Life and Lifeforms in Early Greek Atomism

3.1 Male and Female Animals

The answer to (1) is: Yes, all male animals emit seed. Consider the following testimony.

T4: Democritus of Abdera says that it is in the mother that the difference between female and male is produced, but that it is not because of heat or cold that the one becomes a female and the other male, but depending on whether the seed of the one or of the other dominates that comes from that part by which female and male are differentiated from one another (i.e., the reproductive organs).^[17] (Ar. GA IV 1, 764a6-10 = DK 68 A143 = LM 27 D173)

The testimony describes the process that determines an offspring’s biological sex, a topic that we return to later. For the moment, notice that whichever parent’s seed – specifically, the seed that comes from the reproductive organs – dominates during the offspring’s generation determines the biological sex of the offspring.^[18] The explanation for the presence of male animals, then, is that the male parent’ seeds ‘dominates’ during generation. Hence, male animals emit seed. Yet T4 does not allow us to conclude that all male animals emit seed. Unfortunately, no extant fragments or testimonies can assist in securing this conclusion. We shall point out, however, that Aristotle does not mention anyone that denies that all male animals emit seed.^[19] If someone did hold this position, we suggest that Aristotle would have mentioned it.

T4 also provides some evidence that female animals emit seed. Since whichever parent’s seed dominates during the offspring’s generation determines the biological sex of the offspring, there are female animals because their female parents’ seeds dominated during generation. Hence, female animals emit seed. There is another testimony that supports this conclusion.

T5: Democritus: the female too emits a seed, for she has the (spermatic) ducts inverted. And that is why she too has desire for sexual activities.^[20] (Aet. 5 5 1 = DK 68 A142 = LM 27 D166)

We suggested above that all male animals emit seed. For female animals, however, there may be evidence to the contrary: female mules.

T6: Democritus says that the passages in the wombs of mules have been destroyed because at the beginning they were not born from living beings of the same species.^[21] (Ar. GA II 8, 747a29-31 = DK 68 A149 = LM 27 D178)

Τ7: As for mules, he [Democritus] says that they do not give birth. For they do not have wombs similar to the other animals, but ones of a different form, not at all capable of receiving seed. For the mule is not a product of nature, but rather an artificial supplement and theft deriving from a human inspiration and audacity one might call adulterous. “It seems to me,” he said, “that after an ass had violated a mare, she became pregnant by chance, and that humans learned from this violence and then progressed to the point of making their procreation a habit.”^[22] (Ael. Nat. anim. 12 16 = DK 68 A151 = LM 27 D179)

We learn from these testimonies that female mules are incapable of receiving seed – not just the seed of male mules but, presumably, any seed. The passages (πόροι) in the wombs of female mules were destroyed because of what Aelian describes as their unnatural origin: the union of a male mule with a mare. Worse still – at least, from Democritus’ perspective – this continues because of the ‘adulterous audacity’ of human beings. This suggests that the origin of the mule violated what we call the ‘like begets like’ principle – that parents of the same species shall produce an offspring of the same species – seen in the following testimony.^[23]

T8: And for his part Democritus says that a human burst out of a human, and a dog out of a dog, and a bull out of a bull.^[24] (Ps.-Gal. An animal sit 5 = DK 68 B32 = LM 27 D163c)

Should we infer from the female mule’s inability to receive seed that female mules also cannot emit seed, and therefore that not all female animals emit seed? We maintain that the answer depends on where the seed comes from. For our purposes, there are two options: either the seed comes from one or more – but not all – of the body’s parts or the seed comes from the whole body. If the seed comes from one (or more) of the body’s parts and that part is the reproductive organs, then it is possible that damage to the passages in the wombs of female mules results in female mules being incapable of emitting seed, in addition to receiving seed. If the seed comes from the whole body, however, then damage to the passages in the wombs of female mules need not preclude female mules from emitting seed, even if they cannot receive seed. We must, then, answer (3) to complete our answer (2).

3.2 Part of the Body or the Whole Body?

According to the Atomists, the seed comes from the whole body.

