Pak

"Why do so many religions include a race of immortal beings who are constantly battling one another? What's the justification for ancestor worship?"

- Jack Brennan, 2125.

The Pak, known to Humans as Homo habilis, are a humanoid primate species from a world at the core of the galaxy. Their life cycle notably includes three stages: Child, Breeder and Protector, of which only the latter is sapient. The transition to the Protector stage is triggered by a virus found only in the roots of the tree-of-life plant, which grows naturally on their planet, but cannot grow on Earth.

The Human species is believed to descend from Pak who colonized the Earth 2.5 million years ago.

Biology
Pak are shorter than Humans, and have comparatively long arms, low foreheads and prognathous jaws. Like most species, they start life as children and progress into sexual maturity, at which point they become known as Breeders. Pak Children and Pak Breeders are not entirely sapient: they are mostly animal-like in behaviour, and need to be taken care of by Protectors. However, at least some Pak Breeders are intelligent enough to make fire.

When Pak Breeders reach a certain age (the equivalent of a Human of about 42), a physiological transformation occurs, which causes them to perceive the smell of the tree-of-life roots as irresistible, when they previously found it to be repugnant. Since the plant grows throughout their entire planet, it is practically impossible for a Breeder of the appropriate age to fail to consume the roots, triggering his or her transformation into a Pak Protector.

Protectors
Protectors differ radically from Breeders, with the most important differences being their superhuman strength and intelligence. When a Breeder transforms into a Protector, their skull expands backwards to allow the brain to increase in size tremendously. A bony ridge forms from the forehead to the back of the head. Their posture becomes slouched. Their hair and teeth fall off, the genitals disappear, and the skin becomes tough enough to be impenetrable to most blades. The lips and toothless gums merge into a rigid blunt-edged black beak, with two slits for nostrils. The joints on their limbs and shoulders swell grotesquely, providing much better leverage to the muscles. Even the finger joints expand, to the point that their fingers resemble strings of walnuts. Their nails transform into retractable claws, while the fingertips become more sensitive, to facilitate the manipulation of tools. Finally, a second heart develops inside the abdomen.

Pak Protectors can lift ten times their own weight, live for thousands of years (provided they keep on consuming tree-of-life roots), and recognize their descendants by scent. A Protector's physiology is deeply linked with their social role of protecting their descendants (sired during the Breeder stage, since Protectors themselves can't breed). When they have no living descendants left, they stop feeling hunger and are likely to die of starvation.

Culture and society
Pak are only sapient in the Protector stage. Despite their superhuman intellect, a Pak Protector's behaviour is dictated by a hardwired instinctual need to protect their bloodline, to the point that it's been questioned whether they even have free will. As a result, the Pak homeworld is in a constant state of warfare between Protectors trying to exterminate each other's Breeders. Other sapient species are viewed as nothing more than a potential threat, and eradicated without guilt.

Pak Protectors feel no desire for companionship, entertainment or sensorial stimulation. Art and luxuries are incomprehensible to them. They can spend centuries in a small enclosed space without feeling boredom. However, a Protector with no living descendants will lose their desire to eat and die of starvation, unless he or she finds a way to be useful for the Pak species as a whole, adopting a view in which all Pak Breeders are treated as their bloodline. For this reason, childless Protectors migrate to their world's vast Library, and dedicate themselves to science, technological development and other activities that might make them feel useful. Even so, most eventually stop eating and die sooner or later.

Protectors typically dress themselves in vests with multiple pockets. They don't wear anything else, since they have no genitals and their tough leathery armored skin provides all the protection they need against the elements.

Pak are an ancient species whose civilization has existed for over 3 million years.

Appearances

 * Protector, by Larry Niven (1973)