scholarly journals On the origin of biological construction, with a focus on multicellularity

2017 ◽  
Vol 114 (42) ◽  
pp. 11018-11026 ◽  
Author(s):  
Jordi van Gestel ◽  
Corina E. Tarnita
Keyword(s):  
Life Cycle ◽  
Hierarchical Organization ◽  
Central Research ◽  
Biological Organization ◽  
Evolutionary Trajectory ◽  
Bottom Up ◽  
Evolutionary Transitions ◽  
Ant Colonies ◽  
Starting Point ◽  
Multicellular Organisms

Biology is marked by a hierarchical organization: all life consists of cells; in some cases, these cells assemble into groups, such as endosymbionts or multicellular organisms; in turn, multicellular organisms sometimes assemble into yet other groups, such as primate societies or ant colonies. The construction of new organizational layers results from hierarchical evolutionary transitions, in which biological units (e.g., cells) form groups that evolve into new units of biological organization (e.g., multicellular organisms). Despite considerable advances, there is no bottom-up, dynamical account of how, starting from the solitary ancestor, the first groups originate and subsequently evolve the organizing principles that qualify them as new units. Guided by six central questions, we propose an integrative bottom-up approach for studying the dynamics underlying hierarchical evolutionary transitions, which builds on and synthesizes existing knowledge. This approach highlights the crucial role of the ecology and development of the solitary ancestor in the emergence and subsequent evolution of groups, and it stresses the paramount importance of the life cycle: only by evaluating groups in the context of their life cycle can we unravel the evolutionary trajectory of hierarchical transitions. These insights also provide a starting point for understanding the types of subsequent organizational complexity. The central research questions outlined here naturally link existing research programs on biological construction (e.g., on cooperation, multilevel selection, self-organization, and development) and thereby help integrate knowledge stemming from diverse fields of biology.

scholarly journals Viruses and mobile elements as drivers of evolutionary transitions

2016 ◽  
Vol 371 (1701) ◽  
pp. 20150442 ◽  
Author(s):  
Eugene V. Koonin
Keyword(s):  
Genomic Analysis ◽  
Life Forms ◽  
Comparative Genomic ◽  
Biological Organization ◽  
Evolutionary Transitions ◽  
Selfish Genetic Elements ◽  
Cellular Life ◽  
History Of ◽  
Eusocial Animals ◽  
Multicellular Organisms

The history of life is punctuated by evolutionary transitions which engender emergence of new levels of biological organization that involves selection acting at increasingly complex ensembles of biological entities. Major evolutionary transitions include the origin of prokaryotic and then eukaryotic cells, multicellular organisms and eusocial animals. All or nearly all cellular life forms are hosts to diverse selfish genetic elements with various levels of autonomy including plasmids, transposons and viruses. I present evidence that, at least up to and including the origin of multicellularity, evolutionary transitions are driven by the coevolution of hosts with these genetic parasites along with sharing of ‘public goods’. Selfish elements drive evolutionary transitions at two distinct levels. First, mathematical modelling of evolutionary processes, such as evolution of primitive replicator populations or unicellular organisms, indicates that only increasing organizational complexity, e.g. emergence of multicellular aggregates, can prevent the collapse of the host–parasite system under the pressure of parasites. Second, comparative genomic analysis reveals numerous cases of recruitment of genes with essential functions in cellular life forms, including those that enable evolutionary transitions. This article is part of the themed issue ‘The major synthetic evolutionary transitions’.

scholarly journals Did Human Culture Emerge in a Cultural Evolutionary Transition in Individuality?

2021 ◽  
Author(s):  
Dinah R. Davison ◽  
Claes Andersson ◽  
Richard E. Michod ◽  
Steven L. Kuhn
Keyword(s):  
Hierarchical Organization ◽  
Evolutionary Transitions ◽  
Major Transitions ◽  
Social Communities ◽  
Human Culture ◽  
Eusocial Insects ◽  
The Social ◽  
History Of ◽  
Cultural Evolutionary ◽  
Multicellular Organisms

