What Is Human Hair Made Of?
Hair might seem simple—just something you brush, cut, or style—but it’s actually a complex part of your body made from special materials with important roles. From its strong structure to its surprising ingredients, hair helps protect your body and gives clues about your health.
Let’s explore what human hair is made of, how it forms, and why it’s more fascinating than you might think.
🔎Dive Deeper
- What Are the Main Parts of Hair?
- What Is Keratin and Why Is It So Strong?
- What Gives Hair Its Color?
- What About the Root and the Follicle?
- Is Hair Alive or Dead?
- 🎯Final Thoughts
- 📚 References
What Are the Main Parts of Hair?
Each hair on your body has two main parts:
| Hair Part | Location | Function |
|---|---|---|
| Hair Shaft | Above the skin | The visible part you can touch or style |
| Hair Root | Below the skin | Inside the skin, where the hair grows |
The hair shaft is made up of three layers:
- Cuticle – the outer layer, like scales on a fish
- Cortex – the middle layer that gives hair its color and strength
- Medulla – the soft center (not always present in thin hair)
🔬 Fun Fact: The hair shaft is made almost entirely of a protein called keratin, which is also found in animal horns, hooves, beaks, feathers, and claws.
What Is Keratin and Why Is It So Strong?
Keratin is a fibrous protein that’s packed tightly into the hair shaft. It forms tough, water-resistant strands that can bend and stretch without breaking easily.
Keratin contains lots of sulfur atoms, which create disulfide bonds—tiny chemical links that act like glue to keep your hair strong and durable.
📊 Statistic: Human hair can hold up to 100 grams (about 3.5 ounces) of weight without breaking, and a full head of hair could support over 12 tons if evenly distributed
What Gives Hair Its Color?
Hair gets its color from a pigment called melanin, made by special cells in the hair follicle called melanocytes. There are two types of melanin:
- Eumelanin: Gives brown or black hair
- Pheomelanin: Gives red or yellow-blond tones
The mix and amount of each pigment determines your hair color. As people age, melanocytes slow down—causing hair to turn gray or white.
🎨 Interesting Note: Blonde hair has less melanin, not different melanin!
What About the Root and the Follicle?
Hair grows from a small pit in the skin called a hair follicle. Inside the follicle is the hair root, which is surrounded by tiny blood vessels. These vessels deliver nutrients and oxygen to the growing hair.
The very bottom of the root is called the hair bulb, and it’s the only part of the hair that is alive. Cells in the bulb divide rapidly to push new hair upward, forming the hair shaft as they die and harden.
📊 Super Stat: Most people in good health have an average of 80,000 to 120,000 hairs on their head!
Is Hair Alive or Dead?
It may surprise you, but the hair you see and touch is actually dead. Once hair cells leave the hair bulb and form the shaft, they no longer have blood supply or nerves.
That’s why it doesn’t hurt to cut your hair—you’re trimming cells that are already dead. But the living root needs care and nutrients, which is why good nutrition helps keep your hair healthy.
🧪 Did You Know? Hair grows a tiny bit every single day? Each day your hair grows about .35mm which adds up to a 1/2 inch per month and 6 inches per year!
🎯Final Thoughts
So, what is human hair made of? Human hair is more than just a style statement—it’s a powerful protein structure made of keratin, formed deep in the skin, and colored by pigments called melanin. While the hair shaft is made of dead cells, its root is alive and depends on the body’s systems to grow new strands. Understanding what hair is made of gives us a peek into how the body works at the microscopic level—and shows just how amazing even a single strand can be.
📚 References
📚Murphrey MB, Agarwal S, Zito PM. Anatomy, Hair. [Updated 2023 Aug 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513312/
📚F. Costa, R. Silva, A.R. Boccaccini. “7 – Fibrous protein-based biomaterials (silk, keratin, elastin, and resilin proteins) for tissue regeneration and repair.” Editor(s): Mário A. Barbosa, M. Cristina L. Martins, Peptides and Proteins as Biomaterials for Tissue Regeneration and Repair Woodhead Publishing, 2018, Pages 175-204, ISBN 9780081008034, doi.org/10.1016/B978-0-08-100803-4.00007-3.
📚Scientific American. “Test the Strength of Hair.” https://www.scientificamerican.com/article/test-the-strength-of-hair/
📚A.S. Cole, J.E. Eastoe, Chapter 5 – Peptides and proteins, Editor(s): A.S. Cole, J.E. Eastoe, Biochemistry and Oral Biology (Second Edition), Butterworth-Heinemann,1988, Pages 44-70, ISBN 9780723617518, https://doi.org/10.1016/B978-0-7236-1751-8.50012-0.
📚Harland, Duane P., et al. “The Susceptibility of Disulfide Bonds to Modification in Keratin Fibers Undergoing Tensile Stress.” Biophysical Journal, vol. 121, no. 11, Apr. 2022, pp. 2168–79. https://doi.org/10.1016/j.bpj.2022.04.029.
📌Learn More About Human Hair
- What Is the Rarest Hair Color✂A Look at the World’s Uncommon Locks
- What Causes Gray Hair✂The Science Behind Silver Strands
- Why Do People Have Different Hair Colors✂The Genetics Behind Every Shade
- What Causes Hair to Stand Up (Goosebumps!) ✂The Body’s Chilly Reflex Explained
- Why Does Hair Fall Out✂The Science Behind Shedding Strands