Adult stage of the Pak and other hominids. This form is achieved when a breeder stage hominid consumes the virus present in Tree-of-Life. It is described as a 'fighting machine,' with armor-like skin, super-human strength and super-human intelligence.
A species called Pak lives on a planet near the Milky Way core. The species has three main stages of development: Child, Breeder, Protector. A Pak is born, and matures into a Breeder, at which point he and she may bear children. Breeders are not particularly intelligent. Around 40 years of age, the root of the Tree-of-Life plant begins to smell delicious to all Breeders, and they eat it and metamorphose into the Protector stage via a virus that lives in the plant. A Protector's joints expand to give his muscles a greater moment arm, his skin wrinkles into a tough armor, and his nails turn into retractile claws. A second heart develops near the groin, the mouth fuses into a beak, and all sexual characteristics disappear. The most important change is that the brain expands, giving a Protector a tremendous intellect. A Protector has no motivation other than the preservation of his bloodline, and to that end the Pak homeworld is never free from war, since all Protectors are constantly trying to ensure their progeny's survival at the expense of everyone else. If a Protector has no children left, he no longer feels the urge to eat and dies unless he can adopt the entire Pak race and work towards their benefit.
Physiology and AppearanceEdit
There are many physiological changes that one undergoes during the transition to protector. Needs elaboration
Once the protector transformation is complete, a protector must periodically consume more Tree-of-Life root to maintain the virus in its body. Without the virus, a Protector will weaken and die as his DNA is degraded; the virus supplies replacement DNA.
Protectors are fully sentient, and are far more intelligent than ordinary hominids. However, this superior intelligence only serves a protector's instincts to protect its bloodline at any costs. Pak Protectors (and likely all protectors) are highly sensitive to the smell of their close relatives and 'weed out' those that smell wrong, which may indicate a potentially dangerous mutation. This weeding also suppressed positive mutations, this essentially halted the Pak's evolution. Protectors have an innate compulsion to protect close relatives.
Protectors typically die from starvation (from lack of will to live, e.g. if the protector's bloodline has died out) or violence. Although protectors have a vastly extended lifetime, it is not infinite; during the original half million year journey to Earth it is suggested that some protector colonists died from old age.
It is suggested that humans, and other sentient hominids that have turned into protectors are far more intelligent than their Pak counterparts.
When a protector has no bloodline to protect, it usually stops eating and starves; some childless protectors have been known to find reason to remain active, most assuming responsibility for their race as a whole.
Protectors on the crowded Pak home-world would constantly war against each other to gain advantage for their family and that alliances would last only until one ally sees advantage in betrayal. Human protectors, and those on the Ringworld, seem to be less warlike and better able to work for the betterment of the entire species (in some cases all Ringworld hominids) rather than only their bloodline, though this may simply be a function of how few protectors with families encounter each other.
Because of their enormous intelligence and instinctive need to protect their family (or their species, etc.), protectors are efficient, ruthless and quite amoral. It is observed several times that this intelligence combined with instinct also compels action so completely that protectors often see themselves as having little to no "free will".