Exactly. The control group is there to, for example, make sure your culture of Ebola is really that, viable and so on. If they didn't get sick, let alone die,

Exactly. The control group is there to, for example, make sure your culture of Ebola is really that, viable and so on. If they didn't get sick, let alone die, you'd know your experimental group results were invalid. Monkeys are also very expensive animals to do research on, and no one likes to kill them, or at least we don't tend to have the same sentiments about mice and rats.