Human Hair

Head hair are grown on the head and is the most noticeable part of human hair, which can grow longer than on most mammals and is more dense than most hair found elsewhere on the body. The average human head has about 100,000 hair follicles. Its absence is termed alopecia, commonly known as baldness. Anthropologists speculate that the functional significance of long head hair may be adornment, a byproduct of secondary natural selection once other somatic hair had been lost. Another possibility is that long head hair is a result of Fisherian runaway sexual selection, where long lustrous hair is a visible marker for a healthy individual (with good nutrition, waist length hair—approximately 1 meter or 39 inches long—would take around 48 months, or about 4 years, to grow).
Each follicle can grow about 20 individual hairs in a person's lifetime. Average hair loss is about 100 strands a day.
The average human scalp measures approximately 120 square inches (770 cm²)