IHFM

The Increased Human Fertility Mutation (aka: Breeder Mutation) is a mutation engineered by the Zetan Aliens.

Purpose
The purpose of the mutation is to speed up the repopulation of life on Earth. However, the Zetan Chief of the Science Department at the time felt it would be most efficient to create a single mutation allowing a single species on Earth to act as a breeder species. Humans proved to be most suited for the mutation, and were chosen as the breeder species.

Effects
The most noticable effects of the IHFM is the fact that women carrying the mutation are capable of reproducing with any animal living on Earth, and go through these pregnancies at a faster pace than usual. To get the infected women to be willing to breed, the mutation was engineered in such a way that women would often end up with a near insatiable sex drive when not pregnant, resulting in them having themselves impregnated just to get rid of the bad feeling.

Unintentional side effects include Advanced Mutations, in which women can draw traits from long time bestial partners. This process can be drastically sped up if the woman in question is put in a highly stressful situation whilst continuously being exposed to the animals. This effect is caused by the mutation forcing the body of the recipient to adapt to the animal attempting to impregnate the host. Intended to allow normally incompatible pregnancies to occurr (e.g. insectoid) without problems. Long term exposure to the same animal causes these adaptations to take a more permanent form.

Variants
The various "versions" are designated with an "S" (Strain) followed by a number. The most common variant of the mutation found is the S9 strain. Although all strains past S6 allow for bestial pregnancies, the Advanced Mutations could appear as early as S4, due to the mutation forcing the hostess's body to adapt to the donor animal. This resulted in some women in the Boston area to sometimes experience the side effects, without the pregnancy.

Timeline
A list of data on the IHFM (Increased Human Fertility Mutation):

-2070: The IHFM initially started production before the Great War, simply because the aliens wanted to see if they could do it. -2205: Ritual Clarity, the head of the science department aboard Mothership Zeta, managed to convince the captain to release some funds to resurrect the old project, stating it would mean more life forms would live on Earth, which would be beneficial to the aliens.

-2210: Science department resumed work on the IHFM.

-2215: The science department were able to map the human reproductive system even after over a century of radiation and mutations.

-2220: IHFM ups conception chance from 10% to 50%. Although they had achieved their goal, they didn't stop there. (S1)

-2225: Conception chance upped from 50% to 75%, pregnancy duration reduced from 100% to 90% (S2)

-2225-2235: lack of test subjects diverted to IHFM research means a stalling in progress.

-2235: Science department clears additional funding, work progresses at full speed.

-2235: Flexible organic tissue implemented. Skin, muscles and organs can now stretch and compress easily, allowing for faster growth rates or larger offspring. Additionally, this took away sagging of breasts and abdomen skin after pregnancies and lactation had ended. (S3)

-2240: Pregnancy duration reduced to 75% (S4)

-2245: Capture of animal test subjects to map chances of cross-species breeding.

-2250: Initial trials with bestial pregnancies fail. Although fun to watch, results are not made.

-2255: Conception chance increased to 90%, pregnancy duration reduced to 50% IHFM now vastly increases female libido to stimulate their cooperation in bestial trials. (S5)

-2255: Science department receives permission to spread the first viable strain of the mutation on Earth to watch its effects in the humans' natural habitat. Location: Boston.

-2260: First cross-species pregnancy completed with dogs. Pregnancy duration reduced to 40% (S6)

-2265: 50% of known animals can now crossbreed with human females, mostly mammals. Complications are common. Tissue flexibility improved. (S7)

-2270: 80% of known animals can now crossbreed with human females, with a focus on eggs and incubation. Complications become rare. Pregnancy duration reduced to 30%. (S8) IHFM now spreads through micro-organisms, basically making it a virus. The virus lives in the human womb, and spreads through sexual contact. Test subjects with outdated strains of the virus are sent back to Earth carrying so-called Impregnation Rays, which infect the target with the IHFM and instantly teleport a 90% developed fetus into the target's womb. (Fatal results for men.)

-2275: 95% of animals can now crossbreed with humans. Conception chance upped to 100% pregnancy duration reduced to 10% (S9)

-2277: 100% of animals can now crossbreed with humans. Pregnancy duration reduced to 5%. Complications no longer occur. Tissue flexibility vastly increased: subjects can now withstand womb expansion to own bodysize in 90 seconds without serious strain. Larger fetus or faster expansion rate only cause severe discomfort, no health risks. All internal organs share the same flexibility. (S10)

-2277: Due to numerous test subjects escaping from captivity, the virus was launched prematurely and landed in the Capital Wasteland and Mojave Wasteland. The launched strain was S9, instead of the near-perfect S10.