|Commander John Shepard (left) and Lightning (right), a Male and Female Human, respectively|
|Classification||Mammal (simian subgroup)|
|Average Height||Approximately 5' 11"|
|Skin color||Pale to dark brown|
|Average Lifespan||typically up to 100 or 120 standard years; ages up to approximately 200 to even agelessness have been reached among superaturally-powered individuals|
Humans, taxonomically referred to as Homo sapiens, are an excessively numerous sentient species, noted both for its relatively unassuming characteristics, and for their adaptability and malleability to a variety of scenarios (typically a result of their normally unassuming characteristics). Humans can be found anywhere, engaged in many different pursuits: spacers, mercenaries, smugglers, merchants, soldiers, assassins, farmers, crime lords, laborers, slaves, slavers, and many others.
Bilaterally symmetrical bipedal primates, Humans were a warm-blooded humanoid species. They had two hands and two feet, each of which had five digits. The Human hand featured an opposable thumb and their fingers had multiple points of articulation. The average Human life span had gradually increased during their history. At one point, it was only 35 years, but intelligence born of a greater understanding of the universe around them gave them the knowledge to extend their lifespan, which now sits at near 120 years.
They had two sexes, as was common to many humanoid species. The female of the species was fertile once a month after she reached puberty until the onset of a biochemical stage known as menopause. The make-up of Human DNA structure was significant, as, with some modifications, it allowed them to crossbreed successfully with a wide range of other races across the galaxy.
On average, Humans were not as physically strong as some species. They were, however, resilient in other ways. They were more adaptable to incarceration than many other races. They could survive with one lung or kidney, despite having two of these organs initially. Humans could also go days without water and weeks without food due to their bodies' ability to conserve water and live off stored fat. Their bodies' efficient temperature regulation allowed them to resist and survive hot or cold temperatures that would adversely affect other species.
Humans had iron-based hemoglobin in their blood. Each individual's blood could be one of several blood types, which included AB-positive, O-negative, and B-negative.
The Human genome was considered to be remarkably elastic. In reaction to environmental changes, selection pressures only needed few millennia to engage new genes and reshape the Human bodies. A consequence of that exceptional adaptability was the existence of many Near-Human species—that is offshoots of the baseline Humans who had followed their own evolution.
Humans were noted for being naturally learning and extremely adaptable—not only in terms of physiology, but also mentality and society. Their societies were capable of transforming very quickly in response to a wide array of conditions, which explains why two Human populations could have next to nothing in common culturally speaking. Some Human peoples had more in common with neighbors of other species than with their own kind.