Biological Big Bang

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My guess this is because it does not easily fit the scenario of a rampant genetic exchange. More primitive multi-cellular organisms were in existence well before the Cambrian era and it is hard to imagine a scenario in which multi-cellular organisms would be involved in a large-scale swap of genetic material. On the other hand, it is becoming progressively more and more clear that during or immediately before the Cambrian explosion Nature experimented with different schemes of wiring the regulatory network for embryonic development see e.

Another Big Bang for Biology

Erwin, Science , Thus a more traditional explanation of the Cambrian explosion involves no rampant horizontal gene transfer but just a very rapid burst of innovation and diversification following the appearance of a new scheme for information processing in this case represented by the regulatory network orchestrating the embryonic development.

I would very much like Eugene to share his thoughts on whether he feels that a large-scale genetic recombination is in his opinion a necessary condition for a Biological Big Bang to occur? Certainly, I do not insist on a large-scale swap of genetic information i. I suggest leaving the causes of the acceleration of evolution in this and other late transitions wide open. I would suspect that bursts of mobile element dissemination could be important as briefly mentioned at the end of the paper, and possibly, other forms of information exchange.

The issue of network rewiring is also touched upon in the revision, with two papers of Eric Davidson cited, and in this context, the possibility of causes of BBBs distinct from genetic exchange is acknowledged. However, a truly detailed discussion of animal evolution is outside the scope of this paper. If it is not I could imagine extending the analogy even further to describe rapid technological transitions such as most recently the appearance of the Internet and the World Wide Web.

Here again the singular act of invention of a new information processing tool was followed by a burst of innovation utilizing it in every imaginable way. As in any of the BBB described in the manuscript in this case the initial rapid innovative phase will inevitably be replaced by a much slower phase in which various "body plans" for Internet-based services are tested and gradually refined or altogether discarded.

Very interesting ideas, indeed This is a very provocative and thought-provoking paper: The hypothesis sounds reasonable and very plausible to me. Below I sketch some directions of the theoretical research that can further elaborate evolution through BBBs. I found the manuscript to be very well written but somewhat redundant. I think it will benefit from shortening. This makes the introduction somewhat lengthy.

I wish a reader had a shorter road to the exciting core of the paper pages 13—16, in my opinion. I understand the sentiment but these are highly non-orthodox ideas, so I believe the long introduction should be helpful for most readers. The emergence of the new folds in attributed to the first BBB. I would think that each BBB leads to the emergence of new genes and folds, specifically the one that lead to the emergence of the eukaryotic cell with its unique eukaryotic genes and folds.

There seems to be a bit of a misunderstanding here. Certainly, there was some though, limited emergence of new folds associated with different BBBs. The emergence of eukaryotic cell and eukaryotic lineages are put together into a single BBB. The emergence of the bacteria and formation of bacteria lineages, in contrast, are split into two distinct BBBs. Perhaps eukaryotic BBB can be thought of as a two-stage process: The proto-eukaryotic cell may contain the hallmark of the eukaryotes e.

An alternative view would be that both processes were happening independently and at the same time. This possibility sounds questionable, as it may not be able to explain the common features of all eukaryotic cells. I think description of this BBB needs some clarification. Yes, I envisage this BBB more like a two-stage process. A variety of amendments and clarifications were made to the description, in part, also, in response to the criticisms of Reviewer 1.

Emergence of the protein synthesis — one of the most puzzling, to my mind, event in evolution, remains untouched in this new picture of evolution leaving it to be invented in the bubbling guts of the hydrothermal vents. I wonder whether the BBB view of evolution can shed light on this mystery. Of course, the origin of protein synthesis a great challenge, indeed! Beyond that, however, I am not immediatel sure how the BBB model could help. For two complementary perspectives, see my recent papers: On the origin of the translation system and the genetic code in the RNA world by means of natural selection, exaptation, and subfunctionalization.

Biology Direct , 2: The cosmological model of eternal inflation and the transition from chance to biological evolution in the history of life. An intriguing theoretical problem is to develop a mathematical model of evolution in the population of cells through extensive HGT or, broadly, with "leaky" cell walls and rapid exchange of genetic material.

