ABSTRACT
The
current theoretical framework of evolution and heredity is influenced by
neo-Darwinism and promotes the view of organisms being determined by the
internal programming of their immutable genomes. Rare, small and random
DNA mutations are thought the only source of heritable variations, and natural
selection is claimed to be the sole engine of evolution. This view was
developed in the early decades of the 20th century,
and it hardened into a dominant orthodoxy of the Modern Synthesis between the
1940s and 1960s. Controversies of the 1970s, which posed risks of the
rise of Creationism and neo-Lamarckism, led to further hardening of accepted
views and conservative attitudes among scientists. Combined with the lack
of research of variability, it prevented empirical verification of the orthodoxy
till the Human Genome Project in the 1990s. Instead of confirming the
orthodoxy, as was expected, the project challenged the accepted views. As
a result, the old assumption that life would be understood once the genomes of
organisms were known is giving way to a realisation of a gap of understanding
between the DNA sequence and living organisms. The sizes of genomes and
numbers of genes are not commensurate with evolutionary advancement and
complexity. DNA has been found to do much more than to code for
proteins. Various regulatory modifications to the genes, without changing
the DNA structure, have been found to be as important as genes themselves.
These epigenetic modifications have added to the known, but little explored,
structural DNA alterations. Also, instances have been identified of
evolution occurring much faster than claimed by neo-Darwinists. This new
evidence indicates that genomes are flexible and likely to change under the
impact of the environment. It also hints that the genome is not only a
blueprint for the organism but also a regulatory mechanism and a receptacle of
memory of past modifications, which is passed on to the next generation.
This flexible DNA arrangement appears to be interpreted according to the needs
and circumstances of the organism. Observed genomic stability of
organisms could reflect their inherent “resistance to change” that typically
involves discomfort such as pain, hunger and excessive cold or heat. The
resultant, apparent genomic constancy during long, stable periods could be a
transient phenomenon masking innate flexibility which is likely to produce
significant genetic modifications during stressful and turbulent periods.
Evidence gathered over the last two decades points to a different model of evolution
and heredity from the one promoted by the Modern Synthesis. Evidence of
“fast-paced” evolution indicates that natural selection is not the only engine
of evolution. While supporting this view, Darwin failed to adjust his
theory and mistakenly believed that it would collapse if evolution was shown to
involve a mechanism that was different from the slow, gradual process of small
changes driven by natural-selection. This has contributed to formulating
an incomplete neo-Darwinian view of evolution and heredity. Instead of
being a slow, gradual process, evolution may have followed an
upheaval-and-stability pattern. In this model, natural selection is the
main evolutionary engine only during long periods of stability, when the
Malthusian law, combined with variations among organisms, leads to survival of
the most successful organisms and in species adapting to the environmental
niches they occupy. During these stable periods organisms undergo
relatively minor changes, under the force of natural selection, which affect
the existing species to make them more successful in adaptation to their
environments. This slow process of minor changes during extensive periods
of stability creates an impression of inherent rigidity in the genome.
The emergence of new species is likely to occur during relatively short and
dramatic developments in natural environments. During these episodes, new
species form through significant modifications of their genetic material under
the influence of environmental impacts. Due to the large volume and
magnitude of these modifications, natural selection may be of secondary
importance in driving evolution during these periods. Corresponding with
a limited role for natural selection is the emerging realisation that Mendelian
genetics is only a special case among the mechanisms of heredity, rather than
the dominant mechanisms as consistent with neo-Darwinism. The gap of
knowledge identified by the Human Genome Project may indicate that, despite
claims of reductionist views in science, the unknowable is inevitable in
biology. The element of life with its innate propensity for replication,
distinguishing animate from inanimate nature, appears the key unknowable
element in biology. Acceptance, rather than avoidance of it, may lead to
more focused engagement with the knowable and a more reliable understanding of
biology.
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CONCLUSION
The current understanding of evolution and heredity continues to be influenced by neo-Darwinism. It has promoted the view of the organisms being determined by internal programming contained in their inflexible genomes. According to this view, minute, rare, random DNA mutations are the only source of heritable variations, and natural selection is the only engine of evolution.
This view, which was developed in the early decades of the 20th century, was solidified between the 1940s and 1960s into an orthodox, dominant platform of the Modern Synthesis. Promotion of neo-Darwinism has resulted in a general acceptance that DNA is immune to environmentally induced changes and the genes are the sole determinants of biological organism and their heredity.
