There are a great many options for a catastrophe that could be fatal for humanity. From an asteroid hitting the Earth to a nuclear war. However, scientists remain optimistic and consider options for the revival of the human population after a possible apocalypse. Some of them are published by LiveScience.
Various disasters can create different conditions for human survivors, ranging from a volcanic winter to radiation. However, there is a chance for humanity to survive. For example, a relatively small number of people is enough to restore a viable human population.
A population of only a few hundred people will be able to exist for many centuries, as has happened at various times in history on Earth. However, life will survive primarily outside cities, which depend on electricity and completely import all food supplies. Small villages of about a thousand people are more likely to survive. However, provided there is an influx of “fresh blood” into the communities from other human settlements, to maintain genetic diversity.
Another option for survival after a global catastrophe is also possible: shelter on another planet. For example, in the case of a 6,300 Earth-year flight to the exoplanet Proxima Centauri B, a ship’s crew of 49 unrelated pairs able to reproduce under control during the journey would be sufficient. However, to preserve genetic diversity, scientists are still inclined to the need to send at least five hundred progenitors of future colonists on the voyage.