Information, Darwin and a new Evolution perspective

I will briefly share today an HTML paper (PDF downloadable) that I received from a Google Scholar feed.

It is called Updating Darwin: Information and entropy drive the evolution of life, and it is a nice new perspective on the Evolution of Life through an informational lens. It is argued that evolution of life follows from a fundamental struggle (self-perpectuated engine) between the inevitable second law of thermodynamics, stipulating an ever increase in entropy and complexity, and its counterpart which is preservation of information. Interestingly it is also stated that complexity is an emergent automatic property of information itself. This process is driven by autocatalysis, and as it is explained in its Wikipedia entry it explains how life and information may be inextricably linked by catalysis (chemically) automatically, by nonlinearity and spontaneous generation of order.

This paper is part of a broader discussion within the Biology  research community as to the need to update Darwinian Biology on the one hand, and on the other if we should be mor conservative regarding this update. The author of this paper is of a position closer to the former, and thinks that persistence of outdated ideas isn’t always a virtue by itself, and sometimes it obstructs progress and a better idea from seeing the light of recognition.

Updating Darwin: Information and entropy drive the evolution of life

 

Abstract

 

The evolution of species, according to Darwin, is driven by struggle – by competition between variant autonomous individuals for survival of the fittest and reproductive advantage; the outcome of this struggle for survival is natural selection. The Neo-Darwinians reframed natural selection in terms of DNA: inherited genotypes directly encode expressed phenotypes; a fit phenotype means a fit genotype – thus the evolution of species is the evolution of selfish, reproducing individual genotypes. 

            Four general characteristics of advanced forms of life are not easily explained by this Neo-Darwinian paradigm: 1) Dependence on cooperation rather than on struggle, manifested by the microbiome, ecosystems and altruism; 2) The pursuit of diversity rather than optimal fitness, manifested by sexual reproduction; 3) Life’s investment in programmed death, rather than in open-ended survival; and 4) The acceleration of complexity, despite its intrinsic fragility.  

 

            Here I discuss two mechanisms that can resolve these paradoxical features; both mechanisms arise from viewing life as the evolution of information. Information has two inevitable outcomes; it increases by autocatalyis and it is destroyed by entropy. On the one hand, the autocalalysis of information inexorably drives the evolution of complexity, irrespective of its fragility. On the other hand, only those strategic arrangements that accommodate the destructive forces of entropy survive – cooperation, diversification, and programmed death result from the entropic selection of evolving species. Physical principles of information and entropy thus fashion the evolution of life.

 

I am indeed sympathetic to this author’s claim. But science needs also to be humble as to what it can ultimately know. The conservative position isn’t volitional resistance to impede further progress, most of the time. It is rather a position of knowledgable modesty as to what our often flawed hypothesis and speculations can really accomplish. In the case of darwinian biology, I am also of the opinion that it is time to take some stock:

Evolution of living organisms is probably the one incontrovertible “law” of biology, and Charles Darwin sponsored the idea 1. It only remained for biology to combine Darwin’s concept of survival of the fittest with Mendelian genetics and the discovery of DNA to generate what has been called the Neo-Darwinian synthesis – the ruling paradigm of today’s biology 2. After a half century of research, any ruling paradigm, however revered, needs reexamination in the light of the findings that have emerged since its conception. Science advances by periodic review of its most cherished teachings; an outdated paradigm is not mere excess baggage: it actually obstructs new ideas and new experiments 3.

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Fig1. The Neo-Darwinian Paradigm.

The seminal idea is that the inherited, individual genotype encodes the individual phenotype that undergoes fitness testing imposed by the environment. Organisms within a species differ in their genotypes/phenotypes and the individual with the fittest genotype/phenotype survives and, through reproductive success, enriches the species with the fittest genes. The process continues to cycle, continuously adapting the species to the changing environment

.

The paper’s arguments are supported by recent findings in biomedical sciences. For instance the evidence of mutual cooperation between living systems is highlighted, with the findings about the human microbiome being one such example. It stroke my mind as to the conceptual similarity between mutual cooperation and the now important machine learning and statistical learning concept of mutual information…:

More recent advances in the biomedical sciences have highlighted four universal characteristics of multi-cellular organisms that are not easily explained by selfish individual struggle and dominant reproduction:

  • 1)
    Mutual cooperation marks living systems. A telling example of the importance of cooperative living – symbiosis – is the discovery that individual multi-cellular organisms, humans included, house as many bacterial cells – the microbiota – as eukaryote cells; indeed, healthy microbiota genes (the microbiome), which usually outnumber one’s inherited genes, are essential for health, and health is essential for adaptive survival 6, 7. Universal symbiosis contradicts the Neo-Darwinian assumption that the individual’s phenotype is the functional expression of the individual’s genotype; it is not. The living phenotype is actually a consortium that expresses the individual’s inherited genotype along with the genotypes of the individual’s symbionts – the individual phenotype emerges from cooperative interactions between multiple genotypes ( Figure 2); even identical twins house different symbionts, brains and immune systems. Hence, the individual is an ecosystem and the environment tests the fitness of the individual ecosystem, and not just the fitness of the individual’s inherited genes. Consequently, the survival and procreation of the composite individual feeds back on the frequency of particular genes in the breeding species and on the genes composing the symbiotic microbiome. In other words, even the basic individual is a group – the fittest individual expresses the fittest collective of interacting cells, prokaryote and eukaryote, within a single body; Neo-Darwinian natural selection now has to be considered as some type of group selection 8 Essential symbiosis obliges us to revise our understanding of the game plan of evolution 5.

 

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Fig2. A multi-genomic, composite phenotype is tested for survival by the environment.

Contrary to Neo-Darwinian teachings, the individual phenotype is not encoded exclusively by the inherited genotype. Rather, multiple genotypes generate the expressed, composite phenotype; the formative genotypes include the inherited genotype plus all the genotypes of the essential symbionts housed by the individual. The survival of the fit individual thus feeds back genetically both on the frequency of the heritable genetic alleles housed by the host species and on the frequency of the cooperating genotypes of the symbionts

My plan for this post was for it to be a short one. Therefore I encourage all the interested readership to read the full paper The information Age today commented and shared. This Blog encourages also that readers post comments and suggestion to improve its content, in very best spirit of Information, Life, mutual cooperation and the future of an ever better content. Thank you!

featured image: Biological Information – Entropy, Evolution and Open Systems 11-15-2014 by Paul Giem

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