Parasites appear frequently in biology-inspired fiction from ancient times onwards, with a flowering in the nineteenth century. [1] These include intentionally disgusting [2] alien monsters in science fiction films, often with analogues in nature. Authors and scriptwriters have, to some extent, exploited parasite biology: lifestyles including parasitoid, behaviour-altering parasite, brood parasite, parasitic castrator, and many forms of vampire are found in books and films. [2] [3] [4] [5] Some fictional parasites, like Count Dracula and Alien 's Xenomorphs, have become well known in their own right.
In evolutionary biology, parasitism is a relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life. [6] The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". [7] According to the immunologist John Playfair, the term 'parasite' is distinctly derogatory in common usage, where a parasite is "a sponger, a lazy profiteer, a drain on society". [8] The idea is however much older. In ancient Rome, the parasitus was an accepted role in Roman society, in which a person could live off the hospitality of others, in return for "flattery, simple services, and a willingness to endure humiliation". [9] [10]
Parasitism featured repeatedly as a literary motif in the nineteenth century, though the mechanisms, biological or otherwise, are not always described in detail. [11] For example, the eponymous Beetle in The Beetle by Richard Marsh, 1897, is parasitic and symbolically castrates the human protagonist. [11] Bram Stoker's 1897 Dracula starts out as an apparently human host, welcoming guests to his home, before revealing his parasitic vampire nature. Conan Doyle's Parasite, in his 1894 book The Parasite , makes use of a form of mind control similar to the mesmerism of the Victorian era; it works on some hosts but not others. [12]
Parasites, represented as extraterrestrial aliens or unnatural [13] beings, are seen in science fiction as distasteful, [13] in contrast to (mutualistic) symbiosis, and sometimes horrible. [13] Practical uses can be made of them, but humans who do so may be destroyed by them. [13] For example, Mira Grant's 2013 novel Parasite envisages a world where people's immune systems are maintained by genetically engineered tapeworms. [14] They form readily understood [13] characters, since, as Gary Westfahl explains, parasites need to exploit their hosts to survive and reproduce. [13]
The social anthropologist Marika Moisseeff argues that Hollywood science fiction favours insects as villain characters because of their parasitism and their swarming behaviour. Such films, she continues, depict a ceaseless war of culture and nature as involving extraterrestrial species somewhat resembling insects, with humans as their hosts." [4]
The range of accounts of fictional parasites and the media used to describe them have greatly increased since the nineteenth century, spanning among other things literary novels, science fiction novels and films, horror films, and video games. [11] [3] [5] [15] The table illustrates the variety of themes and approaches that have become possible.
Author | Work | Medium | Date | Parasite | Effect | Biological counterpart |
---|---|---|---|---|---|---|
David Cronenberg | Shivers | Science fiction body horror film | 1975 | Genetically engineered | Useful in organ transplants; sexually transmitted and aphrodisiac when modified by a deranged scientist | Genetic engineering and its ethical implications [16] |
Metroid | Video game | 1986 | X Parasite | Deadly infection; confers useful energy and powers to vaccinated people | Pathogens such as bacteria, viruses; vaccines [15] [17] | |
Hideaki Sena (pharmacologist) | Parasite Eve | Science fiction horror novel | 1995 | Mitochondria cut free from mutualism in human cells | Deadly parasitism | Mitochondria, power-generating organelles, formerly free-living prokaryotic organisms, became mutualistic by symbiogenesis c. 2 billion years ago [18] [19] [20] |
Irvine Welsh | Filth | Novel | 1998 | Talking tapeworm | Sinister, comic; [21] "the most attractive character in the novel"; becomes the sociopathic policeman's alter ego and better self. [22] | Tapeworms, intestinal parasites [22] |
