A hairy business

Let your hair down: 10 amazing facts about human hair

Image: Ali Pazani

The human body is incredible, from its mechanics to its ability to heal and adapt to multiple environments and situations. Hair, as part of our body, is no exception to this complexity and wonder. Let’s take a look at 10 amazing facts about our hair that you may not know!

Image: Ian Talmacs

The word hair is used to describe two separate and distinct components: the follicle and the shaft. The follicle—what we commonly refer to as the root—is a living organ located in the dermis of the scalp. It’s responsible not only for growing hair but also for helping regenerate skin after a wound.

On the other hand, the shaft—often referred to as the strand—is a filament composed of layers of keratin, the same protein that makes up our nails. Unlike the follicle, the hair shaft is technically dead because it consists of dead cells.

Image: Joyful Bird

Each hair strand is composed of three layers. The innermost layer is the medulla, and even scientists are still uncertain about its exact function. Surrounding the medulla is the cortex, which absorbs water and provides strength to the strand. The cortex also contains melanin, the pigment that determines hair color, and its shape plays a major role in whether hair is straight or curly. The outermost layer is the cuticle, which serves primarily to protect the hair shaft.

Image: Tyler McRobert

Hair color is primarily influenced by several genes, including MC1R, which plays a key role in melanin production. However, not everyone produces the same type or amount of melanin. Higher amounts of melanin result in black hair, while varying levels and types of melanin—along with genetic variations—produce brown, blond, and other shades.

Red hair, the rarest natural color, is caused by a mutation in the MC1R gene and is inherited in a recessive pattern. This means a person must inherit two copies of the mutated gene (one from each parent) to have red hair, though many people carry the gene without expressing the trait.

Image: William Warby

Growing at a rate of about 0.2 to 0.5 inches per month, hair is the second-fastest growing tissue in the human body—surpassed only by bone marrow. This rate is influenced by factors such as genetics and ethnic background. Other variables, such as age, lifestyle, or health, can also have an impact on our hair growth and density.

Image: Sohan Rahat

We usually think of cats or dogs when it comes to shedding, but humans also shed hair regularly. After all, hair is a trait shared by all mammals. The average person sheds between 50 and 100 strands of hair per day, though this number can increase in response to stressors such as illness, hormonal changes, or emotional stress. Once the stress subsides and the body readjusts, the excess shedding typically stops.

Image: Joseph Chan

Commonly associated with aging, grey hair isn’t a color in itself but rather the result of a loss of pigment. As part of the natural aging process, melanin production in the hair follicle gradually decreases and eventually stops, causing strands to appear grey or white.

Genetics and ethnic background play a major role in determining when and how the greying process begins. Some people are even genetically predisposed to start greying at a very young age.

Image: Jaroslav Devia

Hair texture is commonly associated with ethnic background, but that’s not the only factor involved. Texture is primarily determined by genetics, and while genetics are closely tied to ancestry, all hair textures can be found across different populations.

Scientists believe that hair texture—specifically curl pattern and volume—is a result of the shape of the shaft. A round shaft typically produces straight hair, while flatter or more oval-shaped shafts tend to create curls and waves.

Image: Amritanshu Sikdar

Depending on the structure of your hair cuticle, your hair may be more or less water-repellent. Hair shafts with a more porous cuticle absorb water easily but also lose moisture quickly. In contrast, shafts with a tighter-packed cuticle struggle to get wet and are slow to dry.

Image: Sonja Langford

Hair doesn’t grow continuously or all at once—each strand follows a cycle with distinct phases. First comes the growing phase, which varies depending on the type of hair (for example, facial hair grows faster and for a shorter period than scalp hair). Eventually, growth slows down, and the strand detaches from the root.

After this, the hair enters a resting phase, during which it remains in place until it is naturally shed. At any given time, we have hairs in all stages of this cycle, which is why we regularly shed hair without going bald.

Image: Hans Reniers

Like any other part of the body, hair contains DNA and genetic material, which means a person can be genetically identified from a single strand, provided it includes the root. But hair holds even more information. The analysis of a hair strand can reveal substances that were present in a person’s bloodstream over time, including vitamins, minerals, medications, alcohol, and other substances.

The 12 longest-living animals on Earth (and how they cheat time)

Nature doesn’t just create beauty, it crafts survival miracles. While most animals have short lives, a rare few have mastered the art of staying alive for centuries, even millennia. These aren’t just long-lived creatures; they’re nature’s ultimate time travelers. From the frozen depths of the oceans to the darkest corners underground, they’ve developed bizarre, brilliant strategies to cheat death. Get ready to meet 12 animals whose lifespans will absolutely blow your mind.

Record age: up to 15,000 years

This unassuming sea sponge thrives in the freezing waters of Antarctica, where temperatures hover around 28.6 °F—so cold that biological processes hit the brakes. In such icy conditions, metabolism slows to a crawl, allowing these sponges to live for thousands of years.

