I thought of a brood parasite that co-existed with humans and has evolved to mimic humans and to infiltrate human families as a brood parasite -- similar to a cuckoo birds -- as adopted children who are placed by this species in adoption centers or dropped of at front doors as babies.

Its lifecycle: After infiltrating a family, it would eat as much food as its fake human parents can get, and this species is sapient and intelligent so they would learn their parents' language and mimic what they do to help integrate itself into human society. Also, in another thing similar, to the cuckoo bird, it will try to kill off any siblings and un-necessary family members through (accidents supposedly) to prevent any food and attention heading for other people. After it reaches adulthood and its fake human parents becoming a liability, it would collect as much food and abandon them and survive off foraging, hunting, you name it and repeats the cycle.

Is this species plausible or not and if not why?

  • 6
    $\begingroup$ If this parasite looks like a human, and is intelligent enough to pass for one, it is basically a (somewhat psychopathic perhaps) human. Foraging and hunting is a lot harder than buying food in a grocery store. Especially if you've never hunted before adulthood. So at the point of reaching adulthood the parasite may just as well get a job, make money, and be able to have more food than it would ever need. That's what a lot of humans do, too. It may even figure that it is not competing for food with family members, so killing them off does not result in having more food. $\endgroup$
    – void_ptr
    Aug 10, 2020 at 23:37
  • $\begingroup$ Isn't that like the premise of Parasyte? $\endgroup$
    – DKNguyen
    Aug 11, 2020 at 1:16
  • 2
    $\begingroup$ You've more or less described changelings. These are human children swapped for inhuman ones. Usually faery but in some cases it might the changeling might be demonic in origin, for example. The changeling lore itself comes from Europe but similar myths can be observed in many places in the world in different variations but overall similar premise. The myth was used in order to justify children behaving bad, therefore the substitute child is ascribed malevolence or at least non-conformance to "good" behaviour. $\endgroup$
    – VLAZ
    Aug 12, 2020 at 6:31

1 Answer 1



Intelligence is a highly energy intensive trait, and it is wasting most of it. Why would it head off for a life of foraging and hunting when it could instead live in human society and get its food far easier? Most animals in the wild devote most of their energy to getting food. (For one thing, they can't have it cooked in the wild. Cooking greatly increases the ease of absorbing nutrition.)

Mimicking human behavior well enough to not be institutionalized as a child would make living in society much easier than living in the wild. Then, why would its foster family be liabilities and not assets as they are for human beings? Especially since too many accidents are likely to have the cuckoo child institutionalized as psychotic.

Gorging on food will also have the cuckoo child morbidly obese, bringing down a lot of medical attention.

Finally, nowadays the child would have to pass as human in the face of intensive medical investigation while they ensured that being abandoned had not harmed the child. This is implausible.

  • 3
    $\begingroup$ Maybe it gets dumber as it gets older. $\endgroup$
    – DKNguyen
    Aug 11, 2020 at 1:17

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .