Macphail’s ‘null hypothesis’, that there are no differences in intelligence, qualitative or quantitative, between non-human vertebrates has been controversial. This controversy can be useful if it encourages interest in acquiring a detailed understanding of how non-human animals express flexible problem-solving capacity (‘intelligence’), but limiting the discussion to vertebrates is too arbitrary. As an example, we focus here on Portia, a spider with an especially intricate predatory strategy and a preference for other spiders as prey. We review research on pre-planned detours, (...) expectancy violation and a capacity to solve confinement problems where, in each of these three contexts, there is experimental evidence of innate cognitive capacities and reliance on internal representation. These cognitive capacities are related to, but not identical to, intelligence. When discussing intelligence, as when discussing cognition, it is more useful to envisage a continuum instead of something that is simply present or not; in other words, a continuum pertaining to flexible problem-solving capacity for ‘intelligence’ and a continuum pertaining to reliance on internal representation for ‘cognition’. When envisaging a continuum pertaining to intelligence, Daniel Dennett’s notion of four Creatures (Darwinian, Skinnerian, Popperian, Gregorian) is of interest, with the distinction between Skinnerian and Popperian Creatures being especially relevant when considering Portia. When we consider these distinctions, a case can be made for Portia being a Popperian Creature. Like Skinnerian Creatures, Popperian Creatures express flexible problem solving capacity, but the manner in which this capacity is expressed by Popperian Creatures is more distinctively cognitive. (shrink)

Testing of candidate biological control agents to estimate their likely field host ranges in the area of release has been part of weed biological control for several decades, with evolving techniques and goals. Similar efforts have been made less often for parasitoids and predators being introduced for arthropod biological control. Here, we review both techniques of host range testing and social objectives of such screening. We ask whether agents introduced for arthropod biological control should be subjected to host range testing (...) before release, and if so, are methods used for estimating host ranges of herbivorous arthropods appropriate, or are different approaches needed. Current examples in which host range testing has been employed for arthropod biological control are reviewed. We conclude with recommendations concerning guiding principles about use of host range testing. We recommend modest expansion of host range testing for arthropod biological control for projects on continents. We recommend more extensive testing for projects of introduction onto islands. We note that introductions to islands could provide opportunities to gain experience in use of host range estimation for this class of organisms and to conduct post release evaluations of host ranges. We urge caution in efforts to mandate host range testing but simultaneously recommend consultation between biological control workers and insect conservationists. (shrink)

The fruit fly, Drosophila melanogaster, patterns its segments rapidly and simultaneously, via a mechanism that relies on the ability of transcription factors to diffuse between blastoderm nuclei. Ancestral arthropods patterned posterior segments sequentially in a cellular environment, where free diffusion was likely to have been inhibited by the presence of cell membranes. Understanding how the Drosophila paradigm evolved is a problem that has interested evolutionary developmental biologists for some time. In this article, I review what is known about arthropod (...) segmentation mechanisms, and present a model for the evolution of the Drosophila paradigm. The model predicts that the primary pair‐rule genes of Drosophila ancestrally functioned within and/or downstream of a Notch‐dependent segmentation clock, their striped expression gradually coming under the control of gap genes as the number of segments patterned simultaneously in the anterior increased and the number patterned sequentially via a segmentation clock mechanism in the posterior correspondingly decreased. BioEssays 26:1108–1116, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

I review how both the parasegmental and segmental frames are used in constructing the body plan of the arthropods. The parasegment is the primary genetic unit, as shown by Hox gene expression, and the parasegmental design is maintained in the nerve cord. It is, however, not maintained in the epidermis, where the cuticle grooves are segmental, and in the musculature, which is segmental in organisation. This frame shift is reflected in the sensory and motor nerve connections between the ganglia (...) and the periphery. I suggest that the need for movement in an organism equipped with a hard exoskeleton was the functional constraint that shaped this apparently complex mode of development. BioEssays 26:1117–1125, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Insect and crustacean lineages diverged over 500 Myr ago, and there are continuing uncertaintles about whether they evolved from a common arthropod ancestor or, alternatively, they evolved independently from annelid worms. Despite the diversity of their limbs and lifestyles, the nervous systems of insects and crustaeeans share many common features both in development and in function. Cellular and molecular embryology techniques reveal good evidence for homologies in the developing segmental ganglia. In the visual system, this seemingly common programme of insect (...) and crustacean CNS development culminates in common adult neural function. Comparisons of the cellular anatomy and physiology of animals as diverse as flies and crayfishes indicate that the neural circuits in the lamina of their optic lobe have been inherited largely unchanged from a common ancestor with good compound eyes. (shrink)

Deep‐level arthropod phylogeny has been in a state of upheaval ever since the emergence of molecular tree reconstruction approaches. While a consensus has settled in that hexapods are more closely related to crustaceans than to myriapods, the phylogenetic position of the latter has remained a matter of debate. Mitochondrial, nuclear, and genome‐scale studies have proposed rejecting the long‐standing superclade Mandibulata, which unites myriapods with insects and crustaceans, in favor of a clade that unites myriapods with chelicerates and has become known (...) as Paradoxapoda or Myriochelata. Here we discuss the progress, problems, and prospects of arriving at the final arthropod tree. (shrink)

