The Oankali are a race of aliens in Octavia Butler's Xenogenesis trilogy (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 their 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 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 moon-sized, 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, much like mitochondria. The books suggest that this organelle is the driving force in Oankali civilization, to acquire and absorb biological diversity, much like the selfish gene concept.

Table of contents
1 Appearance and Physiology
2 Reproduction
3 Psychology and Sociology
4 Constructs

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. (Their natural form is an elephant-sized slug-like form, which communicates by direct neural connection.) They are covered with sensory tentacles in unique patterns, and also have sensory patches. Sensory tentacles can also directly connect Oankali to other organisms, nerve system to nerve system. They can also sting lethally if the Oankali is attacked.

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 response.

The tentacles give Oankali senses greater 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.

Ooloi 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 also breath water as easily as air. Their bodies are highly resistant to injury and heal rapidly; even gunfire is unlikely to seriously injure them.

Present day Oankali have undergone extensive genetic manipulation, incorporating traits from numerous other life forms.

Reproduction

Oankali have three sexes: male, female, and ooloi. All three are necessary to reproduction and the social system. Children are born sexless and go through a period of metamorphosis before they become adult. Ooloi are referred to by the "it" pronoun.

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. 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.

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.

The books imply that Oankali are incapable of 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. However, as humans cannot neurally connect with other organisms, they remain second class citizens within Oankali society.

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.

Constructs

The Oankali plan is to colonize the Earth with Oankali-human hybrids called constructs. Constructs are born from five-person family groups comprising one female Oankali, one male Oankali, one female human, one male human and one Oankali ooloi.

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.

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, only female constructs were created. Male 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. These ooloi have conscious control over their own bodies even greater than Oankali ooloi, 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.