Better Together

Symbiosis between species is common in nature - an evolutionary pathway by which two species each gain advantage from the existence of the other, and eventually become dependent on one another for their mutual survival. As with so many other natural phenomena, science fiction has explored an extrapolation of symbiosis - extending the idea of symbiosis to a logical extreme.

[Note: the dictionary definition of symbiosis extends to cover a range of relationships, including extreme parasitism, in which the benefit to the relationship is entirely one-sided. I’m going to use a narrower definition here and exclude, for the sake of this entry at least, the controlling parasitic relationships common in science fiction such as in Robert Heinlein’s The Puppet Masters (novel, 1951).]

Symbiotic ecospheres

As we considered in a previous entry on this blog, symbiosis is prevalent throughout the natural world in the form of mycelial networks - fungal strands which link the roots of vegetation in soils… and increasingly in science fiction. Examples such as Avatar (film, 2009) imagine entirely planets in which organisms are linked and mutually dependent. However fungal mycelium is not the only mechanism for transferring information or resources across a biological network.

An early story to consider bacteria as the ultimate symbiotic networkers is Drop Dead (short story, Clifford D Simak, Galaxy Science Fiction, July 1956). In this story a survey ship lands on a world that appears idyllic, with abundant life. However events soon take an ominous turn. All the life on this world proves to be interconnected, with just one type of grass, one type of bacterium and one type of “critter” the size of a cow and appearing to be a strange melding of plant, fish, animal and bird.

From their heads and other parts of their anatomy sprouted a weird sort of vegetation, so that it appeared each animal was hiding, somewhat ineffectually, behind a skimpy thicket. To compound the situation and make it completely insane, fruits and vegetables - or what appeared to be fruits and vegetables - grew from the vegetation.

As a character notes:

“That’s the most fantastic case of symbiosis I have ever seen,” he said. “If it weren’t lying over there, I’d say it was impossible. Usually you associate symbiosis with the lower, more simple forms of life.”

The survey crew pitch camp, and soon thereafter a “critter” walks into the camp and drops dead, apparently as a ready made food supply. When their own food stuffs are destroyed, they have no choice but to accept it. Pretty soon, first the Earth animals fed native matter as a test, and then members of the hungry crew, begin to disappear leaving behind strange shells. Eventually the crew find evidence for bacterial contamination in their own blood samples, and are forced to the conclusion that they are in the process of being absorbed into this strange biosphere and will ultimately themselves mutate into critters.

The story was adapted for radio drama anthology X-Minus-One in 1957 and continues to be popular, being reprinted in one of the British Library SF Classics anthologies a few years ago (Nature’s Warnings, ed. Mike Ashley, 2020). While much of the story draws on the same body horror tropes as fungal infection and mutation stories, traceable back at least as far as William Hope Hodgson’s A Voice in the Night, 1909), it is the bacterial component of life on the new world that provides the connection between what were originally different organisms, and which will ultimately bring the human visitors into the planet-wide gestalt.

At its conclusion, the narrative asks whether the ultimate symbiosis described here is a positive or a negative - whether it is worth persevering as an individual when one can be content, comfortable and even happy as one of a community.

Symbiotic civilisations

Also affecting an entire planet, although this time less directly or invasively is the unlikely symbiosis found in Of Ants and Dinosaurs by Cixin Liu (novel, 2010; in English translation 2020 by Hanlon and Nahm). This narrative, set in the Cretacious period, begins when a group of hungry ants decide to remove and feed on the meat caught between the teeth of a dinosaur, relieving its dental discomfort. Over time, repeated dental services evolves into a full medical service provided by the ants to the dinosaurs in return for food, and then into a more complex interrelation when the ants provide the dinosaurs with the fine dexterity required first for record keeping and then for more general technical and technological devices. In return, the ants are not only fed and housed but also benefit from technological innovation and development. We’re told that the collective intellect of ant communities lacked the drive and creativity of the individual dinosaurs, while the dinosaurs lacked a way to pass records and knowledge between generations or to turn their dreams into reality without vast consumption of resources and devices on huge physical scales.

Over the course of millennia, two complementary civilisations arise and interact symbiotically. However eventually a combination of internecine rivalry between two continents of dinosaurs and their excessive resource consumption cause the ants to remove their services from the dinosaurs, and eventually consider their annihilation. The result of losing the dinosaur’s imaginative input and help with physical tasks, as well as of environmental cataclysm, is that the ants regress to simple and isolated colonies. Unlike many symbioses, this is not a matter of immediate life or death. The symbiosis is cultural rather than physical and is dismissed in importance and diminished in priority by its members as a result. However both partners benefit enormously from it, and without their creative partners, the remaining half of the symbiotic pairing cannot survive in anything approaching its original state.

