Nathalie Gontier

Depicting the Tree of Life: the Philosophical and Historical Roots of Evolutionary Tree Diagrams

It is a popularly held view that Darwin was the first author to draw a phylogenetic tree diagram. However, as is the case with most popular beliefs, this one also does not hold true. Firstly, Darwin never called his diagram of common descent a tree. Secondly, even before Darwin, tree diagrams were used by a variety of philosophical, religious, and secular scholars to depict phenomena such as “logical relationships,” “affiliations,” “genealogical descent,” “affinity,” and “historical relatedness” between the elements portrayed on the tree. Moreover, historically, tree diagrams themselves can be grouped into a larger class of diagrams that were drawn to depict natural and/or divine order in the world. In this paper, we trace the historical roots and cultural meanings of these tree diagrams. It will be demonstrated that tree diagrams as we know them are the outgrowth of ancient philosophical attempts to find the “true order” of the world, and to map the world “as it is” (ontologically), according to its true essence. This philosophical idea would begin a fascinating journey throughout Western European history. It lies at the foundation of the famous “scala naturae,” as well as religious and secular genealogical thinking, especially in regard to divine, familial (kinship), and linguistic pedigrees that were often depicted by tree images. These scala naturae would fuse with genealogical, pedigree thinking, and the trees that were the result of this blend would, from the nineteenth century onward, also include the element of time. The recognition of time would eventually lead to the recognition of evolution as a fact of nature, and subsequently, tree iconographies would come to represent exclusively the evolutionary descent of species.

Evolutionary epistemology as a scientific method: a new look upon the units and levels of evolution debate

Evolutionary epistemology can provide a unified scientific methodology that enables scholars to study the evolution of life as well as the evolution of cognition, science, culture and any other phenomenon displayed by living organisms. In this article, three heuristics are provided that allow for a thorough search for the units, levels and mechanisms of evolution. Contrary to previous approaches, units, levels and mechanisms are not identified by pointing out essential features, but rather ostensive definitions are preferred. That is, units are considered as such if a level of evolution and a mechanism of evolution is identifiable. Levels are levels if one can point out units that evolve at that level according to evolutionary mechanisms, and mechanisms are considered as such if one can point out units and levels where the mechanism is active.

Genes, brains, and language: An epistemological examination of how genes can underlie human cognitive behavior.

How do genes encode for the formation of morphological structures such as the brain? Can genetic material also encode for behavior such as cognition, language, or culture? For many years, evolutionary biologists as well as scholars who work within extrabiological fields such as psychology, linguistics, and archaeology could only answer the above two questions in a speculative manner. This is because until recently, empirical observations on how genes underlie anatomy or behavior were generally lacking. This situation has now changed. Several genes (MCPH1-MCPH6) have been implicated in the regulation of brain size and a first gene (the FOXP2 gene) has been identified that might underlie linguistic behavior. These discoveries allow us to finally test some of the long-standing theoretical assumptions on how genes do or do not determine morphology and behavior.

Introduction to evolutionary epistemology, language and culture

Evolutionary epistemology (EE) is about developing a normative framework, based upon evolutionary thinking, that can explain all of an organism’s phylogenetic and ontogenetic evolution. (1) EE is sketched as an inter- and transdisciplinary field that evolved out of naturalized epistemology as a reaction against logical empiricism and sociology of knowledge. (2) Different schools of evolutionary epistemological thinking are examined and compared. (3) It is argued that within EE today, the search for a normative evolutionary framework is narrowed down to the development of a framework based upon Neo-Darwinian theory. Because of this, other evolutionary theories that are very useful to explain certain phenomena are neglected. (4) These theories are briefly discussed. (5) It is shown how EE can be implemented in the scientific study of language and culture.

Reticulate Evolution Everywhere

Reticulation is a recurring evolutionary pattern found in phylogenetic reconstructions of life. The pattern results from how species interact and evolve by mechanisms and processes including symbiosis; symbiogenesis; lateral gene transfer (that occurs via bacterial conjugation, transformation, transduction, Gene Transfer Agents, or the movements of transposons, retrotransposons, and other mobile genetic elements); hybridization or divergence with gene flow; and infectious heredity (induced either directly by bacteria, bacteriophages, viruses, prions, protozoa and fungi, or via vectors that transmit these pathogens). Research on reticulate evolution today takes on inter- and transdisciplinary proportions and is able to unite distinct research fields ranging from microbiology and molecular genetics to evolutionary biology and the biomedical sciences. This chapter summarizes the main principles of the diverse reticulate evolutionary mechanisms and situates them into the chapters that make up this volume.

Evolutionary epistemology and the origin and evolution of language: Taking symbiogenesis seriously

Symbiogenesis is a form of horizontal evolution that occurred 2 billion years ago, with the evolution of eukaryotic cells. It will be argued that, just as we can develop universal selection theories based upon a general account of natural selection, we can also develop a universal symbiogenetic principle that can serve as a general framework to study the origin and evolution of language. (1) Horizontal evolution will be compared with and distinguished from vertical evolution. (2) Different examples of intra- and interspecific horizontal evolution will be given to show that horizontal evolution is quantitatively and qualitatively the most commonly occurring form of evolution throughout the history of life. (3) Finally, three examples are given of how a universal symbiogenesis principle can be implemented in the study of language origins and evolution, more specifically within: (a) the study of language variation, (b) language genes and (c) conceptual blending.

