Normally in the history of philosophy the earliest Greek thinkers are referred to as “pre-Socratics”, but in biology, the first systematic thinker is Aristotle, so here we look at his predecessors.
One of the issues in histories of ideas is that one can find precursors for nearly every idea you like. Back in the 1890s, a neo-Lamarckian palaeontologist seeking to deprecate the originality of Darwin, Henry Fairfield Osborn, wrote a book From the Greeks to Darwin in which he found evidence among the pre-Aristotelians of evolution and natural selection. A similar issue appeared when Darwin was accused of not giving credit to his predecessors by Lamarckians and others, resulting in the Historical Sketch in the third edition of the Origin and subsequent editions. We shall address this as we go, but I must note that these thinkers were not, primarily, naturalists or natural historians (as biology and geology were known prior to the nineteenth century), and they thought about a great many other things. We choose these thinkers just because of their influence on later biological thinkers and naturalists. It pays to be careful when we do this, because we can end up with the impression that history has a definite lineal nature, when in fact it, like evolution itself, is a process of branching, extinction and repetition.
Prior to these thinkers, so far as is recorded, explanations of things like seasons, generation (a word that roughly means development in modern terms), and the existence of organisms were given in religious stories, and consequently had little to no predictive power. Gods do things for their own reasons, and these stories, like the Enuma Elish or Bereshit (Genesis, which consists of several traditions of Hebrew thinking), or the Greek Hesiod in his Works and Days, tended to be focused upon giving an account of the right relations between gods and humanity, rather than passing on knowledge of living things. In short, explanations boiled down to the whims of the gods.
The first (known) thinker to reject this was a Hellene in what is now Turkey, Thales of Miletus in the sixth century before the Common Era (flourishing around 585 BCE). Thales held that things had their own natures based upon an underlying nature (which he identified as water). The properties of the basic stuff determined in a regular manner the way things behaved, and so explanations should be sought in terms of this underlying stuff. Such a position is called now monism, because there was a single (monos) cause of the order of things (kosmos). Thales was thus the first western materialist.
He was not the first materialist though. A school that preceded the Vedic traditions in the Indus Valley was also materialist: the Lokayata or Carvakist schools which began in the eighth century BCE. They held that matter precedes consciousness, and that the soul did not survive death, and they also were strongly empiricist. I sometimes think that given the extensive trade from India through Persia and thence to Greece, that a number of philosophical ideas in the Hellenic world were borrowed from, or influenced by, the Indian thinkers.
Thales’ views created a school known as the Milesian school, with Anaximander (fl. 550) arguing that the single cause was the apeiron (something like stuff of unbounded possibility), and Anaximenes that it was air, which when denser caused earth and rocks to come into being, and when less dense, fire. What is significant about these early views is that at no point in their accounts of natural processes did they invoke the gods.
The basic reason why such accounts were necessary had to do with the question of knowledge. If knowledge is possible about the world, there must be some invariant stuff that makes it possible to know. If one could explain all things as rearrangements of some property-bearing stuff (which came to be called substance, or that which stands under, in the Latinate tradition of a few centuries later), then knowing what the properties of the stuff itself was meant one had a complete (in principle, anyway) explanation of why physical things did what they did. Shortly after the Milesians came the atomists, which believed that all things were made from rearrangements of eternal and indivisible (atomos) small particles of varyings sizes and shapes.
So far we have nothing much to do with life, though. But one Milesian – Anaximander, did produce a kind of theory both of the origins and the generation of living things. There are only a few reports of his views:
“Anaximander says that the first animals were produced in moisture, enclosed in thorny barks. When their age increased they came out into the drier part, their bark broke off, and they lived a different mode of life for a short time.” Aetius (5.19.4)
“He also declares that in the beginning humans were born from other kinds of animals, since other animals quickly manage on their own, and humans alone require lengthy nursing. For this reason, in the beginning they would not have been preserved if they had been like this.” Pseudo-Plutarch, Miscellanies (179.2)
“Anaximander… believed that there arose from heated water and earth either fish or animals very like fish. In these humans grew and were kept inside as embryos up to puberty. Then finally they burst and men and women came forth already able to nourish themselves.” Censorinus, On the Day of Birth (4.7)
This has been (for example by Osborn) interpreted as an evolutionary account. Instead, it is better to see this as being spontaneous generation – living things arising out of pre-existing non-living matter due to the drying of the waters,, and then humans forming within fishlike beings until they could survive on their own. Confusion between spontaneous generation (we would now call it origins of life, or as I prefer, etiobiology) and evolution (the changes over long periods of time of organisms) continues even today, and this simply is not about the gradual changes of one kind of organism to another, let alone one of relatedness of species.
Moreover, the function of these speculations is to shore up the underlying metaphysics of their monism, rather than to investigate the living world. At this stage we do not have much in the way of a biological tradition.
Next, I will discuss the atomists.
Have I missed something? Made an error? Let me know in the comments. This series will be revised as we go.