A less overt and more insidious form of symbiosis affecting entire species is described by Brian Aldiss in his novel Hothouse (1962). This imagines a distant future in which the Earth is much hotter, as a result of solar evolution, and is tidally locked to the Sun. Vegetation has grown beyond all recognition compared to today, filling most ecological niches. The remaining humans have regressed to primitive tribes living amongst the tree tops, and are themselves small in stature and of low overall intelligence.

However one of the few remaining male humans becomes infected by a fungus - a morel - which enhances his intelligence. The morel reveals that throughout human history, its species has had a symbiotic relationship unknown to their hosts. Humans have benefited from increased intelligence throughout their evolution, but the morels benefited from mobility, sensory perception and were able to direct the decision making of their hosts when they chose. While both benefitted, the lack of volition and awareness on the part of human hosts means that this relationship borders on the parasitic. Indeed it began that way and then evolved into true symbiosis:

“So the real race of men developed,” intoned the morel, throwing up a storm of pictures. “They grew and conquered the world, forgetting the origins of their success, the morel brains which lived and died with them.”

Unfortunately for both parties, the sun’s evolution brings this to an end:

“Men were physically stronger than morels. Though they survived the stepping-up of solar radiation, their symbiotic brains did not. They quietly died, boiled alive in the little bone shelters they had fashioned for themselves. Man was left… to fend for himself equipped only with his natural brains, which were no better than those of higher animals… Small wonder he lost his splendid cities and took again to the trees!” (Hothouse, Aldiss, chap. 14)

Implausible as this future-fantasy is, it makes a clear point: that a symbiosis can exist unknown to one party, and not be missed until it is lost.

Symbiotic Partnerships

Moving from the population scale to a more personal one, we find examples in science fiction of individuals within a population existing in symbiosis with other life.

Amongst these, the best known may be the Trill of Star Trek. The planet Trill evolved two sentient species - the humanoid Trill hosts and the invertebrate Trill symbionts. The latter arise in cave-pools and are capable of independent existence. However they also have the ability to merge their nervous systems with around half of the human-like hosts, and to exist embedded within the host abdomen. When this occurs, the Trill symbiont accesses the memories, personality and sensory perceptions of the host, while the host in turn accesses the memories of the symbiont and all its previous hosts. Within a few days of being joined, the condition becomes permanent and necessary for continued survival until the host dies and the symbiont is transferred (or vice versa). The symbiont benefits from access to new experiences while the host benefits from accumulated wisdom and guidance. The perceived mutual benefit is apparent from the demand for joining, which is fiercely competitive and selective since the hosts outnumber the symbionts considerably.

Trill were first introduced in the Star Trek: The Next Generation episode “The Host” (TV episode, 1991), in which a symbiont is transferred temporarily to a human as an emergency measure when its host dies off-world. A Trill character, Jadzia Dax, became one of the regular team in Star Trek: Deep Space Nine (TV series, 1993-1999), with the symbiont later transferred to a new host Ezri Dax. This offered an opportunity to explore the impact of symbiosis on personality further. An earlier pairing, Curzon Dax, had been a friend of Deep Space Nine’s commander Sisko, and Jadzia retained memories of that friendship, while nonetheless differing in personality and preferences to the previous host. Likewise, Ezri retains memories of Jadzia’s relationships, and feels affection for Jadzia’s bereaved loved ones, but is unable to continue those relationships. Indeed, we are told that reassociation with previous romantic partners was taboo in Trill society.

More recently, another Trill main character has appeared in the prequel series Star Trek Discovery (TV series, 2017-2024). Again, in this case, a Trill symbiont is transferred in an emergency to a human host, but this time remains permanently. Adira Tal is initially unable to access more than distorted echoes of the Tal symbiont’s memories. Only after returning to the planet Trill for assistance is the integration able to become complete, suggesting that the symbiosis is not impossible between species, although co-evolution between the symbionts and hosts on Trill have clearly made it more straight-forward.

