V. Life's Corporeal Evolution Develops, Encodes and Organizes Itself: An Earthtwinian Genesis Synthesis

4. Multicellular Fauna and Flora Organisms in Transition

Parker, Joseph. Parker, Joseph. Organ Evolution: Emergence of Multicellular Function.. Annual Review of Cell and Developmental Biology.. June, 2024. As the abstract notes, a CalTech bioengineer contributes new reasons how and why segmented, modular living systems came together for mutual benefit on this course of nested complexity.

Instances of multicellularity across the tree of life have fostered the evolution of complex organs composed of distinct cell types that cooperate and produce emergent biological functions. To study how organs originate I propose a cell- to organ-level transitions framework, whereby a division of labor sets in between cell types by functional niche creation, cell type and ratcheting of cell interdependencies. These discrete components of functional variation may be deployed or combined within cells to introduce new properties into multicellular niches, or partitioned across cells to establish division of labor. (Excerpt)

Pennisi, Elizabeth. The Power of Many. Science. 360/1388, 2018. A series of simple steps can explain the momentous transition from single cells to multicellular life. A science journalist gathers the work of Laszlo Nagy, Ben Kerr, Nicole King, Nicholas Butterfield, William Ratcliff and others to report new findings about how this evolutionary ascent unto complex organisms seems meant to readily proceed. An innate natural affinity for rudimentary cells to band together, repurpose, diversify, divide labor, and more so to gain group level benefits appears to be written in.

Pfeiffer, Thomas and Sebastian Bonhoeffer. An Evolutionary Scenario for the Transition to Undifferentiated Multicellularity. Proceedings of the National Academy of Sciences. 100/1095, 2003. The initial phase in this emergence is seen as the formation of simple, undifferentiated cell clusters wherein cooperative behavior became more advantageous for survival than competition.

The first step in the evolutionary transition to multicellularity likely was the evolution of simple, undifferentiated cell clusters….Here we argue that in populations of unicellular organisms with cooperative behavior, clustering may be beneficial by reducing interactions with noncooperative individuals. (1095)

Pilcher, Helen. Back to Our Roots. Nature. 435/1022, 2005. A News Report chronicles the latest theories on an original “urmetazoan” from which all multicellular life arose. This ancestor had a “toolkit of genes” which specified four features: body-plan genes, specialized cell types, cells “glued” together, and a communication system.

Puri, Devina and Kyle Allison. Multicellular self-organization in Escherichia coli.. arXiv:2503.03001. Washington University, Saint Louis and Emory University, Atlanta biologists find persistent evidence of life’s constant trendings toward multiple cell to cell assemblies for metabolic and survival benefits. See also Escherichia coli self-organizes developmental rosettes by DP and KA in PNAS (121/23, 2024).

Escherichia coli has long been a trusty companion, maintaining health in our guts and advancing biological knowledge in the laboratory. In light of recent findings, we discuss multicellular self-organization in E. coli and develop general ideas for multicellularity, including dynamics and interpretation. In this context, We next discuss the self-organized behaviors such as rosette formation and internal communication. (Excerpt)

Rados, Theopi, et al. Tissue-like multicellular development triggered by mechanical compression in archaea. Science. April 3, 2025. Brandeis University, MPI Biology and MRC Laboratory of Molecular Biology, Cambridge, UK microbioogists have achieved the first quantified detection of an inherent transit to a higher cellular ordered phase in this category (see below). Thus life’s three eukaryote, microbial and now archeal domains are all found to exhibit an innate tendency to combine into integral unions.

Multicellularity has evolved multiple times in eukaryotes and is observed in bacteria. Rados et al. explored haloarchea, demonstrating that many archaea species can also form multicellular tissue–like structures when compressive forces are applied. These results establish multicellularity as a feature of all three domains of life and highlight the role of mechanical forces in shaping archaeal tissues. (Editor)

The advent of clonal multicellularity is a critical evolutionary milestone, seen often in eukaryotes, rarely in bacteria. We show that uniaxial compression induces clonal multicellularity in haloarchaea, forming tissue-like structures. Archaeal tissues undergo a multinucleate stage followed by tubulin-independent cellularization. Our findings highlight the potential convergent evolution of a biophysical mechanism in the emergence of multicellular systems across domains of life. (Excerpt)

Archaea and bacteria, while both prokaryotes, differ significantly in their cell structure, biochemistry, and genetics. Key distinctions includ membrane lipids (ether-linked in archaea, ester-linked in bacteria), and unique genetic elements like introns in archaeal DNA.

Raff, Rudolf. The Shape of Life: Genes, Development and the Evolution of Animal Form. Chicago: University of Chicago Press, 1996. An often cited work on the stability and ontogenetic recurrence of bodily plans.

Rainey, Paul and Silvia De Monte. Resolving Conflicts During the Evolutionary Transition to Multicellular Life. Annual Review of Ecology, Evolution, and Systematics. 45/599, 2014. By late 2014, Massey University, Auckland, and Ecole Normale Superieure, Paris, biologists are able to well describe this distinct and persistent advance of life’s unicellular phase within the major transitions scale. Two major themes are its achievement by a mutual balance between each component and the whole organism, i.e. competition and cooperation, along with acquiring a novel degree of individuality. See also Katrin Hammerschmidt, et al (2014) for a similar contribution.

