The Oankali are a fictional race of intelligent extraterrestrials in Octavia Butler's Xenogenesis book trilogy (Dawn, Adulthood Rites, and Imago, also published in an omnibus edition under the title Lilith's Brood).
After the near-extinction of humanity in a nuclear war, the Oankali arrive in an organic interstellar ship and rescue the few remaining survivors for the purpose of genetic "trade": they intend to interbreed with humanity. In particular, certain types of cancer are extremely valuable, as studying and integrating them will enhance Oankali healing and regenerating abilities.
Oankali are natural genetic engineers, and are driven to seek out new lifeforms and trade with them in order to keep themselves from overspecializing and stagnating. They travel between the stars in immense living ships, and send down smaller ships as shuttles and to plant living communities.
The Oankali, their ships, their various specialized organisms, and all life on Earth after contact, contain the Oankali organelle in every cell. This organelle, much like human mitochondria, was once an independent microscopic organism which entered a symbiotic relationship with the ancient Oankali. The books suggest that the organelle is the driving force in Oankali civilization, to acquire and absorb biological diversity.
Appearance and physiology
Most of the Oankali seen in the books have been modified to resemble humans in size and shape, and use spoken language, to facilitate interaction with humanity. The Oankali apparently do this prior to first contact with a new species. Before meeting humanity, they had an elephant-sized slug-like form, which communicates by direct neural connection, since they have no vocal organs and no sense of hearing. Individuals who have chosen not to participate in the trade (known as the Akjai group) have kept this form.
The Oankali are covered with sensory tentacles in unique patterns, and also have sensory patches. Sensory tentacles can directly connect Oankali to other organisms, nerve system to nerve system. They can also sting lethally if the Oankali is attacked; only individuals of the ooloi gender have the ability to control the toxicity of their sting.
Sensory tentacles indicate Oankali emotions. The tentacles go smooth against the body when pleased or happy, merge into cones pointed at people or things when interested, and retract into knots when frustrated or frightened, a vestige of the sting reflex response.
The tentacles give Oankali senses greater range than those of humans. They perceive the ultraviolet and infrared spectrums and hear a greater range of frequencies. Because of their heightened senses, Oankali can easily read unconscious human non-verbal communication and see no problem with acting on a human's unspoken desires if they are at odds with their spoken wishes. Oankali can hear human heartbeats at a distance, as well as sub-vocalization (words murmured to oneself without actually opening the mouth), and their sense of smell allows them to detect the species, gender, and emotional status of humans. This has contributed to some humans' (wrong) belief that the Oankali can read minds.
Oankali can consume practically anything organic, though they consider eating other animals immoral. Their digestion is highly efficient and they produce almost no wastes. They can breathe in water as easily as in air, and need far less oxygen than humans. Their bodies are highly resistant to injury and heal rapidly; even gunfire is unlikely to seriously injure them. They are immune to most poisons and toxic inorganic substances, which they can usually resist and expel from their bodies with minor difficulties.
Internal anatomical detail is not discussed extensively in the books, but it is known that Oankali have two hearts and a specialized organ called yashi employed for collection, preservation and manipulation of genetic material; the ooloi yashi is larger and has more complex abilities than that of females and males.
Present-day Oankali have undergone extensive genetic manipulation, incorporating traits from numerous other lifeforms on other planets.
Oankali have three sexes: male, female, and ooloi. All three are necessary for reproduction and the social system. Children are born sexless (eka) and go through a period of metamorphosis before they become adult. In English, ooloi are referred to by the neuter pronoun it.
Ooloi have an additional pair of "sensory arms", specialized organs for connecting to other organisms, absorbing genetic information, and making alterations. Ooloi go through a second metamorphosis, during which they develop their sensory arms (between the two metamorphoses they have some ooloi abilities but cannot reproduce). Unlike males or females, ooloi need not sting lethally.
Once a male, a female and an ooloi are mated together, the male and female find touching each other unpleasant, though not painful. All contact, whether for mating or for recreation, is mediated through the ooloi, which also genetically mixes any children and provides intense pleasure. This is the pattern imposed on humans who elect to intermingle with Oankali; the resisters are rendered sterile and left to fend for themselves, since the Oankali believe that humanity is genetically doomed to destroy itself again and consider it immoral to allow humans to reproduce under those conditions.
Excluding the obvious extra pair of arms in ooloi, specialized genital organs are absent. Other anatomical differences are not extreme; the female tends to be larger than the male, and the ooloi usually smaller than the two others.
The ooloi takes genetic material directly from the bodies of its partners as needed. The female is said not to have a uterus equivalent; children are kept inside her body, and exit it through a random location after a long pregnancy (15 months). Labor does not cause pain in the female, but is temporally debilitating and needs her full attention, as well as the presence of her partners.
