Going through my race/genetics folder, I came across articles I had kept on the CCR5-Delta 32 gene. Why do this? Well, from my cuttings, CCR5-Delta 32 provides protection against the HIV virus, preventing HIV from entering the cells of the immune system. What is interesting from an ethno-racial perspective, is that the highest levels of this gene are fund in Scandinavia with relatively lower levels in the Mediterranean. The gene is found in Europeans, and is rare, or totally absent in other populations, such as East Asians and Africans.
There are various hypotheses about how this HIV immunity gene arose, such as a response of Europeans to the plague, or that people under ancient Roman rule, somehow lost their immunity, perhaps because the Romans from their travels introduced a disease that the Nordics carrying CCR5-Delta 32 were highly susceptible to.