So I am Asian (but more east Asian – japan side :P) and I have brown hair, not black…but this is because my father is English and my mother is Korean so I am a bit of a mix :P. My mother has black hair and a lot of my Indian friends do as well. Why?
Because of evolution, and we are all separated in different countries with different environments (like hot weather or rain), in the asian countries it is hotter and warmer, and so we have more melanin in your skin to stop us burning, This is why we have darker skin. But we also have this protective pigment in our hair.
Why is it a dark colour like black or brown?? these colours are the most dominant when we inherit our genes from our parents. if you had a blue eyed dad and brown eyed mum, you would always more certainly have brown eyes 😀 It just so happened that everyone in these countries we born with these dominant colour genes because these dark colours protect them from the environment they lived in (hot sun, no rain)
But I do not an oriental friend who has grey eyes and she is so beautiful 😀
Thousands of years ago, the land that our ancestors were living on broke up into chunks, forming the continents that we have now. Because they hadn’t invented boats or means of travelling long distances other than by foot, this trapped our ancestors in groups. They largely stayed in these groups meaning that they had to mate with each other.
Eventually, in groups like this, certain genes needed for survival start to be seen really often. That’s because the best adapted members of the group are more likely to pass on their genes to children and they’re more likely to have lots of children.
Black hair is caused by having a lot of melanin in the hair – melanin absorbs UV light so it doesn’t harm our cells. In Asian groups where the amount of sunlight was high, black hair was a good adaptation because it meant that more harmful UV light from the sun would be absorbed. So people with black hair were most likely to survive and pass on their genes to the next generation.
I’m going to answer in a slightly different way. The darkness of asian hair is a result of a molecule called Eumelanin, which has two subtypes of black or brown. A low concentration of brown eumelanin results in blond hair, whereas a higher concentration of brown eumelanin will color the hair brown. High amounts of black eumelanin result in black hair
Some some parts of India there are people with red hair!