Psychology and sociology
Oankali society is non-hierarchical and strongly group-based. Decisions are made by consensus, during which adult Oankali join together via direct neural link for debate. Direct conflict is rare, and conflicts are usually resolved by peer pressure, psychological manipulation or "going around the problem".
Nearly all Oankali are part of a family unit or a pair of siblings. Males and females usually remain in the same family, while ooloi, once mature, leave to join or found new families. Brothers and sisters of similar ages usually mate (the possible genetic problems derived of incest are avoided by the ooloi who comes from another family).
The books imply that Oankali are incapable of deliberate cruelty or deception. Their human charges are never punished or physically brutalized, but are kept under tight control and emotionally manipulated to integrate them into Oankali families. Uncontrollable, violent humans are kept permanently unconscious or sedated, and left to live their natural terms. However, even cooperative humans cannot neurally connect with other organisms, and as such they remain second class citizens within Oankali society (treated in many ways like children).
Oankali apparently have no art (at least that humans would recognize), music or written language. They have no religion other than a belief in the sacredness and continuity of life. They have perfect memories (even of experiences while unconscious) and can relay experiences and information to each other directly. This explains their indifference to perpetuating human culture.
Imago, the last book of the trilogy, implies that ooloi, unlike the other genders, are capable of deception, keeping secrets and feelings of possessiveness.
The Oankali plan is to colonize the Earth with Oankali-human hybrids called constructs. Constructs are born from five-person family groups, ideally comprising one female Oankali, one male Oankali, one female human, one male human and one Oankali ooloi. Construct siblings come in pairs, one from the human mother, one from the Oankali mother, and remain extremely close as they grow up - the developing sex of the younger during metamorphosis is influenced by the sex of the elder.
Constructs look human to varying degrees, but all have at least one sensory tentacle, and most have sensory patches on their skin. Unlike humans, they can neurally connect with other organisms directly. Unlike Oankali, they enjoy music and have human-like sexuality (at least before they join a family).
Like Oankali, constructs go through a period of metamorphosis, during which their appearance can radically change and develop more or fewer traits of each species. Metamorphosis comes some years after going through human-style puberty.
At first, female constructs born to human females and male constructs born to Oankali females were created. Male human-born constructs were seen as too close to "the human contradiction" (intelligence combined with hierarchical behaviour), and therefore unstable and dangerous. The first male constructs were introduced carefully and slowly.
The final stage of integration of Oankali and human (or human assimilation into Oankali) was the creation of construct ooloi, at first unintentionally. These ooloi have conscious control over their own bodies, even more than Oankali ooloi do, and instinctively alter themselves to look attractive to the people around them. Construct ooloi emit pheromones that calm and seduce humans, so powerful that a few minutes of exposure can turn a mortal enemy into a friend.
The Oankali were originally common carbon-based lifeforms. Either in their home planet or elsewhere, they acquired the Oankali organelle, and with it the need to find and combine with other organisms. One group of these ancestors, for example, gave them their characteristic stinging tentacles. Based on their own genetic material and contributions from other species, they crafted large, resilient, plant-like organisms capable of feeding off solar radiation and travel through space carrying a self-contained environment, producing and recycling nutrients for their hosts indefinitely. A female of this species (Chkahichdahk) orbits Earth beyond the orbit of the Moon and was used to keep the human survivors. We are not told how many they were or how large the ship is. The male ships are much smaller, used as shuttles and as the foundations for living communities. Upon settling the Earth, the Oankali took many "seeds" and planted them. These seeds grow quickly into a flat carpet-like organism that covers the ground, looks for water and nutrients, and synthesizes food for its hosts. The Oankali can instruct it to grow projections to serve as houses, walls, tables, platforms, etc. The colony where Lilith and her mates and children live is named Lo. In due time, these organisms will cover the whole Earth and turn into females. Presumably they will fold into themselves, becoming Chkahichdahks, and depart Earth, carrying their Oankali construct hosts and the whole biosphere, and leaving behind only barren rocks. In Adulthood Rites, Lilith's construct son Akin is kidnapped and eventually comes to sympathize with a group of human resisters; he later persuades the Oankali to allow them to colonize Mars and reverse their sterilization. Upon contact with another species, the Oankali divide themselves in three groups: Akjai, who will keep their forms and will not participate in the trade; Toaht, who will take part but will not settle the planet; and Dinso, who will come down and "harvest" the planet as explained. The books, of course, deal mostly with Oankali of the Dinso group. By the time frame of the last book, the mother ship Chkahichdahk is reproducing itself asexually, splitting in two; one daughter ship will be for the Akjai, and another for the Toaht. These two, along with the Dinso ships, will part and go their own ways in a matter of centuries, probably never to find each other again.