Repopulation
Repopulation is the phenomenon of increasing the numerical size of human inhabitants or organisms of a particular species after they had almost gone extinct.
Organisms
An example of an organism that has repopulated after being on the brink of extinction is the Dryococelus australis.{{Cite web|url=http://www.bbc.com/future/story/20160113-could-just-two-people-repopulate-earth|title = Could just two people repopulate Earth?| date=13 January 2016 }}
Humans
The repopulation of humans after a catastrophic event is a hypothetical concept that sometimes features in fictional as well as traditional literature.{{cite book|last1=Firestone|first1=Richard|title=The Cycle of Cosmic Catastrophes|url=https://archive.org/details/cycleofcosmiccat0000fire|url-access=registration|date=2006|page=[https://archive.org/details/cycleofcosmiccat0000fire/page/154 154]|publisher=Inner Traditions/Bear |isbn=9781591430612}} In this scenario, only two members of the opposite sex are survivors after some sort of calamity that has happened.{{cite book|last1=Shapiro|first1=Jerome|title=Atomic Bomb Cinema: The Apocalyptic Imagination on Film|date=2013|page=77}} This couple, the last two humans on Earth, ends up reproducing and their offspring reproduce with one another, until after a certain amount of time, the planet Earth has a sizeable number of people.{{cite book|last1=Bleiler|first1=Richard|title=Science-fiction: The Gernsback Years|date=1998|page=5}}