The content of Darwin`s theory
In the classical Darwinian theory of evolution and today’s common synthetic theory of evolution, the term evolution refers to the gradual irreversible change of species through generations and time.
The statement “change of species” is the decisive difference to Frankfurt’s organismic theory, which states “change of organisms”. Species and organism are linked at the biological level, but they are by no means the same thing. In terms of scientific theory, the two statements are two different object definitions, and the two theories as working concepts therefore have different areas of validity.
In the 19th century, the question was whether species were constant or changeable in the long term. Lamarck had already assumed the gradual change of species in 1809: Each species arose through primordial generation and acquired its present given form over the course of generations. He had developed a theory of change, but not of the descent of species.
The explanation for them only came from Darwin. He wrote the content of his theory in the title of his book (1859): The Origin of Species by means of Natural Selection.
Darwin argued on the basis of breeding practice. The individuals of a species are not identically the same, but they are variants within a species. Darwin saw the processes of nature: the inheritance of traits, overproduction of offspring, survival of the fittest, and Darwin saw how well everything fits together in nature. Obviously, living beings have adapted to each other and to the earth, air and water, – to their environment.
The environment determines who is “fit for life” and who gradually declines and thus falls victim to “selection”. Selection and environmental adaptation are thus closely linked and, in this conception, become the driving force of evolution. It is no inversion to say that the environment shapes the species, as Charles Lyell stated: If the earth had a climate like the Jurassic, there would be dinosaurs again.
Darwin had thus created a theory of selection and thus a theory of long-term change.
From today’s perspective, it is worth noting: The parallel to the economic system of free trade in Victorian England is unmistakable: here
everyone could produce and offer their goods and the market (i.e. the environment) decided what sold and could continue to be produced and thus became established, and which goods were not accepted and were thus taken out of production. We may take a humorous view: Nature is all English and England is all natural.
Moreover, as species spread and penetrate further spaces, they can enter and adapt to different environments and thus split into two or more species at the edges. The origin of species is species that divide and change. Darwin had thus developed a theory of descent in addition to the theory of selection and transformation.
At that time, people spoke of Darwin’s theory of descent and Darwin’s theory of transformation. The term evolution (for both) only gradually became established; at that time it was still associated with the old idea of preformation, which assumed that a sequence of embryos was stored in the female body, which would develop one after the other – evolvere means to unwrap something.
The central concepts in Darwin’s theory and in the Frankfurt Organismic Theory
Species
The species is a community of similarity, in many cases also a reproductive community of a large number of individuals, which, according to Darwin’s explanation, is essentially characterized by environmental adaptation. All attempts to create a scientific definition of the term “species” that applies to all living beings have failed. Even Darwin was aware of the vagueness of the term “species”. Ultimately, the conclusion remains that a species is what zoologists or botanists consider it to be, “species are cultural kinds” (Gutmann & Janich 1998). This means that the “species” as a central concept of the Darwinian theory of evolution cannot be defined scientifically; it remains at the level of naturalism. This also applies when we speak not of species, but of populations and the change in their characteristics controlled by genes.
Selection
Darwin’s term “selection” takes on an expanded meaning in the Frankfurt Organismic theory. Selection is not limited to the relationship between the individual and the environment. Selection is a process on several levels: the level of molecules, that of body structures and their functioning – “internal selection” – and the level of interaction with the environment in the broadest sense (“external selection”), which is concerned with the acquisition of food, use of space, or competition within the species or with other species. (Linguistically, the word selection is unsuitable to describe the situation, because selegere – to select – is an active word that goes back to Darwin’s breeding practice. There is no actively intervening authority in nature. At best, organisms can die through their own inadequacy or gradually die out.
Adaptation
Darwin and Wallace applied this concept to the relationship of the individual and species to the environment, although they themselves saw the difficulty of explaining this concept, namely in the birds of paradise of New Guinea, which had formed quite different species in the same environment. Critics Webster and Ho say that the idea of adaptation is a piece of natural theology from which Darwin could not completely free himself.
Because the term is vague, it could be used in an almost inflationary manner, as critically summarized by Edlinger (2009). Two suggestions were made to drop the concept of adaptation and instead speak of viability (Edlinger 2009) or specialization (Grasshoff 2014). These two terms refer to the body structure, its functionality and its relationship to the environment.
In our modern view, it is the mechanical and physiological properties that determine which habitats the organisms can penetrate and still be viable; they specialize in a certain way of life. They influence their environment through their spatial presence and their material and energy turnover. They are the subjects of evolution and not the objects of environmental demands.