A common trope in speculative fiction considers the differences in body odour between different species. Each of us has a metabolism that produces a number of chemical compounds which are released into the air as we move or exhale. We shed skin cells, and release microscopic droplets of perspiration, as well as digestive and respiratory gases through our breath. The majority of these are either at too low a concentration to trigger conscious awareness in humans, or are compounds to which we have no receptors in our olfactory system (i.e. sense of smell).

For the majority of us, we only become conscious of body odour when in close contact with another individual, or when secretions such as perspiration are enhanced through exercise or allowed to accumulate between bathing. In fact, we can cease to become aware of such odours entirely through repeated exposure and familiarisation. By contrast another alien race might have olfactory receptors which are sensitive to small concentrations of our bodily odours and to which they have not become desensitised through familiarity. In turn they may release aromatic compounds to which we are more sensitive than they would expect. Both scenarios are relatively frequent occurrences in science fiction, particularly in fiction franchises in which a large number of alien species are brought into contact.

In the Star Trek universe we learn of several races who appear to find the odours of others offensive. In Star Trek: Enterprise (TV, 2001-2005), for example, we learn that female Vulcans have a more sensitive sense of smell than their male counterparts, and one of the main cast of characters, T’Pol, is thus required to take nasal suppressant medications in order to work with humans in Starfleet [1]. Similarly Star Trek: Voyager (“Distant Origin”, 1997) encountered reptilian aliens who perceive all mammals to have an offensive smell. The odour of Klingons to human perceptions is also mentioned in Star Trek: Deep Space Nine (“Trials and Tribbleations”, 1996) - "kind of a peaty, earthy aroma... with just a touch of lilac" - although here it is perhaps less clear whether those speaking are merely teasing their colleague.

More significant problems are noted in the television series Babylon 5 (1994-1998). The Pak’ma’ra race make for unpopular neighbours due to the smell of their quarters - although this arises primarily from the carrion they consume rather than the sentient species themselves.

Another race, the Hyach (“Secrets of the Soul”, 1998) present a more serious problem. This species does not excrete waste as we do, but rather excretes waste substances through their skins, giving them an odour that the humans on the station find difficult to ignore. One of the many challenges faced by the crew of Babylon 5 is to negotiate with this race, without letting their own physical abhorrence affect their rational decisions.

 While in each of these cases, body odour is discussed as a serious problem, more often in science fiction (as in fantasy and - unfortunately - real life) accusations of distasteful odour are thrown out as jokes or insults in passing, rather than explored in detail. Perhaps unsurprisingly, narratives which focus on conflict, such as Space: Above and Beyond (TV, 1995-6) include characters that comment negatively on the stink of the alien aggressors (known deprecatingly as Chigs), while in the Star Wars Universe there are recorded comments on the smell of Lasats (SW: Rebels) and of wet Wookies (e.g. Solo). By contrast the comedy Doctor Who special “Curse of the Fatal Death” (1999) mentions the "most shunned race in the Universe" - the Tersurans who were friendly and peaceful but communicated through controlled flatulence. John Scalzi’s comedic science fiction novel Agent to the Stars (online 1999, Subterranean Press 2005) discusses a similar issue at length - it features an alien race who hire a Hollywood talent agent to represent them when they realise that their amorphous appearance and use of foul odours for communication will be problematic.

In each case here, odour is used to guide a consideration of how our perceptions shape our interactions with others. The Doctor Who joke about “the most shunned race” rings uncomfortably true. Accusations of unpleasant smell have always been part of humanity’s sorry legacy of racial injustice, sometimes reflecting the impact of different diets on body odour, but more often simply demonstrating prejudice. Science fiction of this kind both warns us against the dangers of taking our own preconceptions about what is 'normal' forward beyond our own species, while also questioning our ability - whatever our intention - to disconnect physical reactions from rational intentions.

Odour moves from a problem of interaction to one of survival in two science fiction texts. “The Coffin Cure” is a short story by Alan E. Nourse which was published in Galaxy magazine in April 1957, and adapted as a radio play in the anthology series X-Minus-One. In this narrative, a team of medical researchers find a cure for the common cold and start to distribute it first to volunteers and then more generally. 

The consequences gradually become apparent:

“Every day it grew a little worse. They began smelling smells they never dreamed existed—noxious smells, cloying smells, smells that drove them gagging to the sinks. Their nose-plugs were rapidly losing their effectiveness. Mealtimes were nightmarish ordeals; they lost weight with alarming speed.”

In eliminating the cold virus, the researchers had released a hitherto unsuspected potential in the human sense of smell… but one poorly adapted for a modern human world:

“The smells were driving them crazy, they said. They couldn't even bear to be close to their best friends. They wanted something done about it, or else they wanted blood.”

This short story deals with the narrative in a semi-comic way, and a solution is found relatively quickly. However a second narrative takes the same premise to its logical conclusion and shows just how severe the consequences could have been. Telempath is a science fiction novel by Spider Robinson, published in 1976. In this post-apocalyptic tale, civilisation has collapsed, and the remaining people fled the cities. This occurred as a result of the deliberate release of a virus which enhanced the sensitivity to smell - the Hyperosmic Plague. As well as the exodus from the cities, the virus led to massive insanity and death from sensory overload, and revealed the existence of another sentient species on Earth, who exist and interact through subtle odours. Almost two decades later, the protagonist, a young man called Isham Stone, is sent out on a mission to find the scientist responsible, only to learn that the story was not as simple as he had been taught.

Underlying this novel are a number of themes, including the way in which false testimony can distort individual realities, concerns over the unrestrained application of dangerous technologies, and a running undercurrent of racial legacies and the way that they too modify or distort perception. Throughout odour is used as a tool, with natural and artificial odours both shown as problematic.

Both these stories assume an innate capacity of human noses to detect odours that our brains are unable or unwilling to process. They also act as a critique of the difficulties of urban living and the products of our civilisation. As a character in Telempath notes:

“Has it ever occurred to you,” I persisted to my everlasting regret, “that nearly all the undesirable by-products of twentieth-century living - Technological Man’s most unlovable aspects - quite literally stink? The whole world’s going rancid.” - Futura edition (1979) pg 22

As in so many science fictions, this critique of modern living is also twinned with a caution regarding the irresponsible use of science. In both respects, it is perhaps unsurprising that odour is used as a narrative tool. As is the case for the stories of alien interaction, the basic tenet here is that odour, more than virtually any other human sense, evokes an awareness of our animal nature. Despite our efforts, odours such as those associated with flatulence, excretion or perspiration are still difficult to control or suppress entirely, and often provoke visceral reactions of distaste. By reversing the distance from natural odours that has become part of contemporary culture, these narratives serve as a reminder of our origins. Replacing reason with sensation and instinct removes humanity’s claims to superiority over other animals. It thus references a history of conflict between scientific description of humans and our sense of identity as humanity, which can be traced all the way back to arguments between Darwinian evolution and divine creation in the nineteenth century.

Recent scientific analyses have suggested that if and when we ever do encounter alien life, it will very probably inhabit environments which differ from ours in their atmosphere and its smell. Other studies have suggested that odour is fundamental to our perception of ourselves and others, and to our sense of well being. Science fictional narratives offer an opportunity for us to contemplate the impact that our senses, perhaps smell most of all, have on our interactions with the world around us, and to question the extent to which we can ignore the legacies of our evolution - whether in future interactions with aliens, or right now in our interactions with one another.