Look around, and you’ll find people with hair of a variety of colours. Ever wondered what factors lead to this phenomenon? Here is the answer as to why this variation is observed.
VARIETY OF HAIR COLOR
The colour of hair is primarily due to the amount and type of pigment melanin in the cells. These cells are heavily keratinized. Melanin is synthesised by melanocytes, which are scattered in the matrix of the hair bulb. Further, it is passed to the cells of cortex and medulla of hair.
Melanin can further be of two distinct types:
- Eumelanin – determines the dark colour of hair, mainly dark brown.
- Pheomelanin – determines the light colour of hair, basically orange or red.
The Fischer-Saller scale is used to determine the hair colour found in the human population.
MOST COMMON TO RAREST
Undoubtedly, black hair is the most common of all. Around 64% of the people in the world have this dominant colour. Predominantly, the hair contains eumelanin.
Next, the brown colour is estimated in about 13% of the human population. People are also called ‘brunettes’. The hair is mostly composed of the high amount of eumelanin and low amount of pheomelanin.
Auburn hair ranges from brown to dark red. The colour is the product of both eumelanin as well as pheomelanin. Roughly 7% of individuals have this colour hair.
Chestnut hair is more or less similar to Auburn, except that it is a more reddish colour. It can also be described as dark auburn. It is present in about 6% of the world population and mostly occurs in European countries.
About 4% of the individuals have grey hair. In isolated cases, children are born with such hair colour. This is due to deficiency of melanin pigment. Moreover, hair becomes grey due to a progressive decline in the production of melanin in older age. In this case, it contains only a few melanin granules.
White hair occurs in about 2.5-3% population all over the world. It results due to complete lack of the pigment melanin. Moreover, the shaft of the hair gets accumulated with air bubbles.
Blonde hair colour is known to exist in about 2% of the world population.
Lastly, the rarest of all is red or ginger hair. It occurs in almost 1.3% of individuals. The pigment pheomelanin is considerably higher, while eumelanin is lower in red hair. It is prominent in areas such as Scotland, Ireland, Wales, and England.
CHEMICAL HAIR COLORING
Hair colouring involves a chemical process which adds or removes pigment from hair strands.
- Temporary hair dyes coat the surface of a hair shaft. Usually, it washes out within 2-3 hair washes.
- Semi-permanent dyes penetrate moderately into the hair shaft. They do not fade or wash out even after 5-10 shampoo washes.
- On the other hand, permanent hair dyes penetrate deep into the hair shaft. They do not wash out even after numerous washes.
OTHER CONDITIONS AFFECTING HAIR COLOR
- Achromotrichia is a condition which involves greying of hair with an increase in age. But poor diet, smoking, and certain illnesses also speed up the process of pigment loss. Finally, this leads to premature greying of hair.
- Albinism, which is a genetic abnormality, leads to loss of pigment in hair, eyes, and skin. For this reason, hair is white or pale blond, in people suffering from the condition.
- Autoimmune diseases can cause vitiligo, which results into a patchy loss of hair colour.
- Mummies or buried bodies also change hair colour. This is due to oxidation of eumelanin.