Intuitively, evolutionary processes in such communities can be quite different from the picture drawn by the classical population genetics. The spread of this gene will be driven by two processes: Taken together these processes can lead to more rapid than in the classical picture fixation of an advantageous allele.

Thus it is not only the mere fact of extensive production of the new genetic material through HGT, but also the underlying dynamics that can make BBBs effective melting pots of evolution. Yes, I quite agree, hopefully, we will be able to develop a mathematical model in a reasonable future. The next piece of the puzzle to be sought is the understanding of the mechanisms that lead to initiation and termination of BBBs. To my mind, the key question is whether periods of BBB have been triggered by some environmental events or by spontaneous nucleation or both.

Yes, I think both factors were important. For example, the winners in the BBB evolution i. It would be interesting to see whether a model of BBB where cells may stochastically switch from an altruistic open walls to a selfish closed walls behavior lead to spontaneous "sporulation" of selfish wall-sealed cells that have reached locally optimal fitness, thus leading to effective "cooling" of a BBB.

Again, I agree, it will be interesting and, hopefully, feasible to develop such models. As for the initiation of BBB, the author proposes that the small population size may be lead to inventions due to fixation of otherwise deleterious mutations. Perhaps, more generally, one can think of numerous populations that undergo Muller ratchet catastrophes, thus shrinking and leading to this "last whisper" inventiveness. One of which may end up inventing a mechanism for BBB e.

I am grateful to the three reviewers of this manuscript, most especially, to Bill Martin, for helpful comments and criticisms. National Center for Biotechnology Information , U. Journal List Biol Direct v. Published online Aug Eugene V Koonin 1. Author information Article notes Copyright and License information Disclaimer. Received Aug 15; Accepted Aug This article has been cited by other articles in PMC. Abstract Background Major transitions in biological evolution show the same pattern of sudden emergence of diverse forms at a new level of complexity.

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Hypothesis I propose that most or all major evolutionary transitions that show the "explosive" pattern of emergence of new types of biological entities correspond to a boundary between two qualitatively distinct evolutionary phases. Background The enigmatic nexuses The famous single illustration of Darwin's "Origin of Species" shows generalized binary trees. Open in a separate window. Origin of viruses For several major classes of viruses, notably, positive-strand RNA viruses [ 12 ] and nucleo-cytoplasmic large DNA viruses NCLDV of eukaryotes [ 13 , 14 ], substantial evidence of monophyletic origin has been obtained.

Origin of cells The two principal cell types the two prokaryotic domains of life , archaea and bacteria, have chemically distinct membranes, largely, non-homologous enzymes of membrane biogenesis[ 16 , 17 ], and also, non-homologous core DNA replication enzymes [ 18 ]. Origin of the major branches phyla of bacteria and archaea Although both bacteria and archaea show a much greater degree of molecular coherence within a domain than is seen between the domains in particular, the membranes and the replication machineries are homologous throughout each domain , the topology of the deep branches in the archaeal and, especially, bacterial phylogenetic trees remains elusive.

Origin of the major branches supergroups of eukaryotes Despite many ingenious attempts to decipher the branching order near the root of the phylogenetic tree of eukaryotes, there has been little progress, and an objective depiction of the state of affairs seems to be a "star" phylogeny, with the 5 or 6 supergroups established with reasonable confidence but the relationship between them remaining unresolved [ 26 - 31 ].

Origin of the animal phyla The Cambrian explosion in animal evolution during which all the diverse body plans appear to have emerged almost in a geological instant is a highly publicized enigma [ 32 - 35 ]. Unconventional solutions In a seminal paper, Carl Woese proposed that the early stages of life's evolution including that of the Last Universal Cellular Ancestor LUCA , involved rampant horizontal exchange of genetic material between primordial life forms such that individual lineages could not form [ 40 , 41 ].

Table 1 Major transitions in the history of life and proposed Biological Big Bang events.

