The term hok'tar comes from "Hok" meaning "advanced" and "Tar" a slang term for Tauri or "human". The Goa'uld Nirrti had carried out experiments that were designed to advance the "Evolution of Hok'tar" to create a new advanced human host for herself. She infected the children of Hanka, including Cassandra, with a retrovirus that remained dormant in the body for years until puberty, when the virus appeared and began to rewrite the individual's DNA in order to replicate. It caused a high fever, seizures, increased brain activity, and cellular generation of an electromagnetic field resulting in telekinesis. The virus, known as "mind fire" by the Hankans, was considered a sign of being touched by the gods. Affected teenagers went alone into the forest where they would be taken into Nirrti's underground laboratory, and returned cured so that their altered DNA would be passed on to the next generation, each generation getting closer to truly becoming "hok'tar."
Nirrti had wiped out the entire population of Hanka to erase the evidence of her experiments, and later fled to P3X-367. There she renewed her experiments by using a DNA resequencer for genetic manipulation which resulted in mutations including powers of telekinesis and telepathy. After Jonas was exposed to the device, he developed a growth of new tissue in the brain which gave him precognitive abilities, and which was probably another step in Nirrti's quest for the creation of hok'tar.