I will be passing over many philosophers, such as Heraclitus (“everything flows”) only because they said nothing of great influence directly on biology. As we shall see when we finally get to the modern era, this doesn’t mean that some philosophers like Whitehead or Teilhard didn’t draw biological conclusions from them. For perhaps the most detailed, if somewhat obscure, history of philosophy see Windelband 1901, and for the period up until Leibniz, Russell 1946 (after that he gets a bit partisan).
Most histories of biology introduce the pre-Socratics in greater detail than necessary for just biology (e.g., Singer 1931, cp Magner 1994). This seems to be a hangover of older educational expectations and assumptions (that we all know about pre-Socratic philosophy in culture and school).
One source that readers may be surprised that I am not using much here is Ernst Mayr’s The Growth of Biological Thought (1982). There are two reasons for this. One is that Mayr is not reporting much new in that book, and often repeats older mistakes; the other is (see the prelude to this series) he is unashamedly Whiggist, seeing all biology leading up to (his version of) Darwinism. Caveat lector.
Before we continue, a note on the term psyche, which is often translated as “soul”. Due to our Christianised lens, we tend to think of this as some kind of immaterial substance separate from the physical world. This is a (very) late reinterpretation. Initially, and especially in the early period of Greek thinking, psyche means something like “a mover”, analogically to the wind that “blows” (the original meaning of psyche). As the idea of this motive force was discussed, it came to be thought of as that which departs at death, or survives death, and so came to be known as the “life force” in modern New Age terms. However, the early “biologists” (hey, if a Greek thinker can’t be called a biologist, who can? The very word is Greek) sought to account for life in various ways, from heat, moisture, and other elements.
When we get to Aristotle, this will become clearer, but it’s important that the history is understood to be a series of explanations for psyche rather than there being some generic Greek idea of psyche. Societies do not in general have universally shared ideas or interpretations of words.
In contrast to the Milesians, a school of thought called the Eleatics held that knowledge through the senses is misleading, although some (for example the founder of the school, Xenophanes) held that it approximates knowledge “by degrees” (an early version of Bayes?). They therefore did not engage in a study of the natural world either. The Eleatics were based at the residence of Xenophanes of Kolophon, Elea, in Salerno, southern Italy. Ela was a Hellenic colony. Xenophanes was born around 580 BCE in Asia Minor (modern Turkey), and after wandering for a time settled there and began writing poems.
One of them came later to be known as On Nature (peri phuseos in Greek – a number of books were given that title by later scribes and editors), and in this book/poem, which is mostly lost to us apart from some excerpts in other preserved classical authors, he made some claims, based on his physics, about life and its history.
The Eleatics generally held that truth is eternal, and as a consequence, sensory information is misleading – they were idealists, in our terms. However, Xenophanes did think that the primordial element was earth*, which on being compressed from a fluid to solidity, trapped sea shelled animals in mountains, which had once been under the sea. This account of fossilised shells did not become widely adopted before the 17th century when Nicholas Steno proposed it, despite a number of classical and non-European precursors.
Xenophanes argued that religions were human projections, and that other animals would draw gods in their own image. As part of his doctrine that there is only one nature, and all else is mere appearance, he also held that the true deity would be so perfect and abstract that we could not describe it.
Parmenides of Elea apparently held some views on conception and reproduction. There are four fragments of his poem (also later called On Nature):
For as on each occasion a blending (mingling) holds of much-wandering limbs, so noos is present to humans; for the nature (form) of limbs is the same thing that thinks (apprehends: phroneei) in humans (OR:…is the same thing that is thought (apprehended) in (of, for) humans) both for all together and individually; for the full is conceived (no?ma) [of]. (OR:…is what is conceived [of].)
Here Parmenides proposes a widely held view until the nineteenth century known later as “pangenesis”, in which the organs of the body shed parts that are recombined in sex (and draws the analogy with mind here).
Boys to the right, girls to the left
This was read by later classical authors (e.g., Aristotle) to mean that boys are conceived on the right side of the uterus and girls on the left side.
When woman and man [together] mix the seeds of Venus (Love), the power which forms [bodies] (OR:the power which is formed) out of the different blood, if it maintains proper proportion, produces well-formed (well-constituted) bodies. For if the powers, when the seeds are [being] mixed, fight and do not constitute (make) a unity in the body in which the mixture has taken place, then they will terribly (cruelly) torment the nascent (growing) sex with double seed.
The notion, critical in subsequent debates, that proper generation requires balance or harmony of parts and elements, is expressed here.
Overall, the Eleatics tended to use biological examples and explanations as outworking of their metaphysics, and not for their own value.
While Pythagoras himself, perhaps the singularly most influential thinker of the sixth century BCE in Hellene, is not recorded saying much about the living world (which, like everything else he thought to be comprised of numbers), one of his likely students, Alcmaeon, is the first recorded Greek philosopher to carry out direct dissections of animals to learn abut their natures. He may also have studied the development of chicken embryos. He discovered the optic nerve, the (later named) Eustachian tube, and declared that understanding was the only qualitative difference between humans and the other animals. Whether he did or not is debated, as is whether he was actually a Pythagorean. However, he was likely a physician, and his experience in that field may have led him to critical observation, however, primitive from our perspective, as it did the Hippocratic school.
Pythagoreanism did not, so far as we are aware, offer a theory of life other than moral and psychological accounts of sensation.
The Greek focus on permanence and unchanging properties as an explanation for knowledge led to the atomists, who held that underlying all change and different bodies there were elemental particles that had inherent properties. Atomists hypothesised that these particles were indivisible, the Greek for which is atomon. In the 5th century BCE, Leucippus, following the argument of the Eleatic Parmenides, had accepted that change was not possible unless there was a vacuum (non-being) and so he proposed that atoms existed in a vacuum.
His follower Democritus expanded on this view, and proposed an element (possibly fire) that gave living things their growth and movement (their psyche). He also seems to have given an account of generation (as reported by Aristotle and Aetius):
Democritus of Abdera also says that the differentiation of sex takes place within the mother; that however it is not because of heat and cold that one embryo becomes female and another male, but that it depends on the question which parent it is whose semen prevails — not the whole of the semen, but that which has come from the part by which male and female differ from one another. [Aristotle, On the generation of animals, 764a.7ff]
The significance of the atomists’ ideas lies largely in the reaction (quite a strong one by Plato and Aristotle; Plato wished to burn all atomists’ works, by one account) against mechanistic explanations, and Aristotle’s views, based on Empedocles’ view of elements, coloured biology for about two millennia.
* Or perhaps earth and water. The sources are unclear.
Magner, L. N. (1994). A history of the life sciences. New York, Marcel Dekker, Inc.
Mayr, E. (1982). The growth of biological thought: diversity, evolution, and inheritance. Cambridge MA, The Belknap Press of Harvard University Press.
Russell, B. (1946). History of Western philosophy and its connection with political and social circumstances from the earliest times to the present day. London, George Allen and Unwin.
Singer, C. J. (1950). A history of biology to about the year 1900: A general introduction to the study of living things. London, Abelard-Schuman.
Windelband, W. (1901). A history of philosophy: with especial reference to the formation and development of its problems and conceptions. New York, Macmillan.
Have I missed something? Made an error? Let me know in the comments. This series will be revised as we go.