“Uplift” is a term used to describe guided or forced evolution and is a concept found in the science fiction novels of David Brin, as well as explored in the on-line Universe-creation project, “Orion’s Arm”. Generally, Uplift involves the genetic development or transformation of animals into an intelligent species by an already intelligent species.
Uplift is, I feel, one of those species origin tools that should be used sparingly – unless you are running an Uplift game, of course. Otherwise, like the Ancients in the Official Traveller Universe, Uplift becomes the default setting to explain a species’ evolution which, in turn, encourages lazy thinking.
I have used Uplift only once in my RimWorlds Campaign, in the detailing of the H’ran – a rather aggressive lizard-like or crocodilianoid species. I postulated that the H'ran had been Uplifted specifically as assault troops by and for the, now long defunct, Thongaloros Empire. The demise of the Empire, under pressure from invaders entering the RimWorlds via the Whisp Route, had left the H’ran in control of some Empire fleet elements. Much like the sentient Autowars in Orion's Arm (sentient, self-replicating warmachines), the H'ran continued to follow their underlying programming - securing and protecting as much of the old Empire as they could.
The H’ran were able to carve out a reasonable sized Pocket Empire, but then stagnated as they lacked the technological knowledge to maintain their starships. Fortunately for the H'ran, they conquered the Gherlach - a less aggressive, but more tech savvy reptilian species. Eventually, the Gherlach took over so much of the running of the H'ran State and the larger Klarthur Confederacy (of which the H'ran State was the most powerful member) that, in effect, the slave caste had become the new ruling caste of the Confederacy.