This paper argues that extant signalling-based analyses cannot explain a range of cases of biological (and psychological) deception, such as those in which the deceiver does not send a signal at all, but that Artiga and Paternotte’s (Philos Stud 175:579–600, 2018) functional and my (Krstić in The analysis of self-deception: rehabilitating the traditionalist account. PhD Dissertation, University of Auckland, 2018: §3; Krstić and Saville in Australas J Philos 97:830–835, 2019) manipulativist analyses can. Therefore, the latter views should be given (...) preference. And because we still do not have a satisfactory definition of manipulation, the functional analysis, according to which a state is deceptive iff its function is to mislead and it misleads, is currently our best theory of deception. This is not to argue that the signalling-based analyses have no value but only that they should not be used in general analyses of biological deception. We need to move on to some other interesting issues. (shrink)

Communication involves a great deal of uncertainty. Prima facie, it is therefore surprising that biological communication systems—from cellular to human—exhibit a high degree of ambiguity and often leave its resolution to contextual cues. This puzzle deepens once we consider that contextual information may diverge between individuals. In the following we lay out a model of ambiguous communication in iterated interactions between subjectively rational agents lacking a common contextual prior. We argue ambiguity’s justification to lie in endowing interlocutors with means (...) to flexibly adapt language use to each other and the context of their interaction to serve their communicative preferences. Linguistic alignment is shown to play an important role in this process; it foments convergence of contextual expectations and thereby leads to agreeing use and interpretation of ambiguous messages. We conclude that ambiguity is ecologically rational when interlocutors’ contextual expectations are generally in line or they interact multiple times in an informative context, enabling for the alignment of their expectations. In light of these results meaning multiplicity can be understood as an opportunistic outcome enabled and shaped by linguistic adaptation and contextual information. 1Meaning Multiplicity in Communication 2Ambiguous Signalling through Pragmatic Inference 2.1Preliminaries 2.2Signalling behaviour 2.3Communicative success 2.4Iterated interactions 3Predictions for Single and Iterated Interactions 3.1Simulations 3.2Exploration and past experience 3.3Preemptive adaptation 4Discussion 5Conclusion Appendix. (shrink)

Various writers have attempted to use the sender-receiver formalism to account for the representational capacities of biological systems. This paper has two goals. First, I argue that the sender-receiver approach to representation cannot be complete. The mammalian circadian system represents the time of day, yet it does not control circadian behaviours by producing signals with time of day content. Informative signalling need not be the basis of our most basic representational capacities. Second, I argue that representational capacities are primarily (...) about control, and only when specific conditions obtain does this control require informative signalling. (shrink)

Communication involves a great deal of uncertainty. Prima facie, it is therefore surprising that biological communication systems—from cellular to human—exhibit a high degree of ambiguity and often leave its resolution to contextual cues. This puzzle deepens once we consider that contextual information may diverge between individuals. In the following we lay out a model of ambiguous communication in iterated interactions between subjectively rational agents lacking a common contextual prior. We argue ambiguity’s justification to lie in endowing interlocutors with means (...) to flexibly adapt language use to each other and the context of their interaction to serve their communicative preferences. Linguistic alignment is shown to play an important role in this process; it foments convergence of contextual expectations and thereby leads to agreeing use and interpretation of ambiguous messages. We conclude that ambiguity is ecologically rational when interlocutors’ contextual expectations are generally in line or they interact multiple times in an informative context, enabling for the alignment of their expectations. In light of these results meaning multiplicity can be understood as an opportunistic outcome enabled and shaped by linguistic adaptation and contextual information. (shrink)

This paper aims to provide a philosophical and theoretical account of biological communication grounded in the notion of organisation. The organisational approach characterises living systems as organised in such a way that they are capable to self-produce and self-maintain while in constant interaction with the environment. To apply this theoretical framework to the study of biological communication, we focus on a specific approach, based on the notion of influence, according to which communication takes place when a signal emitted (...) by a sender triggers a change in the behaviour of the receiver that is functional for the sender itself. We critically analyse the current formulations of this account, that interpret what is functional for the sender in terms of evolutionary adaptations. Specifically, the adoption of this etiological functional framework may lead to the exclusion of several phenomena usually studied as instances of communication, and possibly even of entire fields of investigation such as synthetic biology. As an alternative, we reframe the influence approach in organisational terms, characterising functions in terms of contributions to the current organisation of a biological system. We develop a theoretical account of biological communication in which communicative functions are distinguished from other types of biological functions described by the organisational account (e.g. metabolic, ecological, etc.). The resulting organisational-influence approach allows to carry out causal analyses of current instances of phenomena of communication, without the need to provide etiological explanations. In such a way it makes it possible to understand in terms of communication those phenomena which realise interactive patterns typical of signalling interactions – and are usually studied as such in scientific practice – despite not being the result of evolutionary adaptations. Moreover, this approach provides operational tools to design and study communicative interactions in experimental fields such as synthetic biology. (shrink)

Game theory has a prominent role in evolutionary biology, in particular in the ecological study of various phenomena ranging from conflict behaviour to altruism to signalling and beyond. The two central methodological tools in biological game theory are the concepts of Nash equilibrium and evolutionarily stable strategy. While both were inspired by a dynamic conception of evolution, these concepts are essentially static—they only show that a population is uninvadable, but not that a population is likely to evolve. In this (...) article, we argue that a static methodology can lead to misleading views about dynamic evolutionary processes. We advocate, instead, a more pluralistic methodology, which includes both static and dynamic game theoretic tools. Such an approach provides a more complete picture of the evolution of strategic behaviour. 1 Introduction2 The Equilibrium Methodology3 Common Interest Signalling3.1 Lewis’s signalling game3.2 Static analysis3.3 Dynamic analysis4 The Sir Philip Sidney Game4.1 Static analysis4.2 Other equilibria4.3 Dynamic analysis5 Related Literature6 Static and Dynamic Approaches. (shrink)

