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The School of UnLearning: Skin
Skin

The History of Skin

The untold story of our largest organ

By J.T. Alvarez


Some two million years ago, early hominids - the family of primates that includes extinct early humans as well as modern people - emerged from the dense, cool forests of primeval Earth into sunny, wide open plains. Our distant cousins, some of the oldest in the Homo genus, were covered in thick hair, a hindrance in their new, warmer environment. Over the course of eons, they shed the full coverage look, adapting to the heat through sun avoidance, changes in skin tone, and full body sweating.

The plains provided food to forage and game to hunt, but there was a drawback: harmful rays from the harsh sun. Along with causing certain skin cancers, UV radiation destroys folic acid, an important B vitamin involved in cell growth. A critical nutrient in reproduction, a lack of the vitamin during pregnancy has been tied to miscarriages and congenital diseases. Luckily, the sun does more than photolyze.

Exposure to the sun also creates vitamin D and triggers the process of melanogenesis, the production of melanin, a pigment-producing immune cell found in many organisms. By absorbing sun rays and blocking UV radiation from penetrating the epidermis, individuals with the darker melanin found in deep brown skin had a reduced risk of radiation-caused disease, boding well for the continued survival of their offspring.

Hundreds of thousands of years passed, and some early humans from Africa and late hominid groups - like Neanderthals and Denisovans - ended up far from the equator. Sparsely populating places like pre-historical Siberia and Northern Europe, our early predecessors once again found themselves in starkly different environments than their ancestors. But if the Homo genus is great at anything, it’s adaptation. With less sun exposure, northerly skin and hair lightened over time, likely to aid in vitamin D absorption and due to a lack of UV activated melanin cells, while humans closest to the equator remained brown skinned. Interbreeding with Neanderthals also lent a hand to northerly humans facing the cold by way of thicker skin; studies show that the 1-3% of the Neanderthal genome that remains in European and East Asian populations today is rich in keratin, a fibrous protein responsible for the thickening of skin, nails, and hair.

Of course, there’s a variety of skin tones above the equator and that may be, in part, due to diet. Vitamin D, while typically gained through sun exposure, is also found in seafood. With the ability to get vitamin D through their diet and exposure from UV rays reflected off bright white snow and ice, some coastal peoples in the north - like Indigenous groups in Alaska and Canada - could maintain deeper skin tones without the risk of vitamin deficiency. 

Pure Bathing Culture

Jetted tubs and detachable shower heads are pretty new, but bathing itself has a long history too. Whether it was dipping into a nearby creek or a more formal affair in a dedicated structure, people all over the world have used steam and water to wash their skin throughout recorded history. Along with water, clay, and oils, exfoliating instruments were used to remove dirt from the skin, with some baths including milks, salts, or herbs meant to moisturize, heal, and soothe the body.

Many sites of cleansing served both hygienic and religious purposes: the pre-colonial Mesoamerican temazcal, a stone sweat lodge used for purifying the body after exertion; the Turkish hammam, modeled after Greek and Roman public baths; or, the Japanese yūya inside 8th century Buddhist temples. While the practices of public bathing have changed some over time, communal, religious washing sites still exist in modernity, like the natural body of water Pushkar Lake in Rajasthan, India or the constructed Jewish mikvahs and Christian baptismal fonts. 

 

Public hammams, Russian banyas, Korean jjimjilbangs, and Finnish saunas weren’t just places to scrub down. They were - and still are - fundamentally social spaces that host everything from group spa days to informal business and political meetings. Though plumbing and private bathrooms are now the norm in modern homes, lessening the need for such institutions, public baths and the culture around them live on.

Radium and Rose Hips

Humans have put a lot of thought into looking our best over the centuries. Creating beauty and maintaining the skin beyond mere cleansing has been a priority across continents and cultures who drew from a wide breadth of knowledge and materials to get the job done. Donkey’s milk, rose petals, radium, and honey; many naturally occurring ingredients have shown up in beauty products with varying level of success.

Rose hip oil, derived from the fruit of the “dog rose” (Rosa canina), has been used therapeutically for centuries. As told by Hippocrates, a physician from the Classical period of ancient Greece known as the “Father of Medicine,” and Pliny the Elder, a naturalist from ancient Rome who authored the model for modern encyclopedias Naturalis Historia, rose hip oil was used to treat scrapes and cuts as well as bites from “mad dogs,” which may explain the quirky name.

The common, natural element lead has long been an ingredient in facial creams, whitening powders, and kohl makeup stretching back to antiquity. Too bad it’s also a heavy metal that can be highly toxic to humans if ingested or repeatedly absorbed through the skin, causing a range of serious health problems, or even death. After the fall of the Roman Empire, lead production plummeted, and its use as a lightening agent in the Mediterranean lessened. However, the powder-white look lived on in Edo era Japan and was all the rage in Elizabethan England. Despite an established record of adverse health effects, lead impurities - typically from color additives - can still be found in some cosmetics today. 

The Content of Our Character

People have long made distinctions between themselves. I’m from here, you’re from there. Alongside physical appearance, languages, cultures, and faiths have made evident differences between us, but how deep do those differences go? 

