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Stepwise molecular evolution of bacterial photosynthetic energy conversion.

The concept of continuity in molecular evolution implies a stepwise formation of metabolic systems and processes. In this manner, chemical and biological evolution have given rise, step by step, to such complicated systems as the photosynthetic apparatus and thus, such elaborate processes as photosynthesis in the living cell. Among currently living organisms, the bacteria contain a much less complex photosynthetic system than the algae and higher plants, which uniquely are capable fo splitting H2O. But also the bacterial system is a very highly evolved and sophisticated, membrane-bound apparatus for the transformation of light energy to other biologically useful energy forms. The study of its molecular evolution is here undertaken by the method of attempting to break down the system into its main components and functions in order to elucidate how they had originated and evolved, and how, by divergent and convergent evolutionary steps, the stage was set for the arrival of bacterial photophosphorylation.

Adenosine Triphosphatases↗

Acute coronary syndromes and heart failure may reflect maladaptations of trauma physiology that was shaped during pre-modern evolution.

We hypothesize that the pathophysiology of many cardiovascular diseases reflects a maladaptation of the triad of trauma response: adrenergia, inflammation, and coagulation. During biologic evolution, trauma has likely been a prevailing factor in natural selection. Components of the trauma triad act to limit hemorrhage, defend wounds against microorganisms, and initiate reconstruction. Response pathways that enable survival after trauma confer obvious adaptive advantages especially if the individual goes on to reproduce. Modern humans have shaped their own ecologic environment in such a way that the incidence of trauma has waned and previously unseen pathologies have emerged. Manifestations of modern diet, changing lifestyles, and extended lifespan have suddenly created new pathologic challenges to our prehistoric physiologic system. During our evolutionary heritage, endothelial injury and end-organ hypoxia were likely exclusively associated with physical trauma and the responses of the trauma triad were appropriate. Today, endothelial injury is more often precipitated by distinctly modern stressors such as hypertension, smoking, diabetes, and dyslipidemia. The once-adaptive trauma response can maladaptively initiate dangerous, self-propelling cycles of adrenergia, inflammation, and coagulation. Acute coronary syndromes perhaps best exemplify this phenomenon. Congestive heart failure, which often ensues, can similarly be seen as a maladaptation of the trauma triad. Whereas end-organ hypoxia was once commonly associated with trauma, now hypoxia is more often attributable to distinctly modern stressors such as pump failure. The fluid conservation and inflammation that results from the trauma triad was clearly adaptive in our prehistoric past, but in congestive heart failure the response is maladaptive, engendering self-propelling exacerbations of pump failure and vascular disease. Our maladaptive trauma response hypothesis portends new diagnostic and therapeutic paradigms for cardiovascular diseases and has ramifications for many other conditions such as stroke, venous thrombosis, vasculitis, aortic disease, arterial disease, pulmonary embolism, and restenosis.

Acute Disease↗

[Computer simulation of different types of evolutionary process].

The computer model of two alternative variants of biological evolution is proposed. The first variant supposes random while the second--directed change of individual features, thus corresponding to the Darwinian and non-Darwinian evolution. The evolution of fish communities in fresh waters serves as a particular example. The model is executed using object-oriented method of programming and mathematical apparatus of fuzzy logics. The investigation of the model showed that process of Darwinian evolution is connected with significantly greater species diversity and variability of evolutionary process trajectories than non-Darwinian one. On the other hand, non-Darwinian type of evolution provides fast achievement of high individual fitness, especially under conditions of constant environment. Non-Darwinian type evolution failed in big evolutionary alteration (for example, transition to predation); while the Darwinian evolution under the same conditions can produce such alterations though it took more time and many extinct species. Phylogenetic tree of Darwinian evolution is always more complex than of non-Darwinian one under the same conditions.

Animals↗

The physics of symbols: bridging the epistemic cut.

Evolution requires the genotype-phenotype distinction, a primeval epistemic cut that separates energy-degenerate, rate-independent genetic symbols from the rate-dependent dynamics of construction that they control. This symbol-matter or subject-object distinction occurs at all higher levels where symbols are related to a referent by an arbitrary code. The converse of control is measurement in which a rate-dependent dynamical state is coded into quiescent symbols. Non-integrable constraints are one necessary condition for bridging the epistemic cut by measurement, control, and coding. Additional properties of heteropolymer constraints are necessary for biological evolution.

Biological Evolution↗

Information and entropy in a simple evolution model.

A model of evolution which combines mutations and speciation mechanisms is presented and analyzed. Information and entropy of the populations generated by the model are calculated and followed through history. It is found that the model allows simultaneous increase of information and entropy with time, consistent with notions of physical entropy increase as well as biological evolution.

