Quantum evolution (alternative)
Encyclopedia
Quantum evolution is the hypothesis that quantum effects can bias the process of mutation towards adaptive genetic variation. It should not be confused with quantum evolution
, a theory related to the modern evolutionary synthesis
. The first publication on this subject, which appeared in a peer review journal, is by Vasily Ogryzko. Biologist Johnjoe McFadden
and the physicist Jim Al-Khalili
subsequently published their own theory in 1999 in which they proposed a mechanism based on enhanced decoherence of quantum states that interact strongly with the environment. McFadden published his book Quantum Evolution in 2000.
of cells
is based on a mechanism whereby cells individually undergo mutation
, with the process of natural selection
then culling out those mutations which are less beneficial to the organism. Quantum evolution is an attempt to provide a theoretical mechanism which would skew these random mutations in favor of some outcome beneficial to the cell.
It should be stated at the outset that this theory would only be useful if indeed there were evidence that some sort of adaptive mutation
occurs - in other words, if there were experimental data showing that the classical model of random mutation is lacking, and that certain mutations are "preferred" (occur more frequently) because they confer a greater benefit to the organism. This is a controversial subject in and of itself; a plethora of papers have been published on the enigmatic phenomenon of adaptive mutation
and the issue of their origin and mechanism remains unresolved. To date there is no such generally accepted mechanistic explanation of adaptive mutation
.
A mechanism proposed by quantum evolution is to imagine that the configuration of DNA
in a cell is held in a quantum superposition
of states, and that "mutations" occur as a result of a collapse of the superposition into the "best" configuration for the cell. The proponents of this approach liken the operation of DNA to the operation of a quantum computer
, which selects one from a multitude of possible outcomes.
Several problems need to be overcome for this theory to be consistent with our current knowledge of quantum physics. Most importantly, the state of quantum superposition must last long enough to allow the DNA to do its normal job (produce RNA
). Without this, there would be no way for a comparison of the outcomes of various mutations to occur and thus no basis for the system to bring about adaptive mutation. Protein formation occurs at a rate of on the order of 10,000 times a second (10−5 seconds per protein formed). However, DNA is not translated directly into protein, instead DNA is transcribed
into a messenger RNA
and this RNA copy is then used for protein biosynthesis
. A gene
is therefore never directly linked to its protein product, making any possible mechanism for signal transmission between a protein and the DNA that encodes it hard to imagine without action at a distance
.
Although some have, by analogy to the technique of NMR
imaging, posed state coherence times as long as half a second, this analysis has been challenged by Matthew J. Donald (but see also McFadden and Al-Khalili's rebuttal , and Donald's response ), and coherence times on the order of 10−13 seconds seems to be a much more realistic outcome. This latter time would be far too short by many orders of magnitude for the protein formation required for a superposition of quantum states to affect mutations.
However recent evidence indicates that quantum coherence of electrons and protons does indeed occur in some (maybe all) enzyme reactions in living cells, such as those involved in photosynthesis and may even be responsible for the huge catalytic enhancement of reaction rates provided by enzymes .
If the theory of quantum evolution were indeed true, one could further speculate that a similar, more robust process could explain observed phenomena such as the apparent "jumps" in the fossil record as adaptive mutations on an even larger scale; this would require even longer periods of state coherence than those described by McFadden et al. yet this has not been proposed by any of the advocates of quantum evolution who have limited their speculations to molecular processes.
A different critique on quantum evolution can be made by asking why, if the cell can make use of quantum superpositions, it's not used for more purposes? Our immune system contains "general" agents that attack anything foreign and "specialised" ones (antibodies) that bind to specific proteins on specific bacteria. The latter must be made on demand. But why not use quantum superpositions to immediately attack the bacteria with every conceivable antibody at the same time and select the one that works? The answer is likely to be that more complex systems (than single protons in DNA or electrons and protons in enzymes) cannot be maintained in quantum coherent states for long enough to have biological significance.
Science fiction writer Greg Egan
, in his book Teranesia
, posited a similar mechanism, whereby large adaptive mutations occur in multiple species under the aggressive quantum mechanical influence of a new protein.
However, the theory, at least that proposed by McFadden and Al-Khlaili , did not propose that certain states are identified as 'best' by the quantum system but only that certain states interact with the environment more strongly than other states and thereby promote more rapid decoherence. For a starving cell, these more interactive states are those DNA states that encode mutations that allow the cell to grow.
