A group of biologists examine the multitude of unseen bacteria and viruses that inhabit every part of the globe, as well as the distinct differences between “good” and “bad” microbes.  The guests emphasize that the key to understanding microbes is their amazing evolutionary potential, or the ability to change properties quickly.  The surprising element in the show is when they debate how microbes can cause certain kinds of cancer and may even be the culprits behind a wide range of human afflictions, from Alzheimer’s Disease to neurological disorders.  With Agnes Day, Paul Ewald, Alice Huang, Lucy Shapiro.