What about effects of lifestyle?
This is interesting data indeed, however if we're looking at eunuchs who served under kings we should also take into account lifestyle. Someone serving royalty would have access to much better food, healthcare, and living standards than a typical person, which are factors that could also extend their life. So if we're comparing lifespans of eunuchs to kings with the average male of the time, most of whom would be farmers or laborers with a markedly different lifestyle, then we can't ignore these important factors as part of the outcome. For example, what's the difference in average lifespan of someone in the royal circles vs. an average field work from that time period? I bet there would be enough of a gap to take into account.
