Melanin

www.nationalgeographic.com/science/healt...ody/human-body/skin/

www.everydayhealth.com/skin-and-beauty/s...about-your-skin.aspx

Largest organ of the human and melanin !
Melanocytes make melanin, the pigment that provides color to the skin.
People with darker skin have melanocytes that produce more melanin
Exposure to sunlight also can increase melanin production, causing freckles or a suntan.

Body organs aren't all internal like the brain or the heart

There's one we wear on the outside.
Skin is our largest organ
—adults carry some 8 pounds and 22 square feet of it.

yes! well I know dat. I thought you had something more to add

I've read that people with more melanin in their skin, produce vitamin D less efficiently and not as quick as people with less melanin. That's because they rarely burn when exposed to sunlight. And for a person to produce vitamin D they need their skin to turn red when they sunbathe. There has been research that has shown that people with dark complexion have lower levels of this crucial vitamin in their blood.

I don't know about less efficient..or more efficient. how and why do they use such terms and comparatives?

who did the research? that may expose the quality of that research and why we have been told such a conception.
if you are cold adapted with less melanin... which is for the production of the essential VitD from minimal sunlight in the cold regions..and you are suddenly exposed to lots of sunlight in a warm region what would be the immediate reaction?

I assume the light skin would in fact very quickly produce a lot of VitD. but is that efficiency? is it good for the body that has changed environmental regions?

what is the continuing response of the body so exposed then......?

it darkens as much as it could in the sunlight..very very quickly. the longer that body stays in the sunlight it darkens up as much as it could. and if that is not enough, the head on the body tells the body to go get sun screen in order to live. the very quick production of VitD is mitigated, slowed down in the sunlight

the more that body darkens, the more it becomes like bodies that are dark all the time and deals with sunlight in that way. the permanently dark bodies are sun adapted, have all the VitD they need and want in the sun drenched environment. they live and have no problems in reproduction. no bone problems which the cold adapted have all the time in the cold..caused by insufficient VitD.

is that an efficient process taking place according to how people move about the planet or not?

what happens when the Black skin moves into the cold adapted regions for extended periods of stay? the dark skin must lighten and or supplements must be found or there is the development of problems from VitD deficiency.

there is an environmentally driven global biological process of human survival going on that is obvious

the cold adapted body adapts to the greater sunlight, becomes like the sun adapted bodies in order to survive. how else to explain the phenomena of skin darkening in the sunlight? it is a biologically protective response and so efficient..more efficient, most efficient
any increased production of VitD by the lighter skin in the greater sunlight is only temporary. the darkening of the skin quickly reduces such production, bringing it into line with the sun adapted

it follows that there is a whole lot involved in the interaction between humans and the sun and that we don't know all as yet..far from it, and that the relationship is one that the human body uses and adapts to all the time on planet earth..that it is an on-going and changing relationship due to tons of factors like the life of the sun itself which changes all the time..in intensity for sure.

the only fact that seems constant is human ability to adapt and adjust biologically to live..so far.

it is nonsense to speak of efficiency/inefficiency relative to these things. we don't even know all that's going on. and more is not efficiency..or more efficient.

I mean if you improve a machine that makes cakes, to produce 5k cakes where it produced 3k cakes before.. that way more may be of greater efficiency than less, if you have demand for 2k more cakes. but I don't see that that is the way nature works. man made linear-functioning machines yes...but not natural processes

but hol' orn! deh soon include AI..artificial intelligence to machines and look out. they mimic nature and may on their own develop means to evolve themselves. Pheeeeeeew