VI. Earth Life Emergence: Development of Body, Brain, Selves and Societies
1. The Evolution of Cerebral Form and Cognizance
Salas, Cosme, et al. Evolution of Forebrain and Spatial Cognition in Vertebrates: Conservation Across Diversity. Brain, Behavior and Evolution. 62/1, 2003. Although the vertebrate brain shows a range of diverse radiations, a common pattern of basic organization is consistently conserved across the long evolution of fish into monkeys.
We analyze here recent data indication a close functional similarity between spatial cognition mechanisms in different groups of vertebrates, mammals, birds, reptiles and teleost fish, and we show in addition that they rely on homologous neural mechanisms. (72)
Satterlie, Richard. The Search for Ancestral Nervous Systems: An Integrative and Comparative Approach. Journal of Experimental Biology. 218/4, 2015. A select article in an issue on the Evolution of the First Nervous Systems by a University of North Carolina marine biologist about the latest evidences of life’s insistence from its earliest phases on cerebral learning capabilities. See also Convergent Evolution of Neural Systems in Ctenophores by Leonid Moroz, and Evolution of Basal Deuterostome Nervous Systems by Linda Holland, Elements of a “Nervous System” in Sponges by Sally Leys, and Introductions by its editor Peter Anderson, the University of Florida marine bioscientist.
Even the most basal multicellular nervous systems are capable of producing complex behavioral acts that involve the integration and combination of simple responses, and decision-making when presented with conflicting stimuli. This requires an understanding beyond that available from genomic investigations, and calls for a integrative and comparative approach, where the power of genomic/transcriptomic techniques is coupled with morphological, physiological and developmental experimentation to identify common and species-specific nervous system properties for the development and elaboration of phylogenomic reconstructions. With careful selection of genes and gene products, we can continue to make significant progress in our search for ancestral nervous system organizations. (Abstract)
Savage-Rumbaugh, Sue, et al, eds. Apes, Language, and the Human Mind. New York: Oxford University Press, 1998. With regard to the sequential, complementary way brains evolved, its initial primate capacity is seen as a “wholistic intelligence” whence an entire scene is taken in all at once. Later hominids and human beings are characterized by a “hierarchical intelligence,” which is an analytical subset of the earlier global survey.
Schmidt-Rhaesa, Andreas, et al, eds. Structure and Evolution of Invertebrate Nervous Systems. Oxford: Oxford University Press, 2016. This 750 page, 55 chapter tome by European and international neuroscientists is a comprehensive, consummate survey of this research field, which, it is said, was not possible until now. Many entries about classes such as Tardigrada, Brachiopoda, Cnidaria, Rotifera, Nemertea, and Scorpiones are interspersed with Perspectives on Evolution of Neural Cell Types (Detlev Arendt), The First Brain, Neural Systems Development, Evolution of Neurogenesis in Arthropods (Angelika Stollewerk), and The Origin of Vertebrate Neural Organization. As one may peruse this reconstruction by Anthropo Sapiens of the many creatures far and near from which we came, as the quotes broach, a constant theme emerges. From the earliest, originally complex, rudiments arose radiating homologies of forms and senses, a recurrent convergence leading onto vertebrate species. In regard, an evolutionary developmental gestation, lately reaching our global phase able to achieve this knowledge is once again clearly evident, just as Darwin’s day intimated.
Inescapably, the stunning presence in basal metazoans of cellular modules that belong to diverse cell types in the complex bilaterians implies that these modules are distributed over relatively few, hence multifunctional cell types. This means that metazoan ancestors likewise possessed few complex cell types, including early neural cells. Thus, metazoan cell type diversification started from multifunctional cells. (19) The transition from a few cell types with multiple functions in early metazoans to many cell types with specialized functions in animals implies that, at least in many cases, cell type evolution involved a differential distribution of functions and modules among emergent sister cells. This process has been referred to as a “segregation of functions” or “division of labor.” (20)
Singer, Wolf. The Evolution of Culture from a Neurobiological Perspective. Levinson, Stephen and Pierre Jaisson, eds. Evolution and Culture. Cambridge: MIT Press, 2005. Advances in bipedal gait, labor-sharing societies, agriculture, and language, are accompanied by a ramification of brain size and anatomy. An expanded cerebral cortex by way of iterative, self-similar processes achieves a series of “metarepresentations” through symbolic communication and a sense of what others may think and know.
Smaers, Jeoroen, et al. The Evolution of Mammalian Brain Size. Science Advances. 7/18, 2021. Twenty two neuroresearchers from across the USA and onto Germany, the UK, Austria, Canada, Madagascar, South Africa and Australia provide a most comprehensive, quantified, graphic reconstruction of cerebral anatomies to date for this major animalia class. By view of its international occasion, one might consider the current advent of an emergent sapiensphere which is proceeding to learn how all manner of beings evolved and grew smarter on their way to this worldwise retrospect.
Relative brain size has long been considered as a measure of cognitive capacities. Yet, these views about brain size rely on untested assumptions that brain-body allometry is a stable scaling relationship across species. Using the largest fossil and extant dataset yet assembled, we find that shifts in allometric slope underpin major transitions in mammalian evolution and are often characterized by marked changes in body size. Our results reveal that the largest-brained mammals achieved their relative sizes by divergent paths. These findings prompt a reevaluation of the traditional paradigm and open new opportunities to improve our understanding of the genetic and developmental mechanisms that influence brain size. (Abstract excerpt)
Smith-Ferguson, Jules and Madeleine Beekman. Who Needs a Brain? Slime Moulds, Behavioural Ecology and Minimal Cognition. Adaptive Behavior. Online January, 2019. University of Sydney neurobiologists contribute to current realizations that an evolutionary continuum is evident from invertebrate rudiments all the way to complex animals. For example, familiar “cognitive” behaviors are found in insects (bees can count) and even for prokaryote bacterial colonies. As our Evolutionary Intelligence section conveys, this rising, cumulative acumen seems quite traces a central track. See also Van Duijn, Marc. Phylogenetic Origins of Biological Cognition: Convergent Patterns in the Early Evolution of Learning by Marc van Duijn in Interface Focus (7/3, 2017) for a similar perception.