That question became an urgent one only a few hundred years ago when Enlightenment age European naturalists began classifying different species of plants and animals and attempted to use similar methods on people. By linking superficial characteristics shared by people from the same geographic region with close common ancestry, European and American thinkers began to classify human beings into biologically distinct groups; the most intelligent, moral, and ideal individuals being themselves. Carl Linnaeus, the 18th century Swedish “father of taxonomy,” initially grouped humans into five varieties: Africanus, Americanus, Asiaticus, Europeanus, and Monstrous, a category which included ‘feral children’ and legendary creatures. 

Following the French and American Revolutions and the emergence of a politically active humanist movement which insisted all men were created equal, the mass enslavement, murder, and displacement of West African and Indigenous peoples by European colonizers created quite the conundrum. In response, colonizers affirmed they had the right to add to their respective empire’s wealth and glory however they saw fit as was customary (non-chattel slavery has historically been an accepted economic practice throughout the world). And furthermore, they had the responsibility to ‘civilize’ their conquests through forced labor, conversion, etc. because such conquered peoples were biologically inferior. Thomas Jefferson, slave owner and founding father, remarked in his 1781 book Notes on the State of Virginia:

“I advance it therefore as a suspicion only, that the blacks, whether originally a distinct race, or made distinct by time and circumstances, are inferior to the whites in the endowments both of body and mind.”

‘Race science’ informed everything from public policies like slavery, segregation, and residential schools to psychology and criminology, fundamentally shaping American and contemporary European societies and identities in unique ways. Its consequences have been far reaching, namely in the form of eugenics, from the forced sterilization of Indigenous women to the mass genocide of Jewish, Romani, and disabled peoples during WW2 on the basis of their supposed inferiority.

To this day, myths persist about significant biological differences between people of different skin tones. A 2016 survey of white medical students revealed a third of them believed that Black skin was thicker compared to other races and half thought that Black people’s nerve endings are less sensitive. Never has there been any evidence supporting such assertions, which stem directly from justifications of the hard use and abuse of Black bodies during slavery. Other common myths about darker skin include the belief that it is insusceptible to skin cancer, doesn’t require sunscreen, ages slower, and bruises and scars less (in fact, almost the opposite is true: darker skin is statistically more likely to produce keloid scars because of melanocytes). 

DNA testing through Ancestry.com and 23andMe are part of a new wave of race science that is increasing in popularity. Packaging complex genetic data into easily digestible but misleading data points (What does it truly mean to be 2% anything?) has furthered the notion of genetic, identifiable race despite inconsistent and unclear evidence. In 2003, upon completion of the international scientific research project that mapped 92% of human genetic material, the Human Genome Project stated:

"People who have lived in the same geographic region for many generations may have some alleles [specific gene variants] in common, but no allele will be found in all members of one population and in no members of any other.” 

Comprehensive, reproducible science that takes into account centuries of misinformation and economically motivated propaganda is the key to breaking down destructive myths about what it means to be human. Imperfect methodology, cultural bias, and outright manipulation of data all contribute to the flawed conclusions people have internalized about race. Only when we are willing to meaningfully engage with our own errors and assumptions can we eliminate the influence of our imperfections on scientific study and embrace the truth that our differences are, quite literally, only skin-deep.

Our largest organ is our most visible one. Methods of its care, cleaning, and decoration have changed over time along with the significance of its color. Human skin's distinct features set us apart from other primates, but they shouldn’t set us apart from one other. The differences between us reflect the vast genetic and bacterial diversity of all biological organisms. Such diversity isn’t just worth protecting, it’s worth celebrating.


References

Colin Kidd, The Forging of Races: Race and Scripture in the Protestant Atlantic World, 1600–2000, 2006

Robert Wald Sussman, The Myth of Race. Harvard University Press, 2014

Human Genome Project (2003). "Human Genome Project Information: Minorities, Race, and Genomics". U.S. Department of Energy (DOE) – Human Genome Program

Kelly M. Hoffman, Sophie Trawalter, Jordan R. Axt, M. Norman Oliver, 2016Racial bias in pain assessment and treatment recommendations, and false beliefs about biological differences between blacks and whites. Proc Natl Acad Sci U S A. 2016 Apr 19; 113(16): 4296–4301

Serre, D., Pääbo, S., 2004“Evidence for gradients of human genetic diversity within and among continents." Genome Res. 14 (9): 1679–85

Prescott, S.L., Larcombe, DL., Logan, A.C. et al. 2017. The skin microbiome: impact of modern environments on skin ecology, barrier integrity, and systemic immune programming. World Allergy Organ Journal 10, 29 (2017)

Joel Z. Garrod, 2006A Brave Old World: An Analysis of Scientific Racism and BiDil. McGill Journal of Medicine, (2006) Jan; pp. 54–60

Andrew Best, Jason M. Kamilar, 2018. The evolution of eccrine sweat glands in human and nonhuman primates. Journal of Human Evolution, V. 117 (2018), pp. 33-43

Jablonski and Chaplin, 2000. The evolution of human skin coloration. Journal of Human Evolution, 39 (2000), pp. 57-106

Jablonski, 2004. The evolution of human skin and skin color. Annual Review of Anthropology, 33 (2004), pp. 585-623

Folk and Semken, 1991The evolution of sweat glands. International Journal of Biometeorology, 35 (1991), pp. 180-186

Wheeler, 1984The evolution of bipedality and loss of functional body hair in hominids. Journal of Human Evolution, 13 (1984), pp. 91-98


About the Author

J.T. Alvarez is a writer and editor for CRUDE and the School of UnLearning. Find them on Instagram or Twitter @judeanism.