T9: Democritus: (The seed comes) from the whole of bodies and from their principal parts, like the bones, flesh, and muscles.^[25] (Aet. 5 3 6 = DK 68 A141 = LM 27 D165)

T10: Democritus … (says that the seed separates out) from the whole body; Democritus says, “One will be humans and a human will be all.”^[26] (Ps.-Gal. Def. med. 439 = DK 68 B124 = LM 27 D164)

The Atomists’ embryology is a form of pangenesis, in that each part of the body emits seed. The question is what it means to say that the seed comes from ‘the whole body’. Aristotle presents three possibilities (GA I 18, 722a16-b3): the seed contributes only homoeomerous, or like-parted, components to generation, such as bone, flesh, and muscles; the seed contributes only non-homoeomerous parts, such as face and hand; or the seed contributes both homoeomerous and non-homoeomerous parts to generation.^[27] We can dismiss the possibility that the seed contributes only non-homoeomerous parts, as T9 confirms that the seed contributes at least homoeomerous parts. Specifically, the seed comes from bone, flesh, and muscles, which are described as ‘principal parts’.^[28] Therefore, the choice is between only homoeomerous parts or both homoeomerous and non-homoeomerous parts. We maintain that the καὶ in T9 is coordinative, not explicative.^[29] If so, T9 is evidence in favour of the position that the seed contributes both homoeomerous parts, like bone and flesh, and the rest of the non-homoeomerous parts. This conclusion also provides part of an answer to (4).

Moreover, T9 indicates that the Atomists’ pangenesis is preformationist: the parts contained in the seed are, quite literally, already-formed miniature copies of the parents’ parts. Consider the following testimony.

T11: A human bursts out of a human, he says, and is torn away from him, being divided off by a kind of blow.^[30] (Ps.-Hippol. Ref. 8 14 4 = DK 68 B32 = LM 27 D163d)

The result is that once the offspring is ‘assembled’ in the womb, it undergoes only enlargement.

These observations permit us to provide a tentative answer to (2). In the previous subsection, we asked whether damage to the passages in the wombs of female mules, which causes female mules to be incapable of receiving seed, might also prevent them from emitting seed. Since the Atomists’ embryology is a form of pangenesis, however, even if damage to the passages in the womb prevents the emission of seed, it is prevented for only this part of the animal. That is, while the seed of female mules would not contain a miniature womb – for this part is not contributed to the offspring’s generation – it would still contain miniature sinews, legs, arms, and so on, since the seed is drawn from the whole body. We tentatively conclude, then, that all female animals emit seed, just as all male animals emit seed. So far, there are no discernible differences in the generation of living beings.

This leads us to why the Atomists adopted a pangenesis embryology. Aristotle suggests that there could be four reasons. First, the intensity of the pleasure experienced through sexual intercourse: ‘The same affection becomes pleasanter if there is more of it, and that which occurs in all the parts is more than that which occurs in one or a few’ (GA I 17, 721b15-7, trans. (Balme 1992)).^[31] Second, the fact that mutilated parents have mutilated offspring: ‘Since the part is missing (in the parent) no seed comes from it, and that the part from which no seed comes is consequently not produced’ (721b18-20).^[32] Third, the resemblance between parents and offspring generally: ‘Just as offspring resemble them in body as a whole, so they do part for part; therefore, if the reason for the whole’s likeness is that the seed come from the whole, the reason for the parts’ likeness must be that something came from each part’ (721b21-2).^[33] Four, the “whole/part” assumption: ‘Just as there is some first thing in the whole out of which the whole develops, so there is in each part; hence if the whole has a seed, each part must have a seed of its own’ (721b22-4).^[34]

The extant evidence suggests that the Atomists considered the third reason support for pangenesis. In addition, it indicates that this is the case for modified versions of the first and second reasons. There is no independent evidence, however, that the Atomists considered the fourth reason evidence for pangenesis. This explanation, then, is likely to be Aristotelian (de Ley 1980, 132–3).

The following testimony confirms that the Atomists considered sexual intercourse an intense experience.

T12: The sophist of Abdera called sexual intercourse a small attack of epilepsy, considering it to be an incurable disease. For indeed is it not accompanied by feelings of faintness comparable to the magnitude of what is lost (i.e., the semen)? For a human is born out of a human and is torn away from him.^[35] (Clem. Alex. Paed. II 10, 94 3–4 = DK 68 B32 = LM 27 D163b)

Yet the Atomists do not maintain that it is the intensity of the pleasure experienced that is evidence for pangenesis. Rather, it is the feeling of faintness experienced after sexual intercourse, a feeling that is proportionate to the magnitude of what is ‘torn away’ from the animal. That is, the more that is ‘divided off by a kind of blow’ from the animal’s body, the greater the feeling of faintness.