Biological Evolution↗

Cosmic radiation and evolution of life on earth: roles of environment, adaptation and selection.

The role of ionizing radiation in general, and cosmic radiation in particular, in the evolution of organisms on the earth by adaptation and natural selection is considered in a series of questions: (1) Are there times during the evolution of the earth and of life when genetic material could be exposed to heavy ion radiation? (2) Throughout the course of chemical and biological evolution on the earth, what fraction of environmental mutagenesis could be attributable to cosmic and/or solar ionizing radiation? (3) Is ionizing radiation an agent of adaptation or selection, or both? (4) What can the cladistics of the evolution of genetic repair tell us about the global history of genotoxic selection pressures? (5) How much genetic diversity can be attributed to the selection of radiation-damage repair processes?

Animals↗

Resistance to antimicrobial chemotherapy: a prescription for research and action.

The growing problem of resistance to antimicrobial chemotherapy was discussed by participants at the February 1995 workshop at Emory University on population biology, evolution, and control of infectious diseases. They discussed the nature and source of this problem and identified areas of research in which information is lacking for the development of programs to control of the emergence and spread of resistant bacteria. Particular attention was given to theoretical (mathematical modeling) and empirical studies of the within and between-host population biology (epidemiology) and the evolution of microbial resistance to chemotherapeutic agents. Suggestions were made about the kinds of models and data needed, and the procedures that could be employed to stem the ascent and dissemination of resistant bacteria. This article summarizes the observations and recommendations made at the 1995 meeting and in the correspondence between participants that followed. It concludes with an update on the theoretical and empirical research on the between- and within-host population biology and evolution of resistance to antimicrobial chemotherapy most of which has been done since that meeting.

Bacteria↗

Quantum computation, non-demolition measurements, and reflective control in living systems.

Internal computation underlies robust non-equilibrium living process. The smallest details of living systems are molecular devices that realize non-demolition quantum measurements. These smaller devices form larger devices (macromolecular complexes), up to living body. The quantum device possesses its own potential internal quantum state (IQS), which is maintained for a prolonged time via reflective error-correction. Decoherence-free IQS can exhibit itself by a creative generation of iteration limits in the real world. It resembles the properties of a quasi-particle, which interacts with the surround, applying decoherence commands to it. In this framework, enzymes are molecular automata of the extremal quantum computer, the set of which maintains highly ordered robust coherent state, and genome represents a concatenation of error-correcting codes into a single reflective set. The biological evolution can be viewed as a functional evolution of measurement constraints in which limits of iteration are established, possessing criteria of perfection and having selective values.

Adaptation, Physiological↗

Looking for the most "primitive" organism(s) on Earth today: the state of the art.

Molecular phylogenetic studies have revealed a tripartite division of the living world into two procaryotic groups, Bacteria and Archaea, and one eucaryotic group, Eucarya. Which group is the most "primitive"? Which groups are sister? The answer to these questions would help to delineate the characters of the last common ancestor to all living beings, as a first step to reconstruct the earliest periods of biological evolution on Earth. The current "Procaryotic dogma" claims that procaryotes are primitive. Since the ancestor of Archaea was most probably a hyperthermophile, and since bacteria too might have originated from hyperthermophiles, the procaryotic dogma has been recently connected to the hot origin of life hypothesis. However, the notion that present-day hyperthermophiles are primitive has been challenged by recent findings, in these unique microorganisms, of very elaborate adaptative devices for life at high temperature. Accordingly, I discuss here alternative hypotheses that challenge the procaryotic dogma, such as the idea of a universal ancestor with molecular features in between those of eucaryotes and procaryotes, or the origin of procaryotes via thermophilic adaptation. Clearly, major evolutionary questions about early cellular evolution on Earth remain to be settled before we can speculate with confidence about which kinds of life might have appeared on other planets.

Archaea↗

Towards a unified science of cultural evolution.

We suggest that human culture exhibits key Darwinian evolutionary properties, and argue that the structure of a science of cultural evolution should share fundamental features with the structure of the science of biological evolution. This latter claim is tested by outlining the methods and approaches employed by the principal subdisciplines of evolutionary biology and assessing whether there is an existing or potential corresponding approach to the study of cultural evolution. Existing approaches within anthropology and archaeology demonstrate a good match with the macroevolutionary methods of systematics, paleobiology, and biogeography, whereas mathematical models derived from population genetics have been successfully developed to study cultural microevolution. Much potential exists for experimental simulations and field studies of cultural microevolution, where there are opportunities to borrow further methods and hypotheses from biology. Potential also exists for the cultural equivalent of molecular genetics in "social cognitive neuroscience," although many fundamental issues have yet to be resolved. It is argued that studying culture within a unifying evolutionary framework has the potential to integrate a number of separate disciplines within the social sciences.

