why does the sun darkens your skin while it lightens your hair?
553892
Melanocytes (cells in our skin) upon receiving signals of damage to DNA (due to UV radiation) begin producing melanin in large amounts.\nMelanin is a polymer that captures UV and thus protects cells from DNA damage.\nHair doesn't have melanocytes. It is made of keratin (protein) and minerals. So typical reaction will be - no change or in constant exposure to sun rays- damage to keratin and bleaching.
336780
The amount of melanin in the skin.  This trait is passed down from your parents, so it is genetic.  But the amount of the dark pigment melanin in the skin determines the color of your skin.
620979
All guys c_ocks are a bit darker shade than the rest or their skin.  That way when we go suntanning, we don't have to burn our peepee, it's already tanned.
1164007
Because of the hormone that makes your skin light or dark.  The more melatonin you have the darker the skin.  If you have light skin you should use a sunscreen or stay out of the sun.  Or in about 20 years you'll look like a prune.
843407
I see what you're saying.  I've thought the same thing.  If you have light skin, you'll stay cooler in the hot climate than if you had darker skin, so why would you want to get your skin darker if you'd only feel hotter the darker you got?  Right? \n\nTherefore if evolution were really working like it should, people who live up in colder climates like Norway and Sweden would have dark skin to absorb the most of the sun's rays and stay warmer and the people down in Africa would have lighter skin to repel most of sun's rays to keep them cooler.\n\nSeems like that would make sense to me.
536374
If you have the kind of hair that lightens in the sun (like blonde), then the lemon juice will intensify the process. If you are a brunette, it won't do much.
1071239
When the skin cells get too much UV radiation it triggers the cells to make more melanin and put it up above them selves, shielding their nucleus from the UV.  Some races naturally make more of this at a baseline than others.
1177873
By birth there is no colour difference.but as they grow up they expose to the sunlight and when the body lacks Vit A the body in order to protect itself from the harmful UVA and UVB rays produce more melanin in the body and as a result the skin darkens at knees and elbows.
329146
It probably has to do with the beginning pigment/ color of your skin- for example, maybe your skin was light to begin with, then got darker with one tanning. On your second tanning, maybe it barely got darker, because your skin was already tanned. Some skin has a limit for tanning. This is because some people have more or less oil in their skin, and some people's skin does not tan nearly as much as other people's; both are examples of the array of different skin types. Also, the condition of your skin fluxuates between seasons and different weather (dry vs. oily, etc.), which may also be a factor in accepting the oils/UV rays from the tannning bed. P.S.- Try not to do this too much if you want healthy skin.
1108264
haven't you been listening?  it is not wise to get too much sun.  cancer is not fun.  cancer can kill you.  skin cancer is not always detected before it's too late.  once the cancer starts - it will not stop - it has to be cut out - which leaves a scar.\n\nwhat is the big deal about changing the natural color of your skin?  you really won't be a different person for changing it.  if you're hoping to attract someone by being unaturally dark, you aren't being real with yourself.  i hope you don't try to build a relationship based on skin tone.  if you aren't desireable as a personality, the skin thing will only complicate the relationship thing.  \n\nand the cancer will screw everything up.
989150
It's because of evolution, yes. When people are exposed to higher levels of ultraviolet light, extra melanin in the skin will reduce the risk of skin cancer and will therefore be a survival advantage, so natural selection will favour dark-skinned individuals with the genes for producing extra melanin. Individuals with these genes are more likely to survive to childbearing age and will be more likely to pass on the genes. In colder climates, extra melanin does not affect the chances of survival as much so it is not selected for, though characteristics such as extra body hair and fat may be selected for.
553775
The reason for it to get darker is because when it absorbes water it fills up little micoscopics air caveties and ones is does this it absorbes more light, therefor it looks darker. (is doen't change its color, just looks like it)
653585
tanning is a reaction of your skin to protect itself from UV rays, melanin is produced to help absorb some of the radiation.  Sunburn is an actual burn, damage done from overexposure to the radiation.  What determines the difference is the intensity of the radiation and the duration.
1128092
nothing to worry about. there can be reasons like heredity, but not really due to stress and all that other bs. your hair loses the pigment and turns lighter. mine is turning really white and started when i was about your age!  i love color. highlighting masks it better.
759228
I am the same.  I was always very pale until recently.  In the summer I would go from red, back to white.  Now I tan.  Is your hair color the same?  probably not?  Everything changes!
653907
There is a relationship between sunlight and Vitamin D - a vitamin that controls many things inside your body including calcium.  What begins with light hitting your skin continues with another special reaction that occurs in your kidney.  Does this help your concern?
914931
The dark skin comes from a compound called Melanin and it is a sort of built in sun screen. Blacks are VERY rarely known to suffer from Skin Cancer but could potentially suffer from Vitaimin D deficiency without direct contact with sunlight in an an area with very little sunlight like black sailors on a submarine, blacks in arctic climates where the days are very short and majority of time is spent indoors because of the climate. Melanin historically has protected the people from damage from the suns rays.