When Charles Darwin’s Origin of Species was published 150 years ago it was a response to the biggest problem posed at that time by natural history. His interpretation of a series of observations in nature supported the evolutionary origin of living beings, and this situated the evolutionary process in the perspective of “cause and effect”. Like all scientific theories, it implied a vision of the world and man — something we will come back to later.
Natural selection is not everything in evolution
To Darwin, random changes occurring in some individuals within a population (variation) allowed them to choose (natural selection) the most suitable environment in which to live longer and thus leave more descendants. The idea of natural selection in the evolutionary process is clever and accurate; scientists recognise that it has been directing adaptation over thousands of generations — we might say, improving the species. However, natural selection by itself is not a sufficient explanation of evolution.
Natural selection is even less able to explain the emergence of the human family. Darwin’s gaze was interdisciplinary: geological, zoological and botanical. But, due to his personal dispositions, he missed looking at man beyond the zoological sphere.
If Darwin had known the new biology, with its understanding of vital phenomena as an expression of dynamic processes of information; if he had known about the dynamics of development through which a multicellular organism develops from a single-cell stage, and could read the genomes of Homo sapiens and the chimpanzee, surely he would have extended the idea of variation and selection as we do today. He would have gone beyond what amounts to a mechanistic approach.
Darwin’s mechanistic idea of living realities
Biology has been, until very recently, static and deterministic, because life sciences have carried with them the mechanistic paradigm of physics from which they were born. The great insight of Darwin fell within this conceptual framework. His approach is well understood: a) an agent causes a change (material cause) in the materials of life — that is, in DNA, the genotype, where genetic information is being carried; b) this agent changes genetic information and consequently the phenotype (formal cause); c) the agent causing DNA changes would not affect the efficiency of these individuals themselves, nor would it cause by itself an evolutive progress; on the contrary, the efficient cause is natural selection as a function of change in environment; d) and, reasonably from that perspective, the evolutionary process could not have another direction (final cause) than that marked by “the blowing wind”, as Darwin put it.
improved stage could be reached. Natural selection improves existing beings gradually, but it would not cause complex innovations to appear.
|Importantly, Darwin does not explain the fact that the complex is preceded in time by the simple. Something must be added to natural selection so that a significantly improved stage could be reached.|
Importantly, Darwin does not explain the fact that the complex is preceded in time by the simple. Something must be added to natural selection so that a significantly
From the tenets of his theory on evolution Darwin realized that he could not resolve the question of the direction towards complex improvements: how a new organ appears, or how more complex functions become added to an existing organ, or how a design unit is an integrating part of a living being. Darwin launched upon the world, so to speak, the challenge of applying his theory to the complexity of an eye, determined by nature in very different models, but all of them effective for seeing. In The Origin of Species he wrote: “if it can be demonstrated that there has been a complex organ that could not have been formed by numerous successive slight modifications, my theory would fail completely.”
Certainly, no system appears complex from scratch, but begins as a simpler system with less complex functions. Therefore, evolution is not simply variation and selection depending on the environment. Evolving means changing, little or much, the actual program of building the body, the design. The selection is not carried out by the environment, but by the internal dynamics of the body; it is an internal selection.
Complexity and design: artificial and living entities
A system is complex when it is composed of several interactive pieces, well regulated and adjusted to each other, contributing to the basic function of the unit, such that the removal of any component would cause the system to stop functioning. But there is a radical difference between complex artificial systems, such as a mousetrap, and the complexity of living beings.
The design of a mousetrap is external to the pieces needed to construct it. The inert materials to construct it lack the information to make the pieces needed, to assemble them according to the design, or to evolve and generate a more elaborate and perfect mousetrap.
By contrast, the starting materials of living beings (inherited from progenitors) do contain the genetic information to construct an organism step by step, integrated in a functional unit designed to live, transmit life and evolve.
Evolving from simple to complex – how?
We know today that genetic material is informative material; every living being has genetic information (the sequence of nucleotides in its DNA) which is a first level of information, and a further type of information — epigenetics — springing up with the process of the life of each individual — which is a second level information. The first level of information contained in the genome is inherited from generators. Nucleotide sequences of DNA allow specific chemical interactions with certain other entities thus providing a map of complementary functional groups. Each sequence of bases of DNA carries specific information content. Each gene, a sequence with an ordered language of design, may be translated into the language of proteins; its functional message is then recognized. Messages contained in nucleotide sequences may be translated into proteins that perform specific functions.