The first of the three along with the origins of viruses and cells original, great BBBs that might have shared a physical substrate, the primordial gene pool, probably, abiogenically compartmentalized. This BBB would give rise to the tree pattern of evolution gene trees for the first time in the history of life.

The second of the three great BBBs occurring in the primordial gene pool. The third and last of the three great BBBs occurring in the primordial gene pool. Crucial processes involve the formation of selfish cooperatives, extensive transfer of genetic material between compartments, and sampling of genes into emerging protocells.

Probably, numerous trials on cell formation, with only two types fixed. Continued, albeit more constrained process of gene sampling, with numerous trials on more robust cells capable of departing the primordial mats. Emergence of the eukaryotic cell and the supergroups of eukaryotes Extensive gene flow from endosymbionts to the host chromosome s accompanied by massive invasion of introns and pervasive genome rearrangement. Distinct symbiotic events giving rise to the 5 supergroups of eukaryotes. The 5 eukaryotic supergroups are: Plantae green plants, green algae, red algae 2.

Chromalveolates alveolates, including Apicomplexa, dinoflagellates, and ciliates, and stramenophiles including diatoms, oomycetes and many other groups 3. Unikonts Animals, fungi, Amoebozoa 4. Rhizaria Foraminifera and a variety of other, poorlycharacterized groups 5. Excavates kinetoplastids, euglenids, diplomonads, trichomonads, and other, poorly characterized groups [28].

The chloroplast symbiosis, obviously, gave rise to Plantae, and a symbiosis between a primitive unicellular eukaryote and a red alga led to the emergence of the Chromalveolata. The remaining endosymbiotic events that are postulated to underlie the emergence of other supergroups might not have left morphologically distinct vestiges [67, 70] Origin of the major lineages within supergroups? Invasion of mobile elements; rewiring of regulatory networks; more? Discussion and Conclusion The essence of the Biological Big Bang model is that evolution consists of two, fundamentally different, alternating phases which are underpinned by sharply distinct processes: Reviewers' comments Reviewer 1: William Martin University of Duesseldorf If these ideas are drawn from cosmology, that could be stated, but I don't think they are.

Sergei Maslov Brookhaven National Laboratory The manuscript by Eugene Koonin describes a compelling analogy between several major evolutionary transitions in the history of life referred to as Biological Big Bangs or BBBs and the inflationary model describing the early dynamics of our Universe or rather the multiverse following the cosmological Big Bang.

Leonid Mirny Massachusetts Institute of Technology This is a very provocative and thought-provoking paper: Evolution with extensive HGT An intriguing theoretical problem is to develop a mathematical model of evolution in the population of cells through extensive HGT or, broadly, with "leaky" cell walls and rapid exchange of genetic material.

Mechanism and causes of "heating" and "cooling" The next piece of the puzzle to be sought is the understanding of the mechanisms that lead to initiation and termination of BBBs. Authors' contributions EVK developed the model and wrote the manuscript. London , John Murray; Generelle Morphologie der Organismen. Berlin , Georg Reimer; Tempo and Mode in Evolution.

New York , Columbia Univ. Tempo and mode in the macroevolutionary reconstruction of Darwinism. Punctuated equilibrium comes of age. The Major Transitions in Evolution. Oxford , Oxford University Press; Rokas A, Carroll SB. Bushes in the tree of life. Estimating the number of protein folds. Estimating the number of protein folds and families from complete genome data. A unifold, mesofold, and superfold model of protein fold use. Evolution and taxonomy of positive-strand RNA viruses: Crit Rev Biochem Mol Biol.

Common origin of four diverse families of large eukaryotic DNA viruses. Evolutionary genomics of nucleo-cytoplasmic large DNA viruses.

The ancient virus world and evolution of cells. On the origins of cells: Ancestral lipid biosynthesis and early membrane evolution. Did DNA replication evolve twice independently? On the origin of genomes and cells within inorganic compartments.