Some have reached impressive sizes of over 3 feet tall and have been around since mammoths were still thundering across the tundra. They don’t move, they don’t stress, and they barely change, just quietly existing while centuries pass them by. Their secret to extreme longevity? Glacial patience, deep-sea stillness, and a lifestyle that redefines "low-maintenance".

Age: technically… infinite

This tiny jellyfish, no bigger than a fingernail—less than 0.2 inches—is like the ocean’s very own Benjamin Button. What makes it truly extraordinary is its ability to rewind its life story, flipping back to a youthful, juvenile stage whenever it wants. While it’s not completely invincible (predators and other threats are still very real), if left undisturbed, it can keep hitting the reset button on aging indefinitely, making it one of the most fascinating "time-benders" in nature.

Record age: 507 years

In 2006, a special clam was discovered buried deep in the seabeds of the North Atlantic. Scientists were able to determine that it had been there since at least 1499—that’s centuries before the United States was even a thought! This ancient marvel, nicknamed "Ming", was able to perfect a slow-and-steady approach to life. Growing at a snail’s pace and barely budging, Ming’s sedentary lifestyle turned out to be a brilliant strategy for beating the clock. Who knew doing almost nothing could be the ultimate secret to longevity?

Record age: estimated 392 years

These sharks aren’t your average ocean cruisers—they can stretch over 20 feet long and weigh up to 2,200 pounds. But what’s really mindblowing is how slowly they move, like they’re in a permanent state of deep relaxation. Living in the icy Arctic waters, these giants don’t hit adulthood until they’re about 150 years old, and some can glide through the depths for nearly 400 years. Imagine that! These ancient swimmers were already around before America declared independence... and they are still out there, silently roaming the seas!

Record age: over 211 years

This whale is a true ocean giant, stretching up to 60 feet long and weighing a staggering 200,000 pounds. But what makes it stand out isn’t just its size but its age. Some of these majestic creatures carry harpoons from the 1800s still lodged in their skin, like walking history books. Just picture living so long that you’re literally carrying outdated technology embedded in your body—talk about being a time traveler of the seas!

Record age: 200 years

Spanning the chilly Pacific coastline from California all the way up to Alaska, this spiky little ball—about 7 inches across—is full of surprises. It munches on algae and calls the deep, dark ocean its home, thriving at depths of up to 300 feet. Don’t let its size fool you: this prickly creature is a true elder of the cold seas, quietly outliving many ocean neighbors while keeping a low profile. A tough, slow-living veteran wrapped in spikes!

Record age: 226 years

Meet Hanako, a legendary Japanese koi who swam through life for an astonishing 226 years. Scientists discovered how old she was by studying the rings on her scales, much like counting the growth rings of a tree. These colorful, ornamental fish aren’t just symbols of good fortune; they’re also secret long-lifers with the potential to celebrate over two centuries of birthdays, as long as they get the right care and a peaceful pond to call home.

Record age: 190 years

Jonathan is a male tortoise living on the remote island of Saint Helena in the South Atlantic Ocean. He was born back in 1832, and he’s still happily chomping lettuce and soaking up the sun today. Weighing in at more than 400 pounds and measuring around 3 feet long, Jonathan holds the title of the oldest known living land animal on the planet. If he could share tales, they’d span nearly two centuries of history. Imagine that!

Record age: 152 years

This ancient-looking fish, with its whisker-like barbels, looking like a tiny underwater submarine, prowls the lakes of North America. It can reach an impressive length of up to 7 feet and weigh around 200 pounds. These slow-living creatures don’t rush into adulthood—they start breeding only around age 20—and then take their time cruising through life at a leisurely pace. Believe it or not, one legendary catch in Wisconsin was estimated to be over 150 years old!

Record age: over 90 years

This chunky, night-loving parrot from New Zealand is a true oddball—it can’t fly, snores like a grumpy grandpa, and smells like fresh flowers. Despite its quirks, this bird boasts an impressively long lifespan. Sadly, it teeters on the edge of extinction. The oldest known kakapo, affectionately named Richard Henry, lived 90 years, earning him the title of the charmingly eccentric elder statesman of the avian world.

Record age: 37 years

This tiny, kooky rodent—barely 3 inches long and just over an ounce in weight—could’ve been cast straight from a sci-fi apocalypse flick. Dwelling in vast underground colonies across Africa, it’s practically invincible to cancer, pain, and the usual effects of aging. Scientists are fascinated by this little marvel, even if it’s not winning beauty contests anytime soon. Its superpowers make it a star in longevity research!

Record age: estimated 100+ years

Lobsters have a totally different rulebook than us when it comes to aging. They don’t really grow old; they just keep getting bigger and bigger. Some giant lobsters weigh over 40 pounds and stretch beyond 3 feet long. Their biggest threats? Not old age, but predators or the risky process of shedding their shells. In theory, they could live forever if left alone—but let’s be honest, not many get to enjoy a peaceful, lobster-sized retirement!