Another reason for pangenesis is the case of mutilated offspring. Aristotle reports that Democritus explains ‘monstrous births’ or mutilated offspring in the following way.

T13: Democritus said that monstrous births were caused by two seeds meeting, the one impelled first, the other later. This one too enters the womb after it is emitted, so that the parts grow together and become intermingled. And he says that in birds, since their copulation takes place rapidly, both the eggs and their colours are always intermingled.^[36] (GA IV 4, 769b30-36 = DK 68 A146 = LM 27 D168)

We saw above that female mules are born with destroyed passages in their wombs because they are the product of a union that violates the like begets like principle. This is one cause of mutilation in an offspring. T13 introduces a different cause: the growing together and intermingling of two seeds in the womb, where one seed enters the womb before the other. The testimony’s context indicates that the seeds in question are, and can only be, male seeds. It is not the case that the female’s seed causes mutilation of an offspring (Ar. GA IV 4, 770a4-6). Still, there are questions. First, must the seed that enters the womb later be another male’s seed?^[37] Second, in what way do the parts that each seed contributes act jointly and similar, with the result that they grow together and intermingle? We address the latter in our discussion of resemblance between an offspring and its parents.

We are fortunate that Philoponus, in his commentary on Aristotle’s Generation of Animals, expands on T13 (Philop. In GA 185, 33–186, 19 = (Luria 1970), 546). His discussion suggests that the second seed that enters the womb need not be another male’s seed: the same male partner can cause an offspring to become malformed by discharging a second seed into the womb. For even though the female’s partner is the same, each seed produced by the male is different in some way. For support, Philoponus consider the case of birds’ eggs, which are both white and yellow, as opposed to being either white or yellow. He writes that since copulation between birds is rapid, the male bird shall discharge several seeds into the female bird. Perhaps the respect in which the male bird’s several seeds are different is the colour they contain – either whiteness or yellowness. Whatever the difference, though, the result is a growing together and intermingling of the seeds, which produces a ‘monstrous’ egg. Yet this malformation of birds’ eggs is not perceived as a malformation, because it always happens, whereas a human being with two heads and four feet is rare.

The example tells us something important. Even though we write of ‘monstrous births’ and ‘malformed’ or ‘mutilated’ offspring, this need not imply something extraordinary – a human being with two heads and four feet, once again – since even destroyed passages in the wombs of female mules and multicoloured birds’ eggs are considered monstrous. The category of monstrous births, then, is quite inclusive. For the early Atomists, something is a monstrous birth just in case it is either the product of a union that violates the like begets like principle or the product of two male seeds that meet in the womb, grow together, and intermingle.

Overall, did the Atomists considered monstrous births to be evidence for pangenesis? T13 and Philoponus’ commentary suggest that the explanation for multicoloured birds’ eggs – or a human being having two heads and four feet – is an overabundance of parts in the womb. So, while Aristotle presents as evidence for pangenesis the case of an offspring’s missing some body part, the Atomists would present as evidence for pangenesis the case of an offspring’s having too many of some body part(s).

Finally, we turn to the question of heredity. The Atomists explain the resemblance between parents and their offspring in the following way.

T14: Democritus: The parts common (to both sexes) come from either the one (parent) or the other, by chance. On the other hand, the parts that are peculiar to each are also due to the dominance (of one parent).^[38] (Aet. 5 7 6 = DK 68 A143 = LM 27 D174)

T15: Democritus reports that the nature of the parent whose principle was first to occupy the place is reproduced.^[39] (Censor. Die nat. 6 5 = DK 68 A143 = LM 27 D177)

Each parent’s seed contains two sorts of parts: common parts and peculiar parts. Some examples of common parts include face, hand, bone, and sinew, which both parents have. The peculiar parts, however, are those that distinguish male from female – namely, the reproductive organs. Both sorts of parts struggle for dominance of their places during the ‘assembling’ of the offspring. It is the ‘victorious’ parts that occupy the place, and these cause an offspring to resemble one of its parents and not the other in infancy by, say, having blue eyes, brown hair, or large ears, or in adolescence or adulthood by having a broad torso, long legs, or thick fingers. An offspring’s biological sex is determined in the same way: whichever parent’s ‘principle’ – that is, the miniature copy of its reproductive organs – is victorious in its struggle, occupies its place and determines whether the offspring is male or female.^[40]

T14 tells us more: whether an offspring has, say, blue or brown eyes, a large or small nose, or is male or female – in short, whether a parent’s particular common or peculiar part is dominant – is a matter of chance.^[41] This helps explain why, say, some parents’ first offspring is male and the second female; why all of some parents’ three offspring are female; or why two of some parents’ three offspring are male and the third is female; and so forth. That is, it is a matter of chance which of the parents’ peculiar parts shall dominate during the offspring’s generation, thereby determining its biological sex. The same holds for the variation (or lack thereof) in eye colour, hair colour, skin tone, and so forth.