The partner choice approach to understanding the evolution of cooperation builds on approaches that focus on partner control by considering processes that occur prior to pair or group formation. Proponents of the partner choice approach rightly note that competition to be chosen as a partner can help solve the puzzle of cooperation. I aim to build on the partner choice approach by considering the role of signalling in partner choice. Partnership formation often requires reliable information. Signalling is thus important in (...) the context of partner choice. However, the issue of signal reliability has been understudied in the partner choice literature. The issue deserves attention because – despite what proponents of the partner choice approach sometimes claim – that approach does face a cheater problem, which we might call the problem of false advertising in biological markets. Both theoretical and empirical work is needed to address this problem. I will draw on signalling theory to provide a theoretical framework within which to organise the scattered discussions of the false advertising problem extant in the partner choice literature. I will end by discussing some empirical work on cooperation, partner choice, and punishment among humans. (shrink)

“Teleosemantic” or “biosemantic” theories form a strong naturalistic programme in the philosophy of mind and language. They seek to explain the nature of mind and language by recourse to a natural history of “proper functions” as selected-for effects of language- and thought-producing mechanisms. However, they remain vague with respect to the nature of the proposed analogy between selected-for effects on the biological level and phenomena that are not strictly biological, such as reproducible linguistic and cultural forms. This essay (...) critically explores various interpretations of this analogy. It suggests that these interpretations can be explicated by contrasting adaptationist with pluralist readings of the evolutionary concept of adaptation. Among the possible interpretations of the relations between biological adaptations and their analogues in language and culture, the two most relevant are a linear, hierarchical, signalling-based model that takes its cues from the evolution of co-operation and joint intentionality and a mutualistic, pluralist model that takes its cues from mimesis and symbolism in the evolution of human communication. Arguing for the merits of the mutualistic model, the present analysis indicates a path towards an evolutionary pluralist version of biosemantics that will align with theories of cognition as being environmentally “scaffolded”. Language and other cultural forms are partly independent reproducible structures that acquire proper functions of their own while being integrated with organism-based cognitive traits in co-evolutionary fashion. (shrink)

We introduce the virtual special issue on content in signalling systems. The issue explores the uses and limits of ideas from evolutionary game theory and information theory for explaining the content of biological signals. We explain the basic idea of the Lewis-Skyrms sender-receiver framework, and we highlight three key themes of the issue: (i) the challenge of accounting for deception, misinformation and false content, (ii) the relevance of partial or total common interest to the evolution of meaningful signals, and (...) (iii) how the sender-receiver framework relates to teleosemantics. (shrink)

Autophagy and YAP1‐WWTR1/TAZ signalling are tightly linked in a complex control system of forward and feedback pathways which determine different cellular outcomes in differing cell types at different time‐points after perturbations. Here we extend our previous experimental and modelling approaches to consider two possibilities. First, we have performed additional mathematical modelling to explore how the autophagy‐YAP1 crosstalk may be controlled by posttranslational modifications of components of the pathways. Second, since analogous contrasting results have also been reported for autophagy as a (...) regulator of other transduction pathways engaged in tumorigenesis (Wnt/β‐catenin, TGF‐β/Smads, NF‐kB or XIAP/cIAPs), we have considered if such discrepancies may be explicable through situations involving competing pathways and feedback loops in different cell types, analogous to the autophagy‐YAP/TAZ situation. Since distinct posttranslational modifications dominate those pathways in distinct cells, these need to be understood to enable appropriate cell type‐specific therapeutic strategies for cancers and other diseases. (shrink)

Between 300,000 and 250,000 years ago early humans in Africa and Eurasia began to use durable material substances and objects as media for signaling. Initially material signals were confined to ochre and other pigments, but over time objects such as beads were also added as technologies for sending messages. Changes in the types of materials used, their durability and costs, and the contexts of their disposal indicate a series of transitions in how early humans employed signaling media. (...) class='Hi'>Signaling theory from biology suggests that shifts in technologies over the course of the Pleistocene reflect problems in coordinating action and resolving conflicts within increasingly large and internally differentiated societies. (shrink)

Cooption and modularity are informative concepts in evolutionary developmental biology. Genes function within complex networks that act as modules in development. These modules can then be coopted in various functional and evolutionary contexts. Hormonal signaling, the main focus of this review, has a modular character. By regulating the activities of genes, proteins and other cellular molecules, a hormonal signal can have major effects on physiological and ontogenetic processes within and across tissues over a wide spatial and temporal scale. Because (...) of this property, we argue that hormones are frequently involved in the coordination of life history transitions (LHTs) and their evolution (LHE). Finally, we promote the usefulness of a comparative, non-model system approach towards understanding how hormones function and guide development and evolution, highlighting thyroid hormone function in echinoids as an example. BioEssays 27:64–75, 2005. © 2004 Wiley Periodicals, Inc. (shrink)

Ethological theories usually attribute semantic content to animal signals. To account for this fact, many biologists and philosophers appeal to some version of teleosemantics. However, this picture has recently came under attack: while mainstream teleosemantics assumes that representational systems must cooperate, some biologists and philosophers argue that in certain cases signaling can evolve within systems lacking common interest. In this paper I defend the standard view from this objection.

