Causes and Consequences of Sociality in Bats

Kerth, G. (2008). Causes and consequences of sociality in bats. Bioscience58(8), 737-746.


Bats are among the most diverse and most gregarious of all mammals. This makes them highly interesting for research on the causes and consequences of sociality in animals. Detailed studies on bat sociality are rare, however, when compared with the information available for other social mammals, such as primates, carnivores, ungulates, and rodents. Modern field technologies and new molecular methods are now providing opportunities to study aspects of bat biology that were previously inaccessible. Consequently, bat social systems are emerging as far more complex than had been imagined. Variable dispersal patterns, complex olfactory and acoustic communication, flexible context-related interactions, striking cooperative behaviors, and cryptic colony structures in the form of fission-fusion systems have been documented. Bat research can contribute to the understanding of animal sociality, and specifically to important topics in behavioral ecology and evolutionary biology, such as dispersal, fission fusion behavior, group decision making, and cooperation.

Keywords: cooperation, fission-fusion, group decisions, kinship, social behavior

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The Influence of Social Hierarchy on Primate Health

Sapolsky, R. M. (2005). The influence of social hierarchy on primate health. Science308(5722), 648-652.


Dominance hierarchies occur in numerous social species, and rank within them can greatly influence the quality of life of an animal. In this review, I consider how rank can also influence physiology and health. I first consider whether it is high- or low-ranking animals that are most stressed in a dominance hierarchy; this turns out to vary as a function of the social organization in different species and populations. I then review how the stressful characteristics of social rank have adverse adrenocortical, cardiovascular, reproductive, immunological, and neurobiological consequences. Finally, I consider how these findings apply to the human realm of health, disease, and socioeconomic status.


The reactive scope model—a new model integrating homeostasis, allostasis, and stress

Romero, L. M., Dickens, M. J., & Cyr, N. E. (2009). The reactive scope model—a new model integrating homeostasis, allostasis, and stress. Hormones and behavior55(3), 375-389.


Allostasis, the concept of maintaining stability through change, has been proposed as a term and a model to replace the ambiguous term of stress, the concept of adequately or inadequately coping with threatening or unpredictable environmental stimuli. However, both the term allostasis and its underlying model have generated criticism. Here we propose the Reactive Scope Model, an alternate graphical model that builds on the strengths of allostasis and traditional concepts of stress yet addresses many of the criticisms. The basic model proposes divergent effects in four ranges for the concentrations or levels of various physiological mediators involved in responding to stress. (1) Predictive Homeostasis is the range encompassing circadian and seasonal variation — the concentrations/levels needed to respond to predictable environmental changes. (2) Reactive Homeostasis is the range of the mediator needed to respond to unpredictable or threatening environmental changes. Together, Predictive and Reactive Homeostasis comprise the normal reactive scope of the mediator for that individual. Concentrations/levels above the Reactive Homeostasis range is (3) Homeostatic Overload, and concentrations/levels below the Predictive Homeostasis range is (4) Homeostatic Failure. These two ranges represent concentrations/levels with pathological effects and are not compatible with long-term (Homeostatic Overload) or short-term (Homeostatic Failure) health. Wear and tear is the concept that there is a cost to maintaining physiological systems in the Reactive Homeostasis range, so that over time these systems gradually lose their ability to counteract threatening and unpredictable stimuli. Wear and tear can be modeled by a decrease in the threshold between Reactive Homeostasis and Homeostatic Overload, i.e. a decrease in reactive scope. This basic model can then be modified by altering the threshold between Reactive Homeostasis and Homeostatic Overload to help understand how an individual’s response to environmental stressors can differ depending upon factors such as prior stressors, dominance status, and early life experience. We illustrate the benefits of the Reactive Scope Model and contrast it with the traditional model and with allostasis in the context of chronic malnutrition, changes in social status, and changes in stress responses due to early life experiences. The Reactive Scope Model, as an extension of allostasis, should be useful to both biomedical researchers studying laboratory animals and humans, as well as ecologists studying stress in free-living animals.

