Veit suggests that the challenge of coordinating movement in multicellular organisms led to the evolution of a prioritizing value system, which rendered organisms complex enough to be sentient and drove the Cambrian explosion, while the absence of this evaluation system led to the demise of Ediacaran animals. In this commentary we criticize Veit’s terminology and evolutionary proposals, arguing that his terminology and evolutionary scenarios are problematic, and put forward alternative proposals. We suggest that sentience is a system property, and (...) that the evolution of sentience was the outcome of the evolution of open-ended associative learning, which included the coevolution of sensory, motor, memory, and value subsystems. We suggest that these coevolutionary system dynamics were a factor in the Cambrian explosion and contributed to the extinction of the Ediacaran biota. (shrink)

Paulin and Cahill‐Lane explore the origins of event processing and event prediction in animal evolution. They propose that the evolutionary benefit of being able to predict and thus to quickly react to anticipated events may have triggered the evolution of the earliest nervous systems.

In lieu of an abstract, here is a brief excerpt of the content:Reviewed by:Metazoa: Animal Life and the Birth of the Mind by Peter Godfrey-SmithMichael BrownMetazoa: Animal Life and the Birth of the Mind BY PETER GODFREY-SMITH New York: Farrar, Straus and Giroux, 2020Carrying forward the project he began in Other Minds (2016), Peter Godfrey-Smith aims in Metazoa (2020) to cast light on the problem of consciousness by inviting meditation on the minds of our distant deep-sea cousins. To elaborate on (...) the Nagelian question of what it’s like to be a bat, he asks what it is like to be a crab, a shrimp, or a cephalopod. One will not find here the dense and fine-grain argumentation that is characteristic of academic monographs, but instead a freer exploration of ideas ranging from marine biology, to philosophy of mind, to animal psychology. Godfrey-Smith’s more modest goal is not to argue definitively for a single viewpoint, but to acclimate the reader to the challenging conceptual-shift he calls gradualism—namely, “the idea that in evolution, minds and experience come slowly into view, rather than appearing in a single move” (262).In the place of a barrage of observational data or dense philosophical argumentation, Godfrey-Smith paints a rich picture of the underwater environment, describes his personal interactions with the creatures that live there, and invites the reader to reflect on their activities and the cognition behind them. In this capacity, he walks a fine line—not anthropomorphizing the creatures, but presenting their actions as mentally agnostic as possible—to let the reader consider how much mental unity there might be, or how much self-or other-awareness may or may [End Page 130] not be present behind the beady mollusk eyes. Nevertheless, he strives to acquaint us with creatures we otherwise might not engage with. The several drawings of the animals and settings Godfrey-Smith discusses throughout the book aid this goal, as well as eight pages of vibrant photographs featuring several of the book’s “characters.”Because minds are things formed over time, Godfrey-Smith takes us through the first fossil evidence of animals in the Ediacaran, the appearance of shrimp-like ancestors in the Cambrian, the vast increase in size of the Ordovician, and the appearance of the octopus and dinosaurs of the Mesozoic. Yet, minds also develop under pressure and conditions of their environment, so Godfrey-Smith takes us on his dives to consider what environmental conditions led to the development of these submarine minds. As such, the text inventively winds its way across dimensions of space, time, and a variety of academic disciplines.In advancing the gradualist thesis, Godfrey-Smith entertains the Aristotelian notion of continuity between life and mind, as opposed to Descartes’ firm dualism. In this way, as noted in chapter 2, when a cell establishes its boundaries and controls the traffic of ions in and out, it becomes a kind of self. This leads him to a discussion of the glass sponge, multicellular but structurally simple, and yet a “collector and curator of biological light,” referring to its ability to channel light like a fiber optic cable (47). Chapter 3 considers the cnidarians—corals, in particular—in which the first signs of animal action appear. This action, like grasping, requires the appearance of a nervous system, and this increased complexity seems to give rise to agency, and more particularly, subjecthood. Chapter 4 invites us to consider the crab to guide reflections on early animal sensation. Of particular interest to this investigation are signs of feeling pain, such as the release of painkillers and the tending of wounds. Surprisingly, scientists find such behavior in shrimp. Chapter 5 returns to more philosophical considerations, attempting to stitch up false dichotomies of self-awareness and other-awareness, and activity and passivity, to name a couple. This sets the stage for chapter 6’s examination of the mysterious mix of mental unity and disunity in the octopus. With a decentralized nervous system, each arm seems to have a mind of its own, yet the creature nevertheless acts to unified purposes. Godfrey-Smith considers the resemblance to split-brain cases in humans, and the copresence of unified and disunified experience in... (shrink)

Eric Davidson had a deep and abiding interest in the role developmental mechanisms played in generating evolutionary patterns documented in deep time, from the origin of the euechinoids to the processes responsible for the morphological architectures of major animal clades. Although not an evolutionary biologist, Davidson’s interests long preceded the current excitement over comparative evolutionary developmental biology. Here I discuss three aspects at the intersection between his research and evolutionary patterns in deep time: First, understanding the mechanisms of body plan (...) formation, particularly those associated with the early diversification of major metazoan clades. Second, a critique of early claims about ancestral metazoans based on the discoveries of highly conserved genes across bilaterian animals. Third, Davidson’s own involvement in paleontology through a collaborative study of the fossil embryos from the Ediacaran Doushantuo Formation in south China. (shrink)

The article is an ethnographic travelogue of time spent in Oman in 2018 with the Ediacaran subcommission. This is a collective of Earth scientists who globe-trot in search of particular rocks that might be reliable markers for subdividing the long stretch of the Ediacaran period (which lasted ninety-four million years) into intervals that mark global transformations in Earth history. To do so, these scientists are reliant upon the amenability of Petroleum Development Oman, which Omanis credit with ushering Oman (...) into “modernity.” In recent years, critical theorists, cultural historians, and science-and-technology-studies (STS) scholars have argued for the necessity of forging new ways to tell stories that can scale between planetary history and the more familiar scales of human political action. In this article, I do not suggest that geological thinking is the right way to periodize sociopolitical or cultural history. Rather, I intend it as a provocation for us to recognize that periodization—and in particular the work required to nominate periods of duration and succession, unconformity and break—is a theory already built into the world, one which has disseminated across it to correlate time to place unevenly. As such, stratigraphy functions doubly in this article. First, stratigraphy is an object of inquiry: I address where geological timescales come from, and how stratigraphers calibrate eras, epochs, and periods dividing planetary history. Second, it is also an analytic with which I interrogate how thinking stratigraphically might inform how we, as critical theorists, historians, and the like, might think about those problems of periodization. (shrink)