And in the ages after monsters died,
Perforce there perished many a stock, unable
By propagation to forge a progeny.
For whatsoever creatures thou beholdest
Breathing the breath of life, the same have been
Even from their earliest age preserved alive
By cunning, or by valour, or at least
By speed of foot or wing. And many a stock
Remaineth yet, because of use to man . . .
Lucretius. On The Nature of Things, Book V
We can't showcase the entire spectrum and long history of the scientific thought of the ancient world. This exhibit is simply intended to point out some currents within ancient thought that foreshadowed later developments in evolutionary biology.
Evolutionary theory begins with the Ionian philosopher Anaximander (ca. 611 - 546 B. C. E.). Very little is known about his life, but it is known that he wrote a long poem, On Nature, summarizing his researches. This poem is now lost, and has survived only in extracts quoted in other works. Enough survives, however, that Anaximander's thought can be reconstructed with some confidence. For Anaximander, the world had arisen from an undifferentiated, indeterminate substance, the apeiron. The Earth, which had coalesced out of the apeiron, had been covered in water at one stage, with plants and animals arising from mud. Humans were not present at the earliest stages; they arose from fish. This poem was quite influential on later thinkers, including Aristotle.
Had Anaximander looked at fossils? Did he study comparative fish and human anatomy? Unfortunately, we have no way of knowing what evidence Anaximander used to support his ideas. His theory bears some resemblance to evolutionary theory, but also seems to have been derived from various Greek myths, such as the story of Deucalion and Pyrrha, in which peoples or tribes are born from the Earth or from stones. His concept of the apeiron seems similar to the Tao of Chinese philosophy and religion, and to the "formless and void" Earth of the Hebrew creation account and other creation myths. However, even though Anaximander's ideas drew on the religious and mythical ideas of his time, he was still one of the first to attempt an explanation of the origin and evolution of the cosmos based on natural laws.
In the 6th century B.C.E. Xenophanes of Colophon (died ca. 490 B.C.E.), who was a disciple of Anaximander, developed Anaximander's theories further. He observed fossil fishes and shells, and concluded that the land where they were found had been underwater at some time. Xenophanes taught that the world formed from the condensation of water and "primordial mud;" he was the first person known to have used fossils as evidence for a theory of the history of the Earth.
The Greek historian Herodotus (484-425 B.C.E.) also observed fossil shells in Egypt, and cited them as evidence that Egypt had once been underwater. He also described a valley in Arabia, in the Mokattam mountains, where he saw "the backbones and ribs of such serpents as it is impossible to describe: of the ribs there were a multitude of heaps. . . " He ascribed these bones to winged serpents that had been killed by ibises. We now know that these are the bones of fossil mammals that wash out of the rocks every rainy season. Several other ancient historians briefly mentioned fossils in their writings. Finally, the famous Greek physician Hippocrates of Cos (460-357 B.C.E.) is known to have collected fossils; in fact, modern excavations at Asklepion, the famous medical school of Hippocrates's day, unearthed a fragment of a fossil elephant molar.
Another Greek philosopher, the fifth-century materialist Empedocles of Acragas (in Sicily), postulated that the universe was composed of four basic elements -- earth, air, fire, and water. These elements were stirred by two fundamental forces, which Empedocles called Love and Strife. ("Attraction" and "repulsion" might be better modern terms for what Empedocles actually meant.) The constant interplay of these elements, alternately attracting and repelling each other, had formed the universe. Empedocles claimed that the Earth had given birth to living creatures, but that the first creatures had been disembodied organs. These organs finally joined into whole organisms, through the force of Love, but some of these organisms, being monstrous and unfit for life, had died out.
The theory seems a bit bizarre today, but Empedocles had come up with a sort of evolutionary theory: past natural selection is responsible for the forms we see today. Empedocles also ascribed the origin of the life of today to the interplay of impersonal forces, in which chance, not the gods, played the major role. There are, however, major differences between Empedocles's ideas and natural selection in the modern sense: Empedocles conceived of his "natural selection" as a past event, not as an ongoing process. Once again, we do not know whether Empedocles had actually found supporting evidence for his theories. He may have been influenced by existing accounts of mythological creatures that seemed to be "put together" out of the parts of different animals, such as centaurs, sphinxes, and chimeras. But perhaps he had also seen deformed animals, or examined "monstrous-looking" fossil bones.
Much later, the Roman poet and philosopher Titus Lucretius Carus (99-55 B.C.E.) wrote his long philosophical poem De Rerum Natura ("On the Nature of Things"). In this poem Lucretius proposed, among other things, an "evolutionary" theory similar to that of Empedocles (which is ironic, because he attacks Empedocles rather vehemently in other parts of the poem). Here again, species were born out of the Earth, formed by the chance combination of elements. Natural selection led to the extinction of once-living "monstrous" organisms. Those organisms that survived either survived because of their strength, speed, or cunning, or because of their usefulness to people. But Lucretius did not believe in the production of new species from previously existing ones, the "other side of the coin" of true evolutionary theories. He denied that land-dwelling animals could ever have evolved from marine animals. Like Empedocles, he taught that plants and animals had been born from the Earth, and that the formation of new species was finished:
Wherefore, again, again, how merited
Is that adopted name of Earth - The Mother! -
Since she herself begat the human race,
And at one well-nigh fixed time brought forth
Each beast that ranges raving round about
Upon the mighty mountains, and all birds
Aerial with many a varied shape.
But, lo, because her bearing years must end,
She ceased, like to a woman worn. . . And what
She bore of old, she now can bear no longer. . .
Lucretius's poem is an exposition of Epicurean philosophy, and is notable for its insistence on the senses as the only way to obtain knowledge. "For whither shall we make appeal? for what / More certain than our senses can there be / Whereby to mark asunder error and truth?" It is also notable for its long explication of atomism -- the doctrine that everything in the universe is made up of atoms. Lucretius did not originate this theory -- it goes back to the Greek philosopher Democritus of Abdera (fifth century B.C.E) -- but his explanation of it influenced many writers and thinkers of the Middle Ages and Renaissance, despite opposition from the Church.