Mutations and their causes

Radiation
The various types of mutant creatures that inhabit the wastelands were mostly caused by radiation. This is where mantises, geckoes, spore plants, deathclaws, radscorpions, brahmin and the various mutant rodent species come from. Also, this is how ghouls, decrepit, ragged, almost rotting, zombie-like victims of massive radiation poisoning, are made. Most ghouls were created from vault dwellers living in Vault 12 under the city of Bakersfield (better known as the Necropolis after the War). As part of the vast Vault Experiement Program, the Vault 12 vault door was designed not to close properly. Thus, massive amounts of radiation attacked those within the vault, most of whom were turned into the current ghoul population. Generally, in the Fallout universe, massive exposure to radiation causes humans to transform into ghouls. Also, all ghouls are completely sterile. There is only one generation of ghouls in the wasteland and it is the last. Furthermore, the ghoul transformation grants its subjects extremely long life. Ghouls created in the Great War of 2077 were still alive during Fallout (2161) and Fallout 2 (2241). Ghouls are generally as intelligent as normal humans. However, their extreme ugliness and physical frailty makes the life of a ghoul difficult at best. Ghouls are, naturally, immune to radiation. Radiation poisoning can't really get worse for them.

Many would question this and say that radiation wouldnâ€™t create giant scorpions and zombiesâ€�?itâ€™d just kill you. Thatâ€™s entirely true for us. Fallout, however, is different. In this world, in accordance with the 1950â€™s sci-fi physics, radiation just makes things bigger and meaner, though the player can still suffer radiation poisoning in the game and radiation in general is a bad thing.

FEV
The other source of mutations in the Fallout world is FEV: the Forced Evolutionary Virus. In the years leading up to the Great War between China and America, both sides were scrambling to research something that would give them an edge in the coming conflict. What the Chinese research teams developed is unknown, but America tapped its resources of private industry for a secret weapon to beat the Chinese. One company, a high tech outfit called West Tek, was a major defense contractor. In the first Fallout, the player explores a location called the Glow, which is in fact an underground West Tek research facility that was directly targeted by Chinese warheads during the War. While exploring the heavily radioactive ruins, the player discovers that West Tek created a number of useful things for the American military. Laser and plasma weapons were being experimented with here. Power armor, massive self-contained suits that turned a single soldier into a walking tank, was developed here. And most importantly, some terribly important research into immunity drugs was being conducted at West Tek.

One fear among the US military was that the Chinese would deploy biological weapons against American troops: powerful superviruses that would decimate armies without a single shot fired. Thus, West Tek began the Pan-Immunity Virion Project (PVP) to develop a way to counteract Chinese biological agents. It was determined that the way to achieve this was to alter the subject's DNA to cause immunity. During testing of PVP in 2076, abnormal side effects were observed in test subjects. The test animals began to grow dramatically and their brain activity increased. Seeing the potential there, the Army sent its own people to secure the project and renamed it FEV: Forced Evolutionary Virus. Not content with mere immunity to disease, FEV would turn soldiers into abnormally strong and intelligent supermen. When testing on animals reached its logical conclusion, the US military moved FEV research to the Mariposa Military Base where secret testing on human volunteers (read: military prison inmates) proceeded.

However, the grim nature of the research being carried out at Mariposa greatly unnerved the garrison guarding the base. The nature of the scientist's work, which had until then been a secret from the Army grunts, caused them to more or less revolt once they found out. The colonel in charge of the garrison lost his mind and committed suicide. His second in command, Captain Roger Maxson, took command of the troops and began interrogating the scientists. Rattled by the vile things the scientists were doing to test subjects and incredulous of the claim that the science team was only following orders, Maxson had the researchers executed one after the other. Later, he announced the Mariposa Military Base to be in full secession from the United States. Soon after, the bombs fell and the United States ceased to be. Disgusted with the Mariposa base, haunted by the test subjects and the executed scientists, Maxson decided to lead the troops and their families to the Lost Hills government bunker, where they would later use their high tech military equipment and knowledge to form the Brotherhood of Steel.

The Military Base was quiet for a long time. Not long after the war, however, a group of explorers, including Harold, entered the Military Base looking to end a peculiar proliferation of mutated animals which seemed to be coming from the base. The exact date of the expedition is unknown, but Harold's presence as a human being leads me to believe that it can't have been more than ten or twenty years after the bombs fell since Harold is known to have been a vault dweller who emerged shortly after the war's end. Thus, to still be alive and human, he'd have had to have entered the Military Base not long after the war.

Leading the expedition was Dr. Richard Greyâ€�?previously known as Richard Moreau until he was exiled from Vault City. When Grey's team entered the Military Base, most died when they encountered the automated defense systems (robots). Soon, only Grey and Harold remained. Harold was knocked out (he never did find out how) and woke up out in the desert looking like a ghoul. Grey, however, was headed for bigger trouble. He had made it to the vats room, where massive bubbling cauldrons of thick, green FEV waited to be experimented with. Grey was knocked into a vat by a crane and managed to crawl out. FEV was initially meant to be injected into humans, but Grey soon found out that direct physical contact worked as well. He began to mutate in horrible ways, turning into a sort of blobby kind of thing. He developed psychic powers, which were enhanced by consuming living minds to expand his own brainpower. Slowly, as wanderers made it into the base themselves, he started doing his own experiments with FEV.