Despite their frequent appearances in the Star Trek canon and several episodes focussing on their joining, the precise nature of Trill symbiosis remains unclear. Despite mutual memory sharing and shared experience (with inevitable consequences for personality), the two symbiotic partners appear to retain individual identities. While the host is in full command of their movement and appears to be in full command of their decision making, it is unclear to what extent the symbiont might be able to influence these if it chose to do so, rather than remaining passive. Certainly a neurotransmitter, isoboramine, connects the two. An informative illustration of the possibilities can be found in the DS9 episode “Equilibrium” (TV episode, 1994). Here a suppressed personality memory pattern of an incompatible host carried by the Dax symbiont severely distorts host Jadzia’s perceptions and responses to situations - although it is difficult to tell whether this is because the symbiont is taking control (unconsciously or otherwise) or whether it results from a neurological and psychological disturbance in the host.

While Star Trek’s view of the potential of symbiosis is largely positive [1], a darker mirror can be found in the Stargate universe (film, 1994; TV series Stargate: SG-1, 1997-2007). Here the Goa’uld are a parasitic life form which enter the bodies of humans, attaching themselves to the unwilling host’s central nervous system. This presents problems (both in the series canon and reality), since, unlike the abdominal cavity, the central nervous system is extremely sensitive to intrusion and changes in temperature or pressure. While the majority of Goa’uld fall into the classic single-sided puppet-master category, and thus outside the discussion of symbiosis here, two subsets of the species demonstrate the species is capable of mutual benefit instead.

Juvenile Goa’uld are implanted into the abdomen of genetically-engineered human hosts known as Jaffa. While these immature creatures exert no control over the Jaffa, their presence conveys strength and modifies the immune system to produce robust good health and longevity, in return for their stable environment and sustenance from the host’s system. Once past the age of puberty, a Jaffa cannot survive without one (unless its effect is replaced by medication). This symbiotic relationship is usually entered into voluntarily by the Jaffa, as a result of cultural indoctrination, and ends when the symbiont matures.

A much smaller subset of the species are the Tok’ra. These are a group of former Goa’uld who reject the parasitic approach of most of their species. While they still require hosts, they function far more like Star Trek’s Trill, allowing the host and the symbiont each to exert control over their shared body, and to communicate with one another. To emphasise this commensality, Tok’ra adopt the convention that the host speaks normally, while the symbiont applies a reverberant vocal effect to distinguish its own contributions through the same throat. This demonstrates that parasitism is not a necessary part of the Goa’uld lifecycle and that a true and conscious symbiosis is possible.

Both Trill and Goa’uld are endosymbionts, with an invertebrate carried within a human or humanoid body and exerting greater or lesser amounts of control over it. A very different form of individual symbiosis can be found in the Eight Worlds series by John Varley. Here the Symbs are a genetically-engineered, photosynthesizing plant-analogue species which thrive in the open space in the rings of Saturn. They can form symbiotic pairings with human beings, as explored in most detail in the short story Gotta Sing, Gotta Dance (first appearing in Galaxy magazine, July 1976), which explores the tendency of symb pairs to create music and other art beyond any other humans in the system. As we’re told:

“Bailey’s function in the symbiotic team of Barnum and Bailey was to provide an environment of food, oxygen, and water for the human, Barnum. Conversely, Barnum provided food, carbon dioxide and water for Bailey.”

…

“Bailey had no shape of his own. He existed by containing Barnum and taking on part of his shape. He extended into Barnum’s alimentary canal, in the mouth and all the way through to emerge at the anus, threading him like a needle. Together, the team looked like a human in a featureless spacesuit.”

The symbiotic team in this case is an equal pairing, with both fully conscious and speaking to one another with distinct personalities and insecurities. This is all the more remarkable since the symb itself has no consciousness until paired, and uses the human brain to process its own thoughts. The symb can extend into a wide sheet to absorb sunlight, roll back from parts of its human partner, baring their hands, returning the human to normal respiration, and even taking a second human into its envelope temporarily to permit sexual interactions. Most of their time is spent as a solitary pair in freefall in the orbit of Saturn.

The pairing cannot, however, be separated without death for the symb and trauma for the human. Varley addressed this directly in another short story, Equinoctial (1977, first appearing in Ascents of Wonder, eds. Goldin and Gerrold). This looks back on the initial pairing of a pair, as well as its severing. When human Parameter is forcibly separated from her symb Equinox, she is both physically and mentally devastated and on the point of death. She is only saved by being paired with a new infant symb, Solstice. In turn the essence of Equinox only survives in part by fissioning into several parts and attaching to infant humans. Inevitably, both are changed in personality and outlook by the experience, although eventually becoming reconciled to their loss.