Homeostasis, behavioral adjustment and the concept of health and disease


G L Engel’s (1953) theory of homeostasis


The psychiatrist G L Engel is famous for his concept of the‘biopsychosocial model’(BPSM), which has been cited, to date, 14109 times: 

Engel, G. L. (1977). The need for a new medical model: a challenge for biomedicine. Science196(4286), 129-136.

Much less cited but, arguably, a more interesting and significant contribution is Engel’s earlier paper about homeostasis, behavioral adjustment and the concept of health and disease. See details below:


Engel, G. L. (1953). Homeostasis, behavioral adjustment and the concept of health and disease. In R. R. Grinker (Ed.), Mid-century psychiatry: an overview (p. 33–59). C. C. Thomas. 


All the phenomena of disease can be derived from interference with attempts at satisfaction of instinctual needs; inner perception of a disturbed equilibrium or unsatisfied need, with the concept of a danger signal; chemical, physiological, psychological and social adaptive devices coping with the stress; and structural or functional damage resulting from the stress and from attempts at adaptation which are inappropriate or unsuccessful.

Role of Exosomes in the Regulation of T-Cell Mediated Immune Responses and in Autoimmune Disease

Anel, A., Gallego-Lleyda, A., de Miguel, D., Naval, J., & Martínez-Lostao, L. (2019). Role of exosomes in the regulation of T-cell mediated immune responses and in autoimmune disease. Cells8(2), 154.


T-cell mediated immune responses should be regulated to avoid the development of autoimmune or chronic inflammatory diseases. Several mechanisms have been described to regulate this process, namely death of overactivated T cells by cytokine deprivation, suppression by T regulatory cells (Treg), induction of expression of immune checkpoint molecules such as CTLA-4 and PD-1, or activation-induced cell death (AICD). In addition, activated T cells release membrane microvesicles called exosomes during these regulatory processes. In this review, we revise the role of exosome secretion in the different pathways of immune regulation described to date and its importance in the prevention or development of autoimmune disease. The expression of membrane-bound death ligands on the surface of exosomes during AICD or the more recently described transfer of miRNA or even DNA inside T-cell exosomes is a molecular mechanism that will be analyzed.

Keywords: exosomes; extracellular vesicles; immune regulation; autoimmunity.


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Homeostasis and consumer behavior across cultures

Parker, P. M., & Tavassoli, N. T. (2000). Homeostasis and consumer behavior across cultures. International Journal of Research in Marketing, 17(1), 33-53.


The focus of this paper is the process of homeostasis by which the body seeks to regulate its internal environment. In particular, we present a global model for a set of consumer behaviors that may vary across cultures as a direct response to the intensity and duration of sunlight and experienced temperature. This process creates physical and psychological needs, so that changes in sunlight and temperature may be reflected in various behaviors. We integrate research findings from the neural sciences and psychology to generate testable predictions of relevance to the marketing literature. These hypotheses predict how the physical environment motivates variations in the consumption of different types of products, and how mood, expressed affect, and related affective behaviors may vary across cultures. We also consider how variations in sunlight and temperature may affect consumer behaviors related to consumers’ optimal stimulation levels. We conclude by discussing the implications of a physiological model on the debate of global convergence in consumer behavior.

Sleep function and synaptic homeostasis

Tononi, G., & Cirelli, C. (2006). Sleep function and synaptic homeostasis. Sleep medicine reviews10(1), 49-62.


This paper reviews a novel hypothesis about the functions of slow wave sleep—the synaptic homeostasis hypothesis. According to the hypothesis, plastic processes occurring during wakefulness result in a net increase in synaptic strength in many brain circuits. The role of sleep is to downscale synaptic strength to a baseline level that is energetically sustainable, makes efficient use of gray matter space, and is beneficial for learning and memory. Thus, sleep is the price we have to pay for plasticity, and its goal is the homeostatic regulation of the total synaptic weight impinging on neurons. The hypothesis accounts for a large number of experimental facts, makes several specific predictions, and has implications for both sleep and mood disorders

Consciousness without a cerebral cortex

Merker, B. (2007). Consciousness without a cerebral cortex: A challenge for neuroscience and medicine. Behavioral and brain sciences30(1), 63-81.