—Commentary on Mikhalevich and Powell on invertebrate minds.— Whether or not arthropods are sentient, they can have moral standing. Appeals to sentience are not necessary and retard progress in human treatment of other species, including invertebrates. Other increasingly well-documented aspects of invertebrate minds are pertinent to their welfare. Even if arthropods are not sentient, they can be agents whose goals—and therefore interests—can be frustrated. This kind of agency is sufficient for moral status and requires that we consider their (...) welfare. (shrink)

The conditions are outlined under which the body construction of annelids could have been transformed into that of arthropods. As an adaptation to a vagile life and an uptake of food by filtering particles from the sediment, the body was more and more flattened. Thus lateral protrusions, the subsequent pleurotergites, developed, and the parapodia were shifted to a more ventral position and could differentiate into the branched limbs typical for arthropods. This is the condition under which parts of (...) the body wall were kept immobile, so that they could become sclerotized in the form of rigid plates. (shrink)

Large numbers of cells with unique neuronal specificity are generated during development of the central nervous system of animals. Here we discuss the events that generate cell diversity during early development of the ventral nerve cord of different arthropod groups. Neural precursors are generated in a spatial array in the epithelium of each hemisegment over a period of time. Spatial cues within the epithelium are thought to evolve as embryogenesis proceeds. This spatiotemporal information might generate diversity among the neural precursors (...) in all arthropod groups, although the mechanisms regulating the positioning of individual precursors have diverged. However, distinct strategies for the generation of neuronal diversity have evolved in the different arthropod lineages that appear to correlate with specific modes of ontogenesis. We hypothesize that an evolutionary trend towards reduced cell numbers and possibly rapid embryogenesis in insects has culminated in the appearance of stereotyped neuroblast lineages. BioEssays 27:874–883, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Preservation permitting patterns of developmental evolution can be reconstructed within long extinct clades, and the rich fossil record of trilobite ontogeny and phylogeny provides an unparalleled opportunity for doing so. Furthermore, knowledge of Hox gene expression patterns among living arthropods permit inferences about possible Hox gene deployment in trilobites. The trilobite anteroposterior body plan is consistent with recent suggestions that basal euarthropods had a relatively low degree of tagmosis among cephalic limbs, possibly related to overlapping expression domains of cephalic (...) Hox genes. Trilobite trunk segments appeared sequentially at a subterminal generative zone, and were exchanged between regions of fused and freely articulating segments during growth. Homonomous trunk segment shape and gradual size transition were apparently phylogenetically basal conditions and suggest a single trunk tagma. Several derived clades independently evolved functionally distinct tagmata within the trunk, apparently exchanging flexible segment numbers for greater regionally autonomy. The trilobite trunk chronicles how different aspects of arthropod segmentation coevolved as the degree of tagmosis increased. BioEssays 25:386–395, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

It is presumed that the evolution of morphological diversity in animals and plants is driven by changes in the developmental processes that govern morphology, hence basically by changes in the function and/or expression of a defined set of genes that control these processes. A large body of evidence has suggested that changes in developmental gene regulation are the predominant mechanisms that sustain morphological evolution, being much more important than the evolution of the primary sequences and functions of proteins. Recent reports1, (...) 2 challenge this idea by highlighting functional evolution of Hox proteins during the evolutionary history of arthropods. BioEssays 24:775–779, 2002. © 2002 Wiley Periodicals, Inc. (shrink)

We present behavioral lateralizations of spiders and ants and their probable survival value. They clearly conform to the vertebrate lateralizations reviewed by Vallortigara & Rogers and to earlier arthropod studies. We suggest two complementary reviews: differences in lesion susceptibility and muscle strength between left and right body side, and perceptual biases and predator inspection in invertebrates.

Aggregation is one of the most widespread phenomena in animal groups and often represents a collective dynamic response to environmental conditions. In social species the underlying mechanisms mostly obey self-organized principles. This phenomenon constitutes a powerful model to decouple purely social components from ecological factors. Here we used a model of cockroach aggregation to address the problems of sensitivity of collective patterns and control of aggregation dynamics. The individual behavioural rules and the emergent collective patterns were previously quantified and modelled (...) by Jeanson et al.. We first present the diverse spatio-temporal patterns of a derived model in response to parameter changes, either involving social or non-social interactions. This sensitivity analysis is then extended to evaluate the evolution of these patterns in mixed societies of sub-populations with different behavioural parameters. Simple linear or highly non-linear collective responses emerge. We discuss their potential application to control animal populations by infiltration of biomimetic autonomous robots that mimic cockroach behaviour. We suggest that detailed behavioural models are a prerequisite to do so. (shrink)

A 365 million year‐old trilobite moult‐carcass assemblage was described by Błażejowski et al. (2015) as the oldest direct evidence of moulting in the arthropod fossil record. Unfortunately, their suppositions are insufficiently supported by the data provided. Instead, the morphology, configuration and preservational context of the highly fossiliferous locality (Kowala Quarry, Poland) suggest that the specimen consists of two overlapping, queued carcasses. The wider fossil record of moulting actually extends back 520 million years, providing an unparalleled opportunity to study behaviour, ecology (...) and development in early animals. Taking cues from modern analogues, it is possible to quantify precise details about moulting behaviour to determine broad‐scale evolutionary trends, ontogenetic sequences and morphological selection pressures. In this review, we argue that this rich source of data has been underused in evolutionary studies, though has great potential for investigating the life history and evolution of arthropods in deep time. (shrink)

