Theoretical contributions

An introduction to the reproduction and heredity of integrative units

(A summary of an unpublished note by Faustino Cordón)

At present, biology is content to accept two questionable statements on reproduction and heredity. One is that the characters of the phenotype of a cell, a plant, a saprophyte or an animal are predetermined in the characters of the genotype, without considering what process transforms the former into the latter; the other is that the variations of the genotype (mutations) are the primary cause operating in the natural evolution of living beings. We will discuss these two statements below.

Criticism of the statement that the genotype contains the characters of the phenotype of the living being

This statement on reproduction and heredity is basic to current biology. As a critical comment, we can state that it involves accepting two old concepts: preformationism and spontaneous generation. It is currently thought that the emergence -and therefore the nature- of all living beings goes back to the chromosomes of a germ cell that can give rise to free cells, or the cells that constitute plants or animals. This interpretation is equivalent to admitting that the polymers of molecules, nucleic acids, have two qualities that are obviously beyond the scope of the behaviour of the molecule (i.e. they are not found in the laws of chemistry): 1) that the molecular polymers of nucleic acids contain -in potential form- the process that culminates in the structure of the emerging living being (the premise of preformationism); and 2) that these polymers have the capacity, in a moment of this process, to actualize life, i.e. to control a coherent environment to the benefit of their own maintenance, and possibly their growth and reproduction (the premise of spontaneous generation).

However, during the 20th century “molecular biology”, an expression that simplifies a contradiction in terms, has revealed that the only agent of the production and management of the nucleotides of nucleic acids are proteins with known specific functions, and that the role of the nucleotides of nucleic acids is merely to serve these specific proteins as a simple mould for them to exactly reproduce the order of the amino acids in the polypeptides that form the proteins needed by the cell.

Thus, the joint data of “molecular genetics” and the rest of “molecular biology” unequivocally show that the agent, the living being, of a directly supramolecular and sub-cellular level is the protein defined by its particular capacity to apply van der Waals forces to recognize and control molecules, one by one in this case the nucleotides of nucleic acids.

Modern biology has also discovered that all cells are formed by proteins associated so as to establish the cell soma. The cell is the living being of the second level (immediately above the protein and below the animal) that controls masses of water.

It is clear that the animal emerges from cells associated in the animal soma. The animal is the living being of the third and highest biological level, which governs its environment composed of the molecules of the biosphere in different states (solid, liquid and gas) by exercising its peculiar (mechanical) mode of action.

It seems clear that we must try to understand the ontogeny of each living being, i.e. how its phenotype develops from its phenotype.

To avoid resorting to the convenient explanation that the phenotype is predetermined in the genotype (which, in fact, reduces ontogeny to mere growth), we must consider the following problems that are raised in biology today:

1) We must understand the origin of each living being by its phylogeny. In other words, using comparative anatomy and physiology we must induce the emergence of the originary living being of a level from the living beings of the lower level, and the process of evolution of this living being.

2) We must understand the emergence and individual ontogenic development of each living being.

3) We must understand how, at each moment of its individual development, a living being emerges from the living beings of the lower level that form its soma, as a physical field of experience capable of perceiving environmental changes and signalling somatic responses that are suitable for them.

Hence, phylogeny, ontogeny and the emergence in each moment of each type of living being must have the same nature. To satisfy these three premises, our interpretation of the living being must fit all the empirical and experimental data and explain the living being in terms of the natural process that allowed it to emerge and maintain itself.

The knowledge of the phylogeny of each type of living being must allow us to understand the development (and each instant) of its ontogeny, and to deduce its reproduction and heredity.

It must be pointed out that the ontogeny of every living being is a process that 1) recapitulates its phylogeny in a way that biology must understand, considering heredity in the broad sense; and 2) is driven by the living being, which continuously responds to the complementary process of the environment, inevitably with unpredictable nuances that require the living being to apply quanta of freedom. Thus, every new living being is not only a consequence of its evolutionary history, its inheritance: it is a unique individual that prolongs its inheritance with the contributions of its own life.

Criticism of the view that mutations (changes of the genotype) are the primary cause of biological evolution

In response to this second statement on reproduction and heredity, we can say that the cause of biological evolution cannot be attributed directly to random variations of nucleotides in nucleic acids, which are merely instruments that are produced and controlled by proteins at the service of their own reproduction in the cell.

We should not lose sight of the fact that the agents of evolution can only be living beings, i.e. proteins, cells and animals; and that each of the four stages of evolution in the biosphere (that of the molecule, that of the protein, that of the cell and that of the animal) has been governed by the living beings of the higher level.