Musical flutes constructed from bird bone and mammoth ivory begin to appear in the archaeological record from around 40,000 years ago. Due to the different physical demands of acquiring and working with these source materials in order to produce a flute, researchers have speculated about the significance—aesthetic or otherwise—of the use of mammoth ivory as a raw material for flutes. I argue that biological signaling theory provides a theoretical basis for the proposition that mammoth ivory flute production is (...) a signal of increasing social differentiation in Upper Palaeolithic human life. (shrink)

We employ the Social Signaling Model and life history of a Western Dani big-man, Tibenuk, to analyze a neglected curiosity in the career of the big-man type. The big-man is renowned as an economic entrepreneur, the master of material displays. In New Guinea, however, big-men had invariably first gained fame and some influence as eminent warriors. The SSM accounts for this two-part career path by proposing that small-scale social organization rests on honest, competitive signaling of individual and collective (...) fighting strength, with leaders being those who excel in these contests. The performances for which big-men are already known, conspicuous ceremonial displays, broadcast this strength indirectly. Explicitly conceptualized as symbolic fighting, they constituted indexical proxies for their sponsors’ individual and collective willingness and ability to fight. Success on the battlefield, though, signaled fighting strength more directly. Men therefore had to demonstrate strength on both the battlefield and the ceremonial ground if they were to become big-men. This was Tibenuk’s achievement. When he was young and at his physical peak, he demonstrated outstanding capability in war. War is a young man’s game, however, and as his physical capacities waned, he shifted to politics, an older man’s game, honing his political talents and developing extensive political networks that allowed him to sponsor massive pig feasts, the principal form of conspicuous ceremonial display. Tibenuk’s career also reveals synergies between warrior and political talents that hitherto have been overlooked in big-man analysis. (shrink)

This essay ties together some main strands of the author’s research spanning the last quarter-century. Because of its broad scope and space limitations, he prescinds from detailed arguments and instead intuitively motivates the general points which are supported more fully in other publications to which he provides references. After an initial delineation of several distinct notions of meaning, the author considers such a notion deriving from the evolutionary biology of communication that he terms ‘organic meaning’, and places it in the (...) context of evolutionary game theory. That provides a framework for a special type of organic meaning found in the phenomenon of expression, of which the author here offers an updated characterization while highlighting its wide philosophical interest. Expression in turn generalizes to a paradigmatic form of human communication—conversation—and section 4 provides a taxonomy of conversation-types while arguing that attention to such types helps to sharpen predictions of what speakers say rather than conversationally implicate. We close with a view of fictional discourse on which authors of fictional works are engaged in conversation with their readers, and can provide them with knowledge in spite of the fictional character of their conversation. Such knowledge includes knowledge of how an emotion feels and is thus a route to empathy. (shrink)

Researchers typically define animal signaling as morphology or behavior specialized for transmitting encoded information from a signaler to a perceiver. Although intuitively appealing, this conception is inherently metaphorical and leaves concepts of both information and encoding undefined. To justify relying on the information construct, theorists often appeal to Shannon and Weaver’s quantitative definition. The two approaches are, however, fundamentally at odds. The predominant definition of animal signaling is thus untenable, which has a number of undesirable consequences for both (...) theory and practice in the field. Theoretical problems include conceptual circularity and running afoul of fundamental evolutionary principles. Problems in empirical work include that research is often grounded in abstractions such as signal honesty and semanticity, and thereby distracted from more basic and concrete factors shaping communication. A revised definition is therefore proposed, making influence rather than transmission of encoded information the central function of animal signaling. This definition is conceptually sound, empirically testable, and inclusive, yet bounded. Implications are considered in both theoretical and empirical domains. (shrink)

The Motin family proteins (Motins) are a class of scaffolding proteins consisting of Angiomotin (AMOT), AMOT‐like protein 1 (AMOTL1), and AMOT‐like protein 2 (AMOTL2). Motins play a pivotal role in angiogenesis, tumorigenesis, and neurogenesis by modulating multiple cellular signaling pathways. Recent findings indicate that Motins are components of the Hippo pathway, a signaling cascade involved in development and cancer. This review discusses how Motins are integrated into the Hippo signaling network, as either upstream regulators or downstream effectors, (...) to modulate cell proliferation and migration. The repression of YAP/TAZ by Motins contributes to growth inhibition, whereas subcellular localization of Motins and their interactions with actin fibers are critical in regulating cell migration. The net effect of Motins on cell proliferation and migration may contribute to their diverse biological functions. (shrink)

Precision cell signaling activities of reactive electrophilic species (RES) are arguably among the most poorly‐understood means to transmit biological messages. Latest research implicates native RES to be a chemically‐distinct subset of endogenous redox signals that influence cell decision making through non‐enzyme‐assisted modifications of specific proteins. Yet, fundamental questions remain regarding the role of RES as bona fide second messengers. Here, we lay out three sets of criteria we feel need to be met for RES to be considered as (...) true cellular signals that directly mediate information transfer by modifying “first‐responding” sensor proteins. We critically assess the available evidence and define the extent to which each criterion has been fulfilled. Finally, we offer some ideas on the future trajectories of the electrophile signaling field taking inspiration from work that has been done to understand canonical signaling mediators. (shrink)

Growth factor receptor tyrosine kinases (RTKs), such as the fibroblast growth factor receptor (FGFR), play a major role in how cells communicate with their environment. FGFR signaling is crucial for normal development, and its misregulation in humans has been linked to developmental abnormalities and cancer. The precise molecular mechanisms by which FGFRs transduce extracellular signals to effect specific biologic responses is an area of intense research. Genetic analyses in model organisms have played a central role in our evolving understanding (...) of these signal transduction cascades. Genetic studies in the nematode C. elegans have contributed to our knowledge of FGFR signaling by identifying genes involved in FGFR signal transduction and linking their gene products together into signaling modules. This review will describe FGFR-mediated signal transduction in C. elegans and focus on how these studies have contributed to our understanding of how FGFRs orchestrate the assembly of intracellular signaling pathways. BioEssays 23:1120–1130, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

