Evo-Ed: History, Genetics, and Human Skin Color

This is part 4 of our multi-part series on Human Skin Color.

The human species has been on the global scene for about 200,000 years. Skin color hasn't been a fixed characteristic over that time. The earliest humans likely had dark skin, which was a departure from earlier ancestor species that featured light skin and coarse body hair. Dark skin, and less body hair helped early humans to effectively thermoregulate, while having the photoprotective properties that skin pigment affords. Skin color has been in constant flux in the millennia since the dawn of our species, and broadly correlates to a latitudinal gradient of sub exposure. Today, humans come in a wide and beautiful array of different skin shades and tones.

Support for this work was provided by the National Science Foundation's Division of Undergraduate Education program under Award No. DUE2020221

[wannacashmeoutside]

One of my favorite lesser known facts is that the Inuits of the Alaska/Canada/Greenland have dark hair and eyes and didn’t need to adapt lighter hair and eyes because their marine diet has a lot of vitamin D

[antoniotorcoli]

Excellent video. A small correction: according to the latest genetic data, the first Europeans had dark skin.Eventually, during the Mesolithic, they developped blue eyes, but their skin remained dark until the arrival of the neolithic farmers

[Karl-fgnv]

These studies need to be included in basic K-12 education.

[rogwarrior]

I love how you (basically) mentioned we are all one human species. Skin color doesn't matter, it never has and it is something to celebrate our heritage, our ancestry. Great video and I love your shirt.

[Amuzic_Earth]

That's a highly simplified yet precise gist on a complex topic. I would also like it to have the topic of how even the appearances(facial, physical, cranial) changed across the people with different skin colors and whether or not it had something to do with intermixing with other human species such as neanderthals and denisovans etc.

[emmanfey]

Amazing. You unleashed so much scientific facts and revealed so much information in such a short video. And ended with such thoughtful phrase or how important and at same time how skin deep skin colour is. Great job!🎉

[kudjoeadkins-battle]

Good video. I think it’s important to note that that larger population of humans who stayed in Africa continued to diversify genetically.

[mangodoc]

Thank you. Even with a PhD in cell biology I struggle to express the core principles of evolution as meaningfully as you do here. You present the relevant facts without bombarding your audience with a bunch of extra gobbledygook. Again, thank you.

[chrisk]

This is one of the better comments sections on YouTube lol great video !

[fla_girl]

Simplified is an understatement thank you for your video

[MalkiaWaMungu]

Excellent video! Simplified for the simple!

[davidbrown]

I needed that, watched several long videos and didn't get the jist, now I do!

[theknow]

That was pretty informative! Now the goal is to convince those that think they are something special how special we all are.

[lyndansyiem]

Extensive research across many disciplines. Final presentation very good, full of facts but without clutter.

[matthewchapman]

Excellent.. informative.. factual... well presented!! Keeps you watching... All around.. outstanding job! 5 stars. Keep up the research!

[prototropo]

Great, level-headed, factual presentation.

[sharadvishwas]

Very Good information about Human's body colour how its change in Evolution and still changing 👍

[kma]

This is one of the best descriptions I've seen of the Out of Africa hypothesis. Your inclusion of these specific mutations as biological markers really helps illustrate not only the migratory pathway, but also the effects of natural selection on phenotype. Well done. I'll have to check out some more of these!

[megapangolin]

THANK YOU for a technically sound, informative and scientific evaluation of what makes us all different- essentially nothing, we are not different, we are all the same biologically. Yes, there are some gene differences, height, fat deposition, body proportions, eye colour, hair colour, body hair distribution etc, due to adaptation to cold, food, and similar, however, this happens in populations of animals, but in humans, there is not enough difference to create a subspecies or anything similar. However, humans do manufacture culture, and linked to that, religion and it is that which determines our different negative behaviours to each other, colour is just a useful tool for people to use to highlight different cultural norms and then judge other cultures based on our internally generated views of the world, eg cannibalism, child brides, FGM etc. We are just all the same, let's just get on with working together and stop finding fault in anyone who is not our colour. Culture is a different thing though. Great video.

[karaghanascythianslayer]

At the same time, they collected blood samples for genetic studies. They sequenced more than 4 million single nucleotide polymorphisms (SNPs)—places where a single letter of the genetic code varies across the genomes of 1570 of these Africans. They found four key areas of the genome where specific SNPs correlate with skin color.

The first surprise was that SLC24A5, which swept Europe, is also common in East Africa—found in as many as half the members of some Ethiopian groups. This variant arose 30, 000 years ago and was probably brought to eastern Africa by people migrating from the Middle East, Tishkoff says. But though many East Africans have this gene, they don’t have white skin, probably because it is just one of several genes that shape their skin color.

The team also found variants of two neighboring genes, HERC2 and OCA2, which are associated with light skin, eyes, and hair in Europeans but arose in Africa; these variants are ancient and common in the light-skinned San people. The team proposes that the variants arose in Africa as early as 1 million years ago and spread later to Europeans and Asians. “Many of the gene variants that cause light skin in Europe have origins in Africa, ” Tishkoff says.

The most dramatic discovery concerned a gene known as MFSD12. Two mutations that decrease expression of this gene were found in high frequencies in people with the darkest skin. These variants arose about a half-million years ago, suggesting that human ancestors before that time may have had moderately dark skin, rather than the deep black hue created today by these mutations.

These same two variants are found in Melanesians, Australian Aborigines, and some Indians. These people may have inherited the variants from ancient migrants from Africa who followed a “southern route” out of East Africa, along the southern coast of India to Melanesia and Australia, Tishkoff says. That idea, however, counters three genetic studies that concluded last year that Australians, Melanesians, and Eurasians all descend from a single migration out of Africa. Alternatively, this great migration may have included people carrying variants for both light and dark skin, but the dark variants later were lost in Eurasians.

To understand how the MFSD12 mutations help make darker skin, the researchers reduced expression of the gene in cultured cells, mimicking the action of the variants in dark-skinned people. The cells produced more eumelanin, the pigment responsible for black and brown skin, hair, and eyes. The mutations may also change skin color by blocking yellow pigments: When the researchers knocked out MFSD12 in zebrafish and mice, red and yellow pigments were lost, and the mice’s light brown coats turned gray. “This new mechanism for producing intensely dark pigmentation is really the big story, ” says Nina Jablonski, an anthropologist at Pennsylvania State University in State College.

The study adds to established research undercutting old notions of race. You can’t use skin color to classify humans, any more than you can use other complex traits like height, Tishkoff says. “There is so much diversity in Africans that there is no such thing as an African race.”