In the country of Amestris there are people with the extraordinary ability to transmute one thing into another. These alchemists are extremely powerful and in general use their powers to better the lives of those around them, either through philanthropy or through military service. However, there are those whose nature makes them greedy, for power, prestige, or simply scientific achievement. Some of these alchemists are responsible forthe creation of Chimeras: creatures that are an amalgam of two or more species, with some attributes of each. While this practice is generally accepted when it comes to animal chimeras when humans get involved things become much more complicated.
Fullmetal Alchemist: Brotherhoodfollows the story of Edward and Alphonse Elric as they seek to acquire the Philosopher’s stone. The boys believe that this will grant them the power to return Al to his human body which was lost in a tragic human transmutation accident. Ed also lost portions of his own body in the same incident. Though Al does eventually return to his mortal body, the boys learn a few dark truths about alchemy and what the cost of being a State Alchemist can truly be.

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The Sewing-Life Alchemist
The only publicly known alchemist in recent history to dabble in bio-alchemy isthe Sewing-Life AlchemistShou Tucker. Bio-alchemy is the name for the practice of creating chimeras. He was well known for having created many animal chimeras with varying levels of success, but most notably created a chimera that could speak and understand language. It was later revealed that to do so he was transmuting humans into his creations.
Without the introduction of humans into the practice chimeric alchemy is considered a legitimate study, with the various combinations being used mostly as guards,but also as pets, and messengers depending upon what animals were merged. It is briefly alluded to that in the past there have been other bio-alchemists but that the field is largely ignored due to the many dead-ends and limited practical applications.

Government Chimeras
Not as well known to the public, but revealed to the protagonists later in the anime, the government has also been investigating the viability of chimeras. Although Tucker is also a representation of the government as a state alchemist he was notbrought into this projectfor unclear reasons. Using an incomplete philosopher’s stone to boost the alchemical power of the alchemist involved, the government is able to make far stronger and more viable human chimeras than Shou Tucker, as well as a wider range of animal chimeras.
They have four separate classifications for their human chimeras. First, the type that Tucker made, the complete failures. They have almost no social skills and experience debilitating levels of pain due to incompatible or insufficient internal structures. These creatures, despite their defects, still retain their human memories and souls. The next category are those chimeras that have bothhuman and animal physical characteristics,but the mental capacity of humans. They often end up appearing as anthropomorphic versions of the animals with which they were transmuted. They are considered failures since their appearances prevent them from blending in with human society.
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There are two forms of chimera that the government considers a success. Firstly those who appear human outwardly but have some sort of modified internal structure that lends them advantages. This may give them heightened senses or superhuman capabilities, but they are still inconspicuous when out and about. The goal of government chimeras is, ultimately, the ability to shift between an entirely human form and an animalhybrid form at will.These chimeras are also able to hide within society but the advantages they gain from their transmuted counterparts are far greater than the advantages in their more subtle counterparts.
Father in the government also makes ample use of purely animal chimera. Laboratory 5 for example is guarded almost entirelyby feline-reptile hybrids, and it is strongly implied that he has an army of various others at his disposal. These animal chimeras are no less fearsome for their lack of human intelligence. In fact, it is this ability to think that causes more than one of the human chimeras to betray their creator and join the protagonist’s side.
While chimeras are a blend of any two or more creatures they are realistically broken down into two categories within Amestris. Human chimeras, which are considered illegal and immoral, with the creation ofthem being considered trespassingon the domain of god. And animal chimeras which are considered to be a useless endeavor that hasn’t advanced scientifically in decades. Neither of these negatives has stopped various alchemists over time from trying to perfect the art and cement themselves in history as being the first to be successful. Shou Tucker may have failed, and lost his life for his efforts, but the government arguably succeeded. Though morally many would argue that they failed as well.