Grey found that many of the test subjects were turning giant, mindless brutes with the brains of a child, if they survived at all. However, a rare few test subjects yielded super mutants. Immune to disease and radiation and blessed with exceptional strength, intelligence and endurance, super mutants were superior to humans in every way. They also possessed the exceptionally long life of the mutated as well as the total sterility. Grey--who now called himself the Master--lamented the needless destruction of the war. In his warped state, he decided that he would have to force humanity to evolve. If everyone could be as perfect as his super mutants, there would be no more conflict. Those who could not evolve would die. The Master began seeking out uncontaminated humans with which to create mutants and build his super mutant army.

The problem was that to build his army of super mutants, the Master would need uncontaminated humans. But not humans uncontaminated by radiation. Rather, he needed humans who were clean of the mutated strain of FEV from West Tek. When the bombs hit the research facility and turned it into the Glow, they cracked open a few tanks filled with FEV. The bombs' radiation then mutated this FEV into an airborne strain. But this new airborne FEV didn't have any real mutagenic effects on people. All it did was inoculate human subjects against the real FEV, acting as a sort of vaccine, which was troublesome for the Master and his Lieutenant (whose dialog tells us about this FEV inoculation). The ideal dipping subject was someone who hadn't been exposed to the airborne FEV. Such a population was availible: Vaults. Each one contained around 1,000 viable subjects to be dipped and turned into super mutants. This is why the Master is so hell-bent on discovering the location of the Vault Dweller's home.

Aside from super mutants, the Master also created a variety of other creatures. No one is sure where the floaters came from, but then again most would rather not know. Centaurs were created by tossing a varied mix of dogs, cats, brahmin and other animals into a vat and seeing what came out the other end.

Other Mutants
There are a few other types of mutant creatures in the wasteland that donâ€™t directly stem from FEV or radiation. These are mostly the intelligent animals and one plant encountered in Fallout 2. The intelligent deathclaws were an experiment conducted by the Enclave to create super tough soldiers to shred enemies to pieces that could respond to simple orders. The intelligent spore plant and radscorpion in Broken Hills were another, separate experiment conducted by a scientist there. Any other talking animals are flukes. All such creatures can be assumed to all have died the instant Fallout 2 ended. Similarly, the alien creatures encountered in Fallout 2, which were a pre-war experiment conducted by the US military similar to the Enclaveâ€™s intelligent deathclaw research, were all, without exception, killed by the protagonist in Fallout 2. Frank Horrigan, Enclave super toughie, was produced by a series of treatments involving carefully modified FEV, surgery, a variety of other drugs and a great big suit of armor. Heâ€™s dead, too. Lastly, Harold, who looks a lot like a ghoul, but he really isnâ€™t. Ghouls are the result of massive radiation exposure while Harold was mutated by brief FEV exposure without being dipped. FEV is at best unpredictable and you never can tell whatâ€™ll come back out of the vats (just look at the Master). Harold is essentially a fluke, the result of a unique combination of a specific degree of exposure to the virus, a specific degree of radiation within his own body and any number of other factors. While FEV doesnâ€™t crank out ghouls as reliably as it does super mutants, it does occasionally spit out something that looks like one: Harold.

Variants
Over the years, different people have been in charge of Fallout canon and have come up with different interpretations on this subject. Mutant creatures and where they come from is one of the most controversial topics in Fallout canon and itâ€™s very easy to annoy veteran scholars of the setting by getting things wrong or even just partially right.

First, Chris Avellone seemed to prefer the "FEV explains everything!" theory of mutation. He suggests that when the Glow was hit by the Chinese warheads, the tanks holding the virus burst and the FEV was vaporized and shot into the air. It was then mutated by the radiation from the blastâ€�?remember, viruses are living organismsâ€�?and went on to help radiation create the various mutant animals we know and love as well as ghouls. The problem with this theory is that first off itâ€™s a bit redundant since Fallout radiation is already fully capable of producing the mutations seen in the gameworld. Second, we know from the Lieutenant's mention of inoculation from mutant FEV that any airborne strain of FEV could not cause these mutations. If it did, why didn't any humans mutate from exposure to the airborne FEV? Furthermore, if radscorpions, geckoes, molerats, deathclaws and other creepie crawlies are all products of FEV, how can they breed as much as they do? Remember, FEV causes sterility.

Next, Chris Taylor offers a different point of view on how ghouls are made. He suggests that when people with too much radiation damage are dipped, you get ghouls. When people with mild radiation damage are dipped, you get stupid supermutants. When people with very little radiation damage are dipped, you get intelligent supermutants. This would mean Harold is a normal ghoul. The trouble with this one is that it doesnâ€™t account for all the ghouls that are around, namely the Necropolis ones. Also, knowing the Master, any ghouls produced by the vats would probably be consumed or otherwise destroyed for being imperfect. You could say that the Necropolis ghouls were produced by Avelloneâ€™s flying FEV, but that, of course, goes against the simple fact that FEV is not an airborne organism.