About wildlife Democritus (judging by the titles) wrote in his writings: “On Nature”, “Small Myrostroy”, as well as in several books “Causes”. Not everything observed and seen by Democritus directly subordinated to the atomistic hypothesis, but always — to the causal understanding of the world. In the democratic picture of the world, the advanced for their time and already outdated views for Greek philosophy and physics are mixed. Remarkable was Leucippus Democritus’s hunch about the stellar nature of the Milky Way. Aetius testifies: “Democritus says that the Milky Way is the co-luminescence of many small stars, one after the other, glowing together due to their close location.” According to Seneca, “Democritus, the most subtle scientist of all the ancients, also claimed that he suspects the existence of unknown planets.” Democritus correctly believed that in infinite space (“great emptiness”) there is neither “top”, nor “bottom”, nor “center”, nor “edge”. Only in space do atoms fall “down”, as they are attracted to the center of the vortex.
But along with this, Democritus imagined the Earth as flat or shaped like a concave, to hold the seas, a drum (although space, according to Democritus, is spherical). He also believed that the Earth was floating in the center of the cosmos without changing its position. But the Pythagoreans already taught that the spherical Earth, together with other planets, revolves around the “central fire”. There is still one not entirely clear message of Diogenes and Laertius that, according to Democritus, the Earth revolves around the center (perhaps around its axis). Probably at some point in his life, Democritus made some corrections in his cosmology.
In the infinite universe, among other worlds, our Cosmos arose. Various combinations of atoms led to the diversity of this world of material things. Atoms of various shapes and sizes formed the primary combinations: fire, water, air and earth. Water and earth is a mixture of elements, “panspermia” is a “complete set of seeds”.
It is potentially capable of any education, including living ones.
Ordinary atoms, which interlocked with teeth and protrusions and formed large bodies, seemed to slow down their natural movement, become frozen and motionless and move by force of blows and jolts (these are atoms that make up water, earth, and other complex compounds).
Only spherical, or spherical, atoms of fire have a special mobility, because “they touch (others) along the smallest plane and, apparently, because they do not linger in their movement by friction, as a result of which they move forever and constantly. Fire atoms, due to their spherical shape, cannot interlock and create one whole. In their movement, they penetrate everywhere and, if they fill in a sufficient amount of empty pores in the body, give it their movement.
The properties of atoms of fire Democritus explained the heavenly phenomena. He said that thunder is caused by the fact that with great force fire breaks through in the clouds with a very thick cover. When a cloud collides with other clouds, the atoms of fire are sort of filtered through the existing voids and get together — it flashes lightning. Finally, when this stream of bodies generating fire, the Taurus will force downwards, lightning falls to Earth. Like Anaxagora, Democritus said that the stars – stones, and they ignited from the speed of movement. The sun and the moon, too, are not eternal, but arose, like the Earth, “with the unfinished formations of individual worlds,” and their nature was similar to the nature of the earth, not hot. Only later the solar sphere, having expanded, “took fire into itself”, and the sun became “a piece of hot metal or stone”.
Thus, there is a constant interaction between fire and movement: the body is heated by the rapidity of movement, i.e. they receive more and more atoms of fire from their surroundings, and, on the contrary, fast-moving atoms of fire set bodies in motion. It can be said that the motion of the atoms of fire is the force that sets other bodies in motion, for Democritus defined force as that which acts and is the cause of change in the other. Moreover, what is affected and what is being affected is the same, i.e. atoms of the same form interact. Even if the acting is foreign, it acts “in the foreign one, since it is somehow the same, i.e. according to the principle of connecting similar with similar. Therefore, the fiery atoms act on the body from the outside insofar as it has the same atoms inside, and from the inside, because they are connected to the same atoms outside.
That is how Democritus represented the role of fiery atoms in a living organism, atomistically explaining the essence of life. And his concept was a step forward in comparison with the hylozoism of the Ionian philosophers (although Democritus had some remnants of hylozoism). Neither the atoms themselves nor their complex compounds were “alive”. Life was given to them by the atoms of fire.
If you think about the role of the Democritus atoms of fire, then their movement represents in him the second and, perhaps, the highest form of movement. The first elementary form of motion is the vortex of atoms. Secondary movement under the influence of atoms of fire, according to Democritus, constitutes both the essence of life and the essence of the mind or psyche of a person; and this is not a purely external source of movement. The atoms of fire in the human body and in connection with it constitute his “soul” or mind, which, according to Democritus, is one and the same. Atoms of the soul or mind are everywhere, even in dead objects – stones. But there are too few of them, they are far from each other and can neither warm up the object, nor give it movement. If we compare dead objects and living things, then, according to Democritus, life is the result of a quantitative accumulation, a certain concentration of moving fiery atoms located in the tissue of the body. The ancient hylozoism here is transformed into a “physical” (“fiery”) plan and almost disappears: the difference between the living and the nonliving is fixed.
Life on Earth arose from inanimate matter by spontaneous generation from moist earth. According to Democritus, from the heat of the sun “the surface (still a semi-liquid earth) swelled, and some wet substances swell up in many places; in these places there were putrid blisters covered with thin skin. ” Due to the heating, they “began to carry living fruit,” and when “they increased to the proper size, they burst under the influence of the heat of the sun, and various species of animals were born”. With the prevalence of heat (fiery matter), they were birds, earthy substances – land animals, wet – floating. Animals gathered in species on the principle of similar to similar. Trees and plants appeared right from the ground. When the earth finally hardened, it could no longer give birth to large animals and began to give birth only to herbs and other plants, as well as to the smallest animals, and “all animate animals were already born from intermixing”.
This theory, which Diodorus borrowed from his fellow countryman Democritus, the philosopher Hecatey Abdersky, and which is repeated from the scientist Hermippus, is constantly (especially in foreign science) debated. Some scientists recognize it as democritical, others do not. This theory is also given by other authors (Censorin, Aetius, Lactantium). True, it is not stated in terms of the atomic theory, but, firstly, the authors who revised it were not atomists, and secondly, in all other evidence on biology issues, Democritus does not speak directly about atoms; we are talking about compounds, complex bodies.
The biology of Democritus speaks of four elements. The traditional theory of them was in some contradiction with the theory of atoms, but was recognized as atomists. The theory cited by Diodorus contains views that were already prevalent in Ionia before Democritus. In addition, a similar theory is presented in two works by Hippocrates: “On ancient medicine” and “On muscles”. Finally, another abderite – Protagoras, as we shall see later, views on the emergence of life, man, society had much in common with those described by Diodorus. There is no doubt that it was the “naturalist” Democritus who was the main author of the theory transmitted by Diodorus.
A lot of naive and untenable was in the views of Democritus on the origin and development of life. But at the same time, Democritus has a remarkable conjecture, a kind of rudiment of the theory of natural selection.