How epithelial tissues are able to self-renew to maintain homeostasis and regenerate in response to injury remains a persistent question. The transcriptional effectors YAP and TAZ are increasingly being recognized as central mediators of epithelial stem cell biology, and a wealth of recent studies have been directed at understanding the control and activity of these factors. Recent work by Hu et al. has added to this knowledge, as they identify an Integrin-FAK-CDC42-PP1A signaling cascade that directs nuclear YAP/TAZ activity in (...) stem cell populations of the mouse incisor, and define convergence on mTORC1 signaling as an important mediator of the proliferation of these cells. Here, we review recent studies on YAP/TAZ function and regulation in epithelial tissue-specific stem cells, merging the Hu et al. study together with our current knowledge of YAP/TAZ. The Hippo pathway effectors YAP and TAZ broadly regulate adult stem cells, and have recently been implicated in dental epithelial stem cell proliferation and restricted differentiation via an Integrin-FAK-CDC42-PP1A cascade. Here, we discuss the extracellular cues which control YAP/TAZ activity and examine downstream pathways that direct stem cell fate. (shrink)

How epithelial tissues are able to self-renew to maintain homeostasis and regenerate in response to injury remains a persistent question. The transcriptional effectors YAP and TAZ are increasingly being recognized as central mediators of epithelial stem cell biology, and a wealth of recent studies have been directed at understanding the control and activity of these factors. Recent work by Hu et al. has added to this knowledge, as they identify an Integrin-FAK-CDC42-PP1A signaling cascade that directs nuclear YAP/TAZ activity in (...) stem cell populations of the mouse incisor, and define convergence on mTORC1 signaling as an important mediator of the proliferation of these cells. Here, we review recent studies on YAP/TAZ function and regulation in epithelial tissue-specific stem cells, merging the Hu et al. study together with our current knowledge of YAP/TAZ. The Hippo pathway effectors YAP and TAZ broadly regulate adult stem cells, and have recently been implicated in dental epithelial stem cell proliferation and restricted differentiation via an Integrin-FAK-CDC42-PP1A cascade. Here, we discuss the extracellular cues which control YAP/TAZ activity and examine downstream pathways that direct stem cell fate. (shrink)

In recent years, the research field of the evolution of art has witnessed contributions from a wide range of disciplines across the "three cultures". In this thesis, I make both a critical review of existing explanations, and try to do elucidate the evolution of art by employing insights, methods and concepts from different disciplines. First, I critically evaluate the evidentiary criteria from standard evolutionary psychology some accounts employ to demonstrate that art qualifies as a human biological adaptation. I argue (...) that these criteria do not suffice to make that claim. Furthermore, I make the case for a cultural evolutionary approach to the arts. One commonly used evidentiary criterion for art as adaptation is the “tight fit” between artnbsp;human cognition, which is interpreted as suggesting that cognition has undergone selection to produce and appreciate art. However, disentangling cultural and genetic evolution allows formulating thenbsp;hypothesis that art has evolved culturally to match human cognition. Second, I observe that in ancient and modern hunter gatherer societies, artistic activities are virtually alwaysnbsp;with ritual. I discuss what this implies for the adaptive significance of art. Specifically, if the arts have culturally evolved in function of ritualistic purposes, their adaptive value has depended on the adaptiveness of ritual. Third, because architecture is characterized by the combination of utilitarian and aesthetic aspects, it is particularly interesting from an evolutionary perspective and therefore I devote special attention to it. Employing the cross-species comparative approach, I investigate two main purposes human architecture has in common with nonhuman animal constructions: protection andnbsp;Based on the phylogenetic approach I establish that protection may have been the primary function of building aptitudes in humannbsp;and that building was later co-opted for signaling purposes. Subsequently, I comparatively evaluate thenbsp;of signaling models in the cultural evolution of architectural aesthetics. Furthermore I combine insights from environmental psychology, niche construction and cultural evolution theory to develop the hypothesis that a function of religious monumental architecture may have been to support nbsp;or even to galvanize nbsp;social learning. Finally, I connect the account I developed to the cognitive science of religion. I complement the frequently held view that religious monumental architecture is a costly signal with the mechanism of sensory exploitation. I attempt to demonstrate that by exploiting thenbsp;response of awe in religious followers, religious monumental architecture promotes and regulates prosocial behavior and creates in them an openness to adopt supernatural beliefs. Fourth, I dealnbsp;the evolution of visual art, paying again special attention to cultural evolution andnbsp;explanatory value of sensory exploitation. I assert that the relatively late appearance of figurative art in the course of human evolution may be attributed to an increase in the number of social learning opportunities within and between human populations at that time. I support this assertion with archaeological data that indicate overall population growth and increased population densities at that time. These demographic changes, I argue, have allowed the retention and accumulation of innovations required for figurative art making. Contrary to previous accounts, I furthermore aim to show that this process doesnbsp;require figurative art to have served adaptive purposes. Employing sensory exploitation, I establish that figurative art could have evolved by exploiting pre-existing biases of evolved psychology. The dominant themes of upper Paleolithic and late stone age figurative art, animals and humans, seem to support this contention. Fifth, I present a number of experimental studies I conducted to verify whether contemporary art experts would have socially learned to resist exploitation of evolved psychology. One aspect ofrsquo;s exploitative power may be that it elicits aesthetic pleasure by pushing “pleasure buttons” that evolved for other purposes. Consequently, spectators may trade-off rewards from indulging in art and biological activities, resulting in less effort being allocated to reproduction. I contend that, while the generalnbsp; may indeed be exploited, experts, who are typically being exposed to high doses of art, may have socially learned to resist exploitation by selectively preferring art from prestigious art contexts. The latter would be in line with the claim that prestige bias may trump content biases of evolved psychology. The results of three experimental studies supportnbsp;contention. I find that laypeople's art appreciation is positively affected by a content bias for attractive faces, mediated by aesthetic pleasure, whereas experts' appreciation is positively affected by prestige and mediated by admiration for the artist. Moreover, experts confer lower appreciation to attractive compared to moderately attractive content, which is consistentnbsp;the contention that expertise and the use of prestige are associatednbsp;resistance against beautiful content that exploits evolved preferences. This research thus suggests that expertise moderates content and context biases, which may be of relevance to an ongoing debate about their relative importance as drivers of cultural evolution. In addition, this study provides a tentative but novel explanation for the fact, famously established by philosopher Arthur Danto, that beauty lost its central position in Western art during the 20th century. However my findings cannot exclude alternative explanations for the fact that art expert appreciation deviates from evolved aesthetic preferences. Further research may experimentally assess the role of prestige bias and resistance as drivers of this deviation versus other, previously suggested, potential processes. For example, preferences of experts may deviate on account of the fact that art serves as a badge of elite group membership and thus expert art appreciation as a means to distinguish oneself from the masses. Alternatively, art experts may seek intellectual challenges instead of pushing pleasure buttons. Future research may experimentally verify the respective roles of these different hypothesized mechanisms. In addition, it may be investigated how insights from sexual selection research may help elucidating the different processes at play in cultural evolution and particularly in the cultural evolution of art appreciation, given the commonalities between sexual selection and cultural selection models. (shrink)

