Does the Coronavirus Increase Sociability?
Parasite/host relations and how they may relate to the spread of COVID-19.
Posted Mar 07, 2020
Worried about the coronavirus? Me too. Here's an evolutionary take on how this virus may bear on the human social experience.
From an evolutionary perspective, organisms that come to exist in large numbers generally have a broad array of adaptations, or attributes that serve to increase their ability to replicate. This idea is essentially the foundation of modern evolutionary reasoning.
Someone asked me the other day to explain coronavirus from an evolutionary perspective. Easy as pie, unfortunately. The coronavirus, like any organism, evolved properties that facilitate its own reproduction. Any organism that is not effective at facilitating its own reproduction will fail to pass the Herculean test that is natural selection.
According to the World Health Organization, coughing is a foundational symptom of coronavirus (as it is for flu, the common cold, and so many other contagious illnesses).
Ever stop to wonder why coughing (and, often, sneezing) are such hallmark symptoms of these illnesses?
The evolutionary perspective suggests that we look at things from the perspective of the virus itself, in this case. If the virus facilitates coughing—especially in close proximity to others—then it has an increased chance of replicating itself. Done. That’s how Darwinian adaptations work.
Viruses as Manipulators of Host Behavior
We know full well that parasites can affect behavior. As I wrote in this piece from 2018, titled Does the Flu Trick People into Being Sociable:
Do Parasites Affect Behavior? The answer to this question is straightforward: Yes. Many instances of parasites affecting behavior have been documented (see Moore, 2002). Perhaps the best-known instance of this pertains to Toxoplasma gondii, which travels from cats into other mammals, including mice. And humans, often with adverse consequences.
This parasite has a very interesting effect on the behavior of mice. When evidence of a cat is present, a typical mouse makes itself scarce. But a mouse infected with Toxoplasma gondii does anything but become scarce when a cat is nearby. In fact, an infected mouse shows a strong tendency to go right out into the open — easy prey for the furry killing machines. This parasite must make it into the body of a cat to advance its life course, so it makes good sense that these parasites evolved the capacity to manipulate the nervous systems of mice in such a way.
It turns out that mice are not the only mammals that are susceptible to such effects. You and I may be as well.
In a provocative study on the social-behavioral effects of the flu, renowned biomedical anthropologist, Chris Reiber, and her colleagues (2010) found evidence for an increased social drive in young adults who have the flu during the asymptomatic early stages of the illness. In short, it looks like people who have the flu but who don’t yet know it are more likely to seek out social opportunities (such as attending parties) compared with others who are without the flu virus in their system. Think about that.
A Possible Social-Behavioral Component of the Coronavirus?
Importantly, this section is pure speculation. I have not systematically collected social-behavioral data on people infected with the coronavirus. But I will add this: Such speculation may actually be useful because this facet of things does not seem to be something that is being considered by the broader scientific community in a thoughtful and comprehensive manner right now.
We are being told to stop shaking hands with others and to keep a distance from others in general. Further, we know that such social-distancing tactics are helpful in reducing the spread of the virus (see this article at sky.com for a systematic take on this point) .
In light of all this, it may be worth considering if the coronavirus, like the common flu, may actually have some proximate mechanisms by which it increases human sociality in an evolved (and obviously unconscious) effort to facilitate its own replication. Remember, from a Darwinian perspective, this is how natural selection rolls.
For decades, scientists have been aware that parasites often have the capacity to hijack systems within a host’s body so as to lead to responses and behaviors that ultimately serve to help the parasite itself replicate (often at a cost to the host; see Moore, 2002).
As the scientific community works collaboratively to address the current coronavirus crisis, all facets of scientific inquiry that are potentially relevant should be brought to the table. The scientific study of evolution and behavior is, to my mind, highly relevant and, as such, should be included in our efforts.
While the hypothesis proposed here is, to this point, speculation, it seems to me that it would be quite worth knowing if the coronavirus somehow manipulates the behavior of human hosts in ways that serve to increase the spread of the virus. Information on this point might lead to additional ways of thinking about how to fight this crisis that is affecting our worlds more and more each and every day.
This all said, please follow the guidance of the World Health Organization and of other legitimate institutions connected with health as we work together, as one people, to address this threat that has been foisted upon us. As I tell my students and my kids: We got this.
Moore, J. (2002). Parasites and the Behavior of Animals. New York: Oxford University Press.
Reiber, C., E.C. Shattuck, S. Fiore, V. David, P. van Goozen, and J. Moore. 2010. Change in human social behavior in response to a common vaccine. Annals of Epidemiology 20(10): 729-733. DOI: 10.1016/j.annepidem.2010.06.014