AbstractEvolutionary Transitions in Individuality (ETI) have been responsible for the major transitions in levels of selection and individuality in natural history, such as the origins of prokaryotic and eukaryotic cells, multicellular organisms, and eusocial insects. The integrated hierarchical organization of life thereby emerged as groups of individuals repeatedly evolved into new and more complex kinds of individuals. The Social Protocell Hypothesis (SPH) proposes that the integrated hierarchical organization of human culture can also be understood as the outcome of an ETI—one that produced a “cultural organism” (a “sociont”) from a substrate of socially learned traditions that were contained in growing and dividing social communities. The SPH predicts that a threshold degree of evolutionary individuality would have been achieved by 2.0–2.5 Mya, followed by an increasing degree of evolutionary individuality as the ETI unfolded. We here assess the SPH by applying a battery of criteria—developed to assess evolutionary individuality in biological units—to cultural units across the evolutionary history of Homo. We find an increasing agreement with these criteria, which buttresses the claim that an ETI occurred in the cultural realm.

scholarly journals Evolutionary transitions during RNA virus experimental evolution

2016 ◽  
Vol 371 (1701) ◽  
pp. 20150441 ◽  
Author(s):  
Santiago F. Elena
Keyword(s):  
Experimental Evolution ◽  
Metabolic Networks ◽  
Rna Virus ◽  
Biological Complexity ◽  
Biological Organization ◽  
Evolutionary Transitions ◽  
Specific Level ◽  
Major Transitions ◽  
Multicellular Organisms ◽  
John Maynard Smith

In their search to understand the evolution of biological complexity, John Maynard Smith and Eörs Szathmáry put forward the notion of major evolutionary transitions as those in which elementary units get together to generate something new, larger and more complex. The origins of chromosomes, eukaryotic cells, multicellular organisms, colonies and, more recently, language and technological societies are examples that clearly illustrate this notion. However, a transition may be considered as anecdotal or as major depending on the specific level of biological organization under study. In this contribution, I will argue that transitions may also be occurring at a much smaller scale of biological organization: the viral world. Not only that, but also that we can observe in real time how these major transitions take place during experimental evolution. I will review the outcome of recent evolution experiments with viruses that illustrate four major evolutionary transitions: (i) the origin of a new virus that infects an otherwise inaccessible host and completely changes the way it interacts with the host regulatory and metabolic networks, (ii) the incorporation and loss of genes, (iii) the origin of segmented genomes from a non-segmented one, and (iv) the evolution of cooperative behaviour and cheating between different viruses or strains during co-infection of the same host. This article is part of the themed issue ‘The major synthetic evolutionary transitions’.

YOUTH EXPECTATIONS OF SMART CITY LIVING: AN IMPORTANCE- PERFORMANCE ANALYSIS OF YOUNG RESIDENTS’ PERSPECTIVES OF CITY GOVERNMENT

2017 ◽  
Vol 14 (1) ◽  
pp. 118-128
Author(s):  
Jason Cohen ◽  
Judy Backhouse ◽  
Omar Ally
Keyword(s):  
Performance Analysis ◽  
Young People ◽  
Smart City ◽  
Smart Cities ◽  
City Government ◽  
Diagnostic Tools ◽  
City Management ◽  
Bottom Up ◽  
Starting Point ◽  
The City

Young people are important to cities, bringing skills and energy and contributing to economic activity. New technologies have led to the idea of a smart city as a framework for city management. Smart cities are developed from the top-down through government programmes, but also from the bottom-up by residents as technologies facilitate participation in developing new forms of city services. Young people are uniquely positioned to contribute to bottom-up smart city projects. Few diagnostic tools exist to guide city authorities on how to prioritise city service provision. A starting point is to understand how the youth value city services. This study surveys young people in Braamfontein, Johannesburg, and conducts an importance-performance analysis to identify which city services are well regarded and where the city should focus efforts and resources. The results show that Smart city initiatives that would most increase the satisfaction of youths in Braamfontein  include wireless connectivity, tools to track public transport  and  information  on city events. These  results  identify  city services that are valued by young people, highlighting services that young people could participate in providing. The importance-performance analysis can assist the city to direct effort and scarce resources effectively.