Design patterns are generalized solutions to frequently recurring problems. They were initially developed by architects and computer scientists to create a higher level of abstraction for their designs. Here, we extend these concepts to cell biology to lend a new perspective on the evolved designs of cells' underlying reaction networks. We present a catalog of 21 design patterns divided into three categories: creational patterns describe processes that build the cell, structural patterns describe the layouts of reaction networks, and behavioral patterns (...) describe reaction network function. Applying this pattern language to the E. coli central metabolic reaction network, the yeast pheromone response signaling network, and other examples lends new insights into these systems. (shrink)

I propose that a dishonest signaling system can be evolutionarily stable in eusocial animal societies if the amount of dishonesty is balanced by the chance of non-reproductive workers to advance to the reproductive caste in the future. I express this trade-off in a modified form of Hamilton’s rule, where I distinguish between the real and perceived cost of an altruistic act, and between the real and perceived genetic relatedness between colony members. Furthermore, I elaborate how the vertebrate neuromodulator oxytocin (...) could serve as an internal representation of the perceived cost of an altruistic act and of perceived relatedness. Behavioral and receptor localization data support this hypothesis. The encoding of cost and relatedness by oxytocin is likely integrated with a number of other functions related to social bonding. I conclude with a discussion of honesty in signaling, an outline of testable consequences of this hypothesis, and a comparison between vertebrate and insect eusociality. (shrink)

The story of the fall and rise of Zahavi’s handicap principle is one of a battle between models. Early attempts at formal modeling produced negative results and, unsurprisingly, scepticism about the principle. A major change came in 1990 with Grafen’s production of coherent models of a handicap mechanism of honest signalling. This paper’s first claim is that acceptance of the principle, and its dissemination into other disciplines, has been driven principally by that, and subsequent modeling, rather than by empirical results. (...) Secondly, there is a vast literature on biological signalling but few studies that make all of the observations necessary to diagnose the handicap mechanism. My final claim is that many of the applications of costly signalling theory in other disciplines are conceptually confused. Misinterpretations of what is meant by costly signalling are common. Demonstrating that a signal is costly is insufficient and is not always necessary in order to prove that, and explain why, a signal is honest. In addition to the biological modelling of signals, there is an economic literature on the same subject. The two run in parallel in the sense that they have had little mutual interaction. Additionally, it is the biological modelling that has been picked up, and often misapplied, by other disciplines. (shrink)

Human cooperation is held to be an evolutionary puzzle because people voluntarily engage in costly cooperation, and costly punishment of non-cooperators, even among anonymous strangers they will never meet again. The costs of such cooperation cannot be recovered through kin-selection, reciprocal altruism, indirect reciprocity, or costly signaling. A number of recent authors label this behavior ‘strong reciprocity’, and argue that it is: (a) a newly documented aspect of human nature, (b) adaptive, and (c) evolved by group selection. We argue (...) exactly the opposite; that the phenomenon is: (a) not new, (b) maladaptive, and (c) evolved by individual selection. In our perspective, the apparent puzzle disappears to reveal a biological and evolutionary logic to human cooperation. Group selection may play a role in theory, but it is neither necessary nor sufficient to explain human cooperation. Our alternative solution is simpler, makes fewer assumptions, and is more parsimonious with the empirical data. (shrink)

Biochemical networks, including those containing signaling pathways, display a wide range of regulatory properties. These include the ability to propagate information across different time scales and to function as switches and oscillators. The mechanisms underlying these complex behaviors involve many interacting components and cannot be understood by experiments alone. The development of computational models and the integration of these models with experiments provide valuable insight into these complex systems‐level behaviors. Here we review current approaches to the development of computational (...) models of biochemical networks and describe the insights gained from models that integrate experimental data, using three examples that deal with ultrasensitivity, flexible bistability and oscillatory behavior. These types of complex behavior from relatively simple networks highlight the necessity of using theoretical approaches in understanding higher order biological functions. BioEssays 24:1110–1117, 2002. © 2002 Wiley‐Periodicals, Inc. (shrink)

Long‐term potentiation and long‐term depression are thought to be cellular mechanisms contributing to learning and memory. Although the physiological phenomena have been well characterized, little consensus of their underlying molecular mechanisms has emerged. One reason for this may be the under‐appreciated complexity of the signaling pathways that can arise if key signaling molecules are discretely localized within the synapse. Recent findings suggest an unanticipated degree of structural organization at the synapse, and improved methods in cellular imaging of living (...) tissue have provided much‐needed information about the intracellular dynamics of Ca2+, thought to be critical for both LTP and LTD. In this review, we briefly summarize some of these developments, and show that a more complete understanding of cellular signaling depends on the successful integration of traditional biochemistry and molecular biology with the spatial and temporal details of synaptic ultrastructure. Biophysically realistic computer simulations can have an important role in bridging these disciplines. BioEssays 24:1130–1144, 2002. © 2002 Wiley‐Periodicals, Inc. (shrink)

I introduce a range of examples of different causal hypotheses about human mate selection. The hypotheses I focus on come from evolutionary psychology, fluctuating asymmetry research and chemical signaling research. I argue that a major obstacle facing an integrated biology of human behavior is the lack of a causal framework that shows how multiple proximate causal mechanisms can act together to produce components of our behavior.

