Human hair primarily gets its color from melanin, a pigment also responsible for skin and eye color. While we see a range of hair colors from black to blonde to red, humans don't naturally have hair in shades of blue, green, or purple. The reason for this lies in the specific compounds present in hair.
The Role of Melanin
The primary pigment that colors human hair is melanin. Different types and amounts of melanin cause variations in hair color:
- Eumelanin produces brown and black hues.
- Pheomelanin is responsible for red and blonde tones.
These pigments are produced by specialized cells called melanocytes, which are found in hair follicles.
Why Not Other Colors?
While compounds like those that create the red of blood or the greens and yellows in bruises add color to parts of our body, they are not naturally found in human hair. These colors result from:
- The red of blood, which can cause pink cheeks when we blush.
- Compounds produced when blood breaks down, causing green and yellow in bruises.
Here's a comparison:
| Body Part | Coloring Compounds | Colors |
|---|---|---|
| Hair | Melanin (eumelanin & pheomelanin) | Black, brown, blonde, red |
| Skin | Melanin | Various shades of brown |
| Blushing Cheeks | Blood | Pink |
| Bruises | Broken-down blood compounds | Green, yellow |
Therefore, the absence of the compounds that produce a wider array of colors, such as blues, greens, and purples, in hair follicles is the key reason why humans do not have naturally colorful hair beyond the range of browns, reds, and blondes.
