A somewhat unexpected monkey came out of the bag: the data suggested that there was a difference in how old mangabeys would get when they lived their lives in North American versus in European zoos. It remains to be discovered whether this is explained by genetic factors (“good” or “bad” genes), environmental factors (like husbandry, the climate, different diets, etc.), a combination of the two, or something else entirely.
To keep optimizing the welfare and longevity of all mangabeys in zoos worldwide, more research is obviously necessary. Luckily, zoos conduct a ton of research projects and they collaborate with universities, museums and countless other organizations! I talk about this, and about the mangabeys of course, in
this
Naturalis video.