Unraveling the History of Human Hair

iStock/ValuaVitaly
iStock/ValuaVitaly

Be it brown or blond, in a straight or naturally curly hair style, the hair that grows from our heads is a fundamental aspect of the human appearance. Our multitude of hair types is so ubiquitous that it’s actually easy to ignore how weird hair is—and not in the sense that your hair style might be on the wrong side of edgy.

“When it comes to human uniqueness, people come up with all kinds of stuff—culture, intelligence, language,” Tina Lasisi, a doctoral candidate in anthropology at Penn State University, tells Mental Floss. “[But] we’re the only mammals that have hairless bodies and hairy scalps.”

On the surface, our hair types are simple enough. Like fingernails, hair is made mostly of the protein keratin. It can survive for millennia under the right conditions—think Ötzi, the 5300-year-old iceman whose clothing, body, and hair were all preserved when he was frozen in a glacier. In warmer, wetter, more acidic environments, hair can degrade within weeks.

But that’s only what hair is. Why we have different hair types and how they came to be is a mystery that scientists are just now beginning to untangle.

Why Do We Have Hair on Our Heads?

Mother holding child with a braided hairstyle
iStock/Kali9

Some researchers have tried on various hypotheses to explain the patterns of hair growth in Homo sapiens and why they differ so dramatically from our close relatives, like chimpanzees. Losing body hair meant we could sweat more, a cooling mechanism that “helped to make possible the dramatic enlargement of our most temperature-sensitive organ, the brain,” writes anthropologist Nina Jablonski in Scientific American. Other researchers hypothesized that the hair remaining on human heads helped hominins regulate body temperature when they became bipedal and started traveling long distances. Basically, scalp hair created a kind of built-in hat.

Hair doesn’t usually stick around for hundreds of thousands of years the way fossilized bones do. If scientists want to answer the question of how our hair evolved from full-body fur, they have to explore the human genome—and Lasisi found that surprisingly few have done so. That’s partially because of the time and expense of conducting genomic analysis to pinpoint which genes affect the production of hair. But it’s also because it wasn’t a question posed by earlier (male) scientists, according to Lasisi.

“They were like, ‘Oh yeah, hair, it’s sexy on women, it’s probably sexual selection.’ But there was no effort to look into it as a unique human trait because they were more interested in our large brains, bipedalism, and whatnot,” Lasisi says.

How Did Different Hair Types Come To Be?

Blond woman facing forsythia bush
iStock/lprogressman

Even the lack of categorization for hair types is telling. Contrary to what your shampoo bottle may say, there is no real classification system for different hair types. At least not yet.

“Most mammals have straight hair. Only human hair [in African and Melanesian populations] has this tightly coiled configuration. We tend to talk about hair as straight, wavy, curly, in some cases frizzy,” Lasisi says. “But it’s as if we were trying to do genetic studies on height saying, there are short people, medium people, and tall people, now find what genes are related to that.”

In other words, before she could even attempt to answer the question of which genes control the texture and color of hair, Lasisi had to figure out a system for defining those hair textures and colors. Lasisi set about creating a classification system that she eventually hopes to publish, which relies on microscopic analysis of curl radius and measuring precise amounts of melanin in the hair. She then tried to answer the first of many questions: Whether tightly coiled African hair evolved in response to the hot environment. While that research is still ongoing, she says the results may indicate something counterintuitive—the thicker the hair, the better insulator it is from heat.

What's the oldest human hair ever found?

Woman wearing African jewelry viewed from the back
iStock/FernandoPodolski

On the rare occasions when hair is preserved in the fossil record, it can be an incredible source of information about our ancestors’ health and behavior. In 2009, Lucinda Backwell and colleagues described the discovery of what appeared to be human hair in fossilized hyena poop (a.k.a. coprolites) from more than 200,000 years ago—the oldest evidence of human hair to date. Five years later, Backwell and others followed that study with an examination of 48 hairs from hyena coprolites that identified several mammalian species. The presence of all those types of hair mean the hyenas were scavenging from many different remains, including humans.

“In the case of the human hairs in the coprolite, they told us a lot, because there were no bones,” Backwell, an anthropologist with the University of Witwatersrand in South Africa and Instituto Superior des Estudios Sociales, CONICET in Argentina, tells Mental Floss by email. They revealed that humans shared the environment with big herbivores like impala, zebra, kudu, and warthogs in southern Africa 200,000 years ago. Unfortunately for scientists, all of the keratin in that hair sample had been replaced by calcium carbonate that didn’t include any DNA. “The first prize would be to extract DNA and identify whether the hair belonged to a modern or archaic human, or even someone like Homo naledi, with its primitive features and young age,” Backwell said. In addition to helping identify the precise species of hominin, DNA from a hair sample like this could go a long way in telling more about different species’ relationship to one another.

Backwell has also studied human hair found in a high-altitude cave site in Argentina, one of the best environments for preserving hair because it’s “cool, dry, dark, and with a neutral pH,” she says. Like the coprolite hairs in South Africa, dating and identifying hairs in Argentina will help Backwell and others understand the spread of humans across the world.

How Can Hair Shed Light on History?

Woman with brown wavy hair facing the ocean
iStock/lprogressman

When people are exposed to substances in the environment, their hair will retain some of the chemical signatures of those substances. Hair found in ice, in amber, and on mummies from arid regions around the world has allowed researchers to learn fascinating details about the inhabitants of particular regions.

