The contributions of Newton and Darwin

The theories of Isaac Newton and Charles Darwin, two of the most influential scientists in human history, have long prevailed, but the twentieth century has witnessed important discoveries that have limited their postulates.

Newton’s groundbreaking work establishing the laws of motion and gravity, as well as in optics and calculus, helped to spark a revolution that changed the way we think about the Universe. Before him, what we now call science was nothing more than a combination of isolated facts and laws that allowed us to describe and predict some phenomena. His rigorous approach brought to science a unified system of laws applicable to a wide range of physical phenomena.

To Darwin we owe the idea that life has unfolded over time through an evolutionary process. Evolution assumes that:

  1. a) Species change over time;
  2. b) New species come from pre-existing species; and
  3. c) All species share a common ancestor.

What really constitutes his fundamental discovery, however, is so-called “natural selection”, i.e., the mechanism he proposes for this evolution. In the words of Francisco J. Ayala., this “implies that certain genes and genetic combinations are transmitted to subsequent generations on average more frequently than their alternates. Natural selection does not seek to obtain predetermined kinds of organisms, but only organisms that are adapted to their present environments. The variables that determine in which direction it will go are the environment, the pre-existing constitution of the organisms, and the randomly arising mutations.”[1]

Newton’s Law of Gravity was superseded by Einstein’s Laws of Relativity

Newton’s laws of motion and universal gravitation, which governed both the surface of the Earth and the entire Universe, remained undisputed for two centuries. It was possible to explain the movement of the solar system, predict eclipses, and understand the tides.

That was, until Einstein arrived and formulated the laws of relativity. All Newtonian mechanics were based on the assumption that mass, time and distance are constant, regardless of where they are measured. Einstein’s theory of relativity posits the opposite. The law of universal gravitation does not contemplate time; it assumes that gravity propagates instantly, with infinite speed. Instead, relativity considers that the speed of light cannot be exceeded. Where Newton argued that an apple was propelled toward Earth by a gravitational force, Einstein understood that there was no such force, and that the trajectory of the apple is explained by a law that states that motion corresponds to a straight line in a curved space-time. Einstein’s theory clarifies phenomena in the Universe that Newtonian laws cannot explain. However, as we know, for most calculations of phenomena that take place on Earth or even in our planetary system, these laws provide more than acceptable results, so they continue to be the basis for engineering calculations.

Watson and Crick’s discovery introduces the concept of biological information into Darwin’s theory

The superseding of the Newtonian laws came from the hand of a genius, Albert Einstein, who published the two laws of relativity in the short space of five years: Special Relativity in 1905 and General Relativity in 1910.

The case of Darwin’s theory is different, as the contributions of numerous researchers over time have modified our view of the origin and evolution of living beings.

Thus, from the new knowledge about heredity and genes, neo-Darwinism was born in the 1930s. This theory recognizes natural selection and genetic mutations as factors that cause the emergence and expansion of new animal and plant forms, and affirms that the unit of selection is the individual, while the unit of mutation is the gene.

However, the fundamental change came in 1953, when Watson and Crick, in the space of just six weeks, published two articles in Nature[2] that have marked a before and after in our understanding of the mechanisms of biological inheritance. In the first, they described the double helix structure of DNA that led them to state that “the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material”. And in the second, they introduced a concept that would change our view of what life is: “it seems likely that the precise sequence of the bases is the code which carries the genetic information.”

At that time, living beings were assumed to consist of two fundamental entities: matter and energy. During the 1950s and 1960s, however, molecular biologists discovered a third fundamental entity at the base of life: information. In fact, the computational perspective of molecular biology was intuited by one of the fathers of quantum physics, Erwin Schrödinger, who in 1944 wrote a book entitled What is Life[3], in which he proposed that genetic material contains a code and an executive capacity to develop the coded material. He anticipated this important concept before the discovery of DNA structure and information theories.

The information contained in DNA reveals enormous complexity

Indeed, Watson and Crick, on observing the structure of DNA, made a surprising discovery: DNA could store information in the form of a digital code composed of four chemical bases (A, G, C and T) that make up this molecule and that represent the same as the letters of a written text or the digital characters of a computer program. And the complexity of the genetic system is manifested in multiple aspects. Each base binds to a sugar molecule and a phosphate molecule to form a nucleotide. The nucleotides are arranged in two long strands that form a spiral called a double helix. Genes are small sections of the long DNA chain. They are the basic functional and physical units of genetic inheritance. Each cell of a human contains 20,000 genes and a total of three billion bases.

However, the complexity of this system does not lie exclusively in the information capacity of the sequence of genes and bases that we call the genome. The genome also performs two complicated functions: DNA must copy itself so that each new cell has a complete copy of the same genetic information; and it also develops the transcription process by which it creates an intermediate molecule, RNA, to which it transfers the information necessary to generate a certain protein.

The way in which it realizes its functions is often compared to computer code. As Bill Gates observes, “DNA is like a computer program, but far, far more advanced than any software ever created.”[4] In reality, it is something essentially different though, since it does not contain any code to define the individual steps of an algorithm. And, in contrast, every cell of the 30 trillion cells that humans have has its own copy of DNA and, in each cell, genetic expression operates independently, managed locally by the cell nucleus.

The way in which DNA operates to produce the right proteins with which to build a human being, an oak tree or an elephant seems to follow three layers of management. In the first, it is decided which proteins are actually produced and when and in which cells they are made; in the second layer, these protein molecules are modified so that they begin to work; and in the third there is additional supervision. In these operations, 90,000 different functions (the different types of proteins) are managed, with trillions of protein molecules performing each function.[5]

How does this complexity affect Darwinian theories?