This analysis of resemblance between the offspring and its parents, whatever questions remain concerning it, agrees with Aristotle’s third reason for pangenesis (GA I 17, 721b21-2). The offspring resembles one of its parents ‘in body as a whole’ by being either male or female, where this is determined by whichever parents’ principle first occupies its place. In addition, the other bodily parts of the offspring resemble the corresponding parts of each parent because the seeds of each parent also contain common parts. These too struggle for dominance during the assembling of the offspring, and those that are victorious cause the offspring to resemble its parents in particular ways. Thus, the Atomists considered the third reason support for pangenesis and, arguably, this applies to all living beings.

3.3 Complete or Incomplete Preformatist Pangenesis?

Thus far, we showed that the Atomists maintain that the seed, which comes from the whole body, contains both homoeomerous and non-homoeomerous parts, where the latter may be divided into common parts and peculiar parts. This constitutes a nearly complete answer to (4). There remains only to determine whether the seed contains all or only some of the parent’s homoeomerous and non-homoeomerous parts.

We begin with the following passage from Book I of Aristotle’s Generation of Animals.

T16: Further, if it comes equally from all of both parents, two living beings are produced; for they will have every part of each parent. Therefore, if this is the right way to speak, Empedocles’ account seems most consistent with it … for he says that the male and the female contain as it were a tally, and that neither produces a whole, “but sundered in limbs’ nature, part in man’s (seed)…” Otherwise, why do not the females generate from themselves, if in fact the seed comes from all the body and they have a receptacle? But, as it seems, either it does not come from all the body, or comes in the way that Empedocles says, not the same things from each parent, and this is why they need intercourse.^[42] (GA I 18, 722b6-17, trans. Balme)

In T16, Aristotle reports that Empedocles held what we call a version of incomplete preformatist pangenesis: while the seed comes from the whole body, it contains only some of the parent’s homoeomerous and non-homoeomerous parts. The alternative is complete preformatist pangenesis, where the seed contains all of the parent’s homoeomerous and non-homoeomerous parts. And it is the latter that Aristotle questions in T16. If the seed comes from the whole body in this way, why are two offspring not produced? After all, a complete set of parts from each parent is present in the womb. In addition, if the seed comes from the whole body in this way, why do females not generate offspring all by themselves? Aristotle regards these as serious problems for complete preformatist pangenesis.^[43]

The proponent(s) of complete preformatist pangenesis is not named in the first book of the Generation of Animals. When we read Book IV, however, where the discussion of pangenesis continues (764b10ff.), Democritus is explicitly mentioned and frequently set against Empedocles. We conclude, then, that the Atomists were proponents of complete preformatist pangenesis.^[44]

Overall, the Atomists’ embryology is ambospermatic and a version of complete preformatist pangenesis: both parents contribute seed, drawn from the whole body, which includes all bodily parts. Despite its complexities, the Atomists’ embryology appears quite straightforward: ‘torn away’ or ‘divided off by a kind of blow’ from each parent’s body are miniature copies of their parts. These parts struggle against each other for dominance of their place during the assembling of the offspring’s body and, when the war has ended, the offspring, now fully assembled, undergoes only enlargement. We suggest that the Atomists conceive of generation as a process of copying and combining the parents’ atomic structures, producing an atomic aggregate (the offspring) that shares some structural similarities with two other atomic aggregates (the parents). This process of copying and combining yields the possibility that all lifeforms can have similar traits.

Perhaps the way to distinguish different lifeforms is found further up, in the Atomist theory of the beginning of life, soul, and respiration. For the Atomists describe the seed as a fragment of the soul.