Although the evolution both of eukaryotes and of multicellularity mark major transitions between levels of organization, they are often distinguished on the basis of the nature of the alliance among lower-level entities. Evolution of eukaryotic life from two different and once free-living bacteria counts as an “egalitarian” transition characterized by fairness in reproduction and a mutual coming together of disparate entities. The origin of chromosomes from independently replicating genes marks another egalitarian transition. In contrast, the evolution of multicellular life as well as the evolution of eusocial insect societies are “fraternal” transitions, which originate with an alliance of entities that were most likely identical from the outset and in which a division of labor evolved through epigenetic means. (600).

During all major transitions, genetic conflicts arising from competition among cells and among levels of selection are typically viewed as major impediments to be overcome. One aim of this review is to draw attention to the idea that conflicts can be instrumental in fueling the emergence of multicellularity. In fact, evolutionary solutions to the problem of conflict are central to the evolution of higher levels of individual. (602) Cooperation and conflict lie at the heart of biological systems. Multicellular organisms maintain their integrity via complex developmental programs that ensure, as much as possible, alignment between the interests of individual cells and those of the multicellular organism. (613)

Ratcliff, William, et al. Experimental Evolution of Multicellularity. Proceedings of the National Academy of Sciences. 109/1595, 2012. University of Minnesota, Evolution and Behavior and BioTechnology Institute, ecologists start their project by situating it within the popular “major transitions” scale and sequence from proteins to people. By this view, life’s emergent passage from eukaryotic cells to cellular assemblies was a natural next stage of “sophisticated, higher-level functionality via cooperation among component cells with complementary behaviors.” See herein concurrent work by Iaroslav Ispolatov, et al, Carl Simpson below, and Cooperative Alliances in the Emergent Individuality section.

Multicellularity was one of the most significant innovations in the history of life, but its initial evolution remains poorly understood. Using experimental evolution, we show that key steps in this transition could have occurred quickly. We subjected the unicellular yeast Saccharomyces cerevisiae to an environment in which we expected multicellularity to be adaptive. We observed the rapid evolution of clustering genotypes that display a novel multicellular life history characterized by reproduction via multicellular propagules, a juvenile phase, and determinate growth. The multicellular clusters are uniclonal, minimizing within-cluster genetic conflicts of interest. Simple among-cell division of labor rapidly evolved. Early multicellular strains were composed of physiologically similar cells, but these subsequently evolved higher rates of programmed cell death (apoptosis), an adaptation that increases propagule production. These results show that key aspects ofmulticellular complexity, a subject of central importance to biology, can readily evolve from unicellular eukaryotes. (Abstract, 1595)

Ravasz, E., et al. Hierarchical Organization of Modularity in Metabolic Networks. Science. 297/1551, 2002. The universal properties of scale-free systems apply in developing cellular organization which forms many functional modules arranged in interconnected webs with a nested hierarchical iteration.

Here, we show that the metabolic networks of 43 distinct organism are organized into many small, highly connected topologic modules that combine in a hierarchical manner into larger, less cohesive units, with their number and degree of clustering following a power law. (1551)

Reinhard, Christopher, et al. Earth’s Oxygen Cycle and the Evolution of Animal Life. Proceedings of the National Academy of Sciences. 113/8933, 2016. A senior team of geoscientists including Douglas Erwin, and edited by Andrew Knoll, quantify life’s billion year span before the Cambrian profusion some 600 million years ago. Our rare planetary surface balance of both sea and land is seen as a crucial reason that Earth life has developed beyond an anoxic marine phase which is not conducive.

Earth is currently the only planet known to harbor complex life. Understanding whether terrestrial biotic complexity is a unique phenomenon or can be expected to be widespread in the universe depends on a mechanistic understanding of the factors that led to the emergence of complex life on Earth. Here, we use geochemical constraints and quantitative models to suggest that marine environments may have been unfavorable for the emergence and large-scale proliferation of motile multicellular life for most of Earth’s history. Further, we argue that a holistic evaluation of environmental variability, organismal life history, and spatial ecological dynamics is essential for a full accounting of the factors that have allowed for the emergence of biological complexity on Earth. (Significance)

Retallack, Gregory. Great Moments in Plant Evolution. PNAS. 118/17, 2021. A University of Oregon paleontologist reviews notable work, as below, with regard to our whole scale reconstruction of how life proceeded through all the fauna and flora to arrive at a global speciesphere whom is able to do this. Our take, as the Abstract cites, is to muse that these past creaturely occasions appear as if they are intended, indeed expected, stages along the ascendant way.

Just as dinosaurs can be regarded as protobirds (1) and synapsids as protomammals (2), understanding the evolution of plants depends on extinct fossil groups, such as those linking spore and seed plants. A profound paleobotanical surprise in 1904 was discovery of pteridosperms, commonly called seed ferns, because of their unexpected combination of seeds and fern-like leaves. Another paleobotanical surprise in 1960 was discovery of progymnosperms, spore plants with woody anatomy comparable to modern conifer trees. Now, Wang et al. in PNAS (118/11) report a Chinese Permian fossil plant, Paratinga wuhaia. These permineralized fossils convincingly expand the progymnosperm clade to include the enigmatic Noeggerathiales, an extinct order of vascular plants.

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