Exploring Evolved Multicellular Life Histories in a Open-Ended Digital Evolution System

Evolutionary transitions occur when previously-independent replicating entities unite to form more complex individuals. Such transitions have profoundly shaped natural evolutionary history and occur in two forms: fraternal transitions involve lower-level entities that are kin (e.g., transitions to multicellularity or to eusocial colonies), while egalitarian transitions involve unrelated individuals (e.g., the origins of mitochondria). The necessary conditions and evolutionary mechanisms for these transitions to arise continue to be fruitful targets of scientific interest. Here, we examine a range of fraternal transitions in populations of open-ended self-replicating computer programs. These digital cells were allowed to form and replicate kin groups by selectively adjoining or expelling daughter cells. The capability to recognize kin-group membership enabled preferential communication and cooperation between cells. We repeatedly observed group-level traits that are characteristic of a fraternal transition. These included reproductive division of labor, resource sharing within kin groups, resource investment in offspring groups, asymmetrical behaviors mediated by messaging, morphological patterning, and adaptive apoptosis. We report eight case studies from replicates where transitions occurred and explore the diverse range of adaptive evolved multicellular strategies

Toward major evolutionary transitions theory 2.0

The impressive body of work on the major evolutionary transitions in the last 20 y calls for a reconstruction of the theory although a 2D account (evolution of informational systems and transitions in individuality) remains. Significant advances include the concept of fraternal and egalitarian transitions (lower-level units like and unlike, respectively). Multilevel selection, first without, then with, the collectives in focus is an important explanatory mechanism. Transitions are decomposed into phases of origin, maintenance, and transformation (i.e., further evolution) of the higher level units, which helps reduce the number of transitions in the revised list by two so that it is less top-heavy. After the transition, units show strong cooperation and very limited realized conflict. The origins of cells, the emergence of the genetic code and translation, the evolution of the eukaryotic cell, multicellularity, and the origin of human groups with language are reconsidered in some detail in the light of new data and considerations. Arguments are given why sex is not in the revised list as a separate transition. Some of the transitions can be recursive (e.g., plastids, multicellularity) or limited (transitions that share the usual features of major transitions without a massive phylogenetic impact, such as the micro- and macronuclei in ciliates). During transitions, new units of reproduction emerge, and establishment of such units requires high fidelity of reproduction (as opposed to mere replication)

Mechanisms for the Evolution of Superorganismality in Ants

Ant colonies appear to behave as superorganisms; they exhibit very high levels of within-colony cooperation, and very low levels of within-colony conflict. The evolution of such superorganismality has occurred multiple times across the animal phylogeny, and indeed, origins of multicellularity represent the same evolutionary process. Understanding the origin and elaboration of superorganismality is a major focus of research in evolutionary biology. Although much is known about the ultimate factors that permit the evolution and persistence of superorganisms, we know relatively little about how they evolve. One limiting factor to the study of superorganismality is the difficulty of conducting manipulative experiments in social insect colonies. Recent work on establishing the clonal raider ant, Ooceraea biroi, as a tractable laboratory model, has helped alleviate this difficulty. In this dissertation, I study the proximate evolution of superorganismality in ants. Using focussed mechanistic experiments in O. biroi, in combination with comparative work from other ant species, I study three major aspects of ant social behaviour that provide insight into the origin, maintenance, and elaboration of superorganismality. First, I ask how ants evolved to live in colonies, and how they evolved a reproductive division of labour. A comparative transcriptomic screen across the ant phylogeny, combined with experimental manipulations in O. biroi, finds that reproductive ants have higher insulin levels than their non-reproductive nestmates, and that this likely regulates the reproductive division of labour. Using these data, as well as studies of the idiosyncrasies of O. biroi’s life history, I propose a mechanism for the evolution of the first colonies. It is possible that similar mechanisms underlie the evolution of reproductive division of labour in other superorganisms, and of germ-soma separation in nascent multicellular individuals. Second, I ask how ant workers assess colony hunger to regulate their foraging behaviour. I find that workers use larval signals, but not their own nutritional states, to decide how much to forage. In contrast, they use their nutritional states, but not larval signals, to decide how much to eat, suggesting that in at least some ant species, foraging and feeding have been decoupled. This evolution of colony-level foraging regulation has occurred convergently in hymenopteran superorganisms, and is analogous to the evolution of centralised regulation of foraging behaviour in multicellular animals. Finally, I ask how an iconic collective foraging behaviour – the mass raids of army ants – evolved. I find that O. biroi, a relative of army ants, forages collectively in group raids, that these are ancestral to the mass raids of army ants, and that the transition from group to mass raiding correlates with expansion in colony size. I propose that the scaling effects of increasing colony size explain this transition. It is possible that similar principles underlie the evolution of disparate collective behaviours in other animal groups and among cells within developing animals. Together, these studies illuminate the life history of O. biroi, and suggest mechanisms for the evolution of core aspects of cooperative behaviour in ant colonies. I draw comparisons to the evolution of superorganismality in other lineages, as well as to the evolution of multicellularity. I suggest that there may be additional similarities in the proximate evolutionary trajectories of superorganismality and multicellularity