Despite controversies of the 1970s which led to the crisis of the Modern Synthesis, the orthodox views were preserved, accompanied by a hardening of conservative attitudes among scientists due to the perceived risks of the rise of Creationism and neo-Lamarckism. Insufficient research into genetic variability and other related areas of genetics till the 1990s has prevented serious critiquing and rethinking of the orthodoxy. This has changed as a result of the Human Genome Project in the 1990s.
Instead of accomplishing its ultimate goal and reaching the limit of biology, the Project became a prelude to new biology (“Biology 2.0”). The old assumption that life would be understood once the DNA program of an organism is known is giving way to the realisation of a huge gap of understanding between knowing the genome sequence and understanding biological processes in the living organism. The sizes of genomes and numbers of genes have not been found to correspond with the evolutionary advancement and complexity of organisms, and this correspondence is to be expected under the neo-Darwinian model. DNA has been found to do much more than to code for proteins. Various epigenetic modifications to DNA, which regulate the gene expression without changing DNA’s structure, have been found as important as genes themselves.
Evidence gathered over the last two decades points to a different model of evolution and heredity from the one promoted by the Modern Synthesis. Numerous cases of fast-tracked evolution indicate that natural selection is not the only force driving evolution, which is consistent with Darwin’s own thoughts. However, while firmly believing in multiple engines of evolution, Darwin failed to adjust his theory to adequately account for this, and mistakenly believed that his theory would collapse if evolution was shown not to be exclusively driven by small, gradual changes over long periods of time. This inconsistency has led to much misunderstanding about evolution and heredity.
Evolution appears to have followed an upheaval-and-stability pattern, rather than a continuous, slow and long process. It could be a task of the future, new biology to verify this model whose versions have been seriously considered by prominent biologists in the 20th century. According to this model, natural selection is the dominant engine of evolution only during long and stable periods. During these periods, the Malthusian law combined with variations among organisms in species promote competition that results in survival of the most successful organisms and the best adaptation of species to the environmental niches they occupy.
During these stable periods organisms undergo relatively minor changes under the force of natural selection. These changes aim to improve the existing species to make them more successful in adaptation to their environments. This may lead to the formation of new sub-species or even new species. The emergence of new, distinctly different species is the most likely to occur during relatively short, cataclysmic developments in natural environments. During these episodes many organisms are wiped out and new species formed through significant modifications of genetic material under the influence of environmental impacts involving various forms of genetic and epigenetic modifications. Due to the large volume of these changes, natural selection may play a lesser role as the gatekeeper of evolution in comparison with its dominance in the periods of stability.
Genomic flexibility manifests itself through genetic mutations and epigenetic modifications, which may be spontaneous or induced, beneficial, deleterious or neutral to organisms. This flexibility plays a role as an engine of evolution in addition to natural selection. It also indicates that the genome is not only a genetic blueprint but also a regulatory response mechanism and an archive of memory of modifications which is passed to the next generation. This archive is not rigid but can be rearranged and interpreted according to the needs and circumstances of the organism.
Considering the complexity and diversity of the mechanisms of heredity, Mendelian genetics, as contained in Mendel’s first law, only represents a special case applying to dominance and recessiveness of traits. Mendel’s generalisation contained in the second law is incorrect as traits are often dependent on other traits.
The apparent constancy of genomes during stable periods in the earth’s history could be viewed as reflecting resistance to change, which is inherent to biological organisms, rather than structural rigidity of DNA. This tendency to stability and resistance to change could be described as the “force of habit” of successfully adapted species clinging to their environmental niches. The resultant, apparent genomic constancy could be a transient phenomenon masking the innate flexibility, which is likely to produce significant genetic modifications during stressful and turbulent environmental periods.
The unknowable appears inevitable in biology. Attempts to ignore or circumvent it have resulted in evolution and heredity being explained through highly speculative hypotheses, which has not been constructive to the healthy growth of knowledge. The element of life with its innate tendency to replicate, which distinguishes the animate from inanimate nature, appears an important unknowable element in biology. Trying to understand it better could perhaps be a task of “Biology 2.0”. Acceptance of this relatively small unknowable element may lead to a more focused engagement with the knowable and more reliable understanding of evolution and heredity.
Note:
The full version of Preface to New
Biology, An Overview of the Current State and Problems of Genetics and Theory
of Evolution may be found here.
© Robert Panasiewicz 2022
rpanasiewicz@westnet.com.au