Like Barnum and Bailey, Paradox and Solstice are creative, generating and selling music partly for the creative pleasure of it, and partly to fund replenishment of any traces lost from their otherwise closed system.

Better Together

Symbiosis is ubiquitous here on Earth, although - as Simak’s character in Drop Dead noted - usually amongst relatively simple organisms. It is nonetheless a characteristic of some more complex life, such as sharks and cleaner fish, who both benefit from their unequal exchange, in much the same way as Liu’s ants and dinosaurs. On a deeper level, most complex organisms on Earth owe their origin to a symbiotic relationship in the distant past: both mitochondria in animal cells and chloroplasts in plant cells are believed to have originated as bacteria absorbed into endosymbiosis with early eukaryotic (nucleated cell) organisms.

Even now, humans exist in a symbiotic relationship with a range of bacteria which contribute to our health. Bacterial flora play a vital role in preventing vaginal yeast infections, while their role in regulating our digestive tracts is well known. While such asymmetric symbiosis is very different to that of, for example, the Trill in Star Trek, it does raise other questions. As Susan and Robert Jenkins, the authors of Life Signs: The biology of Star Trek (SF reference book, 1998), noted, it would present a problem for technologies such as a matter transporter, or other forms of biocontamination protection. The bacterial flora of one species may be toxic to another, and anyone routinely transported through a bacteria-removing biofilter might well need to be given a species-specific live-culture yoghurt (or equivalent) on a regular basis.

More seriously, symbiosis between sentient individuals of the kind imagined in science fiction provides an avenue for writers to explore questions regarding identity and interdependence in society. Examples such as Drop Dead and Of Ants and Dinosaurs demonstrate the possible end states of symbiosis, asking questions regarding cooperative existence, where it can be highly positive, and when it can become toxic dependency instead. Drop Dead challenges the importance of individuality, but also contains elements of body horror, which extends in other circumstances to questions regarding bodily integrity. Goa’uld, for example, invade human bodies forcefully and violently, even when the joining is consensual, as in the case of the Tok’ra. Even the benign Trill prioritise physical survival of the symbiont over that of the host - as was seen when Jadzia Dax became unwell in the ST:DS9 episode “Equilibrium” and her human friends had to encourage efforts to ensure her survival.

Also part of identity exploration in this fiction is the issue of gender. The Symbs in Varley’s Eight Worlds, for instance, are genderless until paired but their perceived gender is then shaped by the brain they share. By contrast both Trill and Goa’uld symbionts can be transferred between hosts with different genders - and several episodes of Star Trek have explored the impact of carrying memories or personalities associated with genders different to the host, as well as the impact of changed gender perceptions on relationships to others.

Symbionts in science fiction demonstrate the role of the genre in taking the limits of our scientific understanding and pushing beyond them to explore their final consequences. In many cases, science fiction may be the first (or even only) exposure of the public to scientific phenomena such as symbiosis. The examples here demonstrate how such phenomena can be transferred from a matter for scientific experts to one accepted in popular culture. In this regard, symbiosis makes for an interesting example. Science fiction has long been discussed as a tool for dissemination and popularisation of topics in the physical sciences. Biological science examples are perhaps less common.

Having said that, the symbiosis seen on screen also presents a risk of promoting misconceptions and misunderstandings. To the best of our understanding, for one organism to share the full sensory and memory perceptions of another would require a far more complex and invasive symbiosis than any observed in nature. Neural processing in humans is widely distributed, rather than all information passing through a single channel. Indeed, given our current understanding of the human nervous system, it would be impossible for a symbiont to intrude to the necessary extent without destroying the equilibrium necessary for life. The main-stream science-fictional picture of brain-tapping organisms (whether mutually-advantageous symbionts or straightforwardly invasive parasites) is now part of the popular imaginary, and may contribute to misunderstandings and paranoia regarding the (im)possibility of hostile mind control or indeed of some form of imagined technological mind-reading.

Despite that, the majority of symbionts in science fiction convey a powerfully positive message. It is possible for two individuals, species or cultures, working together, to form a whole that is more than the sum of its parts. It is not only possible but common for a transaction or relationship to benefit both its parties, rather than resulting in a winner and a loser. Whether through achieving physical symbiosis or simply taking inspiration from the concept, it’s cheering to know that the world can be made a better place through cooperation rather than competition.