‘Why are there beings at all, and why not rather nothing?’ –Heidegger
Imagine a virus wipes out everyone on the planet except [a man]. […] He finds the last woman on Earth. […] Can they repopulate the Earth? To do so, their children would have to mate with one another, or mom and dad, in order to rebuild the human race. All the incestuous taboos aside, is this even genetically possible?
Inbreeding has unfortunate genetic consequences due to the increased inheritance of recessive genes, which can result in neonatal death. Inbred children that survive are at increased risk of congenital birth defects, reduced fertility, smaller size, immune deficiencies, cystic fibrosis, and more. These defects are also likely to be passed on to their children as well. […]
Some real-life examples of the consequences of inbreeding can be found in places where there are restricted breeding opportunities — for example, within monarchies, islanders, or closed societies. Hemophilia was notoriously prevalent in European royal families. Some Amish societies have a larger number of children born with extra digits on their hands or feet. Jews of Eastern European descent tend to have higher rates of a number of genetic diseases, including cystic fibrosis. […]
The net result of inbreeding is that the resulting population loses a diverse genetic portfolio, which means they are less resistant to rare diseases and deformities. The smaller the gene pool, the faster it gets dirty. Such individuals would also have less diverse immune systems, making it much easier for a single germ to wipe them all out. […]
In addition to the genetic landmines, the family would likely have a very difficult time overcoming the innate resistance most species have against inbreeding. Evolution knows that inbreeding is not good for the species, so it engineered a built-in “incest taboo” that creates a strong aversion to such behavior. A devil’s advocate, however, could argue that the biological barrier to familial sex could be overcome through artificial insemination.
What about using a sperm bank? Sperm is stored in liquid nitrogen, so it would stay frozen for a short time after the power goes out. However, you’d have to act fast because no one is around to monitor the storage tanks and top off the liquid nitrogen as it evaporates.
There are practical concerns to consider as well. The last man and woman, as well as their kids, would need to have large numbers of children and, unless one of the founders happens to be a doctor, it is hard to imagine many of these babies surviving in such a world. Even if they (and mom) survive childbirth, there are countless opportunities for them to perish in this type of environment before reaching childrearing age.
art { Hilo Chen, Beach 166, 2010 }
