# Why so little melanin on palms and soles? **URL:** \ **Category:** Factual Questions\ **Created:** [April 8, 2021, 8:30pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622 "2021-04-08T20:30:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [April 8, 2021, 8:30pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/1 "2021-04-08T20:30:14Z")
Question in the title, but to be clear, the question is not about the physiology which produces little melanin in those areas. Rather it’s about why people would have evolved in such a manner. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 8, 2021, 8:44pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/2 "2021-04-08T20:44:16Z")
Any answer is going to be pure speculation, so I’m going to make up a hypothesis on the spot: early hominids communicated extensively with hand signals, and having pale palms helped with visibility. The pale soles come from shared common genes during development. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [April 8, 2021, 11:33pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/3 "2021-04-08T23:33:58Z")
> [@Darren\_Garrison](#): > > Any answer is going to be pure speculation Why do you say this? Melanocytes exist in abundance in the dermal layers of your palms and soles, but are buried beneath the more heavily keratinized callous layers and rarely receive enough photostimulation to produce melanin. At least I learned that in my residency’s dermatology rotation a while back. ---
**Author:** ![DeathPool](https://avatars.discourse-cdn.com/v4/letter/d/e95f7d/32.png) [@DeathPool](https://boards.straightdope.com/u/DeathPool)\ **Post date:** [April 8, 2021, 11:43pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/4 "2021-04-08T23:43:27Z")
Isn’t there an extra layer of skin there, the Stratum Lucidum? ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 8, 2021, 11:49pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/5 "2021-04-08T23:49:16Z")
> [@Qadgop\_the\_Mercotan](#): > > Why do you say this? Becasuse speculations on specifically why specific traits evolve are mostly [just so stories](https://en.wikipedia.org/wiki/Just-so_story). ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [April 9, 2021, 12:17am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/6 "2021-04-09T00:17:47Z")
> [@Darren\_Garrison](#): > > Becasuse speculations on specifically why specific traits evolve are mostly [just so stories](https://en.wikipedia.org/wiki/Just-so_story). Then why should you make up such a story? Especially as a first answer in GQ. **Qadgop** has given the answer. There is no adaptive evolutionary reason for it. Instead it is just a secondary consequence of the keratin layer in our palms and soles. Many physical features are like that. They have no adaptive value themselves, but instead are a consequence of some other feature that is adaptive. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 12:43am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/7 "2021-04-09T00:43:03Z")
> [@Colibri](#): > > **Qadgop** has given the answer. There is no adaptive evolutionary reason for it. He gave the answer the OP didn’t want: “the question is not about the physiology which produces little melanin in those areas.” and claiming that there is definitly no adaptive reason for it is entirely as speculative as suggesting one. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 12:46am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/8 "2021-04-09T00:46:54Z")
There is a similar “just so story” for why people show the whites of their eyes. > **[Why we show the whites of our eyes](https://pursuit.unimelb.edu.au/articles/why-we-show-the-whites-of-our-eyes)** > > Of all the animals, only humans obviously show the whites of our eyes, making it easier for us to communicate and deceive with just glance. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 1:05am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/9 "2021-04-09T01:05:15Z")
_And_, the “thicker skin” answer is factually incorrect–people have five times fewer melanocytes on their palms and soles, and nobody knows why: > However, virtually nothing is known about mechanisms by which melanocytes stop migrating in the skin in palmoplantar areas during human embryogenesis and why the palms and the soles are generally hypopigmented. > **[Mesenchymal–epithelial interactions in the skin: increased expression of...](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2172049/)** > > We investigated whether or not the topographic regulation of melanocyte differentiation is determined by mesenchymal–epithelial interactions via fibroblast-derived factors. The melanocyte density in palmoplantar human skin (i.e., skin on the palms... ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [April 9, 2021, 1:10am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/10 "2021-04-09T01:10:44Z")
> [@Darren\_Garrison](#): > > He gave the answer the OP didn’t want: “the question is not about the physiology which produces little melanin in those areas.” and claiming that there is definitly no adaptive reason for it is entirely as speculative as suggesting one. Except for a small scientific principle called Occam’s Razor. Don’t invoke adaptive reasons for a feature if you don’t need to. And there was certainly no reason to invoke the absurd explanation you made up. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 1:19am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/11 "2021-04-09T01:19:27Z")
