Arcopel Gene Drive
When the ancient arcopel spread their human specimens throughout the Sealed Kingdoms, they chose to impose certain alterations on the hapless hominids for reasons still not fully understood. From the long ears of the Lepidosians to the powerful physiques of the Karstineans to the shocks of blue found in Evermornan hair, no two groups of near-humans look entirely alike despite insufficient time for allopatric speciation to occur. The tool the arcopel used to accomplish this is known as the 'arcopel gene drive' - or simply 'gene drive' for short.
Transmission & Vectors
The sections added to the human genome through the arcopel gene drive are sex-linked to the extent that they will most often (but not always) be passed only to offspring of the same sex as the carrier parent. This means that, even when two disparate populations of humans comingle, their arcopel-imposed traits remain relatively stable over time.
While the various near-humans of the Sealed Kingdoms region have much of the same underlying DNA - to the extent that inter-breeding is usually successful when groups spend a lot of time together - the physical changes imposed on them beyond environmental pressures are prepetuated by the use of gene drive technology. Heavy error correction in the appended genes helps to prevent deleterious mutations that might drive a group to extinction, but it also makes removing them (if desired) a pernicious problem for groups without advanced genetic engineering technology themselves. Still, mutations in this error correction section can cause the gene drive to mostly fall dormant, with few if any persisten morphological changes present in the resulting individual. Evermornan humans are notably close to their terrestrial human ancestors as a result of such a mutation. Early Evermornans had long noses with a tendency to develop yellow keratinous callouses, pointy ears, and a notable blue-black cast to their hair as a result of gene drive inclusions. At some point, these traits were lost due to natural mutations. Modern Evermornans still occasionally show bluish inclusions in their hair and exhibit more aquiline features despite their regional terrestrial regional heritages, but the effect is much less pronounced. The human residents of the Beta Xymeria System are similarly shorn of their drive-related features. The Cornelians' unusual tallness is borne of the environmental pressures of their low-gravity homeworld, overriding their orginal, similarly avian features.
The arcopel gene drive is a germline intervention, meaning that the first individuals who carried them showed no symptoms but their descendants did. The arcopel are believed to have often chose the traits of animals who resided close to the sample populations on the human homeworld's surface, with the chance of depersistence (see cause) apparently being proportional to the degree to which the target animal differed genetically from the (as of yet unknown) human ancestor. These theories have lent credence to the idea that the arcopel sought to 'tag' their experimental samples through the gene drive, as this would allow the arcopel to tie the population of an experimental world to specific regional populations. Examples of this type of alteration include:
Early Evermornans (corvids, most likely magpies)
Lepidosians (unknown lagomorphs)
Feldeans (felines, most likely lynx)
Early Cornelians (psittaciformes, most likely kea)
Karstineans (unknown robust canids)
Hespartans (unknown gracile canids)
The morphological changes induced by the gene drive are limited. This might include different ear structures, different facial proportions at the edges of human ranges, and alterations in hair, eye, or skin coloration and patterns.
Over time, certain features have become overshadowed by environmental adaptations despite remaining present due to gene drive influence. For example, while Karstineans are have been noted to have larger lower facial features, darker hair, and pointed ears in keeping with their robust canid inclusions, their dark hair has also been selected for because (until recently) their major population centers were equatorial and, thus, recieved ample insolation. Late Karstinean experiments with gene editing successfully disabled the gene drive in select volunteers, but their offspring retained dark hair and complexion overall due to their environment. Similarly, the smaller statures of Lepidosians and Feldeans are believed to be the result of the environmental pressures towards economy of water (desert) and living space (islands), respectively.
Over thousands of years, the features derived from arcopel gene drives have most often become parts of cultural identity for the affected populations. With the exception of the occasional Lepidosian looking to integrate into the closely allied Evermornan culture, there is little desire to eliminate them as such. In rare cases, a gene drive might become mutated in such a way that it would carry deleterious effects on the host despite rigorous arcopel-engineered error correction. Once detected, Evermornan and Hespartan genetic engineering technologies are capable of excising the damaged genes at the expense of rendering the subject's offspring 'doctrinaire' humans. Without these technologies, genetic counselling is important for these individuals, as deleterious mutations carried by a gene drive will spread more quickly within a population. Indeed, such a mutation is believed to be behind the Lepidosians' unbalanced sex ratio - only one in four Lepidosians is born male, though this is gradually rebalancing over generations as selection wins out over the mutated drive.
Hosts & Carriers
All humans and near-humans within the Sealed Kingdoms region possess arcopel gene drives in their genomes, though the drives may lie dormant in some populations.