Editing Nobledark Imperium Notes (section)

== Humanity ==

Editor's Note: Not finished per writefag, put here as a placeholder for now. Written as an in-universe "Humanity 101" Guide aimed primarily at curious Tau and Eldar who may not have had much contact with humans.

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Humans (''Homo sapiens spp.'') are a species of bipedal mammal native to the planet of Old Earth in the Segmentum Solar. Humans naturally range between 90 and 250 centimeters at adulthood, though their size and appearance is heavily dependent on the population they come from. Like many life-bearing worlds, the ecology of Old Earth shows signs of having been tampered with by the Old Ones, however the specific group to which humans belong did not begin to diversify until roughly around the end of the War in Heaven sixty-five million years ago, after a catastrophe wiped out the planet’s formerly dominant organisms, something that is thought to be related to the general Necron purge of Old One vivarium worlds.

Prior to the Age of Strife, humans were organized into the “Great and Bountiful Human Dominion”. The Great and Bountiful Human Dominion, in turn, were organized into the “Interstellar League” a group of allied like-minded xenos species that banded together in the face of external threats, mostly Orks and increasingly up to the Age of Strife raiding parties by the Old Eldar Empire. It is unknown how many other species were part of the Intersolar League, though it is known that the Tarellian Empire were members and there are suspicions that the Kinebrach were as well.

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Life in the Great and Bountiful Human Empire was dominated by the use of the Men of Iron, an artificially created race of sapient artificial constructs, which were linked to the Iron Minds, extremely powerful silica animus. The Iron Minds were originally created by humans, but their thought processes were so alien to humans that communication was nearly impossible. In order to facilitate communication with both the Iron Mind and the rest of the Empire as a whole, humans and the Iron Minds collaborated to created the Men of Gold (Homo sapiens aureus), a genetically engineered subspecies with substantial psychic, biological, and pseudo-cybernetic modification that could act as a link between the god-like Iron Minds and the average human and aid in broader faster-than-light communication to the wider galaxy.

Human (or “human beings” as they are sometimes referred to), are the second, possibly the third most abundant sentient life form in the galaxy, after intelligent orkoids and possibly after tyranids or necrons, depending on how one estimates the populations of these species and whether one considers them “sentient life”.

Prior to the Age of Strife, there were few subspecies of humans aside from artificially created variants like ''H. s. aureus'' (Men of Gold), H. s. navigo (Navigators), and ''H. s. variegatus'' (beastmen), as the human world were linked into a single empire and there were few opportunities for speciation. During the Age of Strife, most human worlds were effectively cut off from one another, which led to genetic isolation and the evolution of many distinct species, including ''H. s. minutus'' (ratlings), ''H. s. hirstutus'' (felinids), the “Ogryn subspecies complex” (''H. s. giganteus'', ''H. s. cranopus'', and related forms).

Hubworlders, although often (mis)classified as ''H. s. rotundus'', are not actually a distinct subspecies from baseline humanity. Genetic analysis of Hubworlders have found them to deviate from inhabitants of Old Earth (who are considered to be the genetic standard for humanity) to a degree comparable to the inhabitants of Cadia or many other worlds across the galaxy: in other words, not enough to be regarded as anything more than a local variant of baseline humanity. (Insert section talking about how their stature is due to gravity, and the AdMech classifying them as abhumans out of revenge for not rolling over for Mars).

As with any sentient species, describing what humans are like to a nonhuman is often very difficult, especially given their wide degree of variation and high number of subspecies. Because most of the individuals reading this guide will be Tau and eldar, comparisons will mostly focus on these two species. Despite their infamous superficial similarity to eldar, detailed examination shows that this resemblance is only skin deep. Instead, humans and eldar appear to have evolved a similar body shape as a solution to similar evolutionary problems despite being very different in biology and behavior in other respects, similar to what occurred between dogs and thylacines (a carnivorous marsupial that was a popular pet during the Dark Age of Technology and as a result can still be found on some human colony worlds) on Old Earth.

Like eldar, humans have permanently enlarged mammary glands, in contrast to a Tau in which the mammary glands are usually small but get larger for the short period of lactation following pregnancy. Additionally, like eldar, humans appear to be a naturally monogamous species (or at least require the care of multiple individuals to increase the likelihood of surviving to adulthood). Humans also exhibit adaptations designed to encourage this behavior, humans in the form of “hidden estrus”, eldar in the form of prolonged fertilization that requires the male to stay around in order to produce viable offspring. Like eldar, humans have a long pregnancy and give live birth to a relatively helpless infant, something that would be expected given the species moderately large soul and psychic presence. However, at nine months human pregnancy is much shorter than the 24 month long term period seen in eldar. Additionally, unlike eldar or tau (or indeed, most other species), human females are nearly helpless for much of their pregnancy due to a quirk of evolution, which causes human military structure to be unusually male dominated compared to most other species, something that really only changed with the advent of advanced weaponry during the Age of Terra.