Global temperature and life

2017 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Life Cycle ◽  
Marine Invertebrates ◽  
Natural World ◽  
Death Valley ◽  
Cell Interior ◽  
Ground Temperatures ◽  
Thermal Limits ◽  
Air Temperatures ◽  
Continental Shelves ◽  
Multicellular Organisms

The extreme meteorological surface air temperatures recorded to date are –89.2 oC in Antarctica, and 56.7 oC in Death Valley, California. Ground temperatures can be higher or lower than these air temperatures. The bulk of oceanic water is cold (< 4 oC) and thermally stable. Whilst data on limits to survival attract considerable attention, the thermal limits to completion of the life cycle (which define the limits to life) are much less well known. Currently identified upper thermal limits for growth are 122 oC for archaeans, 100 oC for bacteria and ~60 oC for unicellular eukaryotes. No unicells appear to grow below –20 oC, a limit that is probably set by dehydration-linked vitrification of the cell interior. The lower thermal limits for survival in multicellular organisms in the natural world extend to at least –70 oC. However in all cases known to date, completion of the life cycle requires summer warmth and the lowest temperature for completion of a multicellular eukaryote life cycle appears to be ~0 oC for invertebrates in glacial meltwater and ~–2 oC for marine invertebrates and fish living on the continental shelves around Antarctica.

scholarly journals An historical framework for psychiatric nosology

2009 ◽  
Vol 39 (12) ◽  
pp. 1935-1941 ◽  
Author(s):  
K. S. Kendler
Keyword(s):  
Psychiatric Illness ◽  
Theoretical Orientation ◽  
A Priori ◽  
Early History ◽  
Top Down ◽  
Species Definition ◽  
Psychiatric Nosology ◽  
Bottom Up ◽  
Starting Point ◽  
History Of

This essay, which seeks to provide an historical framework for our efforts to develop a scientific psychiatric nosology, begins by reviewing the classificatory approaches that arose in the early history of biological taxonomy. Initial attempts at species definition used top-down approaches advocated by experts and based on a few essential features of the organism chosena priori. This approach was subsequently rejected on both conceptual and practical grounds and replaced by bottom-up approaches making use of a much wider array of features. Multiple parallels exist between the beginnings of biological taxonomy and psychiatric nosology. Like biological taxonomy, psychiatric nosology largely began with ‘expert’ classifications, typically influenced by a few essential features, articulated by one or more great 19th-century diagnosticians. Like biology, psychiatry is struggling toward more soundly based bottom-up approaches using diverse illness characteristics. The underemphasized historically contingent nature of our current psychiatric classification is illustrated by recounting the history of how ‘Schneiderian’ symptoms of schizophrenia entered into DSM-III. Given these historical contingencies, it is vital that our psychiatric nosologic enterprise be cumulative. This can be best achieved through a process of epistemic iteration. If we can develop a stable consensus in our theoretical orientation toward psychiatric illness, we can apply this approach, which has one crucial virtue. Regardless of the starting point, if each iteration (or revision) improves the performance of the nosology, the eventual success of the nosologic process, to optimally reflect the complex reality of psychiatric illness, is assured.

scholarly journals Evolutionary trade-offs between unicellularity and multicellularity in budding yeast

2018 ◽  
Author(s):  
Jennie J. Kuzdzal-Fick ◽  
Lin Chen ◽  
Gábor Balázsi
Keyword(s):  
Mitotic Exit ◽  
Fundamental Question ◽  
Bet Hedging ◽  
Evolutionary Transitions ◽  
Wild Yeast ◽  
Yeast Strains ◽  
Trade Offs ◽  
Mitotic Exit Network ◽  
Multicellular Organisms ◽  
Benefits And Costs

ABSTRACTMulticellular organisms appeared on Earth through several independent major evolutionary transitions. Are such transitions reversible? Addressing this fundamental question entails understanding the benefits and costs of multicellularity versus unicellularity. For example, some wild yeast strains form multicellular clumps, which might be beneficial in stressful conditions, but this has been untested. Here we show that unicellular yeast evolves from clump-forming ancestors by propagating samples from suspension after larger clumps have settled. Unicellular yeast strains differed from their clumping ancestors mainly by mutations in the AMN1 (Antagonist of Mitotic exit Network) gene. Ancestral yeast clumps were more resistant to freeze/thaw, hydrogen peroxide, and ethanol stressors than their unicellular counterparts, while unicellularity was advantageous without stress. These findings inform mathematical models, jointly suggesting a trade-off between the benefits and downsides of multicellularity, causing bet-hedging by regulated phenotype switching as a survival strategy in unexpected stress.

scholarly journals The order of trait emergence in the evolution of cyanobacterial multicellularity

