Old for young

Old for young —ie. where "the old sacrifice for the sake of the young," either by self for sake of natural balance, or else by enforced law for sake of population control quotas, is a theme or concept of a custom of human sacrifice typically found within certain types of science fiction stories, however real examples of these customs have been recorded to exist among some indigenous people, such as certain Inuit tribes. This was seen by Emile Durkheim in his study "Suicide" as the product of over integration with society, as people were willing to sacrifice themselves for the greater good. Otherwise referred to as a concept within "enforced population limits" or "population management", stories may promote the concept as a means for ending enduring types of social conflict, or else deride the concept as an example of utopian idealism gone awry.

The concept is somewhat in contrast with certain apparent modalities which underlie various types of current conflict. War, being the primary example, is infamously regarded as "a sacrifice of the young for the sake of the old," (ie. where "old men send young men off to die"), or else a sacrifice of a particular demographic (ie. young men, low-income young people) for sake of another demographic (ie. the society at large, elite-income young people). Such may also have pejorative notions attached —the sacrifice of young belligerents for the sake of more civilised young people, etc.

Some notable examples include:
* "Children of the Corn" in which all the children are sacrificed as soon as they are 19. In the book, the age is lowered to 18 later.
* "Logan's Run" (1967 novel and 1976 film), in which all are mandated to be terminated upon reaching the age of twenty-one years (30 in the film). The dystopian theme is a Cold War allegory, asserting the nature of the "East and West" contrast as one of totalitarianism versus freedom, as these are manifest as artificial and natural drives, respectively.
* The "LifeDeath" story arc in the X-Men comic book, describing the practice of a fictional African tribe, in which the village elder, upon the birth of a new child, allows himself to die for sake of keeping the natural balance found by experience to be necessary for the tribe's survival.
* The Isaac Asimov novel "Pebble in the Sky" — In a distant future, Earth is radioactive and all inhabitants are euthanized at the age of sixty to keep the population under control. A similar idea is present in the "" episode "Half a Life", where the "Enterprise" aids a planet where a person must commit ritual suicide on reaching the age of sixty.
* The "Stargate Atlantis" episode "Childhood's End" — An expedition encounters a colony of humans who perform ritual suicide at the age of 25 in an effort to keep the Wraith away. The team learns that, unknown to the colonists, the tradition was created to stabilize the population size so that it could remain within the range of an ancient defense field. Eventually, the team reveals the truth, and improves the field so that the population can age and increase normally.
* In Lois Lowry's novel The Giver, the protagonist is a young boy living in a seemingly utopian future society which suppresses strong emotions. He has been taught that the elderly (and other "unfit" people) are "released" at a certain age to live outside the community, but eventually learns that they actually are being euthanized. This is meant to eradicate grief by making death normal and monotonous, but ends up making people numb to the horror.