Darwin’s theory seeks to explain how life evolves from simpler pre-existing forms; therefore, as Darwin himself admitted, it did not explain how the first life form appeared. But the same idea of evolution carried over to the origin of life. The fact that both the inanimate world and the living system are made up of atoms and molecules led us to think that the phenomenon of life originated from “non-life”, that chemical atoms and molecules combined in a certain way can create life. This was proposed by the Russian biochemist Aleksandr I. Oparin in 1924: life could have arisen as a result of a series of chemical reactions. This idea seemed to be confirmed by Stanley Miller in 1953 through a famous experiment that managed to partially create organic matter from inorganic matter under the theoretical conditions that the Earth would have had before there was life on it.

However, building the first living cell, the most elementary, necessitates assembly instructions that require the joint work of three types of complex molecules: DNA, RNA and proteins. And so far, despite numerous attempts and tests, evolutionary chemical models have failed to identify a cause capable of generating this.

What has been calculated, though, is the enormous improbability of this happening through known mechanisms and the rules of chance. If we stick to proteins, these are made up of a certain sequence of amino acids in which each amino acid has to be in the right place and in the right order. The absence, addition or replacement of a single amino acid in the structure of a protein causes the protein to become a useless molecular heap.

Research conducted by Douglas Axe at Cambridge University and published in the Journal of Molecular Biology[6] has calculated the probability of random formation of a medium-sized protein composed of a functional chain of 153 amino acids. The result is 1 in 1077. This is the same as saying that there is no probability in the entire time of existence of the Universe, and a minimum of one hundred of them are needed for minimal vital functions, in addition to DNA and RNA.

The origin of life was an unknown for Darwin, but the discovery of the complexity of the information required to create it in its most elementary form has only added to the mystery. We are unable to envision how this can occur spontaneously. The most comparable thing we know to the creation of this complex functional information is the writing of computer programs, which require human intelligence.

Nor does it explain the emergence of new species

The complexity of the information that is needed in all living things opens up a gap in the Darwinian explanation of new species. This argument has been questioned for a few decades, as the biologist Gerd Müller put it in 2016: “genetic evolution alone has been found insufficient for an adequate causal explanation of all forms of phenotypic complexity”.[7]

This is because small microevolutionary changes, such as variation in the size of an animal or the resistance of an insect to a pesticide, occur without altering the existing genetic information. But the macroevolutionary changes needed to build new organs or complete body plans do require the production of new genetic information. And we have already seen that functional proteins are made up of hundreds of amino acids and that creating a functional chain of 153 amino acids through random mutations has no chance of occurring even over the course of billions of years.

Society remains indebted to Newton and Darwin

Isaac Newton’s contribution to science and mathematics has had a profound impact on our understanding of the natural world and has formed the basis of hundreds of years of scientific discovery. His work continues to shape our understanding of the Universe. Einstein gave him special recognition by hanging his portrait in his office.

Perhaps no other scientist has had such a radical influence on society as a whole as Darwin, by making people aware of their place in the evolutionary process. He forced a change in the deterministic way of explaining the reality that prevailed at that time, introducing the universality of randomness and chance throughout the process of natural selection. The concept of evolution remains, although we have not yet been able to understand all the steps of that process. This is confirmed by Gerd Muller: “The theory of evolution is the fundamental conceptual framework of biology all scientific explanations of living phenomena must be consistent with”.[8]

Science is both a body of knowledge and a process for finding new knowledge, sometimes to replace old knowledge. The law of gravity formulated by Newton has been superseded by another more general theory, the laws of relativity, although their complicated mathematical calculation has allowed Newtonian mechanics to continue to be used in low-gravity applications, like most phenomena that occur in our solar system.

Watson and Crick’s discovery led to knowledge of the complexity of information necessary for the creation of life. With this, Darwin’s theory has been superseded, although for the time being, we have no explanation for the origin of life or for the emergence of new species. The explanatory power of adjustments is maintained, adjustments through which an organism adapts to local conditions, such as changes in color, wing style or beak shape, which are the result of small mutations that retain the existing genetic information. The conceptual framework and the notion of evolution are still valid.

It is evident that the imprint of Newton and Darwin remains present.

Manuel Ribes

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia

 

[1]  M. Ribes, Francisco J. Ayala: The legacy of a great scientist, scholar and gentleman lives on in the scientific community Bioethics Observatory UCV, April 2023

[2] WATSON, J., CRICK, F. Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid Nature 171, 737–738 (1953)

WATSON, J., CRICK, F. Genetical Implications of the Structure of Deoxyribonucleic AcidNature 171, 964–967 (1953)

[3] E. SCHRÖDINGER. What is Life? with Mind and Matter – Cambridge University Press 1967. ISBN 978-1-107- 60466-7

[4] Jun Ma et al., Programming Hypothesis on Life Phenomena and the Key Processes Simulation – Advanced Materials Research – January 2013 – DOI: 10.4028 / www.scientific.net/AMR.647.258

[5]  R. Philip Bouchard,  Is DNA Like a Blueprint, a Computer Program, or a List of Ingredients?  The Philipendium – 25 January 2019

[6] Axe DD. Estimating the prevalence of protein sequences adopting functional enzyme folds. J Mol Biol. 2004 Aug 27;341(5):1295-315. doi: 10.1016/j.jmb.2004.06.058. PMID: 15321723.

[7] Müller, G. B. Why an extended evolutionary synthesis is necessary Interface Focus 7: 20170015.

[8] ibid.

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