Humans - Physiology, Anatomy and Society: Humans are a bipedal, mammalian humanoid species that originated on the planet Terra (Old Earth) in the Sol System. There is evidence that Human evolution was strongly influenced by the efforts of the ancient alien civilisation known only as the "Old Ones," who were the first known species to attain self-awareness in the Milky Way Galaxy. It was the Old Ones' common practice to spread life, particularly the seeds of intelligent life, on worlds wherever it might take root. As part of this purpose, the Old Ones were the creators of the early, tree-dwelling primate ancestors of Mankind on primordial Earth tens of millions of Terran years ago who eventually rose to full self-awareness and the development of their own culture.Humans, known taxonomically as Homo sapiens (from the ancient language of the Roma which meant "wise man" or "knowing man"), are the only living species in the Homo genus of bipedal primates in Hominidae, the great ape family. Anatomically modern-appearing Humans originated on the world of Terra about 250,000 standard years ago, reaching full behavioural modernity only around 150,000 standard years before the 41st Millennium.Humans have a highly developed brain, capable of abstract reasoning, spoken and written language, introspection, and problem-solving. This mental capability, combined with an erect, bipedal body carriage that frees the hands for manipulating objects, allowed Humans to make far greater use of tools than any other living species on Old Earth.Other higher-level thought processes of Humans, such as self-awareness, rationality, and sapience, are considered to be defining features of what constitutes a "person," though such features are shared with the other major intelligent xenos species of the galaxy like the Aeldari, the T'au, the Necrons, and the Orks (though some might question the latter).Like most higher primates originally native to Terra, Humans are social animals. However, Humans are uniquely adept at utilising systems of spoken and written communication for self-expression, the exchange of ideas and organisation. Humans create complex social structures composed of many cooperating and competing groups, from families to nation-states to interstellar empires. Social interactions between Humans have established an extremely wide variety of values, social norms, and rituals, which together form the basis of Human society.Humans are noted for their desire to understand and influence their environment, seeking to explain and manipulate phenomena through the practice of science, philosophy, mythology, and religion. This natural curiosity has led to the development of advanced tools and skills, which are passed down culturally, though cultural stagnation or even retrogression is possible, as the grim history of the Imperium over the last 10 millennia so readily demonstrates.Humanity eventually rose to create an industrial and then space-faring civilisation at the very end of the 2nd Millennium on Old Earth. Humanity first colonised habitable or terraformable worlds across the galaxy during the millennia of the Age of Technology. Almost nothing is known about Human civilisation in this time, as this information was lost in the utter chaos and bloodshed of the following Age of Strife.In the 41st Millennium the majority of Humans of the galaxy are now part of the Imperium of Man, although other Human civilisations are known to exist. Unfortunately, Humanity is a species that is relatively easy to corrupt to the service of Chaos. In fact, it is Mankind's dominance in the galaxy that has shaped the Warp and the form the Chaos Gods currently take, as they are ultimately no more than psychic manifestations in the Immaterium of the collective psyches of the intelligent species of the galaxy.Unlike the ancient Aeldari, Humanity has only just begun the evolutionary transition into a fully psychic species. As yet, very few Humans out of the entire population of trillions present in the galaxy develop the genetic mutation that allows them to become psykers, though this number is slowly increasing as the centuries pass. However, most Human psykers lack the mental discipline or inner strength to prevent themselves from becoming Daemonhosts or otherwise being manipulated by the dark entities of the Warp.With Humans present across the galaxy and having adapted to every possible environment, they are currently the galaxy's dominant intelligent species. The current population of Humans in the Milky Way Galaxy in the 41st Millennium A.D. is unknown, but numbers in the many trillions, if not quadrillions.