Signaling through both the transforming growth factor β (TGFβ) superfamily of growth factors and Notch play crucial roles during embryonic pattern formation and cell fate determination. Although both pathways are able to exert similar biological responses in certain cell types, a functional interaction between these two signaling pathways has not been described. Now, three papers provide evidence of both synergy and antagonism between TGFβ and Notch signaling.1-3 These reports describe a requirement for Notch signal transducers in (...) TGFβ- and BMP-induced expression of Notch target genes, as well as in BMP-controlled cell differentiation and migration. These papers uncover a direct link between the Notch and TGFβ pathways and suggest a critical role for Notch in some of the biological responses to TGFβ family signaling. BioEssays 27:115–118, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Systems thinking is an increasingly recognized paradigm in education in both natural and social sciences, a particular focus being, naturally, in biology. This article argues that plant biology, and in particular, plant hormonal signaling, provides highly illustrative models for learning and teaching in a systems paradigm, because it offers examples of highly complex networks, ranging from the molecular‐ to ecosystem‐scale, and in addition lends itself to the use of real‐life biological objects.

The question on how the diverse forms of cooperative behavior in humans and nonhuman animals could have evolved under the pressure of natural selection has been a challenge for evolutionary biology ever since Darwin himself. In this chapter, we briefly review and summarize results from the last 50 years of research on human and nonhuman cooperativeness from a theoretical (biology) and an experimental perspective (experimental economics). The first section presents six concepts from theoretical biology able to explain a variety of (...) forms of cooperativeness which evolved in many different species. These are kin selection, mutualism, reciprocity, green-beard altruism, costly signaling, and cultural group selection. These considerations are complemented by two short examples of evolved cooperative behavior, one from microbiology and one from ethology. The second main section focuses on recent experimental research on human cooperativeness. We present a brief review of factors known to impact individual human decision-making in social dilemmas, most prominently communication, punishment, reputation, and assortment. Our conclusion then draws attention to tasks for further research in this area. (shrink)

It has long been asserted that the evolutionary path to spoken language was paved by manual–gestural behaviors, a claim that has been revitalized in response to recent research on mirror neurons. Renewed interest in the relationship between manual and vocal behavior draws attention to its development. Here, the pointing and vocalization of 16.5-month-old infants are reported as a function of the context in which they occurred. When infants operated in a referential mode, the frequency of simultaneous vocalization and pointing exceeded (...) the frequency of vocalization-only and pointing-only responses by a wide margin. In a non-communicative context, combinatorial effects persisted, but in weaker form. Manual–vocal signals thus appear to express the operation of an integrated system, arguably adaptive in the young from evolutionary times to the present. It was speculated, based on reported evidence, that manual behavior increases the frequency and complexity of vocal behaviors in modern infants. There may be merit in the claim that manual behavior facilitated the evolution of language because it helped make available, early in development, behaviors that under selection pressures in later ontogenetic stages elaborated into speech. (shrink)

Living organisms are exposed to numerous influencing factors. This holds also true for their infrastructures that are processing and transducing information like endocrine networks or nerval channels. Therefore, the ability to compensate for noise is crucial for survival. An efficient mechanism to neutralise disturbances is instantiated in form of parallel complementary communication channels exerting antagonistic effects at their common receivers. Different signal processing types share the ability to suppress noise, to widen the system’s regulation capacity, and to provide for variable (...) gains while leaving the transferred signal to a large extent unchanged. (shrink)

Timers and sensors are common devices that make our daily life safer, more convenient, and more efficient. In a cellular context, they arguably play an even more crucial role as they ensure the survival of cells in the presence of various extrinsic and intrinsic stresses. Biological timers and sensors generate distinct signaling profiles, enabling them to produce different types of cellular responses. Recent data suggest that they can work together to guarantee correct timing and responsiveness. By exploring examples (...) of cellular stress signaling from mitosis, DNA damage, and hypoxia, the authors discuss the common architecture of timer‐sensor integration, and how its added features contribute to the generation of desired signaling profiles when dealing with stresses of variable duration and strength. The authors propose timer‐sensor integration as a widespread mechanism with profound biological implications and therapeutic potential. -/- . (shrink)

The juvenile hormones of insects regulate an unusually large diversity of processes during postembryonic development and adult reproduction. It is a long‐standing puzzle in insect developmental biology and physiology how one hormone can have such diverse effects. The search for molecular mechanisms of juvenile hormone action has been guided by classical models for hormone–receptor interaction. Yet, despite substantial effort, the search for a juvenile hormone receptor has been frustrating and has yielded limited results. We note here that a number of (...) lipid‐soluble signaling molecules in vertebrates, invertebrates and plants show curious similarities to the properties of juvenile hormones of insects. Until now, these signaling molecules have been thought of as uniquely evolved mechanisms that perform specialized regulatory functions in the taxon where they were discovered. We show that this array of lipid signaling molecules share interesting properties and suggest that they constitute a large set of signal control and transduction mechanisms that include, but range far beyond, the classical steroid hormone signaling mechanism. Juvenile hormone is the insect representative of this widespread and diverse system of lipid signaling molecules that regulate protein activity in a variety of ways. We propose a synthetic perspective for understanding juvenile hormone action in light of other lipid signaling systems and suggest that lipid activation of proteins has evolved to modulate existing signal activation and transduction mechanisms in animals and plants. Since small lipids can be inserted into many different pathways, lipid‐activated proteins have evolved to play a great diversity of roles in physiology and development. BioEssays 25:994–1001, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