"Synergistic selection": A Darwinian frame for the evolution of complexity

Non-Darwinian theories about the emergence and evolution of complexity date back at least to Lamarck, and include those of Herbert Spencer and the "emergent evolution" theorists of the later nineteenth and early twentieth centuries. In recent decades, this approach has mostly been espoused by various practitioners in biophysics and complexity theory. However, there is a Darwinian alternative - in essence, an economic theory of complexity - proposing that synergistic effects of various kinds have played an important causal role in the evolution of complexity, especially in the "major transitions". This theory is called the "synergism hypothesis". We posit that otherwise unattainable functional advantages arising from various cooperative phenomena have been favored over time in a dynamic that the late John Maynard Smith characterized and modeled as "synergistic selection". The term highlights the fact that synergistic "wholes" may become interdependent "units" of selection. We provide some historical perspective on this issue, as well as a brief explication of the underlying theory and the concept of synergistic selection, and we describe two relevant models. (C) 2015 Elsevier Ltd. All rights reserved

An Overview of Open-Ended Evolution: Editorial Introduction to the Open-Ended Evolution II Special Issue.

Nature's spectacular inventiveness, reflected in the enormous diversity of form and function displayed by the biosphere, is a feature of life that distinguishes living most strongly from nonliving. It is, therefore, not surprising that this aspect of life should become a central focus of artificial life. We have known since Darwin that the diversity is produced dynamically, through the process of evolution; this has led life's creative productivity to be called Open-Ended Evolution (OEE) in the field. This article introduces the second of two special issues on current research in OEE and provides an overview of the contents of both special issues. Most of the work was presented at a workshop on open-ended evolution that was held as a part of the 2018 Conference on Artificial Life in Tokyo, and much of it had antecedents in two previous workshops on open-ended evolution at artificial life conferences in Cancun and York. We present a simplified categorization of OEE and summarize progress in the field as represented by the articles in this special issue

Almost Mirror Image: Exploring The Similarities And Dissimilarities Of Identical Twins In Theatrical Solo Performance

Almost Mirror Image: Exploring the Similarities and Dissimilarities of Identical Twins in Theatrical Solo Performance Is an exploration of the psyche of identical twins within the context of devised solo performance. The author, an identical twin herself, has long been interested in twins\u27 ability to cultivate both highly independent personalities as well as intensely co-dependent tendencies during development. What can twins tell us about the way we create close relationships and how is their upbringing radically different from the majority of the world that is born alone? Equally intrigued by society\u27s growing technological dependence, the author would like to delve into how the science and development of twins appears counterintuitive to the intra-personal technological world they grow up in by using personal, autobiographic solo performance as her research platform. The data collected from research sources such as Jo Bonney\u27s Extreme Exposure and Michael Kearns\u27 The Solo Performer\u27s Journey, will provide fodder for the thesis document and the author\u27s devised solo piece, entitled Teach me how to be Lonely. While devising her own solo performance, the author will compare and contrast her process with that of a few select solo performers such as Anna Deavere Smith and Rachel Rosenthal. The author will delve into various styles of solo work creation, including the testimony plays of Smith and the autobiographical style of Rosenthal, in order to view her own work with a self-reflective and identity-driven lens. Overall, the author hopes to achieve a more comprehensive understanding of her own experience as an identical twin through the facilitation of her solo work as well as explore how the creation of solo performance can offer artists in the 21st century more freedom of expression and identity than the performance of a standard play

Superorganismality and caste differentiation as points of no return:how the major evolutionary transitions were lost in translation

Four decades of sociobiology have left us with multiple superorganism concepts that are mutually inconsistent and uninformative on how superorganismality originates. These ambiguities can be traced to a broadened concept ofeusociality that denied colonies with physically differentiated castes the special statusthat inspired August Weismann, William Morton Wheeler, Ronald A. Fisher and Julian S. Huxley to consider them as organism-analogs. The heuristic definitions of superorganismality that began to emerge in the 1980s have precluded proper appreciation of which social insect lineages made irreversible evolutionary transitions to superorganismality, andwhich did not. This has impeded straightforward connections between inclusive fitness theory and the major evolutionary transitions towards higher organizational complexity. We evaluate the history by which these inconsistencies accumulated, develop a common causeapproach for understanding the origins of all eukaryotic transitions in hierarchical complexity, and argue that they are directly comparable in inclusive fitness terms and do not require potential internal conflicts to be resolved first. We conclude that recurring controversies over the status of inclusive fitness theory emanate from the arbitrarily defined sociobiological concepts of superorganismality and eusociality, not from the theory itself. The sociobiology-inspired definition of eusociality lumps a diverse spectrum of social systems into a single category, which causes fundamental differences in commitment to social life to be overlooked. We argue that behavioral categories need to be defined and delineated from the presence or absence of distinct traits whose evolutionary origin and maintenance can be explained, and suggest that it is meaningless to ask how eusociality and other categories lacking rigorous definition evolved. Early 20th century naturalists and geneticists realized that the key traits for social insects are reproductive altruism and the irreversible acquisition of an unmated worker caste. Hamilton’s rule is almost universally accepted as the best approximate algorithm for understanding the evolution and maintenance of condition-dependent reproductive altruism, and can also be used to explain evolutionary transitions to unconditional differentiation of permanently unmated castes. The origin and elaboration of somatic tissues in multicellular eukaryotes can be understood in a fully analogous way