Kyle Munkittrick, on the Discover magazine website, writes that the great majority of aliens, far from being as strange as possible, are humanoid. [23] Ben Guarino, in The Washington Post , observes that despite all the "cinematic aliens' gravid grotesquerie", [2] earthly parasites have more horrible [2] ways of life. Guarino cites parasitic wasps that lay their eggs inside living caterpillars, inspiring A. E. Van Vogt's 1939 story "Discord in Scarlet", Robert Heinlein's 1951 novel The Puppet Masters , and Ridley Scott's 1979 film Alien. [2] The eponymous Alien has a "dramatic" [2] life-cycle. Giant eggs hatch into face-huggers that grasp the host's mouth, forcing him to swallow an embryo. It rapidly grows in his intestines, soon afterwards erupting from his chest and growing into a gigantic predatory animal resembling an insect. Guarino cites the parasitologist Michael J. Smout as saying that the "massive changes" [2] are feasible, giving the example of flatworms that transform from an egg to a tadpole-like form to an infective worm. [2] The biologist Claude dePamphilis agrees, too, that parasites can acquire genes from their hosts, giving as example a broomrape plant that had taken up genes from its host on 52 occasions, having thoroughly overcome the host plant's defences. They suggest further themes for future science fiction films, including emerald jewel wasps that turn cockroaches into subservient puppets, able to crawl but unable to act independently; or the barnacle-like crustaceans that castrate their crab hosts, or grow into their brains, altering their behaviour to care for the young barnacles. [2] All the same, a 2013 poll of scientists and engineers by Popular Mechanics magazine revealed that the parasite-based science fiction films The War of the Worlds (Byron Haskin, 1953) and Alien were among their top ten favourites. [24]
Several types of parasite, corresponding more or less accurately to some of those known in biology, are found in literature. [25] These include haematophagic parasites (fictional vampires), parasitoids, behaviour-altering parasites, brood parasites, parasitic castrators, and trophically transmitted parasites, as detailed below.
In ancient times, myths of blood-drinking demons were widespread, including Lilith who feasted on the blood of babies. [26]
Fictional vampires—haematophagic parasites—began in the modern era with Count Dracula, the title character of Bram Stoker's 1897 gothic horror novel Dracula , and have since appeared in many books and films ranging from horror to science fiction. Along with the shift in genres went a diversification of life-forms and life-cycles, including blood-drinking plants like the "strange orchid" in The Thing from Another World (1951), aliens like H. G. Wells's Martians in The War of the Worlds , "cyber-vamps" like "The Stainless Steel Leech" and "Marid and the Trail of Blood", and psychic bloodsuckers, as in Arthur Conan Doyle's The Parasite and Robert Wiene's 1920 film The Cabinet of Dr. Caligari . [12] [27]
The Xenomorph in Alien is a parasitoid, inevitably fatal to its human host. It has a life-cycle stage that grows inside the person's body; when mature, the predatory adult Xenomorph bursts out, killing the host. This behaviour was inspired by parasitoid wasps which have just such a life-cycle. [25] [30] [31]
The molecular biologist Alex Sercel compares Xenomorph biology to that of parasitoid wasps and nematomorph worms, arguing that there is a close match. [30] Sercel notes that the way the Xenomorph grasps a human's face to implant its embryo is comparable to the way a parasitoid wasp lays its eggs in a living host. He compares the Xenomorph life cycle to that of the nematomorph Paragordius tricuspidatus , which grows to fill its host's body cavity before bursting out and killing it. [30]
The marine biologist Alistair Dove writes that there are multiple parallels between Xenomorphs and parasitoids, though there are in his view more disturbing life cycles in real biology. [32] He identifies parallels include the placing of an embryo in the host; its growth in the host; the resulting death of the host; and alternating generations, as in the Digenea (trematodes). [32]
