Imagine that tomorrow a new viral disease moves into the human population. The first recognized case is in Shanghai China, a major international trade city located on the East China Sea (see the map below). This virus is as deadly (virulent) as some of the worst Ebola epidemics (90% mortality), it has an incubation period of a month from the time of exposure and infected people are contagious for 2 weeks before serious symptoms appear. During the 2 week period of contagion, the people have what appears to be a typical cold virus. This virus spreads via all mechanisms (contact, body fluids, and airborne) and a very low dose of virus is necessary for infection. When the symptoms emerge, they are much like Ebola and other hemorrhagic fevers; ultimately, the number of platelets (cell fragments involved in the blood clotting process) drops and bleeding will occur anywhere in the body. The body fluids are highly contagious and patients usually live about 3 days without supportive care and 5-6 days with supportive care.
Imagine now that this virus became a major world-wide epidemic that resulted not just in the deaths of billions of people, but also in the collapse of modern society. Assume that some people have survived (it is only 90% mortality after all) and that there are a few populations in the world that have not encountered the virus. Today, the world population is about 7.7 billion. Immediately after the hypothetical epidemic, the population would be about 770 Million—about the population in 1760—16 years before the American Revolution. Use the information from the assignments for previous units and consider the consequences of this disaster on the human genome over the next 1000 years. Begin by considering what will happen to general and specific populations in the immediate aftermath of such an event. Will human populations be as mobile, more mobile or less mobile than they were in 1760, a time with the same approximate population. Continue to discuss your projections over about 30 to 50 generations (something like 1000 years depending on how long a human “generation” is after this event).
