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.

15 Science Experiments You Can Do With Your Kids

These boys are about to demonstrate osmosis with gummy bears.
These boys are about to demonstrate osmosis with gummy bears.
G&J Fey/iStock via Getty Images

Parents and teachers across the internet have found fun ways to teach kids science, and have documented the experiments for the rest of us. Here are 15 hands-on science lessons that will stick in a kid’s brain far longer than anything they get from a textbook.

1. Make a lemon-scented volcano

Fun Quotient: It's like the classic baking soda and vinegar volcano experiment, but it smells a lot nicer.

Teaches: The baking soda base and the citric acid create an endothermic reaction while releasing carbon dioxide in bubble form. You have to look up endothermic reaction on your own.

Find it: Fun Littles

2. Set money on fire

Fun Quotient: Wait, what? You’re burning money? Why?!

Teaches: Combustion, the process behind fire. Rubbing alcohol is flammable, but the wet, cottony dollar isn't. The fire will go out once the alcohol has been consumed.

Find it: Barefoot in Suburbia

3. Create rock candy skewers

Fun Quotient: It makes pretty rocks you can eat.

Teaches: Water evaporates, but the sugar crystals don’t. The sugar precipitates meaning it separates from the supersaturated sugar water. Seed crystals form on your stick, attracting more sugar crystals, until finally, about a week later, you got yourself some tasty science.

Find it: Science Bob

4. Build an electromagnet

Fun Quotient: Kids get to use sharp things and electricity, which is Frankenstein-level cool.

Teaches: Electromagnets are everywhere. They make motors spin, CDs play, and most modern cars run. This experiment shows the difference between a permanent magnet (the ones on your fridge) and the kind that can be turned on and off at will. When turned on, the electricity forces the molecules in the nail to attract metal, even though the nail itself isn’t magnetic.

Find it: Science Bob

5. Write a message with invisible ink

Fun Quotient: Kids can pretend they're spies sending highly classified information (not recommended in real life).

Teaches: Oxidation, a.k.a. the process that creates rust. Lemon juice is acidic enough to resist oxidation in open air, but a little heat “rusts” it right up.

Find it: Scientific American

6. Walk on eggs

Fun Quotient: Like walking on hot coals, but not as painful.

Teaches: Structure matters. No matter how flimsy an egg shell is, its shape gives it amazing strength, as long as you put the weight in the right place.

Find it: Steve Spangler Science

7. Make a tea bag rocket

Fun Quotient: Every child enjoys watching things burst into flame and fly around the kitchen.

Teaches: Hot air rises and cooler air sinks. But it also demonstrates convection current, which is the force that makes it shoot into the air.

Find it: Physics Central

8. Discover how cornstarch and water can dance

Fun Quotient: Oobleck is a mix of cornstarch and water that can act like a liquid and a solid. By itself it’s fun, but add a sub-woofer and the glop will shimmy in its container.

Teaches: Sound waves. You can’t see them, but they exist, and they like to party.

Find it: Housing a Forest

9. Create an Ivory Soap monster

Fun Quotient: You get to nuke a bar of soap until it becomes a frothy cloud of 99 percent pure mess.

Teaches: When the gas molecules trapped in the soft pliable soap get hot, they need more space. They make a break for it and take the soap with them. As the temperature of the gas increases, so does its volume.

Find it: ThoughtCo

10. Launch marshmallows across the room

Fun Quotient: Weaponized marshmallows, hello!

Teaches: Force equals mass times acceleration. A little thing going very fast will hit you just as hard as a big thing going slow. That’s Newton’s second law.

Find it: Adventure Science Center

11. Poke a "magic" plastic bag

Fun Quotient: You'll find out it's possible to poke a pencil through a plastic bag of water without spilling it.

Teaches: How polymers work. Also, on a different level, why you’re not supposed to take the arrow out of a person after they get impaled in movies.

Find it: Tinkerlab

12. Make gummy bears change shape

Fun Quotient: Deform gummy bears by dunking them in a variety of potions.

Teaches: Osmosis, and which kinds of liquids do it best.

Find it: Sciencing

13. Design an optical illusion

Fun Quotient: Animate a cartoon the old-fashioned way.

Teaches: Your eyes aren’t entirely reliable. Optical illusions occur because our brains fill in the gaps for whatever our eye isn’t processing, so two pictures become one.

Find it: Science Sparks

14. Set up a chain reaction

Fun Quotient: It’s tough to get started, but the payoff is clatter and splatter.

Teaches: A demonstration of potential energy, kinetic energy, and chain reactions.

Find it: The Kid Should See This

15. Make Molecules Move

Fun Quotient: Slow and steady wins here; kids with an artistic streak will love creating designs as the colors move through liquids.

Teaches: Why oil and water don't mix. Kids will witness how molecules of water, fats, and proteins come together and move apart in different substances.

Find it: American Chemical Society

Take a Virtual Tour of One of the Quietest Places on Earth

Paul Robinson, Wikimedia Commons // CC BY-SA
Paul Robinson, Wikimedia Commons // CC BY-SA

Orfield Laboratories in Minneapolis, Minnesota, is notable for what it lacks. Inside the anechoic chamber, you won't hear the sounds of traffic, chatter, or even the hum of appliances. The soundproof room is one of the quietest places on Earth, and you can take a virtual tour of the space in the video below.

According to UPROXX, Orfield Laboratories is primarily used for research. The background noise inside the chamber clocks in at -9.4 dBA. For comparison, the quietest place the average person has access to has sound levels closer to 30 dBA. Without any outside noises to interfere, products tested for noise levels inside the space produce extremely accurate results. The room has other purposes as well, such as preparing astronauts for space missions and freaking out tourists willing to pay for a visit.

Experiencing sound levels lower than what's found in nature has odd effects on the human body. Your ears adapt to pick up sounds that are usually inaudible. With nothing else to fill the space, the sounds of your heart, stomach, and even lungs can become deafening. Dizziness, anxiety, and out-of-body-sensations are a few of the reported responses to spending time in the eerily silent chamber.

Though you won't be able to get the full experience from home, you can pop in a pair of headphones and get a taste of what the room is like in this video. The lab is currently closed to visitors, but when it's open it offers tours starting at $125 per person.

[h/t UPROXX]

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