Bacteria, viruses and the human mind

The following is a quote that I read in the June issue of Harper’s magazine.  It is from the forthcoming book, The Unreality of Memory by Elisa Gilbert.

Viruses and bacteria hijack our minds and make us act weirdly.

For example, Toxoplasma gondii, a parasite found in cat feces, makes mice less afraid of cats; this is an evolutionary strategy, making it easier for the parasite to get from the mouse to the cat.

When it spreads to humans, it may increase their risk-taking.  One study found that people with toxoplasmosis, the infection caused by the parasite, “are more likely to major in business.”  An NBC News story suggested optimistically that the parasite “may give people the courage they need to become entrepreneurs.”

That would be an extreme case of a microscopic parasite altering the course of our lives.  But viruses and bacteria influence our everyday behavior as well.

A 2010 study, for example, found that people become more sociable in the forty-eight hours after exposure to the flu virus, a period in which one is contagious but asymptomatic.  The infected hosts, researchers found, were significantly more likely to head out to bars and parties.

I know of no evidence that coronavirus infection influences human behavior.  None whatsoever.  I am not hinting or implying that it does.

But, as a thought experiment, suppose it did.  How would the virus influence its hosts’ feelings, thoughts and behavior?  What changes would it induce to help itself survive, reproduce and spread?

Tags: Infectious Disease