Of course, DNA, like all molecules, already obeys the laws of quantum mechanics, including quantum superpositions, collapses, and tunneling. The consequences of these laws are more commonly known as quantum chemistry
, which explains all of the familiar chemical laws. Since the chemical behavior of DNA is reasonnably well-understood, and already includes both (ordinary) quantum mechanics and (ordinary) mutations, it is not yet clear where the additional effects of quantum evolution are supposed to arise.
Quantum evolution
Quantum evolution is a component of George Gaylord Simpson's multi-tempoed theory of evolutionary change, proposed to explain the rapid emergence of higher taxonomic groups. According to Simpson, evolutionary rates differ from group to group and even among closely related lineages...
, a theory related to the modern evolutionary synthesis
Modern evolutionary synthesis
The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...
. The first publication on this subject, which appeared in a peer review journal, is by Vasily Ogryzko. Biologist Johnjoe McFadden
Johnjoe McFadden
Johnjoe McFadden is an Irish / British scientist, academic and writer. He is Professor of Molecular Genetics at the University of Surrey, United Kingdom.-Life:He was born in Donegal, Ireland but raised in the UK...
and the physicist Jim Al-Khalili
Jim Al-Khalili
Jim Al-Khalili OBE is an Iraqi-born British theoretical physicist, author and science communicator. He is Professor of Theoretical Physics and Chair in the Public Engagement in Science at the University of Surrey...
subsequently published their own theory in 1999 in which they proposed a mechanism based on enhanced decoherence of quantum states that interact strongly with the environment. McFadden published his book Quantum Evolution in 2000.
Background
The "classical" Darwinian model of the evolutionEvolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
of cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
is based on a mechanism whereby cells individually undergo mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
, with the process of natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
then culling out those mutations which are less beneficial to the organism. Quantum evolution is an attempt to provide a theoretical mechanism which would skew these random mutations in favor of some outcome beneficial to the cell.
It should be stated at the outset that this theory would only be useful if indeed there were evidence that some sort of adaptive mutation
Adaptive mutation
Evolutionary theory describes that mutagenesis occurs randomly, regardless of the utility of a genetic mutation to the organism. If it is beneficial or neutral, the organism will survive to reproduce and pass on the mutation...
occurs - in other words, if there were experimental data showing that the classical model of random mutation is lacking, and that certain mutations are "preferred" (occur more frequently) because they confer a greater benefit to the organism. This is a controversial subject in and of itself; a plethora of papers have been published on the enigmatic phenomenon of adaptive mutation
Adaptive mutation
Evolutionary theory describes that mutagenesis occurs randomly, regardless of the utility of a genetic mutation to the organism. If it is beneficial or neutral, the organism will survive to reproduce and pass on the mutation...
and the issue of their origin and mechanism remains unresolved. To date there is no such generally accepted mechanistic explanation of adaptive mutation
Adaptive mutation
Evolutionary theory describes that mutagenesis occurs randomly, regardless of the utility of a genetic mutation to the organism. If it is beneficial or neutral, the organism will survive to reproduce and pass on the mutation...
.
A mechanism proposed by quantum evolution is to imagine that the configuration of DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
in a cell is held in a quantum superposition
Quantum superposition
Quantum superposition is a fundamental principle of quantum mechanics. It holds that a physical system exists in all its particular, theoretically possible states simultaneously; but, when measured, it gives a result corresponding to only one of the possible configurations.Mathematically, it...
of states, and that "mutations" occur as a result of a collapse of the superposition into the "best" configuration for the cell. The proponents of this approach liken the operation of DNA to the operation of a quantum computer
Quantum computer
A quantum computer is a device for computation that makes direct use of quantum mechanical phenomena, such as superposition and entanglement, to perform operations on data. Quantum computers are different from traditional computers based on transistors...
, which selects one from a multitude of possible outcomes.
Several problems need to be overcome for this theory to be consistent with our current knowledge of quantum physics. Most importantly, the state of quantum superposition must last long enough to allow the DNA to do its normal job (produce RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
). Without this, there would be no way for a comparison of the outcomes of various mutations to occur and thus no basis for the system to bring about adaptive mutation. Protein formation occurs at a rate of on the order of 10,000 times a second (10−5 seconds per protein formed). However, DNA is not translated directly into protein, instead DNA is transcribed
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
into a messenger RNA
Messenger RNA
Messenger RNA is a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. Here, the nucleic acid polymer is translated into a polymer of amino acids: a protein...
and this RNA copy is then used for protein biosynthesis
Protein biosynthesis
Protein biosynthesis is the process in which cells build or manufacture proteins. The term is sometimes used to refer only to protein translation but more often it refers to a multi-step process, beginning with amino acid synthesis and transcription of nuclear DNA into messenger RNA, which is then...
