Only The Onlies was a name used by the remaining inhabitants of Earth Two after 1960 , child ren ranged in age from four to pubescent . Sometime around Earth year 1960 , the life prolongation project annihilated the entire adult population of Earth Two , leaving only children , who were feral and had survived without adult care for over three hundred years until the found them in 2266 . The children scrounged for food where they could . They knew the area where they lived extremely well , and were fond of game s they called foolie s . These games included taunting a landing party from the " Enterprise " . The children occasionally became more violent , especially when they felt threatened . The events of the plague had instilled in them a fear and distrust of grup s ; it took a great deal of effort for James T . Kirk to convince them that he and his people meant them no harm . These children were infected with the life prolongation project , just as the adults had been . In the children , the complex functioned as intended , greatly increasing their lifespan s . But when they reached puberty , the complex entered its fatal form , and death followed rapidly . When the " Enterprise " left , the children remained on their world , in the care of a medical team . Additional specialists were dispatched from elsewhere in the Federation to care for them . If the " Enterprise " hadn ' t found them when it did , diminishing food supplies would have meant starvation for most of the children within a few month s time . ( ) Appendices . Background information . The idea of the Onlies was thought up by writer Adrian Spies . " " When I went to see Gene I offered him the idea of a bunch of kids in this place where they are permanently young , but are really very old , " " recalled Spies . " " If he was to tell you that he came up with the idea , I wouldn ' t say no , but it ' s not my memory . I do remember that he said , ' You have to develop a language for these people . ' I said , ' What the hell are you talking about ? ' He said , ' The kids would talk differently . " " In the same conversation , Roddenberry contributed to the Onlies ' language by suggesting the word " grups " , which Spies appreciated . ( " " , p . 31 ) In the first draft script of " Miri " , the Onlies were akin to the lost boys from " Peter Pan " . Also , their society was filled with ritualism ; when it was discovered that Miri ' s childhood was nearly over , they individually proclaimed they could no longer regard her as their playmate . ( " The Star Trek Compendium " , 4th ed . , p . 42 ) In the final draft script of " Miri " , the group name " Onlies " was consistently formatted with a small initial letter . Also , whereas the final version of the episode does not use the singular term " Only " at all ( consistently pluralizing it ) , it was used several times in dialogue . Miri first used the word when , in an attempt to explain how Onlies developed into grups , she stated , " " When things happen to an only . . . " " She later told Kirk that " " the best thing about being an only " " was that " " nobody expects you to understand . . . you don ' t have to . " " In other ultimately omitted dialogue from the teleplay , Miri stated , " " The Onlies mark down all the hots and colds at a secret place . . . It ' s not much fun . . . But it wasn ' t like that ! . . . We just went on – being Onlies [ . . . ] We just had – foolies [ . . . ] If we were hungry , we just took something [ . . . ] But mostly – mostly it was fun , foolies . . . After all , with no grups to say no , what else would Onlies do , anyway ? " " In addition to " hots " and " colds " , another scripted but ultimately unused Onlies slang term was " mommies " , meaning " can opener s " ; the Onlies were said to have lots of can s and " mommies " . When Miri ' s gang of Onlies first appeared in the final draft script , they were described thus ; " " There are several of them . All sizes and shapes , from toddlers up to about twelve . They have lived without restraint , taking things from empty shelves and empty houses as they need them . We see that in their outlandish clothes – whatever struck their fancy , some of the boys in tuxedo s , some in military uniform s of a sort , some in snazzy sport s clothes . The girls , the same way , but being girls , most are in some form of ' party ' dress [ . . . ] None of these kids are evil [ . . . ] The older ones take care of the younger ones . A sort of paternal thing . " " Apocrypha . The Onlies were the focus of Judy Klass ' novel " The Cry of the Onlies " , in which it was shown that the chief doctor who was sent to gradually bring the Onlies into adulthood and educate them was instead exploiting and abusing them . The Federation was testing a prototype spaceship on the planet , and Jahn stole it and began rampaging across the galaxy after Miri ' s death . Kirk and company straightened out the situation and arranged for Flint to become the Onlies ' new mentor and guardian . Another take on the Onlies was in issue # 3 of Marvel Comics ' " " , titled " Past Imperfect " , which showed Jahn marauding after Miri ' s death , but this time he kidnapped Dr . McCoy ' s daughter , Joanna , because McCoy ' s cure had mutated into an even worse disease .