Why do black people have lighter hands and feet?

Rye · Post by **Rye** » 2006-04-20 12:36pm

Well, the title says it all, really, how come the pigments in their skin aren't as uniform when it comes to the soles of feet and the palms/fingers? I just remembered out of the blue this was something I wondered about as a child and was never answered on.

Post by **Darth Wong** » 2006-04-20 12:39pm

Obviously because they raise their palms to the air when they praise The Lord Jesus Christ, and his divine rays of perfect love lighten their skin by taking away the stain of sin. Haven't you read the Book of Mormon?

Crossroads Inc. · Post by **Crossroads Inc.** » 2006-04-20 12:42pm

I think it has to do with 'thickness' of the skin there.

The undersides of hands and feet are naturally more senstive areas and the hands especially are very dextrious and have a much softer underside then the top. It may simply be that the pigmentation isn't as deep there.

Or conversly, perhaps it is just that as people, we walk around with are hands facing up far more then our palms?

Cao Cao · Post by **Cao Cao** » 2006-04-20 12:44pm

I think it has to do with how our palms and soles are not as exposed to sunlight as much as the rest of our skin. Since darker skin is an adaptation to exposure to more intense sunlight, isn't it?

Nieztchean Uber-Amoeba · Post by **Nieztchean Uber-Amoeba** » 2006-04-20 01:34pm

Cao Cao wrote:I think it has to do with how our palms and soles are not as exposed to sunlight as much as the rest of our skin. Since darker skin is an adaptation to exposure to more intense sunlight, isn't it?

Depends who you ask. Arguments can be made for and against that explanation, since plenty of people living in rather cold, dark places have ended up with dark skin as well.

Turin · Post by **Turin** » 2006-04-20 01:41pm

Nieztchean Uber-Amoeba wrote:
Cao Cao wrote:I think it has to do with how our palms and soles are not as exposed to sunlight as much as the rest of our skin. Since darker skin is an adaptation to exposure to more intense sunlight, isn't it?
Depends who you ask. Arguments can be made for and against that explanation, since plenty of people living in rather cold, dark places have ended up with dark skin as well.

I don't have an online source handy, but a Scientific American article from a few years back explained that skin color is determined by the push-pull of two different forces.

The first that folic acid breaks down in the presence of UV light, and the second that the body needs sunlight to produce certain vitamins from their naturally occuring precusors. Thus, where sun exposure is greater, there is evolutionary pressure towards darker skin, and vice-versa.

Most folks who break this trend are evolutionarily recent immigrants to their region. The one exception mentioned is that of the Inuit people, who have access to the sunlight-dependent vitamins from their fish-rich diets. Thus, the Inuit have no evolutionary pressue to have lighter skin and the pressure to have darker skin wins out.

Turin · Post by **Turin** » 2006-04-20 01:45pm

Turin wrote:I don't have an online source handy, but a Scientific American article from a few years back explained that skin color is determined by the push-pull of two different forces.

Ug, sorry... my google-fu was weak. Here it is:
SciAm (WARNING - PDF!)

Rye · Post by **Rye** » 2006-04-20 01:49pm

Cao Cao wrote:I think it has to do with how our palms and soles are not as exposed to sunlight as much as the rest of our skin. Since darker skin is an adaptation to exposure to more intense sunlight, isn't it?

Well, I thought that initially, but as far as I know, places like the asscrack and genitals don't end up with similar noticable pigment changes.

Big Phil · Post by **Big Phil** » 2006-04-20 02:26pm

Most everybody's palms and footsoles are a slightly different color than the rest of their body. It's just more noticeable with black people. I couldn't explain why, though...

Magnetic · Post by **Magnetic** » 2006-04-20 04:24pm

I agree that it isn't a "sun issue", based upon the already mentioned butt crack.

It's also tru that a lot of times the lower lip is lighter in color as well. That would be another one against the influences of the sun since the bottom lip would receive more sun rays than the top.

Anyway, Rye, as to the question of your OP, I've wondered that same thing too.

Keevan_Colton · Post by **Keevan_Colton** » 2006-04-20 04:42pm

Could it be in some way connected to other issues with differences between the areas? For example the hands and soles dont have any hair folicles...the ass crack and genitals do.

Cao Cao · Post by **Cao Cao** » 2006-04-20 04:45pm

Well, our soles are always in contact with the ground or shoes for walking, and our palms are in contact with all sorts of things.
Since we are a bipedal, tool handling species after all.
So the skin in these areas is not only exposed to less light, but is of a different type.
That's just another guess, mind you.

Magnetic · Post by **Magnetic** » 2006-04-20 05:48pm

I'm not sure, . . .are the hands and feet of gorilla's, chimps, etc lighter colored than the rest of their skin? I'm thinking that their palms and soles of their feet are colored as the rest of their skin. Again, not really sure about that.

Lord Revan · Post by **Lord Revan** » 2006-04-20 05:51pm

Magnetic wrote:I'm not sure, . . .are the hands and feet of gorilla's, chimps, etc lighter colored than the rest of their skin? I'm thinking that their palms and soles of their feet are colored as the rest of their skin. Again, not really sure about that.

it's kind of hard to say as apart of the face palms and bottoms of their feet are the only part that apes don't have hair in.

Sans_Deity · Post by **Sans_Deity** » 2006-04-20 06:01pm

My grandfather asked me this question as a sort of riddle, when I was young. I'll never forget his answer:

Because they were standing like this (lean forward, spread eagle with palms pressed against the wall) when God painted them.

I'm neither a racist nor a theist (my Grandfather was both), but this was amusing enough as a kid that I've never forgotten it.