The discovery of traces of a blood meal in the abdomen of a 50‐million‐year‐old mosquito reminds us of the insights that the chemistry of fossils can provide. Ancient DNA is the best known fossil molecule. It is less well known that new fossil targets and a growing database of ancient gene sequences are paralleled by discoveries on other classes of organic molecules. New analytical tools, such as the synchrotron, reveal traces of the original composition of arthropod cuticles that are more (...) than 400 my old. Pigments such as melanin are readily fossilized, surviving virtually unaltered for ∼200 my. Other biomarkers provide evidence of microbial processes in ancient sediments, and have been used to reveal the presence of demosponges, for example, more than 635 mya, long before their spicules appear in the fossil record. Ancient biomolecules are a powerful complement to fossil remains in revealing the history of life. (shrink)

In order to develop a true biological science of consciousness, we have to remove humans from the center of reference and develop a bottom-up comparative study of animal minds, as Donald Griffin intended with his call for a “cognitive ethology.” In this article, I make use of the pathological complexity thesis (Veit 2022a, b, c ) to show that we can firmly ground a comparative study of animal consciousness by drawing on the resources of state-based behavioral life history theory. By (...) comparing the different life histories of gastropods and arthropods, we will be able to make better sense of the possible origins of consciousness and its function for organisms in their natural environments. (shrink)

How consciousness appeared much earlier in evolutionary history than is commonly assumed, and why all vertebrates and perhaps even some invertebrates are conscious. How is consciousness created? When did it first appear on Earth, and how did it evolve? What constitutes consciousness, and which animals can be said to be sentient? In this book, Todd Feinberg and Jon Mallatt draw on recent scientific findings to answer these questions—and to tackle the most fundamental question about the nature of consciousness: how does (...) the material brain create subjective experience? After assembling a list of the biological and neurobiological features that seem responsible for consciousness, and considering the fossil record of evolution, Feinberg and Mallatt argue that consciousness appeared much earlier in evolutionary history than is commonly assumed. About 520 to 560 million years ago, they explain, the great “Cambrian explosion” of animal diversity produced the first complex brains, which were accompanied by the first appearance of consciousness; simple reflexive behaviors evolved into a unified inner world of subjective experiences. From this they deduce that all vertebrates are and have always been conscious—not just humans and other mammals, but also every fish, reptile, amphibian, and bird. Considering invertebrates, they find that arthropods (including insects and probably crustaceans) and cephalopods (including the octopus) meet many of the criteria for consciousness. The obvious and conventional wisdom–shattering implication is that consciousness evolved simultaneously but independently in the first vertebrates and possibly arthropods more than half a billion years ago. Combining evolutionary, neurobiological, and philosophical approaches allows Feinberg and Mallatt to offer an original solution to the “hard problem” of consciousness. (shrink)

What are the earliest beings that have minds in evolutionary order? Two marks of mind are consciousness and representation. I focus on representation. I distinguish a psychologically distinctive notion of representation from a family of notions, often called ‘representation’, that invoke information, causation, and/or function. The psychologically distinctive notion implies that a representational state has veridicality conditions as an aspect of its nature. Perception is the most primitive type of representational state. It is a natural psychological kind, recognized in a (...) mature science: perceptual psychology. This kind involves a type of objectification, and is marked by perceptual constancies. The simplest animals known to exhibit perceptual constancies, perception, and representation in a distinctively psychological sense, are certain arthropods. Representational mind, or representational psychology, begins in the arthropods. We lack scientific knowledge about the beginnings of consciousness. Consciousness is neither necessary nor sufficient for perception. I conclude by reflecting on the kinds mind and psychology. (shrink)

Invertebrate animals are frequently lumped into a single category and denied welfare protections despite their considerable cognitive, behavioral, and evolutionary diversity. Some ethical and policy inroads have been made for cephalopod molluscs and crustaceans, but the vast majority of arthropods, including the insects, remain excluded from moral consideration. We argue that this exclusion is unwarranted given the existing evidence. Anachronistic readings of evolution, which view invertebrates as lower in the scala naturae, continue to influence public policy and common morality. (...) The assumption that small brains are unlikely to support cognition or sentience likewise persists, despite growing evidence that arthropods have converged on cognitive functions comparable to those found in vertebrates. The exclusion of invertebrates is also motivated by cognitive-affective biases that covertly influence moral judgment, as well as a flawed balancing of scientific uncertainty against moral risk. All these factors shape moral attitudes toward basal vertebrates too, but they are particularly acute in the arthropod context. Moral consistency dictates that the same standards of evidence and risk management that justify policy protections for vertebrates also support extending moral consideration to certain invertebrates. Moving beyond a vertebrate-centered conception of welfare can also clarify foundational moral concepts in their own right. (shrink)

