It's also possible that constant low-grade digestive problems explain a great deal about the Vilani temperament. :)

On Wed, Aug 31, 2016 at 4:14 PM, Richard Aiken <xxxxxx@gmail.com> wrote:

Vilani gut flora would have been under constant siege by the VIlani diet. That is, the contaminant levels would have probably kept the flora levels consistently very low. Given this constant low-level stress, it's possible that those few gut flora that mutated into lethal form killed their hosts too quickly to allow colonization of other human guts.