Humans

* Male
* Female

Humans (*Homo sapiens*), are an intelligent bipedal mammalian species and one of the two known intelligent species in the universe. Originating from the planet Earth in the inner Solar System, they have sizable populations across the solar system, giving them a reputation for expansionism.

Humans are bipedal vertebrates with a tough, rigid endoskeleton strengthened by various calcium compounds. Their brains and the majority of their sensory organs reside in a case of bone resting atop their shoulders. Their two arms and legs generally have six digits each, although some populations have five.

Humanity shares its home system with the Loriset from Earth's sister planet Theia, and has often come into conflict with them. The species has branched into several subspecies as it spread across the solar system, including *Terran* (also known as "baseline"), *Martian*, *Venusian*, and *Savisian* humans. The majority of the human population resides in the United Nations of Humanity and the Savisian Alliance.

## Differences from the Prime Timeline

The main difference between Alternis humans and Prime humans is the capacity for much greater distension in tissues as well as a gestation period nearly four times longer. Alternis humans also have a very strong sense of interoception, being able to feel almost everything going on inside their bodies.

## Biology

### Subspecies

As humanity spread across the Solar System, it gradually diverged into four main branches as populations drifted out of frequent contact. Baseline humans, now known as *Terran* humans, conform the closest to the species' original body plan prior to these branchings. *Martian* humans, who became apparent soon after Mars was granted greater autonomy from Earth due to the long journey there, are generally thinner, have lower bone density, and have more children per pregnancy. *Venusian* humans, the least populous branch living in the clouds of Venus and its moon Neith, tend to be taller, bulkier, and can stomach enormous amounts of food in one gulp. Their gestation periods are up to 1.5 times shorter than baseline. Finally, the *Savisian* humans tend to have greater resistance to cold, are significantly taller and thinner with very low bone density, and have longer gestation periods and significantly more children per birth.. The Savisians are the second most populous branch of the human species, after the baseline Terrans.

### Respiratory System

The human respiratory system is fairly simple and confined to the head and thorax. Air is drawn in through the mouth and nose and channeled down a partially cartilaginous tube called the trachea, which branches many times into microscopic tubules leading to alveoli. The alveoli form an air-collecting surface equivalent to 70 square meters, increasing the efficiency of oxygen intake.

### Digestive System

The digestive system of a human has a simple structure. Food is taken in through the mouth, which can hinge open very wide to swallow large amounts of food. It is then propelled down to the stomach via peristalsis. The stomach is a large bag that produces powerful acids and innumerable kinds of enzymes to rapidly digest food, the nutrients of which are also absorbed through the stomach walls. The human stomach can carry up to 24 gallons, at which point the skin is nearly translucent. After the contents of the stomach are digested and the nutrients and fluids extracted over a period of up to 12 hours, the food is expelled as waste.

### Nervous System

The human nervous system consists of two sections: the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord protected by the meningeal layers, while the peripheral nervous system is everything else, specifically nerves spread through the body. Consciousness is an emergent property of the brain's function.

#### Senses

Humans have six main senses: sight, hearing, touch, smell, and taste, and interoception. The organ of sight is in the form of two eyes mounted on the brain case, which transmit information to the brain via the thick optic nerve. Ears embedded in the skull receive sound through a roughly dish-shaped fold of skin on the side of the head, focusing it onto the eardrum and several tiny ossicles to a tiny organ filled with microscopic hairs which truly "hear" the sound. Taste functions via interpreting large molecules on the tongue, and smell relies on aerosolized particles entering through the nose and hitting sensors there. Touch and interoception are the most widespread, as touch functions through every piece of skin on the body and interoception is functionally a grab bag of a multitude of sensors detecting everything going on inside the body.

### Reproductive System

Humans are *viviparous*, meaning that they carry their young inside their bodies prior to a live birth. Very large egg cells are produced by the ovaries in female members of the species, where they are fertilized by sperm before traveling to a cavity capable of enormous distension called the uterus or womb. The egg implants in the uterine wall, immediately beginning to draw nutrients from the mother. Prior to implantation, the embryo can often split into two or even three or four, each of which then grows separately. During gestation, the mother gradually acquires a distinctive rounded stomach and significant weight gain.

The embryo(s) then experience cell division, expanding enormously over the course of three years until they have became a fully functional human, known as a fetus. The mother's womb distends enormously to accommodate her offspring as they grow, making her nearly immobile past short distances for the last stages of her pregnancy.

Prior to birth, natural painkillers are released, and the two halves of the mother's pelvis split and are pulled several inches outward and upward by muscles. This completely immobilizes the mother, and as such she has the capability to consciously hold off the onset of the process for huge lengths of time. Uterine contractions then push the baby or babies out of the womb, usually within 10-20 minutes unless complications arise. After birth, the offspring are dependent on the parents for up to fifteen years on average. Humans place great cultural importance on pregnancy and birth, and it is often fashionable to wear fake stomachs under clothes in an effort to appear heavily pregnant.

## Demographics

Most of the human population remains in the immediate vicinity of Earth and Theia, with roughly 34% of humanity having left the planet. Of this 34%, roughly 42% of them reside on or near Mars and its orbital zone. 28% of humanity lives in the vicinity of the planet Venus and its moon Neith, 19% of humans live in the Savis system and its trojan asteroid groups, 4% of humans live within the asteroid belt, and the remaining 7% are spread across Mercury, the Handmaiden Belt, Crius, Caelus, the Kuiper Belt, and beyond. The generation ship USS Excelsior was launched roughly 10 years before the Homeworld Wars, and remains the farthest outpost of humanity as it flies towards interstellar space.

## Culture

Much of Human culture rests upon an inviolable honor-shame dynamic. Certain actions bring great honor to a person, and others bring great dishonor. The highest of honors for a human is a glorious death in battle in support of your countrymen or dying in childbirth, which is culturally considered a great battle all its own. Things like traitorous and criminal activity as well as attempted suicide bring great dishonor on a human, often to the point of shunning by the rest of society.

### Religion

Until recently, most humans followed a selection of polytheistic religions originating from across the planet, with rare occurrences of monotheism in various ethnic enclaves. However, with the Second Renaissance shortly after the first landing on Klein, organized religion began to die out, with ~80% of the population being atheist as of the present day.