DNA has information richer than that exclusively due to genes: it has sequences specifically recognized by regulatory molecules. These signal molecules can be proteins, and genes encoding them are called “regulatory” since they control the expression of other genes, and so on. The control of genetic information amplifies and feeds back, step by step, the development and construction of the body: it is an extension of the epigenetic information of genes.
The order in which genes are expressed throughout the life of the individual is a program, an orderly succession of messages, a second-level of information. With this program organs and various types of structures are formed. This is the epigenetic information: an expansion of genetic information linked to the development of the organism itself. The greater complexity of the individuals of a species is dependent on the ability to expand the genetic information and control it.
For evolution to take place the following is necessary: a) a change in DNA (material cause), in such way that b) the genetic information increases (formal cause), c) epigenetic information increases (efficient cause), and d) the development program becomes richer (final cause).
Darwin today: not natural selection but ‘information’ pushes evolution
So what would Darwin say about evolution if he could address us today? First, he would probably speak in terms of information. He would recognise that an increase in epigenetic information is the real push in evolution.
microevolutive processes appear after prolonged periods of time. An agent would create a random mutation in a gene (first-level information), and another agent would select the individual carriers of this change, depending on the environment, to establish differences with respect to the other individuals in terms of reproductive capacity. A microevolutive process, directed by changes in the environment, would explain only differences and adaptation within a species.
|Science clearly shows the existence of an inner design in living beings and in the origin of species, even if it is not design “from the outside” in respect of particular organisms or their parts.|
He would most likely say that
At the same time Darwin could argue that evolution also takes place through macroevolutive processes; the inducing agent would cause, in those cases, a random change in the regulatory DNA (second level of information), increasing the ability to control, as a unit, operations and functions. The power to bring this about is in the process itself, since it enriches the starting information, thus increasing epigenetic information. The new information, innovation, is thus integrated at the highest level.
To come back to the eye. Each type of animal eye is, indeed, built from existing parts, even with some modifications of them, and integrated by a second level of information that controls the assembly in a unit of function, which makes the individual capable of seeing. The filter is the program designed to construct the eye within the program designed to construct the whole organism. It is not natural selection that is responsible for the construction of an eye.
In this sense, Darwin lost his challenge. He would probably recognize today that his theory is not valid to explain the evolutionary process as a whole.
Science clearly shows the existence of an inner design in living beings and in the origin of species, even if it is not design “from the outside” in respect of particular organisms or their parts. Thus a clear space is open to know in a rational way the Author of this wonderful world.
The origin of men, their freedom and dignity
What would Darwin say today about the origin of men? With today’s knowledge of human biology, especially neuroscience, his assertion that the first men originated from a hominoid ancestor — the Australopithecus — would have to be enhanced and completed. He could still account for the peculiarity of this event within the evolution process. The biological sciences show that the emergence of Homo had, as its material cause, a chromosomal rearrangement that increased epigenetic information for building the brain during development.
But human biology shows clearly that we are not confined within pure animal biology. And the mind of a human being remains open to processing information coming from dealing with others along his/her life. The holder of a human body, every man, is free and not confined within either the ecological niche or the present time, as happens with animals; man has the whole world as his niche; he has memory of his past and he may project his future.
The human body is released from the automation of biological processes. This capacity to remain open, or free from confinement within biology, is not caused by an increase of epigenetic information of the human species. On the contrary, the development program of each man is enhanced and empowered with freedom. Each man, not mankind as a whole, is a radical novelty, because he is free.
Where does this freedom come from? The question of the ultimate origin of the personal character of every man, his freedom, his human psyche, cannot be answered relying only on positive sciences. Those who accept that freedom is a gift granted to each man by his Creator, understand that each man has human dignity. Those rejecting the idea of freedom as a gift, however, lack a rational explanation for the fact that man is not submerged in biological determinism.
Natalia López-Moratalla, PhD, and Esteban Santiago, MD, PhD, are both professors of biochemistry at the University of Navarra, Pamplona, Spain.