VI. Earth Life Emergence: Development of Body, Brain, Selves and Societies
E. Universal Gestation: Phylogeny and Ontogeny
In the 19th century, before The Origin of Species and for a while after, an organism’s embryonic development was broadly seen to recapitulate the evolutionary sequence from which it arose. But the comparison was set aside around 1900 as anatomical studies found contradictions to older parallels. Into the 2000s and 2010s a better quantified understanding of and general agreement between ontogenetic development and phylogenetic evolution is allowed, this time in several areas. In addition to embryonic and fetal maturation, a necessary recurrence is recognized for cognitive capacities, behavioral stages and especially for linguistic abilities. The title phrase "universal gestation" was a popular conception in Charles Darwin’s day, which we now take license so to recover its veracity.
Abzhanov, Arhat. Von Baer’s Law for the Ages: Lost and Found Principles of Developmental Evolution. Trends in Genetics. 29/12, 2013. A Kazakhstan-American, Harvard University, professor of organismic and evolutionary biology reviews some two centuries of parallel studies of life’s phylogenesis from protocells to homo sapiens, and the embryonic ontogenesis of individual organisms. In 1828, Karl von Baer (1792-1876), an Estonian-Russian natural philosopher, stated his “laws of embryology” that more general forms of an animal species appear earlier in their embryos than later, special characters. In broad survey, the 19th century held to a recapitulation or “universal gestation” between embryogeny and species evolution. In the 20th century these realms separated, which brought an exclusion of any directional course or cause. But after many decades of quantifying research, into the 21st century by way of an evolution-development (evo-devo) reunion, a deep, actual affinity is now being proven. In regard, this paper concludes there is in fact a “parallelism” between individual ontogeny and Metazoan phylogeny. An example is a correspondence for “Gallus gallus,” the chicken genus, with its embryo stages from fertilization to post-hatching of an adult fowl. Such a real recapitulation adds another insight toward a substantial embryogenesis, and significance at term, to life’s long maturation.
The law of embryology and principles of evo-devo The evolution and development of multicellular animals share many key features. Both processes begin with a single diploid eukaryotic animal cell, the ancestral unicellular protest and a fertilized egg, respectively, the nuclei of which contain genomes already laden with highly sophisticated genetic information, such as genes encoding ligands and their signaling transduction components, cell-cell adhesion molecules, and a multitude of transcription factors that can eb used for the specification of distinct cell fates. Evo-devo compares developmental processes of multicellular organisms to understand how modifications in these processes produce morphological diversity, explain the origin of evolutionary novelties and constraints, and provide developmental basis for homology (conservation) and homoplary (convergence). (714)
Arhem, Peter and Hans Liljenstrom, eds. Consciousness Transitions: Phylogenetic, Ontogenetic and Physiological Aspects. Amsterdam: Elsevier, 2007. From the Royal Swedish Academy of Science, a volume that joins the maturing field of sentience studies with the increasingly popular major evolutionary transitions scale. Notable chapters include “The Evolution of Consciousness in Animals” by R.V. Rial, et al, “On the Origin of Consciousness - Some Amniote Scenarios,” Peter Århem, et al, “The Molecular Biology of Consciousness Investigated with Genetically Modified Mice” by Jean-Paul Changeux, “The Emergence of Consciousness in the Fetus and the Newborn,” Hugo Lagercrantz and “Evolutionary and Developmental Aspects of Intersubjectivity” by Peter Gärdenfors. A tacit theme throughout is a necessary, evident recapitulation of individual persons and sapient species, as the subtitle suggests.
However, we find it reasonable to believe that conscious cognition, in principle, differs from unconscious cognition, that the emergence of conscious cognition was a major transition in the evolution of life. The degree of consciousness, we believe, is associated with the degree of complexity, and conscious cognition would require a rather complex nervous system, that could not be found in any primitive animal. We assume there has been an evolution of consciousness in smaller or larger steps, but in parallel and in interaction with the evolution of the nervous system. (2, Editors Introduction)
Armon, Romy. Beyond Darwinism’s Eclipse: Functional Evolution, Biochemical Recapitulation and Spencerian Emergence in the 1920s and 1930s. Journal for General Philosophy of Science. 41/1, 2010. A Ben-Gurion University of the Negev philosopher of biology finds the holistic contributions of British biochemist Joseph Needham, with inputs from Herbert Spencer and Ernst Haeckel, to achieve an alternative synthesis that better supports a pervasive and necessary recapitulation of ontogeny and phylogeny.
