The Holobiont Blindspot: Relating Host-Microbiome Interactions to Cognitive Biases and the Concept of the "Umwelt"

Food webs in food webs: the micro-macro interplay of multilayered networks

Food webs are typically defined as being macro-organism-based (e.g., plants, mammals, birds) or microbial (e.g., bacteria, fungi, viruses). However, these characterizations have limits. We propose a multilayered food web conceptual model where microbial food webs are nested within food webs composed of macro-organisms. Nesting occurs through host-microbe interactions, which influence the health and behavior of host macro-organisms, such that host microbiomes likely alter population dynamics of interacting macro-organisms and vice versa. Here, we explore the theoretical underpinnings of multilayered food webs and the implications of this new conceptual model on food web ecology. Our framework opens avenues for new empirical investigations into complex ecological networks and provides a new lens through which to view a network's response to ecosystem changes.

Is depression the missing link between inflammatory mediators and cancer?

Patients with cancer are at greater risk of developing depression in comparison to the general population and this is associated with serious adverse effects, such as poorer quality of life, worse prognosis and higher mortality. Although the relationship between depression and cancer is now well established, a common underlying pathophysiological mechanism between the two conditions is yet to be elucidated. Existing theories of depression, based on monoamine neurotransmitter system dysfunction, are insufficient as explanations of the disorder. Recent advances have implicated neuroinflammatory mechanisms in the etiology of depression and it has been demonstrated that inflammation at a peripheral level may be mirrored centrally in astrocytes and microglia serving to promote chronic levels of inflammation in the brain. Three major routes to depression in cancer in which proinflammatory mediators are implicated, seem likely. Activation of the kynurenine pathway involving cytokines, increases tryptophan catabolism, resulting in diminished levels of serotonin which is widely acknowledged as being the hallmark of depression. It also results in neurotoxic effects on brain regions thought to be involved in the evolution of major depression. Proinflammatory mediators also play a crucial role in impairing regulatory glucocorticoid mediated feedback of the hypothalamic-pituitary-adrenal axis, which is activated by stress and considered to be involved in both depression and cancer. The third route is via the glutamatergic pathway, whereby glutamate excitotoxicity may lead to depression associated with cancer. A better understanding of the mechanisms underlying these dysregulated and other newly emerging pathways may provide a rationale for therapeutic targeting, serving to improve the care of cancer patients.

Dances with dogs: interspecies play and a case for sympoietic enactivism

I argue that an enactivist framework has more explanatory power than traditional philosophical theories of cognition when it comes to understanding the mechanisms underlying human-animal relationships. In both intraspecies and interspecies exchanges, what we often find are novel forms of cognition emerging from such transactions, but these "co-cognitive" processes cannot be understood apart from the interaction itself. I focus on a specific form of human-animal interaction-play, as it occurs between humans and domestic dogs-and argue that the best theory suited to the task of explaining how these two species create unique thought processes is a "sympoietic enactivism." Rather than the more common "autopoietic" arguments defended by many enactivists, I argue that what is more accurately occurring during bouts of human-dog play is sympoietic, or "collectively producing." Drawing on several different disciplines that converge on similar conclusions about creativity and collaboration, I show that human-dog play is a quintessential case of cognition that cannot be readily understood by appealing to the inner workings of either individual among the dyad. Thinking, on this view, is a form of play, and in playful interaction what gets created are wholly intersubjective modes of thought.