Regeneration in arthropods and amphibians follows an analogous principle making comparisons between the two phyla possible.Larval arthropods and amphibians possess powers of epimorphic regeneration which wane for many species of these phyla with the completion of metamorphosis or the cessation of moulting. In those species which retain, post-maturationally, the ability to form a regenerative blastema, larval characteristics are carried into the adult and reproductive stages of these organisms. These include many species of: urodeles, ametabolous insects, crustaceans, myriapods and (...) arachnids. The long-standing distinction between embryonic regulation and true epimorphosis would thus appear to be a difference of degree rather than kind. (shrink)

In this paper I explore the value of invertebrates to human society. I initially examine various ecological, utilitarian, scientific, and cultural benefits provided by invertebrate organisms. I then explore the extent of appreciation and understanding of these values among the American public. This assessment was based on a study of residents of the state of Connecticut, including randomly selected members of the general public, farmers, conservation organization members, and scientists. The general public and farmers were found to view most invertebrates (...) with aversion, anxiety, fear, avoidance, and ignorance. Far more positive and knowledgeable attitudes toward invertebrates and their conservation were observed among scientists and, to a lesser extent, among conservation organization members. I finally examine the motivational basis for hostile attitudes toward invertebrates, particularly arthropods, among the general public. Important factors include the possibility of an innate learning disposition, the association of many invertebrates with disease and agricultural damage, differences in ecological scale between humans and invertebrates, the multiplicity of invertebrates, the apparent lack of a sense of identity and consciousness among invertebrates, the presumption of mindlessness among invertebrates, and the radical autonomy of invertebrates from human control. (shrink)

In their target article, Mikhalevich & Powell (M&P) argue that we should extend moral protection to arthropods. In this commentary, we show that there are some unforeseen obstacles to applying the sort of individualistic welfare-based ethics that M&P have in mind to certain arthropods, namely, insects. These obstacles have to do with the fact that there are often many more individuals involved in our dealings with insects than our ethical theories anticipate, and also with the fact that, in (...) some sense, some insects count as more than an individual and, in another sense, they sometimes count as less than an individual. (shrink)

One of the most remarkable recent findings in developmental biology has been the colinear and homologous relationships shared between the Drosophila HOM‐C and vertebrate Hox homeobox gene complexes. These relationships pose the question of the functional significance of colinearity and its molecular basis. While there was much initial resistance to the validity of this comparison, it now appears the Hox/HOM homology reflects a broad degree of evolutionary conservation which has reawakened interest in comparative embryology and evolution.The evolutionary conservation of protein (...) motifs in many gene families (including those for growth factors, secreted and membrane bound signalling factors, adhesion molecules, cytoplasmic receptor kinases, nuclear receptors and transcription factors) has lead to speculation on the extent to which these homology relationships represent common developmental processes and underlying molecular mechanisms. Structural identities in a protein may indicate the biochemical/molecular function that a protein plays in cellular and developmental processes, without reflecting a conserved role in a cascade of developmental events. However, the analysis of genes encoding transcription factors has provided evidence suggesting that there are gene complexes in arthropods and vertebrates which are true homologues and which may share common roles in the specification of regional identity along embryonic A‐P axis. These genes comprise the Box/HOM‐C homeotic complexes. This review will detail some of the evidence for this proposed relationship and will speculate on the functional implications. (shrink)

While life in general can be explained by the mechanisms of physics, chemistry and biology, to many scientists and philosophers it appears that when it comes to explaining consciousness, there is what the philosopher Joseph Levine called an “explanatory gap” between the physical brain and subjective experiences. Here we deduce the living and neural features behind primary consciousness within a naturalistic biological framework, identify which animal taxa have these features (the vertebrates, arthropods, and cephalopod molluscs), then reconstruct when consciousness (...) first evolved and consider its adaptive value. We theorize that consciousness is based on all the complex system features of life, plus the even more complex features of elaborate brains. We argue that the main reason why the explanatory gap between the brain and experience has been so refractory to scientific explanation is that it arises from both life and from varied and diverse brains and brain regions, so bridging the gap requires a complex, multifactorial account that includes the great diversity of consciousness, its personal nature that stems from embodied life, and the special neural features that make consciousness unique in nature. (shrink)

Drawing from a four-year study of US science institutions that support biological control of arthropods, this article examines the decline in biological control institutional capacity in California within the context of both declining public interest science and declining agricultural research activism. After explaining how debates over the public interest character of biological control science have shaped institutions in California, we use scientometric methods to assess the present status and trends in biological control programs within both the University of California (...) Land Grant System and the California Department of Food and Agriculture. We present available data on the number of scientific positions and the types of positions to discuss the impact on the amount of public interest research on biological control in California. We use sociograms to depict how biological control science networks have been reconfigured over time. Our quantitative and qualitative analyses indicate that the following factors contributed to the decline of biological control science in California over the 45-year period analyzed: (1) the institutional reconfiguration of university research priorities; (2) the fraying networks within and increasing specialization of biological control science; (3) the transformation of the social organization of the life science work, including privatization; and (4) the abandonment of this thematic area by civil society activist groups. This broad array of forces suggests that biological control, as a public interest science, will require a deliberate intervention, based on advocacy of clear public interest criteria. (shrink)

