The Caduceus Enclave is a group on Earth dedicated to bettering human life through medical advancement.
The enclave is extremely insular, living in domes refusing to have contact with outsiders, only allowing people in who are in need of extreme medical assistance. It seems that the members of the enclave are raised as vegetarians.
They believe that humanity should not seek contact with alien life. People who chose to leave the society are not welcome back, and they refuse to make contact or allow contact with those who leave.
- Caduceus is the staff carried by Mercury as messenger of the gods. It's used as an emblem of the medical profession and as the insignia of the U.S. Army Medical Corps.