I mentioned once that we had managed to do a little experimentation on your own race. As I said, the boss led us to believe we were looking for a way to give you back the unending life the master took away from you after the boss's failed plan. (As I've said so often before, I don't understand all that happened, much less why; so don't expect an explanation from me.)
We did know one thing. Your bodies, like ours, were designed for a sort of ongoing regeneration. Old, worn out cells are continually replaced. As long as this mechanism works your bodies (like ours) function perfectly. Every organ is, at the most, only a few years old.
I also mentioned our discovery that things happened in a cell that cannot be explained through the laws of physics and biochemistry. This regenerative process involves a number of those unexplainable phenomena. For that reason, we can't figure out why your cells eventually wear down and quit replacing themselves. But it happens.
Granted, few members of your race ever reach that "natural" barrier to longevity. Environmental stresses combined with your natural tendency to engage in harmful behavior usually cause the end of your lives. But your advances in biotechnology mean that you're finding ways to compensate for the damage you have done to your systems. In fact, some of your scientists have sensed the real limit to human longevity -- approximately 120 years. (That limit, by the way, was imposed by the master about the same time we devised our plan to totally destroy your race. Please don't ask me to explain the master's actions.)
At any rate, we did learn a lot about that process. Eventually the boss had us revisit that work. What if, he suggested, we could tamper with the regenerative process? Cells would begin to divide without regard to whether new cells were needed. You've probably already guessed -- you call this cancer. Through this means the boss has imposed much suffering and death on your race.
I have been most baffled by the random nature of the boss's attacks. Of course we aren't directly involved in all occurrences of the disease. Once we introduced the weaknesses into your genetic structure, any number of enviornmental contaminants can set these problems off. Still, it would make sense to me if the boss focused his attacks on those of your race least likely to support our goals. That does happen from time to time, but the boss has been known to directly attack someone who has done much to further our cause among you.
There have been many other attacks on your race. I mentioned earlier the alterations we have made to a number of one-celled organisms. These life forms, originally designed to assist you and the other large animals of your planet with biological processes such as the digestion of food, can be easily altered to attack your tissues. The boss has ordered numerous such alterations.
In the last hundred years or so we have been quite busy adapting these organisms to withstand the substances you have developed to kill them; antibiotics as you call them. This limits the power of your medicines to protect you from these new strains. Your scientists, so far, have continued to believe our cover story, assuming that such rapid transformations can be explained by the large number of generations of these organisms over a relatively short period of time. (Such adaptive modifications do take place "naturally," to be sure. But it takes more time than you think for chance mutations to generate an appropriate adaptation, particularly to substances specifically designed to kill the organism.)
The new fragility of your genetic structures (given the increased bombardment of your planet by cosmic radiation) was bound, eventually, to produce badly deformed individuals. We studied a number of these persons quite thoroughly in the early days after the disaster that nearly destroyed your planet. Then the boss issued one of the orders I most despise.
Generate some alterations, he ordered, that would result in a physically viable but mentally deficit individual. (Yes, he's also ordered alterations that leave an individual barely able to survive physically.) We actually added a chromosome to your DNA to accomplish that.
As I've said repeatedly, I do not understand the boss's desire to impose such damage and suffering to your race. If the master would let me return, I'd leave the boss and go back to our original home. But since the master won't let any of us out of your solar system any longer, and since the boss would wreak violent vengeance on anyone who left him, we all continue to work for him. We really have no choice in the matter.
What will happen when the boss finds out about this book? I tremble to contemplate. Maybe he'll kill me. Given the mess we find ourselves in I might welcome that.