T17: [1] Leucippus …: (the seed is) a body, for it is a fragment of the soul. [3] … Democritus: the power (of the seed and not only its matter) is also a body, for it is of the nature of breath.^[45] (Aet. 5 4 1–3 = DK 67 A35, 68 A140 = LM 27 D162)

We shall see that the soul sets living beings in motion, specifically the respiratory organs that enable them to breathe. The soul, the respiratory organs, and air all contribute to something’s being a living thing. The seed’s being ‘a fragment of the soul’ and ‘of the nature of breath’, then, links embryology and the first formation of the body to the psychology and the beginning of life.

4.1 Sleeping and Dying

We can take this one step further: soul atoms also prevent us from distinguishing living beings from the non-living. Since the fast-moving spherical particles constituting the soul can pass through all sorts of atomic compounds, they can also enter non-living things.

T20: Democritus says that all things have a share in some kind of soul, even corpses, for they always manifestly partake in some kind of heat and sensation, even if the majority has been breathed out.^[51] (Aet. 4 4 7 = DK 68 A117 = LM 27 D140 modified)

T21: On this point, Democritus also notes that the nails and hair of buried bodies grow for some time.^[52] (Tert. An. 51 = DK 68 A160 = LM 27 D142 modified)

Democritus believes that corpses can take in soul atoms, but not many. The evidence for this is threefold: first, corpses contain heat. According to Aristotle’s testimony in T18, fire and soul are composed of the same kind of spherical atoms. Therefore, since corpses ‘partake in some kind of heat’, they too may contain soul atoms. Second, corpses are said to have some sensations, which, as we shall see below, is also the result of swiftly moving atoms colliding with the sense organs. Third, in T21 corpses are said to perform some movements, such as growing nails and hair. Since soul atoms impart motion to things, the limited movement in dead bodies suggests that they are ensouled to a limited extent. The small number of soul atoms, however, is not sufficient for respiration. Therefore, corpses do not breathe and are not alive.^[53]

These texts suggest that to come to life the body does not simply need soul, but rather an adequate number of soul atoms that initiate the respiratory movement. On the other hand, death does not occur when all soul atoms leave the body, but when most particles have been breathed out and thus the body does not have enough soul atoms to produce further respiratory movement. The difference between life and death does not seem to be a difference of process, for soul atoms pass through both living things and corpses. Rather, it is a difference of number, for bodies need to breathe enough soul atoms to compensate for those that have flowed out.

Further support for this comes from the Atomists’ account of sleeping and dying. According to Leucippus and Democritus, there are neither predictable signs of future death nor clear signs that life has ended (Cels. Medic. II 6 = DK 68 A160 = LM 27 D141). What makes death difficult to detect is that there are two kinds of interruptions of the respiratory movement: a temporary and milder lack of breath, which only looks like death, and a severe and permanent one.

T22: On the question of whether sleep and death belong to the soul or the body, Leucippus says that it does not only belong to the body but occurs because of an outflow of the fine part that is greater than the inflow of the heat of the soul; an excess causes death.^[54] (Aet. 5 25 3 = DK 67 A34 = LM 27 D138 modified)

The first kind of suspension is a state of sleep, which Democritus describes as ‘a lack of breathing’ (Tert. An. 43 = DK 68 A136 = LM 27 D137). Sleep occurs when the soul atoms (that is, ‘the fine part’)^[55] the body expels is greater than the particles it breathes in. Hence, when asleep, bodies have fewer soul atoms within themselves. Yet the number is sufficient to reprise the respiratory movement, increase the amount of soul atoms in the body, restore the counteraction of intake and outflow, and thus awake the animal. The second kind of lack of breath occurs when the number of atoms flowing out is much greater than those flowing in and eventually leads to death.^[56] Therefore, sleep is seen as some kind of ante-mortem event: it resembles the loss of soul atoms that leads to death, but it is not as extreme and irreversible.^[57] This, again, suggests that the presence of soul atoms alone does not enable us to determine if beings are alive or dead, asleep or awake, as well as what kind of animal they are. The difference between living things is not a difference in kind, but degree: it depends on the amount and ratio of soul atoms flowing in and out.^[58]

So, when does life begin according to Leucippus and Democritus? The answer is that what separates living from non-living things is their ability to breathe, rather than simply having a soul. Respiration, not soul, marks the limit of life. And what distinguishes different forms of life? Thus far, we have taken both breathing and soul out of the equation. The ability to breathe is shared by all living beings and thus does not separate humans from animals and animals from plants. Soul, in turn, does not even separate the living from corpses. We shall now examine whether specific psychological faculties may be used as a criterion to differentiate forms of life.