A question here asks for the name of the category of viruses that affect only one side of the body. My question is about the evolutionary purpose of that 'affects only one side' behavior.
Chicken pox is not usually fatal, and it's not clear to me why evolution would set such a low bar for eliminating the weaklings in the herd. On the opposite end, small pox was excessively fatal; I guess that's the price of evolution biohacking its way by trial and error.
On the other hand, I can see how shingles, afflicting people only in later life, can be debilitating enough to keep one from going hunting and gathering and moaning one's way to death by starvation. But for that to happen isn't it more efficient for the virus to resurface across the entire nervous system instead of parts of just one side? If shingles happened, say, in the late teens, I could understand that 'affects-only-one-side' eliminates only the weaker part of the herd. But it's mostly older people, well past their reproductive prime, who get shingles, and get it only on one side. I see no benefit to the individual or the group of contracting an 'expire by date' virus early in life and then the virus goes about its expiration-dance in a half-hearted, tentative way. Makes no sense.