Considerable variation exists not only in the kinds of transposable elements (TEs) occurring within the genomes of different species, but also in their abundance and distribution. Noting a similarity to the assortment of organisms among ecosystems, some researchers have called for an ecological approach to the study of transposon dynamics. However, there are several ways to adopt such an approach, and it is sometimes unclear what an ecological perspective will add to the existing co-evolutionary framework for explaining transposon-host interactions. This (...) review aims to clarify the conceptual foundations of transposon ecology in order to evaluate its explanatory prospects. We begin by identifying three unanswered questions regarding the abundance and distribution of TEs that potentially call for an ecological explanation. We then offer an operational distinction between evolutionary and ecological approaches to these questions. By determining the amount of variance in transposon abundance and distribution that is explained by ecological and evolutionary factors, respectively, it is possible empirically to assess the prospects for each of these explanatory frameworks. To illustrate how this methodology applies to a concrete example, we analyzed whole-genome data for one set of distantly related mammals and another more closely related group of arthropods. Our expectation was that ecological factors are most informative for explaining differences among individual TE lineages, rather than TE families, and for explaining their distribution among closely related as opposed to distantly related host genomes. We found that, in these data sets, ecological factors do in fact explain most of the variation in TE abundance and distribution among TE lineages across less distantly related host organisms. Evolutionary factors were not significant at these levels. However, the explanatory roles of evolution and ecology become inverted at the level of TE families or among more distantly related genomes. Not only does this example demonstrate the utility of our distinction between ecological and evolutionary perspectives, it further suggests an appropriate explanatory domain for the burgeoning discipline of transposon ecology. The fact that ecological processes appear to be impacting TE lineages over relatively short time scales further raises the possibility that transposons might serve as useful model systems for testing more general hypotheses in ecology. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:A Far-Future Paleontology: The Baffling Case of Brunaspis enigmaticaAnne-Sophie Milon (bio) and Jan Zalasiewicz (bio)Paleontologists, for more than two centuries, have studied and debated the petrified remains of plants and animals that have evolved over the past three billion years on Earth. They have argued over the grand concepts that they reveal, such as biological evolution and climate change, and also the many specific questions thrown up by these (...) relics: was such-and-such a shell, a mollusk, or an arthropod? Did this fossil fish live high up in the water, among the plankton, or grub in the mud on the sea floor?These studies have for many paleontologists been a blessedly human-free zone, detached from the busy realities of our everyday lives. The science of paleontology, though, is simply one obscure part of a burgeoning and rapidly evolving technosphere that underpins our lives, and that is now evolving millions of new kinds of fossils—technofossils—far more rapidly than ever happened in biological evolution. Many of these objects will, quite certainly, become part of Earth’s future fossil record.If such an endeavor as paleontology were ever to arise again, in a distant post-human future, how would its practitioners deal with these bizarre relics?We provide a preview, on the following pages, of just one such enigma, and how it may be resolved (or not) by our puzzled disciplinary descendants. [End Page 31] Click for larger view View full resolution[End Page 32] Click for larger view View full resolution[End Page 33] Click for larger view View full resolution[End Page 34] Click for larger view View full resolution[End Page 35] Click for larger view View full resolution[End Page 36] Click for larger view View full resolution[End Page 37] Click for larger view View full resolution[End Page 38] Click for larger view View full resolution[End Page 39] Click for larger view View full resolution[End Page 40] Click for larger view View full resolution[End Page 41] Click for larger view View full resolution[End Page 42] Click for larger view View full resolution[End Page 43] Click for larger view View full resolution[End Page 44]Anne-Sophie Milon Anne-Sophie Milon is an artist-researcher who applies her illustration skills (HEAR, Strasbourg, France, 2010) and 2D traditional animation (UWE, Bristol, UK, 2012) to political arts (SPEAP, Sciences Po, 2015) and science and technology studies (HSTS, EHESS, 2022). For the past ten years, she has translated geological narratives–and ordinary ones for Earth sciences–into extraordinary plots for the uninitiated, including the humanities. She is currently working with Jan Zalasiewicz on a play, The Petrified Museum (2024), based on the British Geological Survey (Keyworth, UK), and on a PhD project in science and technology studies looking at limestones’ agencies in extractive industry practices (2025). She regularly collaborates with researchers from the Anthropocene Working Group: The Cosmic Oasis (Oxford University Press, 2022), “The Victims of Carbon Dioxide are Starting to Appear” in Feral Atlas (2021), and The Epochs of Nature (University of Chicago Press, 2016).Jan Zalasiewicz Jan Zalasiewicz is Emeritus Professor of Paleobiology at the University of Leicester. He was formerly a field geologist and paleontologist with the British Geological Survey, involved in the geological mapping of eastern England and central Wales. His interests include Early Paleozoic fossils, notably the graptolites (a kind of extinct zooplankton), mud and mudrocks, the Quaternary Ice Ages, the nature of geological time, and the geology made by humans. In recent years, he has helped develop the concept of an Anthropocene epoch. He enjoys writing popular science articles and books, and being involved in art/science projects.Copyright © 2023 Johns Hopkins University Press and SubStance, Inc... (shrink)

