Can microbes make us better people? Explaining the evolution of host altruism


Summary:  The scientist proposed that natural selection acting on microbes caused them to be more successful when they manipulate the host by changing its behavior, for example by making it more social in order to have a chance to spread to other hosts. That also explains why a person that has received an act of kindness is more likely to reciprocate it, starting what is called a “snowballing effect” of favors, and probably microbial spread.

Connections:  This article connects to the lecture about the human microbiome, and how the kind of microbes living in and on us can affect not only our health, aging, and energy levels, but also our behavior.

Analysis:  This research is extremely important in more than just the field of human medicine; it has the ability to influence what we think we know about ecology and relationships among animals, such as ants/bees and other social insects and animals caring for offspring that is not related to them. It could be considered one of the main theories about the evolution of altruism, and the first to consider factors other than genetics.

Questions:  What happens if the microbe and the host have conflicting interests? How can the host avoid being controlled by its microbes? What is the effect of antibiotics or probiotics on the behavior of the host? Which microbes are able to manipulate their hosts?

2 Comments for “Can microbes make us better people? Explaining the evolution of host altruism”



I find this very fascinating. When doing research for this assignment I came across another article that described an experiment like this being done on mice. When the bacteria of one mouse was given to another the receiving mouse began to display behavioral traits of the donor. What I would like to know is how these microbes are going about changing our behavior. I know rabies effects animal behavior by effecting the gray matter of the brain, maybe these microbes promote altruism in a similar way.

I imagine that if the host and microbe have drastically conflicting interests than this wouldn’t end up being a beneficial relationship. If the microbe causes the host to act in a way that isn’t beneficial to its health then the host dies, and if the host dies then the microbe dies along with it. Seems to me that the microbes would want to work, at least somewhat, in harmony with their hosts.



This article seemed to me to be about how microbes that increase the success of human and as a by product increase their spread seem to be selected for by nature. There is a game called plague inc where you are a microbe trying to wipeout human kind. One of the microbes changes human behavior to increase kissing and thus increase its spread by increasing the production of sexual hormones in their host. According to the article this sort of a microbe would be more positively selected for. As for the question of what happens when the microbe and the host have conflicting interests, according to the article this microbe would be selected against and die out.