At present, biological evolution is driven by that of animals and, increasingly, by the conduct of the human, the hegemonic animal. We must consider the relationship between the behaviour of animals, the protagonists of the current biological stage, and the characters of their somatic cells, all stemming from their germ cells, and the relationship between the behaviours of the germ cells and the characteristics of the proteins that form them.

The behaviour of each animal can never modify its soma or the capacity of the germ cells of its gonad, but it can place the capacity of its germ cells in conditions that allow the selection of the most suitable ones. It does so by dealing with its specific environment and succeeding or failing to reproduce, thereby influencing the average capacity of specific behaviour of the animals of the next generation. The fittest animals of each species are statistically those that manage to reproduce more than the rest; and this ability tends to be inherited by their children, resulting from germ cells that are siblings of the parental germ cell and therefore, on average, more similar to it than to the germ cells of the remaining animals of the species.

Though the germ cells of the gonad of a fit animal (siblings of its own germ cell) often resemble each other, as living beings they have an individuality that is completely unique; i.e. each of the cells of a gonad possesses characteristics that distinguishes it, however little, from all the remaining germ cells produced in the same gonad. These differences in each germ cell depend partly on the differences in their somas, composed of co-associated globular proteins that cannot be all identical to one another either, and partly on the differences in the processes of their cellular environments.

Therefore, an erroneous change in the nucleic acids of a germ cell (a mutation) is not a fortuitous event (although it is unexpected) but rather must be related to the agents that produce and control nucleic acids, their specific proteins; and an erroneous mutation disturbs globular proteins, altering the capacity of behaviour of the germ cell and, accordingly, that of the resulting animal.

However, changes in the nucleic acids can persist if they form proteins in the germ cells that give rise to animal somatic cells that allow animals to have a more suitable behaviour.

Thus, the inheritance of an animal’s ability to exercise its specific behaviour more competently depends, very determinedly, on the refinement with which the cells of its soma perform their associative activity, which is determined by the capacity of its germ cell. In turn, the inheritance of the capacity of the germ cell, through natural selection, depends on the capacity with which the proteins of its soma perform their associative activity.

Although the differences between sibling animals, sibling germ cells and sibling proteins in the capacity to perform their specific behaviour are very small (because they are unique, unrepeatable beings), these differences, operating in the same direction over generations, are the only substrate of animal evolution.

The behaviour of the fittest animals of a species means that, on average, their germ cells (with their respective chromosomal heritage) have specific somatic proteins that allow them to develop this behaviour.

All animals must tend to use their specific behaviour to the maximum in extreme situations of life, on pain of death. However infrequent, these situations involve the maximum application of the associative capacity of the cells of their soma, and this, in turn, requires the maximum applications of the associative capacity of the somatic proteins of their cells.

It is clear that the individuals of each animal species (including humans) differ in the congenital capacity of their specific behaviour. The increasing capacity of the individuals of successive generations cannot be understood only by the selection according to the degree in which they have this capacity (sometimes what is selected is the capacity of cooperation of animals of very social species, of which a culminating example is the human species. La naturaleza del hombre a la luz de su origen biológico) (Spanish). The selection of animals with a more suitable behaviour lies in the selection of their germ cells, whose minimum differences affect precisely their likelihood of creating animal somas that are better able to exploit the new environments. And the selection of these ideal germ cells lies in the selection of the proteins that form their cell somas.

In all processes of speciation, some animals come to refine their behaviour to the point of distinguishing two sub-environments in their previous environment. This establishes the conditions for the animals of this species to subdivide into two groups, each of which adapts progressively in one of the two sub-environments. When the process of speciation reaches a degree such that the differences in behaviour prevent mixed reproduction, the germ cells of the animals of each group have also reached a somatic differentiation of their proteins such that it is reflected in their chromosomal heritage.La evolución conjunta de los animales y su medio. (Spanish).

Thus, the evolution of animals is based on the selection of the individuals with the greatest congenital capacity to perform their specific behaviour. This selection involves the selection of the germ cells of these individuals, and the selection of the germ cells involves the selection of the proteins that form their soma. And the driving force is the imperceptible and unpredictable quantum of freedom of each living being of each level, unlimited by its inheritance, to decide its action in each moment and its behaviour throughout its life. This is what makes it unique and, ultimately, susceptible to natural selection.

Faustino Cordón: Biólogo Evolucionista by Herederos de Faustino Cordón, licensed under a Creative Commons Reconocimiento-NoComercial-CompartirIgual 4.0 Internacional License. Licencia de Creative Commons