What You Look Like

Humans come in one basic model with significant cosmetic variation. Here is what you’re working with.

Basic Anatomy

A human body has:

1 head — contains the brain (command center), eyes (vision), ears (hearing), nose (smell/breathing), mouth (eating/talking)
1 torso/trunk — the main body, contains vital organs (heart, lungs, stomach, liver, etc.)
2 arms — attached at shoulders, ending in hands with 5 fingers each (including an opposable thumb — this is key for tool use)
2 legs — attached at hips, ending in feet with 5 toes each. Used for walking upright (bipedalism — fairly unique among animals)
Skin — covers the entire body; serves as a protective barrier

Size and Shape

Average adult height: ~170 cm (5’7”) globally, with significant variation
Average adult weight: varies widely based on diet, genetics, geography
Humans reach full adult size around age 18–21
Bodies change significantly across a lifespan (see How Your Body Works)

Human Variation

Humans vary in:

Skin color — ranging from very dark to very light, determined by melanin (a pigment). This variation developed due to different levels of sun exposure across geographic regions. It has been, tragically, used as a basis for discrimination throughout human history.
Hair — color (black, brown, blonde, red, gray, white), texture (straight, wavy, curly), and length
Eye color — brown, hazel, green, blue, gray
Body proportions — height, weight, limb length
Facial features — shape of nose, eyes, mouth, ears

🚩 Humans are extremely sensitive about appearance. Commenting negatively on someone’s physical features is considered rude in nearly all cultures. See Cultural Customs & Etiquette.

Sex and Gender

Humans are a sexually reproducing species. There are two primary biological sexes:

Female — typically has a uterus, can bear children, typically develops breasts at puberty
Male — typically has testes, produces sperm

Additionally, some humans are intersex — born with biological characteristics that don’t fit neatly into these categories.

Gender is a social/psychological concept that may or may not align with biological sex. Many humans identify as a gender different from the sex assigned at birth (transgender), and some don’t identify with any gender (non-binary). This is a topic humans are actively navigating with evolving norms.

🚩 Norms around gender vary significantly by culture, religion, and generation. When in doubt, follow the person’s lead on how they describe themselves.

Aging

Humans age visibly over time:

Babies → Children → Adolescents (puberty: ~11–16) → Adults → Middle age → Elderly
Life expectancy varies by country: from ~55 years (some lower-income countries) to ~85+ years (Japan, parts of Europe)
With age: hair grays/thins, skin wrinkles, muscles and bones weaken, cognitive changes occur