations, and thus possessing the faculty of continuing to improve by its own
inherent activity, and of delivering down those improvements by generations to its
posterity!
—Erasmus Darwin, ZoonomiaAlthough Charles Darwin (fig. 4.1) deserves most of the credit for bringing about the
scientific revolution in biology, he was by no means the first to suggest that life had changed
through time. As early as the fifth century B.C.E., Greek philosophers such as Empedocles
promoted the idea that life is constantly transforming. In 50 B.C.E., the Roman philosopher
Lucretius wrote the poem De rerum naturae (“On the nature of things”), which postulated
the existence of atoms and argued that everything in nature was in flux. With the fall of the
Roman Empire, however, this bold style of thinking was suppressed by church orthodoxy,
and the Genesis account of earth and life history ruled for almost 1,300 years. By the early
1700s, most people in Europe and North America still believed in a literal interpretation of
the Bible and in the idea that the earth had been formed about 6,000 years ago, with no fur-
ther change except for decay and corruption due to the sins of Adam and Eve.
During the next century, however, it became increasingly difficult to reconcile the Gen-
esis accounts of the origin of earth and life with the expanding knowledge of nature. As
we discussed in chapter 3, the discovery of faunal succession between 1795 and 1805 made
Noah’s flood explanations of geology more and more implausible. By 1840 flood geology
had been abandoned altogether by devout Christian geologists. By the mid-1700s, natu-
ral historians like Linnaeus and his successors had already recognized over 6,000 species
of animals and many more plants, far too many to squeeze into Noah’s ark. At the same
time, exploration of exotic places—Africa, South America, Australia, and Southeast Asia—
was producing still more new species previously unknown to Europeans, and the ark story
became ludicrous. Instead of showing a pattern that reflected dispersal from Mount Ararat
in Turkey, the distribution of animals showed a completely nonbiblical pattern. There were
many biogeographic puzzles, like the fact that many islands (such as New Zealand, Mada-
gascar, and Hawaii) were inhabited by unique species not found anywhere else on earth or
the fact that Australia was dominated by peculiar beasts such as the egg-laying platypus
and the pouched marsupials but had no native placental mammals. Why had nothing but
marsupials migrated from Mount Ararat to Australia?