During the 1920s and 1930s, many biologists questioned the viability of Darwin’s theory as a mechanism of evolutionary change. In the early 1940s, and only after a number of alternatives were suggested, Darwinists succeeded to establish natural selection and gene mutation as the main evolutionary mechanisms. While that move, today known as the neo-Darwinian synthesis, is taken as signalling a triumph of evolutionary theory, certain critical problems in evolution—in particular the evolution of animal function—could not be addressed with this approach. Here I demonstrate this through reconstruction of the evolutionary theory of Joseph Needham (1900–1995), who pioneered the biochemical study of evolution and development. In order to address such problems, Needham employed Herbert Spencer’s principles of emergence and Ernst Haeckel’s theory of recapitulation. While Needham did not reject Darwinian theory, Spencerian and Haeckelian frameworks happened to better fit his findings and their evolutionary relevance. He believed selectionist and genetic approaches to be important but far from sufficient for explaining how evolutionary transformations occur. (Abstract)
Arthur, Wallace. Creatures of Accident. New York: Hill and Wang, 2006. The title is meant to stick it to Intelligent Design, and is not really accurate. While ID claims the advancing complexity of life forms cannot be explained by Darwinian selection, the author argues it can if a developmental or evo-devo component is included. Chapter Nine, The Embryo Wars, goes on to affirm, as Arthur has done before, a general recapitulation of ontogeny and phylogeny.
Arthur, Wallace. The Origin of Animal Body Plans. New York: Cambridge University Press, 1997. The British paleontologist provides an extensive study of systematic hierarchies with regard to morphological, lineage, and genetic types which verify the basic unity of ontogeny and phylogeny.
My own view, which is influenced by both my neo-Darwinian training and my current advocacy of the nascent discipline of evolutionary developmental biology, is that there is a relationship between the developmental and evolutionary hierarchies, and that it is informative about the nature of evolutionary mechanisms. At the level of major animal body plans there is a good correspondence between genealogy and morphology. (257)
Botha, Rudolf. Language Evolution: The Windows Approach. Cambridge: Cambridge University Press, 2016. The emeritus University of Stellenbosch, RSA, linguist and philosopher proposes an archaeological reconstruction of how primates, hominids, and human beings gained this distinctive faculty of auditory, gesticulate, inscribed communication. For example, sea shells, cave art, beads, hieroglyphs, fossil skulls, !Kung culture, and more have stories to tell. So do theories of proto-utterances (Derek Bickerton, Alison Wray), mother-baby talk (Dean Falk), along with those of Maggie Tallerman, Salikoko Mufwene, James Hurford, Kathleen Gibson, and an array of scholars. But within this survey, what interests us is a general “recapitulation” between individual development (ontogeny) and whole species (phylogeny). This is a picture window upon vital parallels between infants and children and the body language, hand signings, logo drawings, holistic syntax, stages that evolution passed through. While Ernst Haeckel’s 19th century embryo version is set aside, a persistent witness that a similar retracing does indeed go on, as Falk, Gibson, Hurford, and others emphasize.
Burghardt, Gordon. The Genesis of Animal Play. Cambridge: MIT Press, 2005. An extensive study of the evolution of play behavior with a suggestion that its appearance, mode and utility is recapitulated in children.
Burns, Jonathan. An Evolutionary Theory of Schizophrenia: Cortical Connectivity, Metarepresentation, and the Social Brain. Behavioral and Brain Sciences. 27/6, 2004. A psychiatrist from the Nelson Mandela School of Medicine, Durban, South Africa, views this mental disorder as a “costly trade-off in the evolution of complex social cognition.” As part of this well thought case, a close parallel is observed between how brains grew larger and more intricately wired from primates to homo sapiens and the developmental course of individual human cerebral capacity.
Ontogeny may, therefore, recapitulate phylogeny as far as the social brain is concerned. From the discussion of brain evolution so far, it appears that the trend towards increasingly complex connectivity in subsequently more sophisticated regions of the cortex during development reflects the trend during our evolutionary history towards increasingly complex cortical connectivity, social cognition, and metarepresentation. (850)
Calvin, Wiliam and Derek Bickerton. Lingua ex Machina. Cambridge: MIT Press, 2000. A pithy dialogue between a neuroscientist and a linguist about the evolution of language.
