The first organisms in the Earth's history
A biological commentary on G. L. Buffon's Les époques de la nature
In G. L. Buffon's multifaceted activity as a naturalist, geology is represented by two voluminous works: Histoire et théorie de la terre (1749) and Les époques de la nature (1778). Both these treatises shared a cosmogonic hypothesis, according to which the solar system originated as a result of a collision between the Sun and a comet, in which a block of matter that was wrested from the Sun rushed through space and disintegrated into smaller fragments, thus supplying the necessary building material for the future planets. What the treatises differed in was that the second of them contained a much more detailed account of the Earth's past and of the history of the ever increasing number of living organisms that inhabited the Earth. Les époques de la nature, though concerned mainly with major cosmogonic-geological problems, dealt with many interesting theoretical questions relating to biology. One of them, namely the question of how the first organisms in the Earth's past had emerged, was not presented in the treatise in a sufficiently clear way: hence, the present paper is going to provide an elucidation of the views held by Buffon on that matter.
In the third out of the six epochs distinguished by Buffon in the Earth's past, the planet had cooled down to such an extent that the water vapour surrounding it could already be transformed into water, which filled all the hollow parts in the Earth's crust, thus forming the seas; in those primeval seas there emerged the first living organisms. In Les époques de la nature, however, Buffon let this remarkable act in the Earth's history remain without any comment or explanation. In his biological deliberations in that work, he concentrated on completely different questions - those relating to palaeontology, biogeography and ecology; meanwhile some explanation concerning the origin of life could be provided by a conception whose subject-matter had to do with beings and events on the suborganismal level. Indeed, Buffon did develop such a concept and it is known by the name of the conception of organic molecules.
The conception was developed to explain physiological phenomena that take place in already existing organisms and that are the object of direct experience. However, the conception can be extrapolated and used for phenomena that occurred in those epochs in the past where no organism had yet existed; this can be done in order to explain the origin of living organisms, i.e. to do what is clearly missing in Les époques de la nature. The present article tries to justify the possibility of using the concept of organic molecules in such a way. Above all, it draws attention to the easily noticeable and notable tendency in the way that the conception evolved and it also highlights the fact that, in describing events from the Earth's past, Buffon did introduce (albeit only at one point in Les époques de la nature) the motif of organic molecules.
Buffon's organic molecules, which constituted the building blocks of an organism, were endowed with life, were infinite in number, were indestructible and - at least in the first version of the conception - showed no qualitative differentiation; the only variability that they exhibited related to motion. The peculiarity of Buffon's conception was that matter was primarily (and not derivatively) divisible into non-living matter and living matter, for life as such constituted a property of matter. Life was thus not a state into which non-living matter passes when subjected to the action of hypothetical forces that endow it with biological organization. Hence, life should not be treated as a function of that organization, for it is an irreducible (in all the senses of the word) property of matter. This property is to be treated on a par with such properties of matter as extension, mass, attraction etc. Matter endowed with life thus appears in the form of an assemblage of organic molecules which are carriers of that specific quality. In Buffon'as early version of the conception, the molecules were qualitatively homogeneous, i.e. all of them simply had life ascribed to them. Later, the living organic molecules turned out to be also most highly differentiated in qualitative terms, for they carried full information on where in the organismal whole that they were forming they should have their place. They were thus endowed with generic specificity (they made up an individual of a particular species) and they were specific with regard to the organs they formed (they formed muscles, bones, nerves, etc.)
An important part of Buffon's conception was the never explicitly formulated principle of conservation (constancy) of life, according to which the molecules not only were not subject to disintegration and did not undergo internal transformation, but they did not come into being de novo either; the principle thus excluded the possibility of spontaneous generation. The notion of spontaneous generation found in Buffon's works did not embrace the generation of living organisms from inorganic substances or even from organic ones (in the contemporary sense of those terms). What Buffon regarded as spontaneous generation was the formation of random conglomerations of organic molecules that did not use the information, which they were carrying, on their place in the organism; in that way there also formed the animalcula, which only a whole century later were to be refashioned as the contemporary spermatozoa. Thus, in the process that Buffon referred to as spontaneous generation, and which he conceived in a way different from the generally accepted one, there was neither the emergence of life as a new state or new quality of matter (for that state and that quality were a property of the organic molecules), nor was there any generation of entities called organisms, as understood at that time.
In the period of over thirty years that spanned the time when Buffon developed his conception of organic molecules and the time when he started to work on Les époques de la nature (1778), the scientist's views on spontaneous generation had undergone a significant transformation. This transformation is documented in an article contained in the fourth supplement to the Histoire naturelle, which was published a year before the fifth supplement containing Les époques de la nature. In that article Buffon introduced an idea of great theoretical relevance, namely the idea that spontaneous generation was the primary way in which living organisms originated. Buffon also put forward the following daring hypothesis (he made a mention of it also in Les époques de la nature): let us imagine that the Supreme Being has simultaneouly deprived all earthly organisms of life, by bringing about a disorganization of the organic molecules that formed them, without, however, the molecules undergoing any change - either in terms of their number, or in terms of their specific properties (the principle of conservation of life). The molecules that remained at large would then begin to cluster and form new bodies, which would take on the form of organisms. Some of the less perfect ones, would be endowed only with the ability to feed, while others, the more complex ones, would be able to reproduce. In Buffon's hypothesis we can observe the aforementioned evolution of his views on the conception of organic molecules: all the information on the spatial structure of the organisms (and of the features of the species) was now contained in the very molecules themselves. After that hypothetical catastrophe, new forms would emerge, not all of which would be perfect. Among them would be forms that were not perfectly organized, unable to reproduce, or simply those that were damaged; those would disappear. New beings that managed to survive would be slightly smaller than their predecessors, for in the period that separated the two acts of creation, there would be a significant dissipation of the the heat concealed within the Earth.
Heat, in Buffon's conception, played an important role in influencing the ways of formation and the size of the emergent living beings, but was not the factor that triggered their spontaneous generation. Under the influence of heat, the living organic molecules would only display more fully the specific features of life and would begin to participate in the physiological transformations of the organism that had become their habitat. Heat, it could be said, would "bring to life" the organic molecules and set them in motion, while non-living matter would serve as the ground upon which their usual activity could develop: namely, they would generate living bodies by combining with one another due to their specific affinity. Thus, when the Earth cools off completely and there is no longer the heat to stimulate organic molecules to action, and when the organisms inhabiting the Earth perish, releasing at their death and disintegration the molecules that they contain within themselves, the molecules will not cease to exist, they will not be changed, and there will be no decrease in their number; they will only cease to manifest their presence in this excessively cooled-off world. Once the molecules are supplied with sufficient amounts of heat, they will regain their former mobility and will re-enter into the circulation of living substance. It can be assumed that as a result of some successive cosmic catastrophe, the molecules could resume their function once again - that of generating living organisms, beings that they had once been forced to abandon.
In the course of geological transformations life has not appeared on Earth, but only made manifest its eternal presence here (just as it did on other planets), whenever the conditions for that were favourable, and it was heat that had a crucial role to play in creating conditions favourable for the development of life forms. Life, according to Buffon, was as old as the same age as equal age with matter and shared its history; it constituted a form of existence of one of the two varieties of matter - the one that had the form of organic molecules of living matter, which has always accompanied non-living matter on Earth (and in the Cosmos at large).