Apparently, one of the problems caused by climate change is...an increase in Type 2 Diabetes.
A Dutch team discovered - even if they adjusted the results by obesity - that a higher outdoor temperature equates to higher incidence. The theory is that exposure to cold improves certain parts of fat metabolism.
Which made me wonder. We can't go by current ethnic distributions of diabetes in the US, where black people are at higher average risk because of race and poverty issues (obesity has become a disease of poverty in this country). But the "faulty" gene that causes Type 2 diabetes is surprisingly common. It might be that it isn't selected against because even if somebody gets the disease, they've usually already successfully reproduced. And, of course, not everyone with the gene gets the disease, and the better their diet the later they get it (kids getting Type 2 is a very bad sign...it means we aren't feeding our kids right at all).
But what if the "genetic susceptibility" to Type 2 diabetes is actually factors that give a survival advantage in cold conditions? (There's no specific Type 2 gene, and obesity, etc, are a much higher risk than temperature). This would have developed in the last Ice Age. It's a thought, albeit a weird one.
When something is common, it usually means it conferred an advantage at some point in the past or under specific circumstances (e.g. sickle cell anemia).