User:Jaster1

My theory

Nourishment for the adult Wraith is the human "life force". Humans or very similar beings (e.g. Ancients) are the only food source that can properly nourish a Wraith, although they are capable of cannibalism. The Wraith can drain their victims slowly in order to torture and obtain information, or just to perform an act of sadism.

Despite the presence of teeth, the Wraith do not use their teeth to puncture the epidermis of a human. Rather, the life force is drained via specialized organs in the palms of their hands; apparently, one arm is the "feeding arm". Wraith typically attach this organ to their victims' chest, particularly right near the heart, where the skin is punctured. To facilitate the feeding process, a fast-acting enzyme is released to prepare the victim for the life force drain.

The life force draining works on a subcellular level. After the enzyme is released into the victim's body, the Wraith's feeding gland immediately initiates an autonomic process that is both bioelectrical and biochemical wherein the energy reserves in the victim's mitochondria are literally siphoned off into the Wraith. As a result of the mitochondrial-energy depletion, the telomeres (the protective ends of chromosomes) are vastly degraded and there is rapid oxidative stress to the cells as well. Both these effects have the physiological effect of rapid aging.

The rarely used Wraith ability to heal and reverse life-draining is really the exact opposite of the life force draining ability. The Wraith infuses a person's mitochondria with a large surplus supply of energy in a extraordinarily controlled manner. As a result their cells automatically regenerate to a degree and speed that is not usually biologically possible in a human. Temporarily enhanced, the person's own body repairs the oxidative damage and restores the telomores, thereby rapidly reversing the aging and healing the body's systems.

Theory 2

A Wraith places his hand on a human's chest and injects a coctail of fast-acting enzymes to facilitate the feeding process (and the 'enhancing enzyme' to strengthen his metabolism so that he doesn't die of trauma). The enzymes strip away the nutrients from the human cells so that the Wraith can just suck them out of him like sipping drink through a straw. The Wraith also gets rid of the byproducts of his metabolism (free radicals, etc.) by dumping it off into the human, who ages rapidly because of irrepairable cell damage from the enzymes.

The Wraith cannot feed on anything but humans because the enzymes are specifically callibrated to human physiology.