For obvious reasons, I follow lupus research very closely. I recently read an article (I don't remember which journal it was in, so there will be no citations) showing that instances of lupus increase with growing urbanization. This means that as more and more people move to cities, more and more cases of lupus are diagnosed. He specifically discussed an area in Africa where there was almost no lupus until villagers began to move to large cities in search of better work, at which point, lupus diagnoses grew exponentially.
When I read that, I felt so happy, because it (sort of/kind of) confirms a theory I have held for a while now. I'm aware that the explanation for this could be that when people move to cities they have access to better medical care and are more likely to be diagnosed. I am ignoring that for two reasons. 1) It seems wrong to assume that rural doctors don't know what they're doing, just because they made the bad decision to live in a rural area. 2) It doesn't fit with my hypothesis.
Here is my theory, based on my highly scientific observations.
The human immune system evolves based on where you and your ancestors originated. You develop antibodies and resistances to the diseases which you are most likely to encounter in your part of the world. This is evolutionarily prudent, and makes total sense. So my immune system is probably much different from someone who's ancestry hails from sub-Saharan Africa, and and sub-Saharan African's immune system is probably different from someone from China. These immune system differences play a large part in physical attraction between humans. You are more likely to be attracted to someone who has different immunities than you do, because if you breed, you will make babies with super-immunity. You can actually detect these immune system differences by sense of smell. This isn't my own observation - it's actual science. Look it up.
Anyway, my point is we have different immune systems which develop based largely upon ancestral location.
Now here comes the part where I make scientific observations.
Everyone I know who has lupus has undergone a "big move" at some point before experiencing lupus symptoms. By "big move" I don't mean across town. I mean, to a different state or country. For instance, I moved from Washington to California. In addition, many of us have recent ancestors (parents, grandparents or great-grandparents) who underwent a "big move" as well - typically from a different country.
So maybe the factor isn't urbanization - moving to the city - maybe it's just moving in general.
Perhaps there are certain people - maybe people with a genetic predisposition - who's immune systems just can't handle the moving. Our immune systems are wired to deal with specific pathogens, and moving to a new location with its many new and exotic pathogens causes our immune systems to go haywire. It's like the kid who's psycho sports parent shouts too many instructions at him as he's preparing to hit the baseball, and then the coach is shouting at him too, and then his teammates join in, and the kid can't take it anymore and just throws the bat at the umpire, who is the only person who wasn't yelling at him, but he happened to be close by, so...yeah. He just can't handle all this shit anymore, dammit! And he attacks that which he should not attack.
You're welcome, scientific community.