Although human decision making seems complex, there is evidence that many decisions are grounded in simple heuristics. Such heuristic models of decision making are widespread in nature. To understand how and why different forms of information processing evolve, it is insightful to study the minimal requirements for cognition. Here, we explore the minimally cognitive behaviour of the acellular slime mould, Physarum polycephalum, in order to discuss the ecological pressures that lead to the development of information processing mechanisms. By highlighting a few examples of common mechanisms, we conclude that all organisms contain the building blocks for more complex information processing. Returning the debate about cognition to the biological basics demystifies some of the confusion around the term ‘cognition’. (Abstract)
Stevens, Charles. An Evolutionary Scaling Law for the Primate Visual System and Its Basis in Cortical Function. Nature. 411/193, 2001. Allometric, scale-free laws likewise hold for neural development.
The conservation of these scaling relations raises the possibility that a similar basis for the scaling laws exists for all cortical areas. In this view, each cortical area would be provided with a map of some sort - perhaps one with very abstract quantities - and the job of the cortex would be to extract some characteristic of the map at each point that would be represented as a location code by the neurons in each map ‘pixel.’….A 3/2 power relation would result. (195)
Strausfeld, Nicholas. Arthropod Brains: Evolution, Functional Elegance, and Historical Significance. Cambridge: Harvard University Press, 2012. Arthropods represent the broad, ancient genera of invertebrate insects, arachnids, crustaceans, and myriapods. The senior University of Arizona neurobiologist offers a popular exposition on their precursor neural circuitry and surprising cognitive acumen.
In The Descent of Man, Charles Darwin proposed that an ant’s brain, no larger than a pin’s head, must be sophisticated to accomplish all that it does. Yet today many people still find it surprising that insects and other arthropods show behaviors that are much more complex than innate reflexes. They are products of versatile brains which, in a sense, think. Fascinating in their own right, arthropods provide fundamental insights into how brains process and organize sensory information to produce learning, strategizing, cooperation, and sociality. Nicholas Strausfeld elucidates the evolution of this knowledge, beginning with nineteenth-century debates about how similar arthropod brains were to vertebrate brains. This exchange, he shows, had a profound and far-reaching impact on attitudes toward evolution and animal origins. Many renowned scientists, including Sigmund Freud, cut their professional teeth studying arthropod nervous systems. The greatest neuroanatomist of them all, Santiago Ramón y Cajal—founder of the neuron doctrine—was awed by similarities between insect and mammalian brains. (Publisher)
Striedter, Georg. Building Brains that can Evolve: Challenges and Prospects for Evo-Devo Neurobiology. Metode. Vol. 7/Pg. 9, 2017. The Modern Synthesis combined population genetics with comparative morphology but had little or no use for embryology. The UC Irvine neuroscientist and author (search) scopes out a synthesis of bodily and cerebral evolutionary development within a 2010s sense of recapitulation between individual ontogeny and species phylogeny.
Evo-devo biology involves cross-species comparisons of entire developmental trajectories, not just of adult forms. This approach has proven very successful in general morphology, but its application to neurobiological problems is still relatively new. To date, the most successful area of evo-devo neurobiology has been the use of comparative developmental data to clarify adult homologies. The most exciting future prospect is the use of comparative developmental data to understand the formation of species differences in adult structure and function. An interesting «model system» for this kind of research is the quest to understand why the neocortex folds in some species but not others. (Abstract)
Striedter, Georg. Principles of Brain Evolution. Sunderland, MA: Sinauer, 2005. A University of California at Irvine neuroscientist gathers and explains many advances of the last two decades about how brains evolved from invertebrates to humans. An example is to compare two previously optional paths by which brains grow in size – “concerted” whereby distinct modules evolve in concert and size with each other, and “mosaic” whence regions enlarge (or shrink) independently. Upon observation, both modes are variously in effect, depending on the species and its environment. Another aspect is a steady scaling of brain size with body weight through evolution for fish, reptiles, birds, mammals and primates, suggestive of a generally emergent trend. Human brains are special because our late arriving, relatively large neocortex allows us to reconstruct and reflect upon these phenomena.
Striedter, George, et al. NSF Workshop Report: Discovering General Principles of Nervous System Organization by Comparing Brain Maps across Species. Journal of Comparative Neuroscience. 522/1453, 2014. A 27 person team of senior neuroscientists including Barbara Finlay, Hans Hofmann, Erich Jarvis, and Todd Preuss, outline a National Science Foundation program to study the common cerebral anatomy and intellect that is being found to distinguish every creature and kingdom. By our collaborative retrospect, life’s evolutionary development of body and brain is ever again becoming apparent as an embryonic gestation.
A 27 person team of senior neuroscientists including Barbara Finlay, Hans Hofmann, Erich Jarvis, and Todd Preuss, outline a National Science Foundation program to study the common cerebral anatomy and intellect that is being found to distinguish every creature and kingdom. By our collaborative retrospect, life’s evolutionary development of body and brain is ever again becoming apparent as an embryonic gestation.