2006-09-22 09:50:52 · 2 answers · asked by pudding 1 in Science & Mathematics ➔ Biology
Same reason everyone has eyes even though some are blue and some are brown. Melanocytes are useful things to have around.
People of all colours express more melanin when exposed to the sun. It takes more sun for some than others, but it's a useful defense mechanism that just about everyone has.
You'll find likewise that almost nobody produces NO melanin. If you doubt this, compare the appearance of a 'white' person to an albino - they'll look positively dark by comparison!
2006-09-22 09:57:24 · answer #1 · answered by Doctor Why 7 · 1⤊ 0⤋
I think you mean melanocytes. Everyone has the same melanocytes but they undergo melanogenesis (which is the process that produces the pigment melanin) in different amounts. Lighter skinned people's melanocytes will have lower of levels of melanogenesis. Exposure to UV rays increases the rate of melanogenesis which is why people get tans.
2006-09-22 16:55:59 · answer #2 · answered by Anonymous · 1⤊ 0⤋