Bears have evolved natural mechanisms to avoid blood clots while hibernating

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...

Unlike other bears, polar bears do not hibernate

They do not need to wait out winter because they can find enough food in the Arctic winter, using sea ice as hunting grounds. Pregnant polar bears may be mistaken for hibernating while they den for months at a time.

Why don't humans hibernate?

Hibernation is a superpower in the animal world that allows certain species to time travel from difficult times to abundance. This essay in Aeon explains this helpful natural process and why humanity's technological advancements may have hindered our ability to participate in the practice. Learn about the rising interest in human hibernation as a result of modern adversity, and if it could potentially become a reality.

Blood clotting is critical to maintaining life, but dysfunctional clots can be fatal

Clotting is how our body stops bleeding in the event of an injury. Typically, platelets adhere to exposed tissue, becoming sticky and forming a plug. Chemical signals trigger the coagulation cascade, converting fibrinogen into fibrin threads that stabilize the plug. This prevents bleeding but can obstruct vessels if overactive or misplaced.

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

'Buffy coats': The 1% of blood that helps fight off disease

When blood is centrifuged, white blood cells and platelets form a layer called the buffy coat between the plasma and red blood cells. This layer makes up less than 1% of blood, but its heightened leukocyte concentration makes it useful for toxicology research.

Oxygen and nutrients are circulated in tardigrade bodies through physical movement

Rather than having a circulatory system, oxygen is directly absorbed through their skin and spreads through a fluid called hemolymph as tardigrades crawl. When molting to grow, they shed their outer skin and stylets—sharp mouth parts used to pierce prey—which are regrown in their salivary glands.

Large animals like giraffes and elephants have evolved unique cancer defenses

One may expect the larger an animal is, the more likely it is to develop cancer—simply because there are more cells and more chances for a dangerous mutation. However, some large animals show cancer rates almost 10 times lower than humans—a phenomenon known as Peto's Paradox.

Vampire bats are the only mammal to feed exclusively on blood

Scientists believe their ancestors may have eaten parasites and insects off larger animals until vampire bats started feeding directly from those animals. Colonies work together to stay fed, as a vampire bat can die without just two days of eating.

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.

Humanity's reduced body hair slows down wound healing

Cuts to human skin take twice as long to heal compared to chimps and other mammals. Scientists argue this is due to the reduced number of hair follicles on human bodies. Hair follicles contain stem cells which help repair skin cells faster, so as humanity shed its hair over time, so to speak, it also slowed its wound healing.

Why you have to airlift rhinos upside down

Conservationists in Namibia have found that airlifting rhinos upside down is actually better for their health than lying them down on stretchers. A study by Cornell University found that rhinos have higher blood oxygen levels when upside down, which is critical for their survival during transport. The upside-down position also allows the rhino's spine to relax, which can help to prevent injuries. This new finding could revolutionize the way that rhinos are moved.

Animals get SAD—especially those in zoos, like pandas

Giant pandas in locations outside their evolved latitudinal range (from southeast Asia to northern regions around Beijing) exhibit more sluggish behavior, even when they were born there. Researchers have observed that similar sensitivities to "photoperiods" (or time with light) impacts many animals, including birds, insects, and our pets. (Nautilus imposes a metered paywall.)

Pig brain cellular activity was restarted hours after death in study published in 2019

Yale University scientists restored basic cellular activity and circulatory function in pig brains about four hours after death with a synthetic cocktail of preservatives and nutrients. This work— which didn't restart electricity activity in the brain or consciousness—could help advance future human stroke and brain injury treatments.

Snake venoms are repurposed proteins responsible for other bodily functions

Just as saliva aids digestion in humans, proteins responsible for bioactivities such as digestion and blood clotting were eventually secreted in the glands and fangs of snakes across evolutionary history. Organisms that could not withstand the effects of these molecules (e.g., excessive bloodstream clotting) became ideal prey for snakes.

Learn about the Black Bear Sports Group—a hockey conglomerate changing the ice rink industry

Ice rinks are notoriously difficult to operate, due to the complex cooling systems required to maintain the ice itself, and have an average operating lifespan of 25 years. However, Black Bear Sports Group has made millions by buying up failing ice rinks and running robust youth sports programming.

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

Some animals may anchor their brain cells to specific landmarks to determine direction

In a study of bats exploring a new area, specific sets of "head direction cells" were seen becoming active based on bats' orientation when moving, and this activity became more coordinated over time. Researchers suspect, like humans, bats and other animals establish this sense of direction based on movement relative to known points of interest.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Kangaroos evolved exceptionally thick knee cartilage to absorb shock

There is significant conflict in the medical field regarding chronic arthritis. Some advocate for keeping the joint as active as possible while others argue progressive overuse leads to worsening arthritis. To settle the score, scientists have looked outside the human population, discovering kangaroos rarely suffer from arthritis in their knees.

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.

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.

Evolution doesn't want you to see these animals

Invisibility is an oft-coveted superpower that many creatures throughout the animal kingdom have evolved to mimic through transparent camouflage. This article explores the science of this seemingly magical ability. The two critical ingredients in...

Heart attacks are less harmful at night

When heart attacks occur during the day they typically do more harm to the heart tissue than if they occur at night. A 2025 study suggests that daytime heart attacks have higher levels of immune cells called neutrophils to contend with and they appear to worsen the injury. Scientists confirmed this same pattern in experiments with mice. (Some readers may experience a paywall.)

Genetic engineering mice is one idea to reduce Lyme disease transmission

Wild white-footed mice are the main carriers of Lyme. A research team is hoping to genetically engineer mice, using CRISPR, to make the animals immune to Lyme. They're proposing a field trial where they would insert a gene with an antibody to Lyme infection to break the disease transmission cycle on a private island and then try it in Nantucket if that goes well. Simply killing the mice isn't an option because it would upend food webs. Unlike traditional vaccines, this "heritable immunization" would pass from one generation of mice to the next.

The purpose of narwhal tusks has mystified researchers for centuries

Nicknamed the "unicorn of the sea," narwhals have no teeth aside from two canines that grow directly forward as tusks. For roughly 85% of females, they stay embedded in the bone. For males, they grow into large, spirally tusks that are full of nerve endings and blood vessels. Scientists today believe that tusks likely formed for sexual selection purposes and eventually evolved to assist in other processes, such as hunting.

The extremophilic origins of watermelon snow and its impact on glacial melting

Also known as "blood snow," the red coloration is produced by snow algae that thrive in extremely cold conditions and take the shape of red spherical cysts in winter. To protect themselves from more intense summer solar radiation, these psychrophiles accumulate red, orange, and yellow pigments, intensifying their coloration and causing glaciers to reflect less sunlight than if they were white.

Brain conditions and surgery can cause some individuals to feel no fear

Fear is a survival mechanism that originates in the brain's amygdala, triggering the body's fight-or-flight response. However, in modern society, without the same natural dangers, fear can lead to anxiety and mental health issues when unnecessarily triggered. Understanding individuals without fear may help identify new methods to treat anxiety disorders.

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

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

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

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

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

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

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

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

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

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.

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

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

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

The idea for the Federal Reserve was conceived in secret in 1910—with bankers donning duck hunt gear for disguise while traveling to a remote country club on Georgia's Jekyll Island

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

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.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Netflix profits when you're not watching, and its movies are designed that way—read a detail-rich critical essay exposing lesser-known Netflix takes

In 2009, the nation was gripped by the story of a missing young boy who was believed to be floating over Colorado in a homemade balloon, until it was revealed that he was at home the whole time.