Every living entity requires the capacity to defend against viruses in some form. From bacteria to plants to arthropods, cells retain the capacity to capture genetic material, process it in a variety of ways, and subsequently use it to generate pathogen-specific small RNAs. These small RNAs can then be used to provide specificity to an otherwise non-specific nuclease, generating a potent antiviral system. While small RNA-based defenses in chordates are less utilized, the protein-based antiviral invention in this phylum appears (...) to have derived from components of the same ancestral small RNA machinery. Based on recent evidence, it would seem that RNase III nucleases have been reiteratively repurposed over billions of years to provide cells with the capacity to recognize and destroy unwanted genetic material. Here we describe an overview of what is known on this subject and provide a model for how these defenses may have evolved. RNase III nuclease domains are widely used in an array of RNA metabolic functions as well as antiviral defenses. Here, we review their current usage as well as provide insight into how these domains may have shaped all major antiviral pathways over the course of evolution. (shrink)

One of the most fundamental features of the body plan of arthropods is its segmental design. There is considerable variation in segment number among arthropod groups (about 20‐fold); yet, paradoxically, the vast majority of arthropod species have a fixed number of segments, thus providing no variation in this character for natural selection to act upon. However, the 1000‐species‐strong centipede order Geophilomorpha provides an exception to the general rule of intraspecific invariance in segment number. Members of this group, and especially (...) our favourite animal Strigamia maritima, may thus help us to understand the evolution of segment number in arthropods. Evolution must act by modifying the formation of segments during embryogenesis. So, how this developmental process operates, in a variable‐segment‐number species, is of considerable interest. Strigamia maritima turns out to be a tractable system both at the ecological level of investigating differences in mean segment number between populations and at the molecular level of studying the expression patterns of developmental genes. Here we report the current state of play in our work on this fascinating animal, including our recent finding of a double‐segment periodicity in the expression of two Strigamia segmentation genes, and its possible implications for our understanding of arthropod segmentation mechanisms in general. BioEssays 27:653–660, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Although in Drosophila pair‐rule genes play crucial roles in the genetic hierarchy that subdivides the embryo into segments, the extent to which pair‐rule patterning is utilized by different arthropods and other segmented phyla is unknown. Recent data of Dearden et al.1 and Henry et al.,2 however, hint that a pair‐rule mechanism might play a role in the segmentation process of basal arthropods and vertebrates. BioEssays 25:425–429, 2003. © 2003 Wiley Periodicals, Inc.

The permutation of basic atoms—nitrogen, hydrogen, oxygen, carbon and phosphorus―into the biomolecules DNA and RNA, subsequently evolved in cells and brains, defining the origin of life and intelligence, remains unexplained. Equally the origin of the genetic information and the intertwined nature of ‘hardware’ and ‘software’ involved in the evolution of bio-molecules and the cells are shrouded in mystery. This treatise aims at exploring individual and swarm behaviour patterns which potentially hint at as yet unknown biological principles. It reviews theories of (...) evolution with perspectives from the earth sciences, commencing with the earliest observed records of life. This is followed by reviews and discussion of the building blocks of life, marine and terrestrial communities, the arthropods, birds and finally humans. It is suggested that, further to the mutation/natural selection processes established by Darwin and Wallace, an understanding of the evolution of intelligence remains little understood. A directionality of evolutionary trajectories is evident, not least the purposeful thinking process of humans as well as animals. It is not clear how directional intelligence, manifested for example by the collective intelligence of arthropod colonies, has evolved from mutation/natural selection processes. Potential clues for the understanding of life and evolution are provided by Aristotle’s dictum of “the whole being greater than the sum of the parts”, Niels Bohr’s principle of quantum complementarity and George Ellis’ theory of top-down causality. Inherent in the question of the origin of life is an anthropocentric bias, related to the self-referential Anthropic Principle and theological paradigms of man’s supposed dominion over all other species. The Anthropic Principle, however, should be capable of being circumvented using the scientific falsification method, assuming universal verified constants of physics. The phenomenon of the human mastery of fire and the splitting of the atom, leading to the seventh major mass extinction of species, remains incomprehensible. (shrink)

In vertebrates, members of the cysteine‐rich protein (CRP) family are characterized by the presence of two LIM domains linked to short glycine‐rich repeats. These proteins mediate protein–protein interactions and are of fundamental importance for cell differentiation, cytoskeletal remodeling, and transcriptional regulation. To date, a vast amount of information about vertebrate CRPs has become available, including their biological functions, interacting partners, and three‐dimensional structures. Compatible with a molecular adapter role, structural data reveal that the LIM domains within these proteins represent completely (...) independent folded units bridged by flexible linker regions. The physiological roles for individual CRPs was determined by targeted gene disruption analysis and by identification of common and specific binding partners by means of yeast and mammalian two‐hybrid screens. Several CRP‐like LIM domain proteins with close structural and sequence similarity were identified in arthropods, protozoas and plants, supporting the notion that this subset of LIM domain proteins has been highly conserved over the span of evolution thereby emphasizing the importance of their function. BioEssays 25:152–162, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

We have structured our response according to five questions arising from the commentaries: (i) What is sentience? (ii) Is sentience a necessary or sufficient condition for moral standing? (iii) What methods should guide comparative cognitive research in general, and specifically in studying invertebrates? (iv) How should we balance scientific uncertainty and moral risk? (v) What practical strategies can help reduce biases and morally dismissive attitudes toward invertebrates?

