Answer:
According to the film, and based on my understanding of natural selection from class readings, lecture, and discussion, I believe;
Several teams of scientists round the world have, for a while, been analyzing the opportunity that a genetic mutation perpetuated via the organism responsible for bubonic plague, or the Black Death, inside the Middle Ages - Yersinia pestis - would possibly provide humans now sporting the mutation extended resistance to the Human Immunodeficiency Virus (HIV) compared to non-companies. New studies has thrown doubt on the micro-organism that become concept to have precipitated the Black Death, but the link to HIV resistance seems to remain.
In a observe published in the American Journal of Human Genetics (Am J Hum Genet 1998, 62:1507-1515) Stephen O'Brien and colleagues at the US National Cancer Institute, used coalescence principle to interpret current haplotype genealogy. They found that a genetic mutation that gives its providers safety towards the HIV virus became extraordinarily not unusual amongst white Europeans approximately seven-hundred years in the past — the equal length that the Black Death swept into Europe. The group also concluded that the geographic cline of the mutation frequencies and its latest emergence had been regular with a strongly selective historical event (which includes a virulent disease of a pathogen), driving its frequency upwards in populations whose ancestors survived the Black Death.
