Human

Humans are the dominant beings on the planet Earth and comprise most of its animal population. In addition to being the only life forms capable of using tools and skills in an advanced manner, they are also the only known species on Earth capable of performing alchemy.

Additionally, as understood in the Fullmetal Alchemist universe, humans are comprised alchemically of three major parts: the body, the soul and the mind/spirit.

The physical body, which is a complex system of bones, muscles, organs, nerves and blood vessels developed for optimal interaction with the environment, follows standard natural laws and patterns that, while different between species, are similar to all animals life on the planet. It has been stated that, broken down to its basest components, the average adult human body is comprised of Water (35 L), Carbon (20 kg), Ammonia (4 L), Lime (1.5 kg), Phosphorous (800 g), Salt (250 g), Saltpeter (100 g), Sulfur (80 g), Fluorine (7.5 g), Iron (5 g), Silicon (3 g) and fifteen other elements in trace amounts.

The soul, on the other hand, is a component apparently unique to humans in the Fullmetal Alchemist universe. It is the incorporeal and supposedly eternal part of a human, synonymous with the self or psyche, which contains all non-biological and emotional attributes and is said to separate entirely from the physical body at death.

While a human remains alive, however, the body and soul are connected by an entity known as the spirit (but often referred to as the mind). Regardless of how mutilated or altered either the body or soul may become, so long as their both remain intact, the connection between them remains and will cause the two components to resonate with each other and attract one another in an attempt to reunite them.