COLOUR DEMYSTIFIED

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By Dr Farah Sameem

Dr Farah Shameem

Dr Farah Shameem

The colour of a person’s skin has great aesthetic connotations. Be it the Helen of Troy, Cleopatra, Anarkali or the present day Angelina Jolie, the colour of skin is an important attribute contributing to their persona. Besides, be it the colour of skin or hair, the visual effect rendered is immediate and profound. Unfortunately world history is also witness to the fact that the worst form of exploitations and atrocities were committed on the basis of colour alone.

The slave trade of Africa, the continued racial discrimination of Afro-Americans, the “supposed” racial superiority of light-skinned Aryan races, the euphemistic term “People of Colour” used for Asians, Blacks and Hispanics and the derived huge and ever booming market for fairness creams in the Indian subcontinent, the insensitive and biased remarks made on the basis of skin colour by politicos, the skewed preference for the fair as can be judged by a casual perusal of matrimonial columns, the list goes on and on.

What is the colour of skin but an optical illusion produced by the melanin pigment in the epidermis of skin and its effect on the scattering, absorption and reflection of light!

Melanin is a derivate of an amino acid Tyrosine produced by a dendritic cell in the epidermis known as the Melanocyte present in between the basal keratinocytes of the epidermis. The stimulus for melanisation is ultraviolet radiation from sun especially UVA (340-400 nm) acting on the Pineal gland and eliciting the secretion of Melanocyte Stimulating Hormone (MSH) from it. This MSH acts on melanocytes to increase the production and activity of Tyrosinase enzyme, this being a key enzyme in melanin production. Two types of melanin are produced dark black Eumelanin and red pale Phaeomelanin. In the melanocyte the melanin pigment is packaged into small packets or melanosomes. These packets are transferred from melanocytes to the surrounding keratinocytes of epidermis. One melanocyte feeds 36 keratinocytes to constitute one Melanin Unit. The melanosomes in dark skinned are larger and aggregated in the keratinocytes while in light skinned they are smaller and scattered.

Now the basic question….why is melanin produced by the skin? What purpose does it serve? Melanin forms a protective umbrella around the nucleus to protect the nucleus from UV radiation. This prevents mutagenesis and carcinogenesis of Deoxyribonucleic acid and hence prevents skin cancers and photo ageing.

Depending upon the UV radiation at a particular geographical area the melanin factory can be hyperactive or slow. Equatorial areas need more pigmentary protection Hence Africans are melanocompetent. Eskimos need much less, hence they are pale. Now when Europeans moved to Australia their skin protection for the new location was inadequate and hence they become susceptible to melanomas and other skin cancers. The star significance of melanin can be appreciate by Albinos who have no melanin in skin or hair or eyes due to absence of Tyrosinase and are not able to move in the sun.

So much injustice has been done on the basis of colour and yet colour is nothing but interplay between the Pineal gland and the Sun? Stripped of its mystique, it is nothing but an aminoacid derivative?

(Author is lecturer dermatology SKIMS, MCH Bemina.)

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