A reader passes along an unsettling segment on insects:

Another reader writes:

Dan Dennett gave a talk at TED a few years ago wherein he discussed a brain parasite that causes ants to commit suicide. The parasite can only reproduce in the belly of a cow, so it causes ants to climb to the top of grass stalks in a deliberate attempt to be eaten by a cow. It takes over the ant's mind.  Can you image something like that in humans?  Scary.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.