Mind-controlling parasites feature in twentieth century science fiction. In Robert A. Heinlein's 1951 The Puppet Masters , slug-like parasites from outer space arrive on Earth, fasten to people's backs and seize control of their nervous systems, making their hosts the eponymous puppets. [1] In Star Trek II: The Wrath of Khan , the Ceti eel tunnels into the ear of its human host until it reaches the brain. This is a behaviour-altering parasite analogous to Toxoplasma gondii , which causes infected mice to become unafraid of cats. This makes them easier to catch and consume and, once an infected mouse has been eaten, the parasite will then infect the cat, its definitive host, in which it can reproduce sexually. [25] The Goa'uld in Stargate SG-1 enters through the host's neck and coils around the host's spine, assuming control. [25] [33] The Slug/Squid alien in The Hidden similarly enters via the host's mouth before taking over its body. [33]
Brood parasitism is not a common theme in fiction. An early example was John Wyndham's 1957 novel The Midwich Cuckoos , which sees the women of an English village give birth to and then bring up a group of alien children. The aliens are telepathic, and intend to take over the world. In nature, brood parasitism occurs in birds such as the European cuckoo, which lay their eggs in the nests of their hosts. The young cuckoos hatch quickly and eject the host's eggs or chicks; the host parents then feed the young cuckoos as if they were their own offspring, until they fledge. As a plot device, this allows aliens and humans to interact closely. [13] [34] [35] A somewhat similar approach is taken in Octavia E. Butler's 1987–1989 Lilith's Brood , but the offspring born to the human mother there is an alien-human hybrid rather than simply an alien. [36] [37]
Parasitic castration is found in nature in greatly reduced parasites that feed on the gonads of their crab hosts, making use of the energy that would have gone into reproduction. It is seen in fiction in Philip Fracassi's 2017 horror novella Sacculina, named for a genus of barnacle-like crustaceans with this lifestyle. [38] [39] It tells the tale of a chartered fishing boat, far from home, that is overrun by parasites from the deep. [40]
The genetically engineered tapeworm in Mira Grant's novel Parasite, and the talking tapeworm in Irvine Welsh's novel Filth, are fictional versions of conventional intestinal parasites. [14] [22] Tapeworms have complex life-cycles, often involving two or more hosts of different species, and are transmitted as the eggs are passed in faeces and eaten by another host, only for the host to be eaten, passing the parasite on to the predator. [41] The unattractive lifecycle allows the novelists to exploit their readers' emotional reactions to the parasites. The parasite in Welsh's novel has been described as a "kind of sinister but strangely comic element". [21]
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the broomrapes.
Cuckoos are birds in the Cuculidae family, the sole taxon in the order Cuculiformes. The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis. The coucals and anis are sometimes separated as distinct families, the Centropodidae and Crotophagidae, respectively. The cuckoo order Cuculiformes is one of three that make up the Otidimorphae, the other two being the turacos and the bustards. The family Cuculidae contains 150 species, which are divided into 33 genera.
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist guest (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, or a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasitism, distinguished by the fatal prognosis for the host, which makes the strategy close to predation.
Kleptoparasitism is a form of feeding in which one animal deliberately takes food from another. The strategy is evolutionarily stable when stealing is less costly than direct feeding, such as when food is scarce or when victims are abundant. Many kleptoparasites are arthropods, especially bees and wasps, but including some true flies, dung beetles, bugs, and spiders. Cuckoo bees are specialized kleptoparasites which lay their eggs either on the pollen masses made by other bees, or on the insect hosts of parasitoid wasps. They are an instance of Emery's rule, which states that insect social parasites tend to be closely related to their hosts. The behavior occurs, too, in vertebrates including birds such as skuas, which persistently chase other seabirds until they disgorge their food, and carnivorous mammals such as spotted hyenas and lions. Other species opportunistically indulge in kleptoparasitism.
Brood parasitism is a subclass of parasitism and phenomenon and behavioural pattern of animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own, usually using egg mimicry, with eggs that resemble the host's. The strategy involves a form of aggressive mimicry called Kirbyan mimicry.