Facultative bacterial endosymbionts can transfer horizontally among lineages of their arthropod hosts, providing the recipient with a suite of traits that can lead to rapid evolutionary response, as has been recently demonstrated. But how common is symbiont‐driven evolution? Evidence suggests that successful symbiont transfers are most likely within a species or among closely related species, although more distant transfers have occurred over evolutionary history. Symbiont‐driven evolution need not be a function of a recent horizontal transfer, however. Many endosymbionts infect only (...) a small proportion of a host population, but could quickly increase in frequency under favorable selection regimes. Some host species appear to accumulate a diversity of facultative endosymbionts, and it is among these species that symbiont‐driven evolution should be most prevalent. It remains to be determined how frequently symbionts enable rapid evolutionary response by their hosts, but substantial ecological effects are a likely consequence whenever it does occur. (shrink)

The appendages of the adult fruit fly and other insects and Arthropods develop from secondary embryonic fields that form after the primary anterior/posterior and dorsal/ventral axes of the embryo have been determined. In Drosophila, the position and fate of the different fields formed within each segment are determined by genes acting along both embryonic axes, within individual segments, and within specific fields. Since the major architectural differences between most Arthropod classes and orders involve variations in the number, type and (...) morphology of body appendages, the elucidation of the embryology and molecular genetics of the origin and patterning of insect limb fields may help to facilitate an understanding of both the mechanism of appendage formation and some of the major steps in the morphological evolution of the Arthropods. In this review, we will discuss recent studies that have advanced our understanding of both the origin and patterning of Drosophila leg and wing secondary fields. These results provide fresh insights into potentially general mechanisms of how body parts develop and evolve. (shrink)

The vertebrate retina is said to be inverted because the photoreceptors are oriented in the posterior direction and are thus unable to maximize photodetection under conditions of low illumination. The tapetum lucidum is a photoreflective structure located posterior to the photoreceptors in the eyes of some fish and terrestrial animals. The tapetum reflects light forward, giving incident photons a “second chance” to collide with a photoreceptor, substantially enhancing retinal photosensitivity in dim light. Across vertebrates (and arthropods), there are a (...) wide variety of tapeta that vary in structure, chemical composition, and even tissue architecture, indicating repeated convergent evolution. To date, the tapetum has not been observed in any cephalopod, however, which also possess a camera‐like eye, but with the retinal photoreceptors oriented in the anterior direction. We therefore hypothesize that the tapetum lucidum is a compensatory adaptation for the suboptimal design of the inverted retina of vertebrates. (shrink)

In the maximal form of indirect development found in many taxa of marine invertebrates, embryonic cell lineages of fixed fate and limited division capacity give rise to the larval structures. The adult arises from set‐aside cells in the larva that are held out from the early embryonic specification processes, and that retain extensive proliferative capacity. We review the locations and fates of set‐aside cells in two protostomes, a lophophorate and a deuterostome. The distinct adult body plans of many phyla develop (...) from homologous set‐aside cells within homologous larvae. We argue that the stocks from which these phyla arose utilized these respective larvae, and the diversity of their adult body plans reflects diverse pattern formation processes executed in their set‐aside cell populations. Chordates and arthropods develop directly, but share adult characters with indirectly developing phyla. Thus the deuterostome and protostome stocks that were ancestral to chordates and arthropods, respectively, also utilized maximal indirect development. (shrink)

Since the noun phrase `artificial intelligence' (AI) was coined, it has been debated whether humans are able to create intelligence using technology. We shed new light on this question from the point of view of themodynamics and mathematics. First, we define what it is to be an agent (device) that could be the bearer of AI. Then we show that the mainstream definitions of `intelligence' proposed by Hutter and others and still accepted by the AI community are too weak even (...) to capture what is involved when we ascribe intelligence to an insect. We then summarise the highly useful definition of basic (arthropod) intelligence proposed by Rodney Brooks, and we identify the properties that an AI agent would need to possess in order to be the bearer of intelligence by this definition. Finally, we show that, from the perspective of the disciplines needed to create such an agent, namely mathematics and physics, these properties are realisable by neither implicit nor explicit mathematical design nor by setting up an environment in which an AI could evolve spontaneously. (shrink)

It is hypothesized that iron from biological tissues, liberated during decay, may have played a role in inhibiting loss of anatomical information during fossilization of extinct organisms. Most tissues in the animal kingdom contain iron in different forms. A widely distributed iron‐bearing molecule is ferritin, a globular protein that contains iron crystallites in the form of ferrihydrite minerals. Iron concentrations in ferritin are high and ferrihydrites are extremely reactive. When ancient animals are decaying on the sea floor under anoxic environmental (...) conditions, ferrihydrites may initialize the selective replication of some tissues in pyrite FeS2. This model explains why some labile tissues are preserved, while other more resistant structures decay and are absent in many fossils. A major implication of this hypothesis is that structures described as brains in Cambrian arthropods are not fossilization artifacts, but are instead a source of information on anatomical evolution at the dawn of complex animal life. (shrink)