So that’s why language acquisition follows the course it does: a slow and hesitant beginning, a sudden spurt that takes one pretty close to adult competence in a few weeks or months, followed by a gradual filling-in of the picture that takes years. Pretty much the same course, as we have hypothesized that language took when it first evolved, and for exactly the same reasons. (207)
Changeux, Jean-Pierre. Reflections on the Origins of the Human Brain. Lagercrantz, Hugo, et al, eds. The Newborn Brain: Neuroscience and Clinical Applications. Cambridge: Cambridge University Press, 2010. In this lead chapter, the College de France, Institut Pasteur, neuroscientist and author provides a luminous addition via the latest appreciations of pre- and post-natal, fetal and infant, cognitive states to the processive advance of knowing consciousness. In so doing, as the quote notes, strong equivalents can then be drawn between such individual ontogeny and evolutionary phylogeny, across both the collective human species and life’s earthly development.
Phylogenetic Ancestors of the Human Brain. As mentioned above, many important anatomical features of our brain have been inherited from our direct ancestors. The soft parts of their brains may be lost forever, but comparison of the endocranial casts of modern humans and their fossil ancestors provides interesting information. It reveals striking analogies between the various stages of the phylogenetic evolution of the ancestors of H. sapiens and the ontogenetic development of the brain in the modern human. (6) The simplified topography of the human newborn meningeal system strikingly resembles the arrangement in Australopithecus robustus (who lived about three to two million years ago). The meningeal topography of Homo habilis, who lived two million years ago (cranial capacity 700 ml), is rather similar to that of a modern 40-day-old infant. Homo erectus, who lived one million years ago (cranial capacity of about 1000 ml), has a meningeal system topography similar to that of a modern 1-year-old child. (6)
Churchill, Frederick. Living with the Biogenetic Law: A Reappraisal. Laubichler, Manfred and Jane Maienschein, eds. From Embryology to Evo-Devo. Cambridge: MIT Press, 2007. In this volume which considers the 21st century reunion and refreshment of evolutionary theory by organismic development, the Indiana University historian and philosopher of science concludes that after an initial 19th century acceptance, a later subsequent long rejection, by way of present advances in biological sciences, an inherent, basic recapitulation between individual ontogeny and species phylogeny really does exist.
Clune, Jeff, et al. Ontogeny Tends to Recapitulate Phylogeny in Digital Organisms. American Naturalist. 180/3, 2012. Deep parallels between an individual’s course from embrogeny to maturity with life’s evolutionary development are held by every other culture and age. For Darwin’s day it was generally taken as a “universal gestation.” But in 20th century biology, this view became misconstrued and has long been shelved. As this section tries to report, as an actual fact, the similarity keeps being recognized in many ways. With coauthors Robert Pennock, Charles Ofria, and Richard Lenski, Michigan State University systems scientists offer a novel 21st century affirmation and resolve. The paper opens with a concise survey of its contentious history from von Baer and Haeckel to Gould and Mayr (1994). An evolving computational system is then enlisted in which digital organisms proceed to self-replicate, mutate, compete for resources, and evolve. A “complexity correlation effect” is noticed which is not a selective force but results from simpler structures and functions that are used as building blocks for more complex structures and functions. In addition, a “complexity of traits,” and “developmental disruption,” among other factors, leads to the conclusion that a robust tendency for ontogeny to recapitulate phylogeny does indeed exist.
Biologists have long debated whether ontogeny recapitulates phylogeny and, if so, why. Two plausible explanations are that (i) changes to early developmental stages are selected against because they tend to disrupt later development and (ii) simpler structures often precede more complex ones in both ontogeny and phylogeny if the former serve as building blocks for the latter. It is difficult to test these hypotheses experimentally in natural systems, so we used a computational system that exhibits evolutionary dynamics. We observed that ontogeny does indeed recapitulate phylogeny; traits that arose earlier in a lineage’s history also tended to be expressed earlier in the development of individuals. The relative complexity of traits contributed substantially to this correlation, but a significant tendency toward recapitulation remained even after accounting for trait complexity. (Abstract)