Taxonomy

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Primates

• Family: Hominidae

• Genus: Homo

• Species: Homo sapiens

Physiological Characteristics

Humans (Homo sapiens) have an average height of 1.5 to 1.8 metres (4 feet 11 inches to 5 feet 10 inches), and an average weight of 50 to 80 kilograms (110 to 176 pounds), but some ethnic groups and individuals can be outside this range. Their skin can come in colours ranging from pale white to dark brown almost black, with red or yellow undertones. This colouration varies between individuals and ethnic groups, and is caused by the production of melanin within the body; more melanin means darker skin. The iris of their eyes can be various shades of blue, brown, green, or grey, with some ethnic groups and individuals also having reds, yellows, and purples. Their eyes have visible sclera, and this larger amount of ‘white’ in their eye is used in visual and non-verbal communication. The head has two eyes, a single mouth, a nose with two nostrils, two ears with external and visible structures (pinna) and a visible and protruding chin (the amount varies by ethnic group and individual). Their facial structure (from top to bottom) goes eyes, nose, mouth, chin, with ears in line with the eyes but on either-side of the head. They have hair on the top of their head, above their eyes (eyebrows), and a lighter covering on their arms and legs, armpits and genitals, and colour varies between various shades of black, brown, red, blonde, white, with most ethnic groups having an increase of grey and white hairs as a by-product of aging, along with balding. Some ethnic groups and individuals can also have hair in shades of greens, blues, and purples, but these are normally the result of genetic or cosmetic intervention. Human hair can be straight, wavy, or kinky/curly, with variations and combinations found in almost all ethnic groups. They have an endoskeleton consisting of 270 bones at birth, however this decreases to 206 as they age due to bones fusing. Their body consists of a single head attached to a single torso by a neck. The torso then has two upper limbs (arms) and two lower limbs (legs) attached by shoulders and hips (respectively). Each of these limbs is made up of three components; upper arm/leg and lower arm/leg connected by an elbow/knee, and then a hand or foot connected to the lower arm/leg by a wrist/ankle. The hands and feet both have five digits, with the hand digits being highly dexterous and jointed, consisting of four fingers and an opposable thumb. Inside their mouths, Humans have thirty-two teeth, consisting of incisors, canines, premolars, and molars, and a large movable muscled tongue. Like all mammals, Humans are endothermic. They have a single heart, a single set of lungs, and a single stomach.

Biological Characteristics

Humans have an average lifespan between sixty to one hundred years. Their iron and oxygen rich blood is a red colouration. Human males tend to be taller and heavier with broader shoulders, and have darker body hair, with hair growing along the lower half of the face along the jawline, cheek, and mouth region, as well as occasionally on chest and back. Human females develop larger mammary glands, and generally have wider hips. Like many Homo species, Human females have larger and permanent mammary glands than other mammals; even a non-reproductive female can have large mammary glands. Fat distribution also differs between males and females, with males distributing fat more around the abdomen and neck, with females distributing fat around the hips, thighs, and mammary glands (breasts). The average adult male is roughly 1.8 metres tall (5 feet 10 inches) and weigh 80 kilograms (176 pounds), while the average adult female is roughly 1.5 metres tall (4 feet 11 inches) and weigh 50 kilograms (110 pounds), but this varies between individuals and ethnic groups.

Physical Capabilities and Limitations

Like most organisms, Humans require gaseous oxygen to breathe. They require eight hours of sleep and day to continue normal brain and body functions. They can survive up to eight weeks without food, three to four days without water, and three to five minutes without breathable air before brain function deteriorates and they die. Humans have roughly two million sweat glands in their skin across their entire body, and this enables them to have remarkable tolerance for heat. They are also some of the best long-distance runners in the galaxy, with amazing stamina and endurance, and pre-tool Human societies generally hunt down prey by following them until the prey animal dies from exhaustion. Like all sapient species, Humans are capable of metabolising various substances that are highly toxic to non-sapient species, such as theobromine, caffeine, persin, alcohols, and capsaicin. Humans, along with most Homo species, Bugannes, Murids, and Phoenixes, have a higher tolerance to these substances than other sapient species. However, even Humans can die from an overdose of these substances.

Diet and Nutrition

Like most Homo species, Humans are an omnivorous species, and consume a wide variety of plant and animal products, including meat, nuts, berries, fruits, and animal by-products (meat, honey, and eggs).

Immunology

Food allergies, obesity, and cancers are three of the most common ailments that affect Humans. Humans can be infected by viral, bacterial, and fungal diseases, and are prone to internal and external parasites. Most diseases are highly treatable and preventable. Human bodies rapidly repair damaged tissue, and external injuries are sealed and have begun to scar within at least a day or two. A negative side effect to this rapid regeneration of bodily tissues is the increased risk of mutated cells becoming cancerous. 

Reproduction and Development

Humans, as mammals, produce two sex-gametes; one from males (sperm) and one from females (eggs). Humans are sexual reproducers and fertilisation of female sex gametes occurs internally. Human females go through an oestrous cycle once a month, in which they release a single female sex-gamete. After a gestation period of roughly nine months or two-hundred and eighty days, she will give birth to generally one infant. Two or three infants are uncommon, but not unheard of. These infants are born completely dependent on their mother for almost six months, and being mammals, the mother nurses the infant with milk from her mammary glands. After six months, the infant will begin to eat solids and crawl. By one year they are capable of walking and have almost weaned from their mother’s milk. They slowly become more and more physically, emotionally, mentally, and sexually mature until eighteen years, after which young Human females will be able to have children. Some will begin oestrous cycles as early as twelve but will not be ready for children for another few years. At around the ages of forty-five to fifty, Human females go through a process called Menopause. This is the stage where they do not have any more sex-gametes (eggs) and will stop going through oestrous. Females have a limited amount of sex gametes, whilst males will continuously make more throughout their adult life; a male Human can still be fertile well into his eighties, and even up to his death.

List of Human Ethnic Groups