-Matt

Kwizard · Post by **Kwizard** » 2006-04-20 06:05pm

Could it have something to do with fetal temperature in those areas? I've heard that some species of cats can have lighter-colored paws simply becuase those developing structures are exposed to more heat during gestation.

Master of Ossus · Post by **Master of Ossus** » 2006-04-20 06:40pm

I don't actually know the answer to this question, but I want to point out that it's not just black people--I'm Asian for this purpose, and I have less pigmentation on my palms than on the back of my hands, for example.

Big Phil · Post by **Big Phil** » 2006-04-20 06:54pm

Magnetic wrote:I'm not sure, . . .are the hands and feet of gorilla's, chimps, etc lighter colored than the rest of their skin? I'm thinking that their palms and soles of their feet are colored as the rest of their skin. Again, not really sure about that.

And dogs, and cats, and alligators, etc... We need a biologist or a doctor to answer this question.

Tasoth · Post by **Tasoth** » 2006-04-20 07:33pm

It deals with a thinner skin on the hands if I remember correct. You actually lack one of the layers of the epidermis on your hands(not sure about the feet. Faulty memory) The thickness of the upper layers is also decreased also. I'm also willing to be that the fact the feet of our ancestors have been on the ground for the most part and hands do alot of holding that the presence of melanin and melaninocytes isn't as important there since UV light exposure would much less compared to the rest of the body. Of course I could be wrong.

Lusankya · Post by **Lusankya** » 2006-04-21 02:24am

Rye wrote:
Cao Cao wrote:I think it has to do with how our palms and soles are not as exposed to sunlight as much as the rest of our skin. Since darker skin is an adaptation to exposure to more intense sunlight, isn't it?
Well, I thought that initially, but as far as I know, places like the asscrack and genitals don't end up with similar noticable pigment changes.

Not every culture has the same reservations about nudity as ours, remember, and cultures in warmer climates would be even less likely to have their 'bits' covered. Especially when they have the pigmentation in their skin to protect them somewhat against the harmful effects of exposure to the sun.

ROAR!!!!! says GOJIRA!!!!!

Quadlok · Post by **Quadlok** » 2006-04-21 03:14am

Could it have to do with the higher wear, on average, that palms and soles experience? Perhaps it simply isn't worth the effort for skin cells to produce melanin when they'll be gone too fast to justify the energy expended?

CJvR · Post by **CJvR** » 2006-04-21 04:32am

Darth Wong wrote:Obviously because they raise their palms to the air when they praise The Lord Jesus Christ, and his divine rays of perfect love lighten their skin by taking away the stain of sin. Haven't you read the Book of Mormon?

You are wrong, they simply were standing on all four when they were spraypainted...

I suspect that there have been no need for as dense pigmentation on those surfaces it just shows more on Africans.

Lord of the Abyss · Post by **Lord of the Abyss** » 2006-04-21 05:05am

Tasoth wrote:It deals with a thinner skin on the hands if I remember correct. You actually lack one of the layers of the epidermis on your hands(not sure about the feet. Faulty memory) The thickness of the upper layers is also decreased also.

Incorrect; the palms and soles have the thickest skin on the body; they feel thinner and more delicate because of the higher nerve concentration. After a quick google : Link

emedicine.com wrote:Skin also varies in thickness among anatomic location, sex, and age of the individual. This varying thickness primarily represents a difference in dermal thickness, as epidermal thickness is rather constant throughout life and from one anatomic location to another. Skin is thickest on the palms and soles of the feet (~1.5 mm thick), while the thinnest skin is found on the eyelids and in the postauricular region (~0.05 mm thick).

Zac Naloen · Post by **Zac Naloen** » 2006-04-21 09:02am

I always assumed it was due to the wear on that part of the hands and feet, skin is constantly being worn away. Especially on the feet and the melanin doesn't form fast enough to compensate.

GrandMasterTerwynn · Post by **GrandMasterTerwynn** » 2006-04-21 11:04am

Zac Naloen wrote:I always assumed it was due to the wear on that part of the hands and feet, skin is constantly being worn away. Especially on the feet and the melanin doesn't form fast enough to compensate.

It's a trait that our next closest ancestors, the chimpanzees share, in part. Juvenille chimpanzees have significantly less-pigmented skin in the areas where they are hairless, such as their palms, the soles of their feet, their faces, and the rest. Except when they mature, those areas on their body gradually darken to match the rest of their skin. The other great apes don't share this feature, and they're every bit as dexterous and their palms and feet experience just as much wear as ours.

So, the plausible explanation would be that it's a trait that developed sometime after the common ancestor of chimpanzees and humans diverged from gorillas and orangs. However, sometime after human ancestors diverged from the common ancestor of chimps, one of the adaptations that contributed to the current human species had a side-effect of carrying over the reduced pigmentation on the hands and feet into adulthood, while the other areas on the body that usually darkened did so. And finally, there was some other selective pressure that produced hominid infants that were born with the adult pigmentation in place. (It could, however, be said that the common ancestor of humans and chimps had the lighter hands and feet, and that it was chimps who underwent an evolution towards lighter faces in their young.)

In short, there's probably no real good reason for it, apart from some random quirk or side-effect of natural selection.

<ADDENDUM>

One could also suggest some sort of hack evolutionary theory . . . like hominids with pale palms made better toolmakers, since the lighter palms on dark hands and dark rocks would've made it easier to visually judge if a hominid was holding a stone axe or hammer right. (This is as good a reason as any. Stone tools became only slightly more complex as hominids went from Homo habilis through all the variants of Homo erectus, and only really took off when Homo sapiens and Homo neanderthalensis (to a lesser extent) showed up. That's well over 1.5 million years of natural selection. And the genes which control the skin, hair, and pigmentation of the palms are probably the same ones which manage the soles of the feet . . . so what happens to the palms also happens to the feet.)