Although Aristotle was a disciple of Plato, many of his ideas can be traced to Pythagoras and the Pythagoreans. Echoing the later scientific understanding of spontaneous generation, he had this to say:
“…other bloodless animals generate indeed, but not offspring of the same kind; such are all that come into being not from a union of the sexes, but from decaying earth and excrements.” (Generation of Animals 1, 1:20-25)
Thales, who lived cir. 625-540 BCE was a contemporary of Pythagoras, who learned under the Hindu philosophers and taught that the eternal universe was god. Thales, however, broke away from this line of thinking and taught that all things could arise by themselves through natural processes. He also taught water is a first principle and that all life descended or arose from it.
Anaximander was a companion or perhaps a pupil of Thales. Remembering that Darwin admitted, in the 6th edition of his The Origin of Species, that his theory was alluded to in the works of the ancient philosophers, Anaximander taught twenty three centuries before Darwin that humans were originally fishlike creatures. Moreover, he taught that the earliest forms of animal life arose (spontaneously) from moisture evaporating from the sun (Hippolytus, Refutation of All Heresies, 1:6: 1-7)
Empedocles, who lived cir. 490 to 430 BCE, believed in reincarnation, taking it from Pythagoras, describing himself thus “For surely both youth and maid was I, and shrub, and bird, and fish, from ocean strayed”
“He said that all souls change into every sort of animal.” (Hippolytus: Refutation of All Heresies, 1:3.
He was also a believer in what was later called spontaneous generation:
“Empedocles says the greater part of the members of animals were generated by chance…” (Aristotle, Physics 2:8-2).
Democritus, who probably lived in the mid fifth to early fourth centuries BCE, is often called the father of Atomic Theory. He believed atoms came into being by themselves (or were eternal) and randomly created the universe. To develop his theories, he conferred with the gymnosophists of India, and with priests in Egypt, and with astrologers and magi in Babylon.
He also taught that language developed from human grunts and cries like animals:
Democritus contributed… (a) theory of the origin of language… (It was argued in) the fifth century that words were sounds attached quite arbitrarily to things or notions by human agency as the necessity arose for a means of communication more comprehensive and subtle that the grunts or cries of animals or birds. [W.K.C. Guthrie: A History of Greek Philosophy: The Presocratic tradition from Parmenides to Democritus, page 474]
Finally, Epicurus, who lived in the 4th century BCE, also believed in randomness for the formation of the universe out of atoms. Pliny the Elder wrote that Epicurus taught that “chance takes the place of God…” (Pliny the Elder, Natural History).
So, we see that the theory of evolution has been alluded to in the ancient philosophers of Western civilization. Some believed formation of the universe occurred randomly and life arose spontaneously of itself, just as modern science claims. While these philosophers studied and learned from one another, some of the earliest Grecian philosophers were taught by the Brahmans in India, bringing the teaching of reincarnation to the West, and writing that we can take many forms as we progress in the cycle of life to perfection.
 Hippolytus: Refutation of All Heresies, Book1, chapter 3