Archaically, the term “splice” referred to a the special case of a sophont or near-sophont biological splice, genemod in which an animal, plant or other naturally occurring, but non-human, organism is modified with elements of both human and other non-human genomes, usually for service, companionship, or hedonistic purposes. In the current era it is a term for any sophont descended or derived, in part or in total, from an ancestor created in that way. Confusingly to some, furries are also splices in the biological sense, but furries are the descendants of humans who chose to incorporate animal traits whereas sophont splices are nonhuman and nonsophont animals in primary origin. For millennia splices have had full sophont rights in the Civilized Galaxy though this was not so in the past and may not be true in other parts of the Terragen Sphere.
Through spacefaring history, and even before, some terragen organisms were partially provolved by adding human genome to some produce human cognitive functions, and some hominid anatomical traits (erect gait and prehensile thumbs, were almost always standard). What distinguished them from normal genemod animals of the time was this extra intelligence and homomorphization, and what makes them different from the provolves is that the goal never was human-level intelligence and freedom to explore their own potential, but rather a sort of animal-human plaything. Since in many polities they were regarded as nothing more than mere animals, they were treated as such legally. It is true that as early as the Interplanetary Age there were huge sentient rights advances, but much of this progress was lost with the resulting nanotech disaster. The great humanitarian reforms and universal sentient suffrage of the early 13th Era restored rights to splices, although some of these were again sadly lost in less regulated regions, and especially with the loss of civilisation during the Interregnum. In the 14th Era Core Worlds (the so called XIV Occupation, the United Suns), splices, like vecs, were assured of equal status everywhere, and only the most reactionary human supremacist clades would think or say otherwise. Once again, this high civilisation was lost with a new expansion of transingularitans.
Even from the start, splices were diverse; now they are incomparably more so. Originally only popular templates were used, but the demand for novelty meant more and more species had to be spliced, and more combinations, hybrids, neogens, chimeras, and every other biotech combination possible were created. From the early 10th Era onwards, free splice clades and polities have further evolved and modified themselves, or been modified by friendly posthuman or postxenoc entities. With interbreeding and genome sharing between splices, provolves, and furries, the division between splices and provolves eventually became more about the design goals of the originators than any distinguishing feature of splices themselves. Moreover, the fact that splices would often interbreed with and/or incorporate standard hu, tweak, and superior public domain (and even, when they could afford or acquire it, expensive private) genoprints and genmods meant that the graduation between splice and hu very soon blurred.
In the current universe it is not uncommon to find splices that are more plesiomorph human (“human near-baseline”) in appearance than most humans, and conversely there are many furries who are for more theriomorphic than most splices. Often the only way to determine the ancestry is via detailed phylogenetic analysis. Most clades care little for this anyway, since the old distinctions between of race and species have long since disappeared, or are only retained as a marker for cultural, religious, or House-Clade reasons (e.g. House Sevenborg, Genener, etc.).
Even so, many splices do have their cultural and memetic baggage, sometimes well-intended by caretaker beings, sometimes parasitical hold-overs of earlier fearful and wrong thinking. For this reason, splice cultures and subcultures differ as widely as splice genotypes, sometimes along phylogenetic lines, sometimes completely independently. Some splices have become isolationist or paranoid; others supremacist, with proud and even exaggerated traditions of their heritage. Some have retreated to protective enclaves in the Utopia Sphere, while others prefer the company of general mindkind, and can be found in all big population centers throughout the galaxy. The absurd stereotype of the shuffling subsapient splice is a slander that is believed only by a few extremist nearbaseline factions using pseudo-scientific phylogenetic analysis; in fact most splices have baseline if not above baseline intelligence and capabilities, certainly almost all splices are superior to baseline and standard plesiomorph human in physiological terms (enhanced smell, hearing, reflexes, etc. that are part of their animal heritage). While the number of splices is not equal to the number of plesiomorphs or apomorphs, it is still a respectable figure, perhaps one and a half quadrillion in all, and today splices form an important and even essential part of galactic culture and civilization.
Taken from my original write up for Orions Arm, only slightly modified