The anatomy of our hair follicles explains goose bumps

Goose bumps may play a role in hair growth

Research in mice suggests that the same muscles that contract to create goose bumps act as the bridge for the sympathetic nervous system’s connection to hair follicle stem cells. This raises questions about how this knowledge could be used to reactivate the sympathetic nerves in hair follicles to boost hair growth in people.

Goose bumps are often triggered by emotions

A physiologist and professor of zoology explains that the subconscious release of adrenaline, a stress hormone, causes a contraction of skin muscles. It’s released in several situations, including when humans are cold, afraid, or feel strong emotions. (Some readers may experience a paywall.)

Goose bumps require a surprisingly complex series of steps

Watch an anatomical breakdown of how goose bumps work—featuring real skin from a human cadaver, a segmented brain, and a detailed anatomical model of the skin—to learn about all the jargon behind goose bump science. (Warning: Includes graphic footage of cadaver skin.)

There’s a lot we still don’t know about goose bumps in humans

Though goose bumps can be associated with changes in skin temperature, the biggest gaps in our understanding are around measuring goose bumps from nonthreatening exposures. These bumps can often occur without our detection, and we have trouble correctly identifying them. The relationship between emotionally induced chills and goose bumps can also be tenuous.

Scientists have unraveled new details about which nerve cells control goose bumps

Research in 2016 revealed that at least eight different types of neurons are associated with the sympathetic nervous system. One finding revealed that goose bumps and nipple erection are caused by neurons specialized to regulate these specific functions by controlling the erectile muscles in those tissues.

Long-term goose bumps are something to flag to your doctor

Although rarely a cause for concern, persistent goose bumps with no known cause could be a symptom of something to discuss with your doctor, including anxiety, a hair follicle blockage, or conditions that arise from an overreaction of the autonomic nervous system.

Some of us can control our goose bumps

A small 2018 study examined the rare ability to control goose bumps. Researchers found some intriguing associations between having a particularly open and curious personality type and the ability to trigger this sensation—a link that they hope will be explored further in the future.

Artificial goose bumps could theoretically be used for information storage

Inspired by how fine hairs stand on the skin with goose bumps, researchers have recently created artificial skin that raises artificial goose bumps when exposed to a laser. This type of precise, localized, and controllable system could potentially fuel later development of programmable machines that could be used for information storage.

Porcupines, when threatened, go piloerect—essentially, they get goose bumps

If stressed, the animal appears to grow to about twice its normal size because it goes piloerect, which causes the quills to stand erect. If this intimidation tactic to avoid conflict doesn't work on the predator, the animal may get stabbed by the quills upon contact with the porcupine.

Why do you shiver when cold?

Humans are warm-blooded creatures, so our bodies like to maintain internal temperatures separate from and typically above those in their environment. This is made possible by a process known as thermoregulation. When the brain's hypothalamus senses a drop in the body's core temperature, skeletal muscles may be ordered to shiver, sending out waves of muscle contractions and exothermic biochemical reactions whose byproduct includes heat and energy.

Humans likely cannot tickle themselves because there's no element of surprise

Unraveling the neural mechanisms of tickling—formally called gargalesis—is an area of active research, but a leading theory about why we can't tickle ourselves is that the brain's somatosensory cortex processes self-touch differently than it does external touch. The cerebellum already anticipated what was going to happen when you move your hand for self-touch, limiting the effectiveness of a self-tickle.

Complex molecular reactions in our tissues cause muscle contraction

When we want to move a muscle, a signal travels from the brain and into the muscle cells in question, sparking a chemical reaction that causes the muscle's smallest contractile units—sarcomeres—to shorten, forcing the muscle to contract.

Nasal hairs, called vibrissae, help protect the body from particulate matter and other dirt

The nose structure plays a key role in filtering air before it enters our lungs and makes sure that the air temperature and humidity are also suitable for the body.

Allergies occur when our immune system mistakenly considers a substance a threat

Immunoglobulin E antibodies, or IgE antibodies, may bind to an allergen, effectively labeling it as a threat. That triggers a cascade of actions in the body, including the release of histamine, which causes the characteristic itching and hives of allergies. Sometimes a cooked version of an allergen—like a cooked carrot—may look different enough from its raw form to the immune system that antibodies ignore it, and no allergic response takes place.