The sudden appearance in the fossil record of the major animal phyla apparently records a phase of unparalleled, rapid evolution at the base of the Cambrian period, 545 Myr ago. This has become known as the Cambrian evolutionary ‘explosion’, and has fuelled speculation about unique evolutionary processes operating at that time. The acceptance of the palaeontological evidence as a true reflection of the evolutionary narrative has been criticised in two ways: from a reappraisal of the phylogenetic relationships of the early (...) fossils, and from predicitions of molecular divergence times, based on six appropriate metazoan genes. Phylogenetic analysis of the arthropods implies an earlier, Precambrian history for most clades, and hence an extensive period of cladogenesis unrecorded by fossils. A similar argument can be applied to molluscs, lophophorates and deuterostomes. Molecular evidence implies divergence between clades to at least 1000 Myr ago. The apparent paradox between the sudden appearance of recognisable metazoans and their extended evolutionary history might be explained by a sudden Cambrian increase in body size, which was accompanied by skeletisation. A new paradigm suggests that the ‘explosion’ in the record may have been decoupled from the evolutionary innovation. (shrink)

The Evolution of the Sensitive Soul is a landmark attempt to make progress on the problem of animal consciousness. Ginsburg and Jablonka propose a general cognitive marker of the presence of consciousness: Unlimited Associative Learning. They use this marker to defend a generous view about the distribution of consciousness in the natural world, on which a capacity for conscious experience is common to all vertebrates, many arthropods and some cephalopod molluscs. They use this inferred distribution to defend a view (...) about the evolution of consciousness, on which it has evolved at least three times, first evolved at around the time of the Cambrian explosion, and was in fact the driving force behind that explosion. In this essay review, I reflect critically on the book’s central idea: the proposal that Unlimited Associative Learning provides a general marker of consciousness. (shrink)

Paleoneuranatomy is an emerging subfield of paleontological research with great potential for the study of evolution. However, the interpretation of fossilized nervous tissues is a difficult task and presently lacks a rigorous methodology. We critically review here cases of neural tissue preservation reported in Cambrian arthropods, following a set of fundamental paleontological criteria for their recognition. These criteria are based on a variety of taphonomic parameters and account for morphoanatomical complexity. Application of these criteria shows that firm evidence for (...) fossilized nervous tissues is less abundant and detailed than previously reported, and we synthesize here evidence that has stronger support. We argue that the vascular system, and in particular its lacunae, may be central to the understanding of many of the fossilized peri‐intestinal features known across Cambrian arthropods. In conclusion, our results suggest the need for caution in the interpretation of evidence for fossilized neural tissue, which will increase the accuracy of evolutionary scenarios. Also see the video abstract here: https://youtu.be/2_JlQepRTb0. (shrink)

Metaseiulus occidentalis is a representative of an important family of mites (Arthropoda: Chelicerata: Acari: Phytoseiidae) that are effective predators of pest mites in agricultural crops around the world. Like many arthropods, this mite contains multiple genomes, including the genomes of several microbial symbionts as well as its own mitochondrial and nuclear genomes. The mitochondrial genome is “mitey” large at 25 kb, due to duplication and triplication of genes. By contrast, the nuclear genome is “mitey” small at 88 Mb. This (...) mite has a parahaploid genetic system, tolerates inbreeding, and has a haploid chromosome number of 3. This predator was genetically improved for use in agriculture by developing strains that lacked the ability to overwinter in diapause or were resistant to multiple pesticides, and can be genetically modified using recombinant DNA methods. Sequencing the nuclear genome would provide useful insights that could enhance genetic improvement programs that would result in improved pest management, could provide genes needed to resolve the evolutionary relationships of this family, and could serve as a model for understanding the evolution and genetics of chelicerate arthropod predators. (shrink)

Secretory proteins and membranes move in transfer vesicles from the rough endoplasmic reticulum through the transitional region to the outer saccule of the Golgi complex. In both arthropod and vertebrate cells, the GC beads are a characteristic structural component of the transitional region. The beads are particles about half the size of ribosomes arranged equidistantly from one another and the smooth face of the ER. In an active GC, the beads are in rings through which the ER membrane emerges to (...) form transfer vesicles. The beads may be part of the energy‐dependent step required for the movement of proteins along the secretory pathway, since they lose their ring arrangement under conditions that lower cellular ATP. The beads are organizers for Golgi complexes in the sense that they are the first recognizable components of new GCs as they arise from ER. Arthropod GC beads, but not those of vertebrates, can be visualized through their reaction with bismuth in vivo and in fixed tissue. Useful paradigms for traffic between the ER and the GC need to combine structural and biochemical information. Insect fat body, with its readily resolvable bismuth‐stained beads and easily fractionated cell components may have particular value for this problem. (shrink)

Negative attitudes toward invertebrates are a deep-seated, visceral response among Western peoples. These internalized aversions toward insects and other terrestrial arthropods, both in general and specifically as a food source, subtly and systemically contribute to unsustainable global foodways. Insect cuisine is, for Westerners, emblematic of the alien, a threat to our psychological and cultural identity. Yet failure to embrace entomophagy prevents us from seeing the full humanity of those of other classes, races, and cultures, and leads to agricultural and (...) food policy decisions that fail in their objectives to improve nourishment for all people. Key to enabling the world’s peoples to live sustainably with the land are: awareness of the psychological and cultural barriers to a more insect-positive perspective embracing insects as a desirable food resource, understanding the processes by which those barriers are constructed, their negative consequences, and identifying strategies for transforming our attitudes. (shrink)