However, unlike eldar, the human skeleton is made out of the mineral hydroxylapatite rather than wraithbone and humans have a shorter neck with seven, rather than nine, neck vertebrae (among other differences). Humans also lack the helical muscle with long tendinous insertions typical of Shaa-Dome lifeforms, which allows eldar to be deceptively strong despite their thin frame. In general, humans across the board have less acute sense than the eldar, but at the same time proportionally less of their brain is devoted to sensory perception (cognition is about the same) and they are not as prone to stimulatory overload or hedonism (some of this may also be a side effect of Old One genetic engineering). Compared to Tau humans have better depth perception and motion tracking, but poorer peripheral vision and do not see as far into the infrared or ultraviolet spectrum. Humans also have a much poorer sense of smell than most species, though this does not apply to all abhuman variants (e.g., felinids and beastmen). Baseline humans have next to no ability to detect pheromones.

The oral structures used for processing food are actually modified scales made of harder material than the rest of the skeleton, as in the tau, rather than outgrowths of the jaw plate as in eldar. Humans lack the multiple-lobed stomach of the tau or the simplified, highly efficient digestive tract of the eldar (though the latter is thought to be the result of genetic engineering). Human digestive systems are not particularly water efficient and as a result the products of their metabolism system tend to require a lot of water to successfully dispose of waste, rather than the water-efficient crystalline waste of the eldar (analogous to uric acid in birds on Old Earth). And, of course, although small amounts of epigenetic gene expression through methylation are known to occur on occasion in humans and other Terran lifeforms, selective gene expression and the associated, highly-bunched megasomes and quadruple helix DNA are not a defining feature of life on Old Earth as it is of all higher life forms on Shaa-Dome.

Humans are unique among sapient species in having white sclerae, a feature which is thought to have been a chance mutation on their homeworld but aids in non-verbal communication. Despite their similarities, eldar eyes have been described as resembling those of Earth deer whereas tau resemble grazing ungulates. White sclerae are a common feature of all baseline humans and abhuman strains, with a few notable exceptions such as Nightsiders, and their presence is a useful rule of thumb for identifying organisms with significant human geno-splicing. Some xenos individuals have remarked that human eyes are actually unsettling, occasionally giving them a rapacious, predatory look, whereas Nightsiders do not fall into this uncanny valley. The irony being that most human strains are less predatory than Nightsiders.

Human beings are also notable for having some of the lowest resistance to chaos corruption of any known sentiment species. On the Leitek-Bonn scale, which measures a species susceptibility to ambient chaos corruption with 50 representing the average species, human score a mere 28, in contrast to eldar (60), tau (82), orks (97), and of course the gold standard of the Watchers (99.5). This is thought to be due to several reasons. First, humans are naturally a competitive and domineering species. Although standing and social structure are an important component of the psychology of all sentient species, no other species dedicates so much of its time and energy to hierarchy, dominance, and social status as humans, with the possible exception of the pre-biotransference Necrontyr. Much like how the tau’s natural optimism and tendency towards social conformity are thought to derive from their ancestry as herding ungulates. Humans come from a group of animals with a naturally unstable social structure and whose diet (fruits, nuts, and meat) tends to be very unpredictable and hard to find. This gives them a tendency to be paranoid and second guess those around them. As an example, most species, if told that something is dangerous by a member of their own social group, tend to believe that individual. Humans, on the other hand, are often innately suspicious that said individual is lying, believing that the other individual is hiding some that they plan to use for themselves or increase their social standing. This was a useful adaptation millions of years ago when a compatriot might be hiding a piece of meat or stash of fruit, but is decidedly less helpful in the modern day where the “hidden” “resource” might be an actually dangerous Chaos artifact.

Secondly, even among their close relatives on Old Earth, humans are unusual in that the neurological architecture of the brain is very plastic and is not strongly genetically conserved between generations. While this is a common trait of almost all sentient species (and indeed, may be a criterion necessary for sentience to arise), the way in which it arose in humans has a side effect of greatly increasing the risk of mental dysfunction and illness in this species. While some of the worst downsides of this were ironed out by geno-medicine during the Dark Age of Technology, it was not possible to completely stamp out millions of years of evolution. This makes it unusually easy for ambient Warp exposure to cause psychosis at even low levels. While mental illness in and of itself is not necessarily indicative of loyalty to the Ruinous Powers (as Perturabo and Kurze can attest) unexpected warp exposure-induced psychosis can affect the decision-making skills of an individual and cause them to become further corrupted. It is even possible that the domineering nature of humans is in part a response to that natural disorder in their physical and mental environments, trying to impose order where there is none. Although humanity’s low corruption resistance can be overcome by self-discipline, individual fortitude, and training, it is always a good idea to check the mental status of human compatriots to ensure chronic damage has not occurred.

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