primitive mentality

I’m having public health cycle this week. Public health is science and arts about prolonging of life & prevention and promotion of health affects.
Today, when we talk about the demography of the population in the world, my teacher shared something very interesting with us.
Do you roughly know how big is the population is the Artic or the Antarctica? According to her, not reaching a thousand of people is living at that place. Due to such limited number of population, intermarry is common, and thus, many genetic disorder occur among the people. This disorder will be brought to a generation to another generation.
Therefore, in order to introduce a new blood into the family, there is such tradition that, they allow sexual intercourse to occur between the wife and any male traveler. And when their wives got pregnant, there will be a celebration.
Well, I personally think that it’s kind of scary as they have such a primitive mentality.