Human hair grows from tiny organs called follicles embedded in your skin. Each strand starts as living cells deep beneath the surface, fed by blood vessels, and transforms into the tough, dead protein fiber you can see and touch. Your scalp alone holds between 80,000 and 120,000 of these follicles, each one operating as an independent growth factory on its own timeline.
Inside the Hair Follicle
Every hair on your body originates in a small, tube-shaped structure called a follicle. At the very bottom of the follicle sits a rounded area called the bulb, and nestled inside the bulb is a cluster of tissue called the dermal papilla. This is where hair production begins. The dermal papilla contains tiny blood vessels (capillaries) that deliver oxygen and nutrients from your bloodstream to the surrounding cells.
Wrapped around the dermal papilla are rapidly dividing cells known as matrix cells. These cells have one of the fastest division rates of any tissue in the human body. When the dermal papilla sends chemical signals to the matrix cells, they begin multiplying, stacking on top of each other, and pushing upward through the follicle. As they rise, they undergo a dramatic transformation: they harden, lose their internal structures, and fill with a dense protein called keratin. By the time the cells reach the skin’s surface, they are completely dead. The visible strand of hair is essentially a compacted column of dead, protein-filled cells.
Proteins make up roughly 65 to 95 percent of a hair strand’s total weight, with the remainder being water, lipids, and trace minerals. Keratin is not something the cell secretes or releases. It is the cell itself, transformed. The living cell becomes the protein fiber.
How Hair Gets Its Color
Scattered among the matrix cells at the base of the follicle are specialized pigment-producing cells called melanocytes. These cells manufacture melanin, package it into tiny bundles, and transfer those bundles into the developing hair cells through arm-like extensions that reach out to neighboring cells.
Two types of melanin determine your natural hair color. The first, eumelanin, comes in black and brown varieties. Large amounts of black eumelanin produce black hair, while moderate amounts of brown eumelanin produce brown hair. Blonde hair results from very small amounts of brown eumelanin with essentially no black eumelanin. The second type, pheomelanin, produces red and yellow tones. Red hair comes from a roughly equal mix of pheomelanin and eumelanin. The specific balance between these pigments is genetically determined and varies enormously across populations.
When melanocytes slow down or stop producing melanin, typically with age, new hair grows in without pigment. That’s gray or white hair. The strand itself hasn’t changed color; it simply grew in without pigment from the start.
The Growth Cycle
Each follicle cycles independently through three phases. The active growth phase, called anagen, lasts 3 to 5 years on the scalp. During this time, hair grows at an average rate of 0.5 to 1.7 centimeters per month (roughly a quarter to two-thirds of an inch). After anagen, the follicle enters a brief transitional phase where growth stops and the lower portion of the follicle shrinks. Then comes a resting phase lasting 2 to 4 months, during which the old hair is eventually shed and a new strand begins forming.
Because each follicle operates on its own schedule, you’re always losing and regrowing hair simultaneously. Losing 50 to 100 hairs a day is typical. The length your hair can reach is largely determined by how long your anagen phase lasts, which is genetic. Someone whose growth phase runs a full five years can grow hair noticeably longer than someone whose phase lasts three years, even if their monthly growth rate is identical.
When Hair Follicles First Form
Hair follicles develop before birth. Between weeks 9 and 12 of gestation, interactions between two embryonic tissue layers, the outer ectoderm (which becomes the skin’s surface) and the underlying mesoderm (which becomes the deeper connective tissue), trigger follicle formation. By around week 12, a fetus is covered in fine, soft hair called lanugo, from the Latin word for wool. This hair is typically shed before or shortly after birth.
You are born with every hair follicle you will ever have. The body does not create new follicles after birth. What changes over a lifetime is the type of hair each follicle produces: the fine, nearly invisible vellus hairs of childhood can shift to thicker, pigmented terminal hairs during puberty, and terminal hairs can miniaturize back toward thinner strands as part of age-related hair loss.
Why Humans Have Less Hair Than Other Primates
Humans actually have roughly 60 hairs per square centimeter of skin, a count not dramatically lower than other apes. The difference is that most human body hair is miniaturized: thin, short, and lightly pigmented compared to the coarse fur of other primates. The leading explanation for this shift centers on thermoregulation. Early human ancestors living in the hot African savanna needed to shed body heat efficiently. Sweat is the body’s primary cooling mechanism, and dense fur acts as a barrier to evaporation. Reducing hair thickness and length allowed sweat to evaporate more freely, giving early humans the ability to stay active during the hottest parts of the day, foraging and hunting when furred competitors could not.
In other primates, thick hair serves multiple survival purposes: insulation in cold climates, protection from UV radiation and physical trauma, camouflage from predators, and even a way for newborns to cling to their mothers. For humans, the trade-off favored efficient cooling. Scalp hair persisted likely because it protects the top of the head from direct sun exposure, while eyebrows and eyelashes remained to keep sweat and debris out of the eyes.
The Global Human Hair Trade
If your search was about where the human hair in wigs and extensions comes from, the answer is primarily India and China. The global trade in human hair is worth over a billion dollars, with India alone accounting for more than $200 million in exports. India is the second-largest exporter of human hair after Hong Kong (which serves largely as a processing and re-export hub for Chinese manufacturers).
The most well-known source is the temple hair collected at tonsuring halls in Tirumala, in Southern India, where devotees shave their heads as a religious offering. Licensed barbers at these highly organized temples cut hair that took years to grow, producing long, unprocessed strands prized by wig makers. But temple hair doesn’t come close to meeting global demand.
An estimated 70 percent of Indian hair exports come from discarded combings: hair pulled from combs, shower drains, and waste bins. In cities like Varanasi, collectors gather loose strands from roads and gutters. In rural areas, members of nomadic communities such as the Waddar and Vedhwa Waghri travel to low-income neighborhoods and trade cheap household goods, toys, or sweets for hair that families save up over time. From these many collection points, hair moves to sorting facilities and then on to manufacturers in China, where it is processed, treated, and assembled into the wigs and extensions sold worldwide.