In biology, a Chimera is an individual composed of genetically distinct cell lines from two different zygotes.
The most common type of chimera today is the transplant recipient, an artificial chimera created by placing the organs of one being into the body of another. Less common, but much more impressive, are tetragametic chimeras; the opposite of identical twins, tetragametic chimeras are created when two separate zygotes, that would be fraternal twins, merge to become a single individual. This phenomenon is distinct from conjoined twins, which are partially fissioned identical twins, in that chimera are One of the most famous of such chimeras is Lydia Fairchild, who is mistakenly prosecuted for welfare fraud after DNA tests suggested that she wasn't the mother of her children. Since fraternal twins can be of different genders, it is possible for a tetragametic chimera to be both male and female simultaneously, though two fully functional sets of organs are exceedingly unlikely due to conflicting hormones.
The Sixth world have a substantially greater potential for biological chimerism due to the common existence of type-O organs, bioware, black-market orgenlgging, and metatypes.
The most common type of meta-chimerism is a result of of the widespread organ transplantation, most notably the common use to type-O replacement organs and bioware. Spike babies were just as susceptible to congenital defects, toxins, pathogens, and traumatic injury as normal humans were. Childhood organ failure in spike babies, necessitated transplantations at a time long before organ culturing was widely available and the number of dead elf and dwarf child organ donors was obviously small, necessitating the then-common practice of cross-metatype transplantation, usually from humans to elves and dwarfs. In such cases, complications were no greater than those experienced by the baseline transplantee population, proving that elves and dwarfs aren't significantly biologically different from humans.
However, only three of those transplant recipients still have the donated human organs. In most cases, the aging human organs were usable to keep up with their still relatively youthful bodies. Different aging rates is the single most insurmountable obstacle to long-term cross-metatype transplantation and any human organ transplanted into one of the longer-lived races will inevitably need to be replaced, the profit potential of this fact is not lost on some unscrupulous vendors, who even today sell mislabeled human organs as elf and dwarf parts.
After the first round of goblinization, young ork and troll transplant recipients were not so lucky. While there are no major incompatibilities between the goblioid metatypes and and other metatypes, the rate at which a young goblinoid grows often means that they are at high risk of dissection and occlusion and many growing goblinoids died of such complications. The worst complications occurred in those transplant recipients who received their organs before goblinization; the transplanted organ remained the same while the rest of their bodies rapidly changed.
These complications were not faced by those who received human organs well into adulthood, though finding a human heart large enough and strong enough for a troll is a daunting challenge.
Cross-metatype transplants became much more common with the advent of commercial organ cloning and the discovery of Owen Whiting. For well over a decade, Owen Whiting was the only known metahuman with a universally compatible cell-line, and those organs grown from his cells were used indiscriminately in all metatypes, which the exception of human and goblinoid children due to the heightened potential for future complications. Even after Type-O cell lines were discovered for the other major metahuman races, the time and expense required to cultivate such cell lines made Owen's organs the single most common transplant organs amongst all metatypes. Hundreds of thousands of metahumans have at least one of these Owen organs in them today.
Today, metatype matching is always preferred, particularly for engineered bioware, to minimize "essence loss" which has become a hot button issue amongst medical ethicists. Still, in cases of emergencies or when metatype matching would be prohibitively expensive, cross-metatype transplants are not unheard of.
Regional and cultural "metavariants", which are often as anatomically different from their "parent" metatypes as the metatypes themselves are from humans, usually do not have any sort of variant-specific generic organ available to them. Each metavariant is rare and metavarient Type-O cells are rarer still. The common practice is to match these metavariants as if they were members of their parent metatype, but this can be extremely impractical in cases where there are extreme anatomical differences between metatype and metavarrient. For example, satyrs tend to be more compatible with dwarf and organs than they are with standard ork organs, due to their stature, and they must always have replacement legs cultured.
The most striking metahuman chimerism is natural Tetragametic chimerism when the two cell lines have different metatypes. In many cases, all the differences are internal and the chimera externally appears to be a member of one metatype or another, the difference only being detectable by medical examination. Such meta-chimera are extremely rare, constituting only a small fraction is the very rare tetragametic chimeras, and most go undiscovered. When one cell line is a goblinoid and the other is not, however, it can obvious from even the most cursory examination. The mismatched tissues never appear quite right, particularly when there is a mismatched skeleton. Complications from such chimerism range from infirmity to death. In the case of a natural troll metachimera, death is the most common outcome. To the date of this writing, no know part-troll natural metachimeria has ever survived into adulthood.
Mosaicism and "partial goblinization"
In addition to chimeras, there exist metamosiacs. Mosiacism exists when two sets of genetically distinct cells arise in the same person from a single cell line, usually due to mutation. In the case of metamosiacs, there is no medically discernible differences in their DNA of their different-metatype cells, but there may be some unmeasurable differences in their genetic "astral shadows".
The first identified type of metamosiacism, dubbed incomplete goblinization, was discovered in remote hospitals in Hungary, New Zealand, and Venezuela. According to all reports, goblinization symptoms stopped shortly after the patients were brought into these hospitals. For many, it was a short reprieve from the slow and painful process. For others, it was a death sentence as their partially transformed body suffered from fatal cardiovascular, neurological, and respiratory complications.
Those who survived were either just beginning the process or had nearly completed it before it was halted. Later studies have concluded that these hospitals laid on strong mana ebbs, the lower mana level halting the goblinization process.
Once the patients were discharged from these hospitals and left the mana ebbs, they immediately began to goblinize again.
Similar to incomplete goblinization is partial goblinization caused by short duration exposure to very powerful mana spikes. In most cases, people who are partially goblinized are completely unaware of it, since they don't stay in the mana spike long enough for symptoms to begin. They tend to have an extremely limited number of goblinoid cells which go totally unnoticed on even the most through of medical scans. Usually, such metamosaics can only be identified via full autopsy due to the very small number of goblinized cells in their bodies.
In addition to partial goblinization, many humans and metahumans are born with cells of other metatypes, due to differentiated expression in utero. Recent studies by Zafman and Rogers suggest that it is, in fact, common for the children with parents of different metatypes to have some tissues of a metatype that they did not express as, those these differently expressed tissues are rarely life-threatening and never particularly advantageous, generally limited to a small handful of cell in a vestigial organ, only detectable through autopsy.
By studying such differential expressions, as well as goblinizations and ghoul transformations, we may be able to gain a better understanding of how metatype expresses itself. <<<<<Dr. Loveless