A broad range of evidence regarding the functional organization of the vertebrate brain – spanning from comparative neurology to experimental psychology and neurophysiology to clinical data – is reviewed for its bearing on conceptions of the neural organization of consciousness. A novel principle relating target selection, action selection, and motivation to one another, as a means to optimize integration for action in real time, is introduced. With its help, the principal macrosystems of the vertebrate brain can be seen to form a centralized functional design in which an upper brain stem system organized for conscious function performs a penultimate step in action control. This upper brain stem system retained a key role throughout the evolutionary process by which an expanding forebrain – culminating in the cerebral cortex of mammals – came to serve as a medium for the elaboration of conscious contents. This highly conserved upper brainstem system, which extends from the roof of the midbrain to the basal diencephalon, integrates the massively parallel and distributed information capacity of the cerebral hemispheres into the limited-capacity, sequential mode of operation required for coherent behavior. It maintains special connective relations with cortical territories implicated in attentional and conscious functions, but is not rendered nonfunctional in the absence of cortical input. This helps explain the purposive, goal-directed behavior exhibited by mammals after experimental decortication, as well as the evidence that children born without a cortex are conscious. Taken together these circumstances suggest that brainstem mechanisms are integral to the constitution of the conscious state, and that an adequate account of neural mechanisms of conscious function cannot be confined to the thalamocortical complex alone.

Keywords: action selection; anencephaly; central decision making; consciousness; control architectures; hydranencephaly; macrosystems; motivation; target selection; zona incerta

Mentalizing homeostasis: The social origins of interoceptive inference

Fotopoulou, A., & Tsakiris, M. (2017). Mentalizing homeostasis: The social origins of interoceptive inference. Neuropsychoanalysis19(1), 3-28.
Is the self already relational in its very bodily foundations? The question of whether our mental life is initially and primarily shaped by embodied dimensions of the individual or by interpersonal relations is debated in many fields, including psychology, philosophy, psychoanalysis, and more recently, cognitive neuroscience. In this interdisciplinary target article, we put forward the radical claim that even some of the most minimal aspects of selfhood, namely the feeling qualities associated with being an embodied subject, are fundamentally shaped by embodied interactions with other people in early infancy and beyond. Such embodied interactions allow the developing organism to mentalize its homeostatic regulation. In other words, embodied interactions contribute directly to the building of mental models of the infant’s physiological states, given the need to maintain such states within a given dynamic range despite internal or external perturbations. Specifically, our position rests on the following three propositions: (1) the progressive integration and organization of sensory and motor signals constitutes the foundations of the minimal self, a process which we have linked to contemporary, computational models of brain function and named “embodied mentalization”; (2) interactions with other people are motivated and constrained by the same principles that govern the “mentalization” of sensorimotor signals in the individual – and hence the mentalization of one’s body can include signals from other bodies in physical proximity and interaction, especially in interaction with particular bodies. (3) Crucially, given the dependency of humans in early infancy, there is a “homeostatically necessary” plethora of such embodied “proximal” interactions, especially as regards interoception. Collectively, such experiences of proximal intercorporeality “sculpt” the mentalization process and hence the constitution of the minimal self, including the progressive sophistication of mental distinctions between “subject-object,” “self-other” and even “pleasure-pain.” Finally, we explore notions of cardiac and more broadly interoceptive awareness as later, cognitive acquisitions that allow us to progressively solidify such distinctions, as well as understand and empathise with other people.
self; affect; emotion; awareness; social cognition; touch; interoception; intersubjectivity; embodiment; skin ego; minimal self