@ chimpkin, In Star Trek it was explained... The beings known as the ancient humanoids were presumably the first humanoid species to evolve in the Milky Way galaxy, some four and a half billion years before the common era. Their true name lost since time immemorial, they have also come to be known as the Ancient Progenitors, and the Galenites, a name derived from the man whose work led to their discovery, Dr. Richard Galen. (TNG: "The Chase", Star Trek: Dark Horizon, Star Trek: Pendragon) During the height of their existence, they explored the galaxy, but found no lifeforms like themselves. Realizing that their species would one day cease to be, they seeded many primordial planets with the building blocks of life, encoding the DNA so that it would evolve into forms similar to their own. Earth was one such planet. Other species to arise from this seeding program include the Cardassians, Klingon and Vulcans. Encoded within certain DNA fragments were parts of a holographic message, meant for the ancient humanoids' progeny: Though Dr. Galen died before he could complete his work, the message was discovered by Captain Jean-Luc Picard and the crew of the USS Enterprise, along with representatives of the Klingon, Cardassian and Romulan races. (TNG: "The Chase") Episode writer Ronald D. Moore has stated that it is possible, though not explicit, that these ancient humanoids are the Preservers first mentioned in TOS: "The Paradise Syndrome".