Recent years have witnessed tremendous growth in the epidermal growth factor (EGF) family of peptide growth factors and the ErbB family of tyrosine kinases, the receptors for these factors. Accompanying this growth has been an increased appreciation for the roles these molecules play in tumorigenesis and in regulating cell proliferation and differentiation during development. Consequently, a significant question has been how diverse biological responses are specified by these hormones and receptors. Here we discuss several characteristics of hormone-receptor interactions and (...) receptor coupling that contribute to specificity: 1) a single EGF family hormone can bind multiple receptors; 2) a single ErbB family receptor can bind multiple hormones; 3) there are three distinct functional groups of EGF family hormones; 4) EGF family hormones can activate receptors in trans, and this heterodimerization diversifies biological responses; 5) ErbB3 requires a receptor partner for signaling; and 6) ErbB family receptors differentially couple to signaling pathways and biological responses. BioEssays 20:41–48, 1998. © 1998 John Wiley & Sons, Inc. (shrink)

Phosphatidylinositol 4,5‐bisphosphate (PI4,5P2) is a key lipid signaling molecule that regulates a vast array of biological activities. PI4,5P2 can act directly as a messenger or can be utilized as a precursor to generate other messengers: inositol trisphosphate, diacylglycerol, or phosphatidylinositol 3,4,5‐trisphosphate. PI4,5P2 interacts with hundreds of different effector proteins. The enormous diversity of PI4,5P2 effector proteins and the spatio‐temporal control of PI4,5P2 generation allow PI4,5P2 signaling to control a broad spectrum of cellular functions. PI4,5P2 is synthesized by (...) phosphatidylinositol phosphate kinases (PIPKs). The array of PIPKs in cells enables their targeting to specific subcellular compartments through interactions with targeting factors that are often PI4,5P2 effectors. These interactions are a mechanism to define spatial and temporal PI4,5P2 synthesis and the specificity of PI4,5P2 signaling. In turn, the regulation of PI4,5P2 effectors at specific cellular compartments has implications for understanding how PI4,5P2 controls cellular processes and its role in diseases. (shrink)

This is an Element surveying the most important literature using game theory and evolutionary game theory to shed light on questions in the philosophy of biology. There are two branches of literature that the book focuses on. It begins with a short introduction to game theory and evolutionary game theory. It then turns to working using signaling games to explore questions related to communication, meaning, language, and reference. The second part of the book addresses prosociality - strategic behavior that (...) contributes to the successful functioning of social groups - using the prisoner's dilemma, stag hunt, and bargaining games. (shrink)

The exploration of plant behavior on a cellular scale in a minimal invasive manner is key to understanding plant adaptations to their environment. Plant hormones regulate multiple aspects of growth and development and mediate environmental responses to ensure a successful life cycle. To monitor the dynamics of plant hormone actions in intact tissue, we need qualitative and quantitative tools with high temporal and spatial resolution. Here, we describe a set of biological instruments (reporters) for the analysis of the distribution (...) and signaling of various plant hormones. Furthermore, we provide examples of their utility for gaining novel insights into plant hormone action with a deeper focus on the drought hormone abscisic acid. (shrink)

After they diverged from panins, hominins evolved an increasingly committed terrestrial lifestyle in open habitats that exposed them to increased predation pressure from Africa’s formidable predator guild. In the Pleistocene, _Homo_ transitioned to a more carnivorous lifestyle that would have further increased predation pressure. An effective defense against predators would have required a high degree of cooperation by the smaller and slower hominins. It is in the interest of predator and potential prey to avoid encounters that will be costly for (...) both. A wide variety of species, including carnivores and apes and other primates, have therefore evolved visual and auditory signals that deter predators by credibly signaling detection and/or the ability to effectively defend themselves. In some cooperative species, these predator deterrent signals involve highly synchronized visual and auditory displays among group members. Hagen and Bryant (_Human Nature_, _14_(1), 21–51, 2003) proposed that synchronized visual and auditory displays credibly signal coalition quality. Here, this hypothesis is extended to include credible signals to predators that they have been detected and would be met with a highly coordinated defensive response, thereby deterring an attack. Within-group signaling functions are also proposed. The evolved cognitive abilities underlying these behaviors were foundations for the evolution of fully human music and dance. (shrink)

The paper is devoted to a conceptual model of cell patterning, based on a generalized notion of the epigenetic code of a cell determining its state. We introduce the concept of signaling depending both upon the spatial distance between cells and the distance between their cell states (s-distance); signaling can repel cells in the space of cell states (s-space) or attract them. The influence of different types of repelling signaling on the evolution of cells is considered. Stabilizing (...) signaling, namely a signaling monotonically decreasing with s-distance, causes the restoring of cell states after perturbations; destabilizing signaling, i.e., the one in which the signaling monotonically increases with s-distance, causes the appearance of pairs of cells with alternating cell states (one close to the state conventionally called “head”, and another close to the “tail” state). Non-monotonic (in s-space) signaling splits the cells into groups. The model shows that different types of signaling may provide different types of cellular patterns. General principles for applying this model to complex cellular structures are discussed. (shrink)

