Abstract

Source:  Abstract    Tag:  process of heredity
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 20 th  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.


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 obtained from the author.

© Robert Panasiewicz 2013