Animals↗

Astrobiology from exobiology: Viking and the current Mars probes.

The development of an Astrobiology Program is an extension of current exobiology programs. Astrobiology is the scientific study of the origin, distribution, evolution, and future of life in the universe. It encompasses exobiology; formation of elements, stars, planets, and organic molecules; initiation of replicating organisms; biological evolution; gravitational biology; and human exploration. Current interest in life on Mars provides the scientific community with an example of scientific inquiry that has mass appeal. Technology is mature enough to search for life in the universe.

Astronomy↗

Are organisms committed to lower their rates of entropy production? Possible relevance to evolution of the Prigogine theorem and the ergodic hypothesis.

The physiology at limiting and stress conditions challenges the current view that the overall reaction of metabolic processes is always far from equilibrium and, therefore, that organisms are not committed to lower their rates of entropy production. Plausibly, critical steps of natural selection takes place at limiting conditions, near equilibrium, in the linear range response of entropy production, and consequently the trend to lower the rate of entropy production could be the fitness arrow of biological evolution. The evolutionary relevance of the Prigogine theorem is discussed in connection with the ergodic hypothesis of Boltzmann. The emergence of metabolic strategies to economise carbon/energy resources, of resource-waste systems like active transport and the irreversible increase in the complexity of organisms during evolution may be consequences of a more general trend of metabolic systems to lower the rates of entropy production.

Biological Evolution↗

Spatial-temporal correlations in the process to self-organized criticality.

A different type of spatial-temporal correlation in the process approaching the self-organized criticality is investigated for the two simple models for biological evolution. The changed behaviors of the position with minimum barrier are shown to be quantitatively different in the two models. Different results of the correlation are given for the two models. We argue that the correlation can be used, together with the power-law distributions, as criteria for self-organized criticality.

Biological Evolution↗

Consciousness and the brain: evolutionary aspects.

Self-reflective consciousness is distinguished from 'simple' awareness and from conscious awareness. Awareness is a fundamental property of living matter as it reacts to environmental stimuli. A hypothesis is advanced to account for the general phenomenon of decussation of nerve fibres in the central nervous system of vertebrates. This feature, the crossing over of nerve fibres to the opposite side of the brain, is interpreted as exemplifying the inherent caution of living forms. The evolution of increasing complexity of structure in spinal cord and brain is a prerequisite for increasing awareness of the environment and for increasing freedom from its constraints. Conscious awareness is manifested in living forms primarily when they are learning to respond either to new stimuli or to internal demands such as breathing and walking. The relegation of learnt activities to the realm of unconscious reflex allows for concentration on new and more complex responses, which leads to further freedom of action. The seeming simplicity of human thinking rests on the increasing complexity of the evolving brain and of appropriate responses learnt during phylogenetic development. The human brain and its thinking functions are basically trustworthy because they are rooted in biological evolution.

Amoeba↗

The evolution of vocabulary.

Human language is unique among the communication systems of the natural world. The vocabulary of human language is unique in being both culturally transmitted and symbolic. In this paper I present an investigation into the factors involved in the evolution of such vocabulary systems. I investigate both the cultural evolution of vocabulary systems and the biological evolution of learning rules for vocabulary acquisition. Firstly, vocabularies are shown to evolve on a cultural time-scale so as to fit the expectations of learners-a population's vocabulary adapts to the biases of the learners in that population. A learning bias in favour of one-to-one mappings between meanings and words leads to the cultural evolution of communicatively optimal vocabulary systems, even in the absence of any explicit pressure for communication. Furthermore, the pressure to conform to the biases of learners is shown to outweigh natural selection acting on cultural transmission. Human language learners appear to bring a one-to-one bias to the acquisition of vocabulary systems. The functionality of human vocabulary may therefore be a consequence of the biases of human language learners. Secondly, the evolutionary stability of genetically transmitted vocabulary learning biases is investigated using both static and dynamic models. A one-to-one learning bias, which leads to the cultural evolution of optimal communication, is shown to be evolutionarily stable. However, the evolution de novo of this bias is complicated by the cumulative nature of the cultural evolution of vocabulary systems. This suggests that the biases of human language learners may not have evolved specifically and exclusively for the acquisition of communicatively functional vocabulary.

Cultural Evolution↗