I cannot comment on Dr. Chagnon because he was pretty much out of the picture at Michigan by the time that I got there, but it has never seemed to me that Dr. Chagnon was an hapless instrument carrying out Dr. Neel's research program. It is also true that Dr. Neel followed up the genetic consequences of the Japanese atomic bomb blasts. These are topics that are important to the interface of genetics, health, and society. It is important to note that he documented the consequences to those who had been exposed to radiation but he did not expose individuals to radiation. Dr. Neel did observe a 'virgin soil' measles epidemic in the Yanomama.
Earlier accounts hold that the epidemic originated with measles in the child of a missionary.
This is sound from an epidemiological perspective because at the time most adults in Europe and the United States were immune to measles by virtue of childhood exposure. I really cannot give the details of treatments and vaccines delivered by the Michigan team. However, it is worth noting that Dr. Neel was a physician and that he regarded his role as a physician every bit as seriously as he regarded his role as a scientist. He was also well aware of the difference between these roles. His view on the spread of measles was novel and challenged the prevailing wisdom of the 1960s and 1970s but he developed it to explain what he saw.