. A gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
is therefore never directly linked to its protein product, making any possible mechanism for signal transmission between a protein and the DNA that encodes it hard to imagine without action at a distance
Action at a distance (physics)
In physics, action at a distance is the interaction of two objects which are separated in space with no known mediator of the interaction. This term was used most often in the context of early theories of gravity and electromagnetism to describe how an object responds to the influence of distant...
.
Although some have, by analogy to the technique of NMR
Nuclear magnetic resonance
Nuclear magnetic resonance is a physical phenomenon in which magnetic nuclei in a magnetic field absorb and re-emit electromagnetic radiation...
imaging, posed state coherence times as long as half a second, this analysis has been challenged by Matthew J. Donald (but see also McFadden and Al-Khalili's rebuttal , and Donald's response ), and coherence times on the order of 10−13 seconds seems to be a much more realistic outcome. This latter time would be far too short by many orders of magnitude for the protein formation required for a superposition of quantum states to affect mutations.
However recent evidence indicates that quantum coherence of electrons and protons does indeed occur in some (maybe all) enzyme reactions in living cells, such as those involved in photosynthesis and may even be responsible for the huge catalytic enhancement of reaction rates provided by enzymes .
If the theory of quantum evolution were indeed true, one could further speculate that a similar, more robust process could explain observed phenomena such as the apparent "jumps" in the fossil record as adaptive mutations on an even larger scale; this would require even longer periods of state coherence than those described by McFadden et al. yet this has not been proposed by any of the advocates of quantum evolution who have limited their speculations to molecular processes.
A different critique on quantum evolution can be made by asking why, if the cell can make use of quantum superpositions, it's not used for more purposes? Our immune system contains "general" agents that attack anything foreign and "specialised" ones (antibodies) that bind to specific proteins on specific bacteria. The latter must be made on demand. But why not use quantum superpositions to immediately attack the bacteria with every conceivable antibody at the same time and select the one that works? The answer is likely to be that more complex systems (than single protons in DNA or electrons and protons in enzymes) cannot be maintained in quantum coherent states for long enough to have biological significance.
Science fiction writer Greg Egan
Greg Egan
Greg Egan is an Australian science fiction author.Egan published his first work in 1983. He specialises in hard science fiction stories with mathematical and quantum ontology themes, including the nature of consciousness...
, in his book Teranesia
Teranesia
Teranesia is a 1999 science fiction novel by Greg Egan. The novel won the 2005 Ditmar Award for Best Novel but Egan declined to accept the award.-Plot summary:...
, posited a similar mechanism, whereby large adaptive mutations occur in multiple species under the aggressive quantum mechanical influence of a new protein.
Controversy
A primer on quantum mechanics (such as from David J. Griffiths' "Introduction to Quantum Mechanics") suggests that the very notion of having a molecule choose a state over all others purely based on an exterior system, with no simultaneous effects on said molecule, is completely contrary to how quantum mechanics works. Quantum mechanical states are dependent on things like energy and other physical phenomena. Furthermore, imposing a viewpoint that one outcome is best implies that a best configuration needs some formal definition that is independent of mentioning organism lifespan, reproductivity, etc (as quantum mechanics does not depend on those things) and that the best configuration does depend on things such as energy levels, perturbations to the molecule, and similar things. When all of these are taken into consideration then the best state would seem to yield a truly random mutation as per what is perceived by humans as evolution.However, the theory, at least that proposed by McFadden and Al-Khlaili , did not propose that certain states are identified as 'best' by the quantum system but only that certain states interact with the environment more strongly than other states and thereby promote more rapid decoherence. For a starving cell, these more interactive states are those DNA states that encode mutations that allow the cell to grow.
Of course, DNA, like all molecules, already obeys the laws of quantum mechanics, including quantum superpositions, collapses, and tunneling. The consequences of these laws are more commonly known as quantum chemistry
Quantum chemistry
Quantum chemistry is a branch of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems...
, which explains all of the familiar chemical laws. Since the chemical behavior of DNA is reasonnably well-understood, and already includes both (ordinary) quantum mechanics and (ordinary) mutations, it is not yet clear where the additional effects of quantum evolution are supposed to arise.