Recent discoveries have suggested the concept that intracellular signals are the sum of multiple, site‐specified subsignals, rather than single, homogeneous entities. In the context of cancer, searching for compounds that selectively block subsignals essential for tumor progression, but not those regulating “house‐keeping” functions, could help in producing drugs with reduced side effects compared to compounds that block signaling completely. The Ras‐ERK pathway has become a paradigm of how space can differentially shape signaling. Today, we know that Ras proteins (...) are found in different plasma membrane microdomains and endomembranes. At these localizations, Ras is subject to site‐specific regulatory mechanisms, distinctively engaging effector pathways and switching‐on diverse genetic programs to generate different biological responses. The Ras effector pathway leading to ERKs activation is also under strict, space‐related regulatory processes. These findings may open a gate for aiming at the Ras‐ERK pathway in a spatially restricted fashion, in our quest for new anti‐tumor therapies. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Sighs and Tears:Biological Signals and John Donne's "Whining Poetry"Michael A. WinkelmanPhebe: Good shepherd, tell this youth what 'tis to love. Silvius: It is to be all made of sighs and tears...—Shakespeare, As You Like It (5.2.83–84)ISighs and tears permeate John Donne's poetry, as well they should. Crying in particular functions as a costly signal in biological terms: a blatant, physiologically-demanding, involuntary indicator of hurt feelings. "Tears dim (...) mine eyes," laments Donne's Sappho ("Sappho to Philaenis," l. 56); they are "Fruits of much grief" in "A Valediction of Weeping" (l. 7).1 The theory of costly signaling, related to the handicap principle, was developed fairly recently by Israeli zoologists Amotz and Avishag Zahavi. As the Zahavis explain: "in order to be effective, signals have to be reliable; in order to be reliable, signals have to be costly."2 Initially their idea was resisted, but it has since become widely accepted and it has proven very helpful in making sense of both animal and human behavior. Wasteful conspicuous consumption among upper-class Americans, as noted a century ago by sociologist Thorstein Veblen, exemplifies this handicap principle in action. Like gazelles jumping in place or stotting rather than running away when wolves appear, it indicates fitness by flaunting excess resources.Shedding tears when feeling sad is an evolved human adaptation that broadcasts unhappiness. The wailing of infants demands attention, and crying does something similar for grown-ups: among other things, it tests the commitment of hearers to appease the distressed. For instance, in Chaucer's tragic medieval romance Troilus and Criseyde, Pandarus advises [End Page 329] Troilus to provoke a suitable reaction from Criseyde by embellishing his billet-doux: "Towchyng thi lettre... Biblotte it with thi teris ek a lite" (touching thy letter... Be-blot it with thy tears a little).3 Early modern authors also knew their importance. In the words of Robert Herrick, "tears are tongues," while Claudius suspects that "There's matter in these sighs, these profound heaves" (Hamlet, 4.1.1).4As a case in point, Donne was overwhelmed by the death of his dear wife Anne in 1617. As his contemporaneous biographer Izaak Walton reported: "his very soul was elemented of nothing but sadness; now, grief took so full a possession of his heart, as to leave no place for joy."5 Donne even hoped to be literally entombed with her soon: "as the grave is become her house, so I would hasten to make it mine also; that we two might there make our beds together in the dark" (Walton, p. 51). His miserable mood was revealed in his initial sermon after her demise:His first motion from his house was to preach, where his beloved wife lay buried (in St. Clement's Church, near Temple-Bar, London) and his text was a part of the Prophet Jeremiah's Lamentation: "Lo, I am the man that have seen affliction."And indeed, his very words and looks testified him to be truly such a man; and they, with the addition of his sighs and tears expressed in his Sermon, did so work upon the affections of his hearers as melted and molded them into a companionable sadness; and so they left the Congregation.(Walton, p. 52)Listeners responded in kind to his honest confessions, a textbook illustration of the empathy generated by crying. (A related issue—how and why literature affects audiences so strongly—is currently generating some very interesting work from New Humanists investigating the question from an evolutionary perspective.)These qualities make sighs and tears fundamental to love poetry. In other words, writers deploy them because they reflect universal states of mind, rather than originating as some arbitrary, socially-constructed literary device. The copious opening sonnet of Petrarch's magnificent Rime sparse codifies the theme:6You who can hear in scattered rhymes the soundof all that sighing which once fed my heartin my first youthful error, when in partI was a person of a different kind—my changing manner as I weep and reason, [End Page 330] between vain aspirations and vain grief,leads everyone who has known... (shrink)

The identification of molecules controlling embryonic patterning and their functional analysis has revolutionized the fields of Developmental and Cell Biology. The use of new sequence information and modern bioinformatics tools has enriched the list of proteins that could potentially play a role in regulating cell behavior and function during early development. The recent application of efficient methods for gene knockout in zebrafish has accelerated the functional analysis of many proteins, some of which have been overlooked due to their small size. (...) Two recent publications report on the identification of one such protein and its role in zebrafish embryogenesis. The protein, currently designated Apela, was shown to act as a secreted protein whose absence adversely affected various early developmental processes. Additional signaling proteins that have been identified in one of the studies are likely to open the way to unraveling hitherto unknown developmental pathways and have the potential to provide a more comprehensive understanding of known developmental processes. (shrink)

Lysophosphatidic acid (LPA) is a lipid mediator with a wide variety of biological actions, particularly as an inducer of cell proliferation, migration and survival. LPA binds to specific G‐protein‐coupled receptors and thereby activates multiple signal transduction pathways, including those initiated by the small GTPases Ras, Rho, and Rac. LPA signaling has been implicated in such diverse processes as wound healing, brain development, vascular remodeling and tumor progression. Knowledge of precisely how and where LPA is produced has long proved (...) elusive. Excitingly, it has recently been discovered that LPA is generated from precursors by ‘autotaxin’, a once enigmatic exo‐phosphodiesterase implicated in tumor cell motility. Exogenous phospholipases D can also produce LPA, which may contribute to their toxicity. Here we review recent progress in our understanding of LPA bioactivity, signaling and synthesis. BioEssays 26:870–881, 2004. © 2004 Wiley Periodicals, Inc. (shrink)