Submission history

Automatic selection of representative proteins for bacterial phylogeny. Evolution of bacterial RNA polymerase: Genome trees and the tree of life. Genome trees constructed using five different approaches suggest new major bacterial clades. Archaeal phylogeny based on proteins of the transcription and translation machineries: An emerging phylogenetic core of Archaea: The new phylogeny of eukaryotes.

Curr Opin Genet Dev. The deep roots of eukaryotes. The tree of eukaryotes. The origin and diversification of eukaryotes: The new higher level classification of eukaryotes with emphasis on the taxonomy of protists. The Cambrian "explosion" of metazoans and molecular biology: Int J Dev Biol. The Cambrian explosion exploded? A trigger for the Cambrian explosion? Molecular evidence for deep Precambrian divergences among metazoan phyla.

Molecular clocks do not support the Cambrian explosion. Molecular dates for the "cambrian explosion": Animal evolution and the molecular signature of radiations compressed in time. On the evolution of cells. Archaea and the origin s of DNA replication proteins. On the evolution of protein folds: Extreme accumulation of nucleotides in simulated hydrothermal pore systems. Speculations on the early course of evolution. An RNA-making reactor for the origin of life.

Comparison of archaeal and bacterial genomes: Evidence for massive gene exchange between archaeal and bacterial hyperthermophiles.

Evidence for lateral gene transfer between Archaea and bacteria from genome sequence of Thermotoga maritima. Lateral gene transfer and the nature of bacterial innovation. Horizontal gene transfer in prokaryotes: Processivity of ribozyme-catalyzed RNA polymerization. The impact of comparative genomics on our understanding of evolution. Uprooting the tree of life.

Phylogenetic classification and the universal tree. Is it time to uproot the tree of life? Paradigm change in evolutionary microbiology. Pattern pluralism and the Tree of Life hypothesis. Inventing the dynamo machine: Microbial mats and the early evolution of life. Biogeochemistry of hypersaline microbial mats illustrates the dynamics of modern microbial ecosystems and the early evolution of the biosphere. Eukaryotic evolution, changes and challenges. Genomics and the irreducible nature of eukaryote cells. The event is "a perfect match in time" to a sudden infusion of oxygen into the oceans, which may have sparked the explosion of marine biodiversity, says geobiologist and co-author Shuhai Xiao.

Another possible stimulus, he suggests, is a warming of the ocean that occurred back then as an ice age was ending. Whatever the cause, there was one big difference between the Avalon and Cambrian explosions: The Cambrian produced groups that endure to this day, Xiao says, whereas the Ediacaran forms soon vanished. The idea that the Ediacara fossils evolved a wide range of shapes and forms very quickly seems "reasonable and sound" in the context of evolutionary history, says evolutionary biologist Andrew Knoll of Harvard University. But that might not be the most striking aspect of the find.

Rather, he explains, it's that these creatures evolved "much the same way as in later evolutionary radiations, large and small," suggesting that explosions in diversity might share similar dynamics. Why, for example, was the Avalon explosion quashed, he asks, "but the Cambrian explosion prevailed and gave us life as we know it. By David Malakoff Dec. However, microbes and viruses from space continue to fall to Earth effecting evolution on this planet. Joseph, "Living creatures modify the environment, which acts on gene selection giving rise to tissues, organs, and species which had been coded into genes inherited from ancestral species whose own ancestors hailed from other worlds.

What we call "evolution" is under genetic-environmental control, similar to embryogenesis and metamorphosis, and involves complex gene-environmental interactions. Evolution is not random but is instead the replication of creatures which long ago lived on other planets. Further, the genetic evidence compiled by myself, Dr. Joseph, and others, proves conclusively that it took at least 8 billion years for life to evolve from non-life.

It is scientifically impossible for life to have formed in just a few hundred million years on this planet, especially when all the necessary ingredients were missing. Since life was present on this planet from the very beginning, the only logical, scientific explanation is that life on Earth came from other planets. Earth too, is an island, orbiting in a sea of space, and living creatures and their DNA have been washing to shore and falling from the sky since our planets creation.

There just was not enough time and all the essential ingredients were missing.

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