Uniting Micro- with Macroevolution into an Extended Synthesis: Reintegrating Life’s Natural History into Evolution Studies

The Modern Synthesis explains the evolution of life at a mesolevel by identifying phenotype–environmental interactions as the locus of evolution and by identifying natural selection as the means by which evolution occurs. Both micro- and macroevolutionary schools of thought are post-synthetic attempts to evolutionize phenomena above and below organisms that have traditionally been conceived as non-living. Microevolutionary thought associates with the study of how genetic selection explains higher-order phenomena such as speciation and extinction, while macroevolutionary research fields understand species and higher taxa as biological individuals and they attribute evolutionary causation to biotic and abiotic factors that transcend genetic selection. The microreductionist and macroholistic research schools are characterized as two distinct epistemic cultures where the former favor mechanical explanations, while the latter favor historical explanations of the evolutionary process by identifying recurring patterns and trends in the evolution of life. I demonstrate that both cultures endorse radically different notions on time and explain how both perspectives can be unified by endorsing epistemic pluralism.

Macroevolution: Explanation, Interpretation and Evidence

This book is divided in two parts, the first of which shows how, beyond paleontology and systematics, macroevolutionary theories apply key insights from ecology and biogeography, developmental biology, biophysics, molecular phylogenetics and even the sociocultural sciences to explain evolution in deep time. In the second part, the phenomenon of macroevolution is examined with the help of real life-history case studies on the evolution of eukaryotic sex, the formation of anatomical form and body-plans, extinction and speciation events of marine invertebrates, hominin evolution and species conservation ethics. The book brings together leading experts, who explain pivotal concepts such as Punctuated Equilibria, Stasis, Developmental Constraints, Adaptive Radiations, Habitat Tracking, Turnovers, (Mass) Extinctions, Species Sorting, Major Transitions, Trends and Hierarchies n key premises that allow macroevolutionary epistemic frameworks to transcend microevolutionary theories that focus on genetic variation, selection, migration and fitness. Along the way, the contributing authors review ongoing debates and current scientific challenges; detail new and fascinating scientific tools and techniques that allow us to cross the classic borders between disciplines; demonstrate how their theories make it possible to extend the Modern Synthesis; present guidelines on how the macroevolutionary field could be further developed; and provide a rich view of just how it was that life evolved across time and space. In short, this book is a must-read for active scholars and because the technical aspects are fully explained, it is also accessible for non-specialists. Understanding evolution requires a solid grasp of above-population phenomena. Species are real biological individuals and abiotic factors impact the future course of evolution. Beyond observation, when the explanation of macroevolution is the goal, we need both evidence and theory that enable us to explain and interpret how life evolves at the grand scale.

Guest-Editorial Introduction: Converging Evolutionary Patterns in Life and Culture

The natural world demonstrates signs of spatial–temporal order, an order that appears to us through a series of recognizable, recurring and consecutive patterns, i.e. regularities in forms, functions, behaviors, events and processes. These patterns lend insight into the modes and tempos of evolution and thus into the units, levels, and mechanisms that underlie the evolutionary hierarchy. Contributors to this special issue analyze converging patterns in the biological and sociocultural realm across and beyond classic divisions between micro- and macro-evolution; horizontal/reticulate and vertical evolution; phylogeny, ontogeny and ecology; synchronic and diachronic sociocultural and linguistic research; and tree and network diagrams. Explanations are sought in complexity theory, major transitions of evolution, and process and mechanism approaches to change; and consequences for notions such as “life”, “species”, “biological individuality”, “units” and “levels” of evolution are given.

Historical and Epistemological Perspectives on What Horizontal Gene Transfer Mechanisms Contribute to Our Understanding of Evolution

Since the 1990s, results coming in from molecular phylogenetics necessitate us to recognize that Horizontal Gene Transfer (HGT) occurs massively across all three domains of life. Nonetheless, many of the mechanisms whereby genes can become transferred laterally have been known from the early twentieth century onward. The temporal discrepancy between the first historical observations of the processes, and the rather recent general acceptance of the documented data, poses an interesting epistemological conundrum: Why have incoming results on HGT been widely neglected by the general evolutionary community and what causes for a more favorable reception today? Five reasons are given: (1) HGT was first observed in the biomedical sciences and these sciences did not endorse an evolutionary epistemic stance because of the ontogeny/phylogeny divide adhered to by the founders of the Modern Synthesis. (2) Those who did entertain an evolutionary outlook associated research on HGT with a symbiotic epistemic framework. (3) That HGT occurs across all three domains of life was demonstrated by modern techniques developed in molecular biology, a field that itself awaits full integration into the general evolutionary synthesis. (4) Molecular phylogenetic studies of prokaryote evolution were originally associated with exobiology and abiogenesis, and both fields developed outside the framework provided by the Modern Synthesis. (5) Because HGT brings forth a pattern of reticulation, it contrasts the standard idea that evolution occurs solely by natural selection that brings forth a vertical, bifurcating pattern in the “tree” of life. Divided into two parts, this chapter first reviews current neo-Darwinian “tree of life” versus reticulate “web of life” polemics as they have been debated in high-profile academic journals, and secondly, the historical context of discovery of the various means whereby genes are transferred laterally is sketched. Along the way, the reader is introduced to how HGT contradicts some of the basic tenets of the neo-Darwinian paradigm.