A hyperparasite, also known as a metaparasite, is a parasite whose host, often an insect, is also a parasite, often specifically a parasitoid. Hyperparasites are found mainly among the wasp-waisted Apocrita within the Hymenoptera, and in two other insect orders, the Diptera and Coleoptera (beetles). Seventeen families in Hymenoptera and a few species of Diptera and Coleoptera are hyperparasitic. Hyperparasitism developed from primary parasitism, which evolved in the Jurassic period in the Hymenoptera. Hyperparasitism intrigues entomologists because of its multidisciplinary relationship to evolution, ecology, behavior, biological control, taxonomy, and mathematical models.
An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, which can act as a parasite but does not rely on its host to continue its life-cycle. Obligate parasites have evolved a variety of parasitic strategies to exploit their hosts. Holoparasites and some hemiparasites are obligate.
Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causing the death of these hosts. Different species specialise in hosts from different insect orders, most often Lepidoptera, though some select beetles, flies, or bugs; the spider wasps (Pompilidae) exclusively attack spiders.
With over 850 species, the genus Nomada is one of the largest genera in the family Apidae, and the largest genus of cuckoo bees. Cuckoo bees are so named because they enter the nests of a host and lay eggs there, stealing resources that the host has already collected. The name "Nomada" is derived from the Greek word nomas, meaning "roaming" or "wandering."
The Eucharitidae are a family of parasitic wasps. Eucharitid wasps are members of the superfamily Chalcidoidea and consist of four subfamilies: Akapalinae, Eucharitinae, Gollumiellinae, and Oraseminae. Most of the 42 genera and >400 species of Eucharitidae are members of the subfamilies Oraseminae and Eucharitinae, and are found in tropical regions of the world.
Horsfield's bronze cuckoo is a small cuckoo in the family Cuculidae. Its size averages 22g and is distinguished by its green and bronze iridescent colouring on its back and incomplete brown barring from neck to tail. Horsfield's bronze cuckoo can be destiguished from other bronze cuckoos by its white eyebrow and brown eye stripe. The Horsfield's bronze cuckoo is common throughout Australia preferring the drier open woodlands away from forested areas. This species was formerly placed in the genus Chrysococcyx.
The screaming cowbird is an obligate brood parasite belonging to the family Icteridae and is found in South America. It is also known commonly as the short billed cowbird.
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The wasps do not constitute a clade, a complete natural group with a single ancestor, as bees and ants are deeply nested within the wasps, having evolved from wasp ancestors. Wasps that are members of the clade Aculeata can sting their prey.
Parasitic castration is the strategy, by a parasite, of blocking reproduction by its host, completely or in part, to its own benefit. This is one of six major strategies within parasitism.
Cotesia glomerata, the white butterfly parasite, is a small parasitoid wasp belonging to family Braconidae. It was described by Carl Linnaeus in his 1758 publication 10th edition of Systema Naturae.
Loxothylacus panopaei is a species of barnacle in the family Sacculinidae. It is native to the Gulf of Mexico and the Caribbean Sea. It is a parasitic castrator of small mud crabs in the family Panopeidae, mostly in the Gulf of Mexico, the Caribbean Sea and the eastern Atlantic Ocean.
Zatypota percontatoria is a species of parasitoid wasps that is part of the order Hymenoptera and the family Ichneumonidae responsible for parasitizing arachnids, specifically those of the family Theridiidae.
Biology appears in fiction, especially but not only in science fiction, both in the shape of real aspects of the science, used as themes or plot devices, and in the form of fictional elements, whether fictional extensions or applications of biological theory, or through the invention of fictional organisms. Major aspects of biology found in fiction include evolution, disease, genetics, physiology, parasitism and symbiosis (mutualism), ethology, and ecology.
The mafia hypothesis posits that brood parasite eggs are accepted by the host out of fear of retaliation from the brood parasite, in an example of coevolution.
Parasites, in a phrase, are predators that eat prey in units of less than one. Tolerable parasites are those that have evolved to ensure their own survival and reproduction but at the same time with minimum pain and cost to the host.
A satirist seeking to portray client misery naturally focuses on the relationship with the greatest dependency, that in which a client gets his food from his patron, and for this the prefabricated persona of the parasite proved itself extremely useful.