2019 ◽  
Author(s):  
Katrin Hammerschmidt ◽  
Giddy Landan ◽  
Fernando Domingues Kümmel Tria ◽  
Jaime Alcorta ◽  
Tal Dagan
Keyword(s):  
Division Of Labor ◽  
Phenotypic Trait ◽  
Evolutionary Transition ◽  
Evolutionary Transitions ◽  
Differentiated Cells ◽  
Labor Theory ◽  
Significant Events ◽  
Reproductive Life ◽  
History Of ◽  
Multicellular Organisms

AbstractThe transition from unicellular to multicellular organisms is one of the most significant events in the history of life. Key to this process is the emergence of Darwinian individuality at the higher level: groups must become single entities capable of reproduction for selection to shape their evolution. Evolutionary transitions in individuality are characterized by cooperation between the lower level entities and by division of labor. Theory suggests that division of labor may drive the transition to multicellularity by eliminating the trade-off between two incompatible processes that cannot be performed simultaneously in one cell. Here we examine the evolution of the most ancient multicellular transition known today, that of cyanobacteria, where we reconstruct the sequence of ecological and phenotypic trait evolution. Our results show that the prime driver of multicellularity in cyanobacteria was the expansion in metabolic capacity offered by nitrogen fixation, which was accompanied by the emergence of the filamentous morphology and succeeded by a reproductive life cycle. This was followed by the progression of multicellularity into higher complexity in the form of differentiated cells and patterned multicellularity.Significance StatementThe emergence of multicellularity is a major evolutionary transition. The oldest transition, that of cyanobacteria, happened more than 3 to 3.5 billion years ago. We find N2 fixation to be the prime driver of multicellularity in cyanobacteria. This innovation faced the challenge of incompatible metabolic processes since the N2 fixing enzyme (nitrogenase) is sensitive to oxygen, which is abundantly found in cyanobacteria cells performing photosynthesis. At the same time, N2-fixation conferred an adaptive benefit to the filamentous morphology as cells could divide their labour into performing either N2-fixation or photosynthesis. This was followed by the culmination of complex multicellularity in the form of differentiated cells and patterned multicellularity.

Virtual Communities Wish List

2011 ◽  
pp. 520-523
Author(s):  
James Isaak
Keyword(s):  
Life Cycle ◽  
Virtual Communities ◽  
Ad Hoc ◽  
Virtual Community ◽  
Emerging Technology ◽  
Formal Groups ◽  
Community Interaction ◽  
Starting Point ◽  
E Mail ◽  
Push Model

Experience with virtual communities such as Yahoo Groups, Community Zero, Blackboard and WebCT and working with ad hoc and formal groups (such as IEEE committees) has provided a basis for a “wish list” of virtual community capabilities. For any given audience, purpose, life-cycle and culture the relevant elements of this list will vary (Kim, 2000). With emerging technology and evolving experience, additional elements should be added. This, then, is a starting point for identifying the specific requirements for a specific virtual community. Here, general functions are described, as well as functions as seen by users or administrators of a virtual community. The format is intentionally terse to facilitate the use of this information as the basis for a checklist in evaluating requirements, alternatives and priorities. The general concepts of “push” (data is delivered to users, e-mail being an example) and “pull” (where data is only available when the user chooses to seek it out) are highly relevant. Maintaining community “interaction” is dependent on having a core of participants who are regularly interacting, and the “push” model can facilitate this among less experienced users.

scholarly journals Complexity in Biological Organization: Deconstruction (and Subsequent Restating) of Key Concepts

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 885 ◽  
Author(s):  
Mariano Bizzarri ◽  
Oleg Naimark ◽  
José Nieto-Villar ◽  
Valeria Fedeli ◽  
Alessandro Giuliani
Keyword(s):  
Complex Systems ◽  
Scientific Culture ◽  
Biological Organization ◽  
Bottom Up ◽  
Key Concepts ◽  
Deep Sense

The “magic” word complexity evokes a multitude of meanings that obscure its real sense. Here we try and generate a bottom-up reconstruction of the deep sense of complexity by looking at the convergence of different features shared by complex systems. We specifically focus on complexity in biology but stressing the similarities with analogous features encountered in inanimate and artefactual systems in order to track an integrative path toward a new “mainstream” of science overcoming the actual fragmentation of scientific culture.

Sign in / Sign up

Export Citation Format

Share Document