> [@Colibri](#): > > And there was certainly no reason to invoke the absurd explanation you made up. No more absurd than the eye one. I stand by it as as good an evidence-free speculation as others. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [April 9, 2021, 1:52am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/12 "2021-04-09T01:52:06Z")
Am I correct that humans are the only primates that have hypopigmented palms? As far as I can see, chimps, gorillas, etc. have dark palms. That would imply that the trait has evolved fairly recently. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 9, 2021, 1:57am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/13 "2021-04-09T01:57:05Z")
I don’t see any evolutionary advantage to lighter palms and soles. We don’t evolve because it makes sense, we evolve because a change gives us an advantage. Qadgop posted htat callous layers cover our palms and soles. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 9, 2021, 2:11am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/14 "2021-04-09T02:11:05Z")
I was looking at some videos with chimps recently which coincidentally included a lot of closeups of their hands. I noticed that the skin coloration on their fingers was very uneven or blotchy. Some areas of some fingers would be about the shade of a typical Caucasian human, whereas on the same individual much of the rest of their hands would correspond to a rather dark shade of African human. I agree that unlike dark-skinned humans, their palms did not seem much lighter than their general coloration. Net of the blotchiness I mentioned. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 2:25am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/15 "2021-04-09T02:25:58Z")
> [@carnivorousplant](#): > > Qadgop posted htat callous layers cover our palms and soles. And I posted a journal article covering the fact that Qadgop was wrong about that being the reason for lower pigmentation. Another quote: > The melanocyte density in palmoplantar human skin (i.e., skin on the palms and the soles) is five times lower than that found in nonpalmoplantar sites. Palmoplantar fibroblasts significantly suppressed the growth and pigmentation of melanocytes compared with nonpalmoplantar fibroblasts. In other words, it is _not_ a result of skin thickness and an actual developmental adaptation. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 3:14am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/16 "2021-04-09T03:14:59Z")
> [@LSLGuy](#): > > I agree that unlike dark-skinned humans, their palms did not seem much lighter than their general coloration. Net of the blotchiness I mentioned. Good human and chimp hands together photo on this page: > **[%%sitename%%](https://www.projetogap.org/br)** > > O GAP luta pela garantia dos direitos básicos à vida, liberdade e não-tortura dos grandes primatas não humanos - Chimpanzés, Gorilas, Orangotangos e Bonobos, nossos parentes mais próximos no mundo animal. O GAP Brasil existe desde 2000 e conta com 4... ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 9, 2021, 3:54am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/17 "2021-04-09T03:54:47Z")
Good pic and an interesting book review too. That particular chimp has rather more uniform hand coloration than the ones in the vid I watched. ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [April 9, 2021, 4:13am UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/18 "2021-04-09T04:13:11Z")
In fact, there is an [Uncle Remus just-so story on this very subject](http://www.telelib.com/authors/H/HarrisJoelChandler/prose/UncleRemus/negro.html). Warning for people who may not be familiar with [Uncle Remus](https://en.wikipedia.org/wiki/Uncle_Remus): > Uncle Remus is the fictional title character and narrator of a collection of African American folktales compiled and adapted by Joel Chandler Harris and published in book form in 1881. [snip] He wrote his stories in a dialect which was his interpretation of Deep South Negro language of the time. For these framing and stylistic choices, his collection has encountered controversy. The story includes the n-word and dialect that many would consider offensive. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 9, 2021, 12:34pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/19 "2021-04-09T12:34:03Z")
> [@LSLGuy](#): > > Good pic and an interesting book review too. That particular chimp has rather more uniform hand coloration than the ones in the vid I watched. This is interesting–a hairless chimp with the blotchy hands but non-blotchy (except for lots of freckles) body: [https://m.riverfronttimes.com/newsblog/2009/02/18/rip-cinder-saint-louis-zoo-chimp-dies-at-fourteen](https://m.riverfronttimes.com/newsblog/2009/02/18/rip-cinder-saint-louis-zoo-chimp-dies-at-fourteen) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 9, 2021, 12:36pm UTC](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622/20 "2021-04-09T12:36:49Z")
It seems to me that the physiological reason and the evolutionary reason would be tied together. Yes, the thicker, more keratinized skin @Qadgop_the_Mercotan mentioned would be a physiological reason… but there are obvious evolutionary reasons for those two spots to have more keratinization. Another factor would be that the palms of hands and especially the soles of feet are exposed to less sunlight, and so wouldn’t need as much melanin. Though that wouldn’t explain why they do have less melanin, only why they can. [Next page](https://boards.straightdope.com/t/why-so-little-melanin-on-palms-and-soles/939622.md?page=2)