Humanity's reduced body hair slows down wound healing

Skin wounds and burns heal fastest if they occur during the day

Skin cells responsible for healing wounds work more quickly during the daytime, underscoring that the timing of an injury greatly influences recovery time, according to 2017 research. Nighttime burns took an average of 11 days longer to heal than burns incurred during the day. (Some readers may experience a paywall.)

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.

The 4% DNA difference between humans and chimps

On the genetic level, we’re not all that different from chimps. But those small differences in DNA can have huge effects. This 11-minute video digs in to the topic.

Humans may have evolved to need less sleep

Humans sleep less than most primates—but more efficiently. Chimps sleep 9.5 hours with 5% in REM, while humans get seven hours with 25% in REM. Some predict we may one day need just five hours, but for now, our sleep patterns balance rest and function, shaped by evolution and environmental stability.

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.

The halting of human bone growth helps manage heat produced from metabolism

While fish, amphibians and reptiles get bigger throughout their lives until they die, their slower metabolisms allow their bodies to regulate the resulting smaller temperature increases. In humans, hormones triggered during puberty harden growth plates, ending bone lengthening.

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

Humans won't develop more than 5 fingers because it would impact too many body parts

All modern animals have five or fewer digits on each of their limbs. Roughly 348 million years ago, at least two species had eight: the Ichthyostega and the Acanthostega. According to Dollo's law, complex evolved features are very unlikely to recur in evolution. Researchers believe humans won't develop more than five digits because it would impact other body parts too much.

Humans aren't the only mammals who go through menopause, but it's rare in the animal world

While scientists are unsure how many mammals actually experience menopause, they do know for sure that humans aren't the only ones. Orcas and some toothed whales (like belugas and narwhals) go through menopause. And a recent study found chimpanzees also experience the condition, though it's late in life.

Why hibernating bears don't get blood clots

For mammals, long periods of inactivity can lead to health problems—blood flow slows and pools, veins kink and distort, and clots potentially form. Hibernation takes this risk to the extreme, yet for decades why animals like bears did not exhibit...

Limb regeneration research may lead to treatments for arthritis

For scientists pursuing the cure for arthritis, the holy grail of discoveries lies in how to regrow healthy cartilage inside human joints. While this feat has so far resisted our best scientific attempts, there are plenty of other human tissues—such as the liver and fingertips—that will successfully regenerate.

Wild chimpanzees have been spotted with leprosy lesions

In research published in 2021, scientists reported discovering cases of leprosy in wild chimpanzees from Guinea-Bissau and the Ivory Coast—marking the first time the disease has been found in any nonhuman species in Africa. They confirmed that leprosy was the cause of the deformities by testing the animals' poop for the presence of the disease-causing bacteria.

Pigs are preferred for xenografts because of their size and low disease risk

Pigs are of particular interest for xenotransplants because the animals are close to human size, are easily raised in captivity, and have large litters. They’re already routined killed for food and they’re less genetically related to humans than nonhuman primates, which reduces disease transmission risks and some researchers’ ethical concerns.

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

Imagining if humans could perform photosynthesis and how it would change our anatomy

Since chloroplasts reflect green light, becoming photosynthetic would give our skin a green appearance. Because photosynthesis has efficiencies of only 5% to 9%, and humans burn 2,000 Calories daily compared to about 200 burned by a tree, becoming photosynthetic would also require us to adopt a less active, sun-filled lifestyle.

Most fungal pathogens can't survive the heat of our bodies

Fungal pathogens typically struggle to survive human body temperatures, but researchers hypothesize that global warming conditions will force fungi to adapt to hotter temperatures, with implications for their ability to also survive within our bodies. That type of evolutionary adaptation would lead to more dire health threats for humans.

Grief rewires the human brain

The human brain handles stress and emotional traumas similarly. In response to the emotional stress of a situation like the death of a loved one, divorce, or abuse, the brain may strengthen or weaken connections between nerves to form new neural connections. Over time, chronic stress can diminish brainpower, reducing overall nerve growth and memory to shift resources to enable elevated fear responses and enable humans to survive.

Prolonged space travel significantly impacts multiple human body systems

Astronauts can lose 20% of their muscle mass after two weeks and 10% of their bone mass after six months in space. Decreased sharpness of eyesight and changes in neural connectivity, brain structure and gut bacteria have also been observed.

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

Firework or sparkler burns, even if they cover a relatively small area of skin, can significantly affect our range of motion.

A primer on human tears

Tears are one of the many behaviors that differentiate humans from the rest of the animal kingdom. Why do we cry? This comprehensive and well-written essay explores various theories about why we cry, observes tear fluid as the only one that does not elicit disgust, and attempts to interpret the meaning of tears in different circumstances. See what all the fuss is about here.

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

The unapproved peptide—which has received glowing testimonials from bodybuilders, biohackers, popular podcasters, and some in the MAHA movement— is often sourced from China. It has been used for myriad conditions. But scientific questions about the substance abound, including whether it's truly a natural substance produced by the human body, since genetic material that codes for its unique amino acid sequence hasn't been found in the human genome or the gut microbiome. Other unknowns include how it works in the body, which receptors it targets, and its safety, since evidence beyond anecdotes remains scant in humans.

Women tend to tip more often than men

For instance, among people who visit hair salons or barber shops, 62% of female respondents said they always tipped. Only 45% of men said the same. This article includes more takeaways and stats about how Americans tip, and who receives them.

Shorter, more frequent touches are better than longer, rarer ones

That's according to a 2024 meta-analysis of 137 studies on touch. It found that as long as the touch is consensual, the identity of the toucher mattered little for adults, and there was even a benefit to receiving "touch" from objects like weighted blankets or robots. For newborns, however, the identity of the toucher did matter, and the greatest benefit came from parental touch.

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.

Shingles vaccine may slow biological aging in older adults

Research published in 2025 that analyzed data from thousands of older adults found that those who had received the shingles vaccine exhibited signs of slower biological aging, such as lower levels of inflammation and slower epigenetic aging, than those who had not been vaccinated.

How 'the Iceman' got his tattoos remains a mystery

Ötzi the Iceman, discovered in 1991, is one of the oldest human mummies ever found—and his 61 tattoos remain a mystery. This explainer looks at how researchers believe the tattoos were made, what their placement suggests about ancient medicine and culture, and why we’re still piecing together their true purpose today.

Cultural norms about how to handle the bodies of loved ones have hampered Ebola responses in West Africa

Awareness of local burial and grieving traditions eventually helped healthcare workers fight the spread of the virus. As healthcare workers and burial teams altered their procedures during the 2014 West African Ebola outbreak, and as community leaders pressed people to adapt traditional ceremonies, the spread of Ebola began to slow.

When humans discovered fire

Fire has proven crucial for the development of human civilization, but there was a time when our hominin ancestors could not make effective use of it. This article traces the major milestones in humanity's journey with fire based on evidence from...

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

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

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

Cultural norms about how to handle the bodies of loved ones in communities in West Africa have hampered Ebola responses.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

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

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

Many legends about George Washington, including his supposed wooden teeth and the story of cutting down the cherry tree, lack evidence.

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

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

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

US consumers collectively owe more than $1T to credit card companies—almost as much as they owe in auto loans.

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

The United States has had a tumultuous relationship with Cuba since its 1959 revolution, highlighted by a nuclear crisis and a decades-long trade embargo.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.