Infection threat shapes our social instincts

Abstract

We social animals must balance the need to avoid infections with the need to interact with conspecifics. To that end we have evolved, alongside our physiological immune system, a suite of behaviors devised to deal with potentially contagious individuals. Focusing mostly on humans, the current review describes the design and biological innards of this behavioral immune system, laying out how infection threat shapes sociality and sociality shapes infection threat. The paper shows how the danger of contagion is detected and posted to the brain; how it affects individuals’ mate choice and sex life; why it strengthens ties within groups but severs those between them, leading to hostility toward anyone who looks, smells, or behaves unusually; and how it permeates the foundation of our moral and political views. This system was already in place when agriculture and animal domestication set off a massive increase in our population density, personal connections, and interaction with other species, amplifying enormously the spread of disease. Alas, pandemics such as COVID-19 not only are a disaster for public health, but, by rousing millions of behavioral immune systems, could prove a threat to harmonious cohabitation too.

Testing the Disgust-Based Mechanism of Homonegative Attitudes in the Context of the COVID-19 Pandemic

“…Disease avoidance mechanisms and their potential role in explaining social attitudes have recently received much scientific attention (e.g., Mentser and Nussinson, 2020;Kramer and Bressan, 2021). In the context of the ongoing COVID-19 pandemic, they have become even more pertinent (Bressan, 2020;Seitz et al, 2020;Hromatko et al, 2021).…”

Social distancing from foreign individuals as a disease-avoidance mechanism: Testing the assumptions of the behavioral immune system theory during the COVID-19 pandemic

“…Therefore, a number of non-infectious physical and mental abnormalities that are only heuristically associated with disease (such as disfigurements, disabilities or obesity) trigger the system (Miller & Maner, 2011;Park et al, 2003). Also, as Kramer and Bressan (2021) indicate, possibly because parasites make people look or behave unusually, people tend to perceive any atypical appearance as a possible sign of infection (see also Nussinson et al, 2018). Triggered reactions involve behavioral avoidance and are the same reactions that are elicited by people who are actually diseased (Snyder et al, 1979).…”

“…During the COVID-19 pandemic, topics of negative attitudes toward outgroups and the related social distancing tendencies have become important issues among scientists (e.g., Hromatko et al, 2021;Kramer & Bressan, 2021;Meleady et al, 2021;Sorokowski et al, 2020). One of the reasons for this intensified scientific interest is that social distancing, as well as the various factors that precede it, such as prejudices or xenophobic attitudes, have their origin in the perception of threat (Faulkner et al, 2004).…”

Mitochondria-Microbiota Interaction in Neurodegeneration

“…Methionine can be recycled from dysfunctional mitochondria or other cellular debris as well ( Kitada et al, 2021 ). A chemical reaction of methionine with adenosine triphosphate (ATP), which is biology’s most important portable energy store, produces S-adenosyl-methionine (SAM), which is biology’s most important molecule for the silencing or expression of genes ( Loenen, 2006 ; Janke et al, 2015 ; Kramer and Bressan, 2021 ). In fact, it is not methionine itself but SAM that promotes growth and reproduction and diminishes maintenance and recycling ( Kitada et al, 2021 ).…”