In 2013, archaeologists at the University of Chile analyzed 56 mummy samples found in northern Chile. Using gas chromatography-mass spectrometry (a tool that identifies different substances in a sample—and also happens to be used for drug testing), they found that people had smoked nicotine-containing plants continuously from 100 BCE to 1450 CE. “Overall, these results suggest that consumption of nicotine was performed by members of the society at large, irrespective of their social and wealth status,” the researchers wrote in their study.

Another group of archaeologists collected hair samples from 40 mummies found in Peru, Chile, and Egypt to analyze pre-industrial mercury concentrations across the world, ranging in time from 5000 BCE to 1300 CE [PDF]. Their results, published in 2018, indicated much lower levels of mercury in the environment than in the industrial era. Researchers also discovered that each group’s diet determined the actual level of mercury exposure—the Chilean mummies had higher concentrations from their seafood-based diet, while the Egyptians, who ate land animals, had the lowest.

For now, the mystery of hair’s evolution remains partially unsolved. But the next time you’re at the salon, look in the mirror and remember: Hair is part of what makes us human.

Is There An International Standard Governing Scientific Naming Conventions?

iStock/Grafissimo
iStock/Grafissimo

Jelle Zijlstra:

There are lots of different systems of scientific names with different conventions or rules governing them: chemicals, genes, stars, archeological cultures, and so on. But the one I'm familiar with is the naming system for animals.

The modern naming system for animals derives from the works of the 18th-century Swedish naturalist Carl von Linné (Latinized to Carolus Linnaeus). Linnaeus introduced the system of binominal nomenclature, where animals have names composed of two parts, like Homo sapiens. Linnaeus wrote in Latin and most his names were of Latin origin, although a few were derived from Greek, like Rhinoceros for rhinos, or from other languages, like Sus babyrussa for the babirusa (from Malay).

Other people also started using Linnaeus's system, and a system of rules was developed and eventually codified into what is now called the International Code of Zoological Nomenclature (ICZN). In this case, therefore, there is indeed an international standard governing naming conventions. However, it does not put very strict requirements on the derivation of names: they are merely required to be in the Latin alphabet.

In practice a lot of well-known scientific names are derived from Greek. This is especially true for genus names: Tyrannosaurus, Macropus (kangaroos), Drosophila (fruit flies), Caenorhabditis (nematode worms), Peromyscus (deermice), and so on. Species names are more likely to be derived from Latin (e.g., T. rex, C. elegans, P. maniculatus, but Drosophila melanogaster is Greek again).

One interesting pattern I've noticed in mammals is that even when Linnaeus named the first genus in a group by a Latin name, usually most later names for related genera use Greek roots instead. For example, Linnaeus gave the name Mus to mice, and that is still the genus name for the house mouse, but most related genera use compounds of the Greek-derived root -mys (from μῦς), which also means "mouse." Similarly, bats for Linnaeus were Vespertilio, but there are many more compounds of the Greek root -nycteris (νυκτερίς); pigs are Sus, but compounds usually use Greek -choerus (χοῖρος) or -hys/-hyus (ὗς); weasels are Mustela but compounds usually use -gale or -galea (γαλέη); horses are Equus but compounds use -hippus (ἵππος).

This post originally appeared on Quora. Click here to view.

An Ice Age Wolf Head Was Found Perfectly Preserved in Siberian Permafrost

iStock/stevegeer
iStock/stevegeer

Don’t lose your head in Siberia, or it may be found preserved thousands of years later.

A group of mammoth tusk hunters in eastern Siberia recently found an Ice Age wolf’s head—minus its body—in the region’s permafrost. Almost perfectly preserved thanks to tens of thousands of years in ice, researchers dated the specimen to the Pleistocene Epoch—a period between 1.8 million and 11,700 years ago characterized by the Ice Age. The head measures just under 16 inches long, The Siberian Times reports, which is roughly the same size as a modern gray wolf’s.

Believed to be between 2 to 4 years old around the time of its death, the wolf was found with its fur, teeth, and soft tissue still intact. Scientists said the region’s permafrost, a layer of ground that remains permanently frozen, preserved the head like a steak in a freezer. Researchers have scanned the head with a CT scanner to reveal more of its anatomy for further study.

Tori Herridge, an evolutionary biologist at London’s Natural History Museum, witnessed the head’s discovery in August 2018. She performed carbon dating on the tissue and tweeted that it was about 32,000 years old.

The announcement of the discovery was made in early June to coincide with the opening of a new museum exhibit, "The Mammoth," at Tokyo’s Miraikan National Museum of Emerging Science and Innovation. The exhibit features more than 40 Pleistocene specimens—including a frozen horse and a mammoth's trunk—all in mint condition, thanks to the permafrost’s effects. (It's unclear if the wolf's head is included in the show.)

While it’s great to have a zoo’s worth of prehistoric beasts on display, scientists said the number of animals emerging from permafrost is increasing for all the wrong reasons. Albert Protopopov, director of the Academy of Sciences of the Republic of Sakha, told CNN that the warming climate is slowly but surely thawing the permafrost. The higher the temperature, the likelier that more prehistoric specimens will be found.

And with average temperatures rising around the world, we may find more long-extinct creatures rising from the ice.

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