Surfer's ear, from repeated cold water exposure, leads to new bony protrusions in the ear

Frequent exposure to icy cold water, typical in surfing, can cause tiny bony growths to develop in the ear canal, informally called surfer's ear. While the exact cause for these growths is unknown, it may be the body's protective response to shield the ear drum from the cold. These protrusions can heighten the risk of swimmer's ear, lead to wax buildup, and result in hearing loss.

Why do we sometimes jolt awake before falling asleep?

Around 70% of people are estimated to experience the sensation of falling and jerking awake right as they're about to drift to sleep. That mysterious phenomenon is called hypnic jerking. As common as it is, hypnotic jerking remains disconcerting and hard to explain. While we don't yet have clear answers, peruse this article in Popular Science for some possible explanations as to why this happens.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

The immune system fights tattoos

Our skin is a fascinating organ that wants nothing more than to protect our bodies from the outside world. Tattoos penetrate that protective wall to inject ink directly into the sensitive, immunologically rich layer of skin known as the dermis.

Sweat doesn't smell, but bacteria multiply in moist environments—and cause an odor

Body odor is associated with sweat, but odor actually arises from the bacteria that multiply in moist environments on your skin. Hormones, medications, food, and body hair can all affect body odor.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens

This type of extreme reaction to harmless holes, dots, cracks, and seed collections can be debilitating for those who have it, but it is not an officially recognized disorder in the DSM-5.

Red blood, skin, hair, and nail cells destroy their DNA upon maturing

To maximize the amount of oxygen they carry and more easily alter their shape to fit into narrow blood capillaries, red blood cells destroy their own nuclei. Cornified cells found in hair, nails, and the outermost layer of skin destroy their nuclei and other cellular contents to make room for keratin, which provides durability and structural support.

British beard history, 101

The beard has gone in and out of fashion for centuries in Britain. It was hated in the 18th century but became a must in the 19th. This quick list rehashes 15 fascinating tidbits about the beard, including possible useful functions for them (a beard is equivalent to an SPF 21 sunscreen) and how barbers were often also surgeons.

Hail forms in freezing temperatures thousands of feet above the ground

Even if surface temperatures are well above freezing during the summer, updrafts during thunderstorms can push raindrops high into the atmosphere, where they can freeze and form hail. Giant hailstones the size of softballs require updrafts of close to 100 mph.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

A fascinating look at why cucumber tendrils coil in opposite directions

The tendrils of cucumber plants coil when they hit a surface, creating a distinct telephone-cord look. Charles Darwin wrote about the mystery in the 1850s, though it wasn't until the 21st century that scientists figured out just how mysterious the coil is: its tendrils coil in opposite directions.

A history of manicules, or the little hands in books and posters

Manicules are illustrated hands used in many contexts to point something out, whether by medieval readers to highlight passages or in 19th-century advertising. The hands have a quirky, persistent history, showing up over hundreds of years in everything from Petrarch's books to computer cursors and the US Postal Service's "Return to Sender" stamp.

Electromagnetic repulsion prevents objects from making contact with one another

The feeling of touching something is a sensation caused by the electromagnetic force between the electrons on the surface of objects. Since this force grows to infinity with proximity, no two surfaces can ever achieve matter-to-matter contact.

Poison ivy can cause rashes year-round since all parts of the plant contain urushiol, the oil that triggers our allergic response.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

El Niño, Spanish for 'the boy,' was named after Jesus Christ because the phenomenon resembled the weather changes observed around Christmastime.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

See the 25 of the best photos of auroras from around the world.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

American short story writer Flannery O'Connor raised 40 peacocks, which became potent symbols for her fiction's elegant violence

Hotels in Cannes, the glamorous city on the French Riviera, hire hawks to ward off seagulls during the city's famous film festival.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

Abraham Lincoln was almost assassinated weeks before his inauguration as he traveled from Illinois to DC through Baltimore in 1861; it took two independent claims for Lincoln to be convinced the threat was real