Why hibernating bears don't get blood clots

Bears have evolved natural mechanisms to avoid blood clots while hibernating

Movement is essential to keeping blood from clotting, which raises the question of why animals such as hibernating bears don't suffer from clots despite going months lying still. New research suggesting that the animals may have evolved to have lower concentrations of a specific protein may explain this phenomenon.

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.

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.

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.

Tardigrades can survive in a dehydrated state for decades

Despite being known as water bears, these microscopic creatures can shut down their metabolism when entering cryptobiosis, squeezing more than 95% of the water from their bodies. In this tun state, tardigrades can even survive the vacuum of space.

Why don't giraffes get hypertension?

The average blood pressure of a giraffe is about double that of a human, yet they don't suffer from the symptoms of high blood pressure that humans do: stiffening of the left heart ventricle, shortness of breath, fatigue, or swollen legs and ankles. This article explains how giraffes have evolved to have the "biological equivalent of support stockings."

See how the Ebola virus affects blood circulation in the human body

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

Watch an expert's take on the rare disease hantavirus—and why it's not of great concern to the general population

This rare zoonotic disease, transmitted to humans primarily through infected rodent droppings, urine, or saliva, is rarely spread between people. The disease was of particular concern in spring 2026, when an outbreak occurred on a 150-person cruise ship, prompting a flurry of action, including contact tracing for passengers in their home countries. The disease can be fatal. But early care—primarily oxygen support—can help patients survive.

The strange endurance of consuming blood for health

Blood's importance to humanity is best summarized this way: without it, we die. This importance naturally begets assumptions about its medicinal properties, many of which appear accessible through drinking or eating the fluid connective tissue. This article details the history of blood drinking, from ancient Roman gladiators to modern-day sanguinarians.

Reduced inflammation from cold plunges lacks scientific support

The cold water triggers immediate cold shock, increasing heart rate and blood pressure, and prolonged exposure can lead to cold-water incapacitation and hypothermia. Plungers are encouraged to enter the water slowly and manage their breathing to reduce the risk of shock. Warm baths post-plunge are discouraged, and exercise is generally better for recovery.

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.

Some animals seem to live well on little sleep

African bush elephants typically sleep for about 2 hours per 24-hour day, coming in well under a human's recommended seven-hour minimum. Other animals also appear to skimp on sleep, by human standards, without the consequences humans associate with being sleep deprived. This academic article details the sleeping habits of animals that appear to thrive on fewer than 40 winks and explores whether their sleep processes are just built different.

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.

Deer don't get infected with Lyme disease—but ticks do feed on them

Adult ticks feed on white-tailed deer and also lay eggs on the animals, but the deer don't get sick with Lyme disease. Research published in 2023 offered new insights into why deer don't get sick from Lyme disease: It appears that the quadruped may have specific not-yet-identified immune system proteins in their blood serum that kill the bacterium.

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

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.

Continual sitting harms your health in a variety of ways

Prolonged inactivity, like sitting for long periods, slows metabolism, weakens muscles and bones, and impairs insulin function. When these negative changes persist over time, the cumulative result is an increased risk of cardiovascular disease, diabetes, and many cancers.

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.

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.

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.

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.)

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

Less than 1% of aging studies consider menopause and its effects

Nearly all studies researching the biology of aging don't consider menopause in their setup, in part because menopause is difficult to emulate in animal models. Menopause is uncommon in the animal world beyond humans and whales. This presents a problem for medicine and science because about 75% of aging-related diseases are likely influenced by menopause.

Extreme heat is neurologically impairing animals

Dog bites increase in summer, birds struggle to learn, and goats pick more fights. Scientists are unraveling new details about how heat impairs animals' neurological systems.

See a wild bear observe fellow bears at the zoo

At the Sequoia Park Zoo in California, a wild bear visited the bear enclosure to see three bears in captivity. Zookeepers referred to him as a "polite visitor," adding, "He stayed on the boardwalk path, kept two feet on the ground, and didn't try to climb over the railings!"

What exactly are hiccups?

If you don’t know a surefire cure for hiccups, it’s not really a surprise—while there are some known facts about this funny affliction, a surprising amount remains a mystery. Doctors believe that a round of hiccups usually either comes from...

Explaining the icy mystery of the Dyatlov Pass deaths

A decades-old mystery from Soviet Russia could be explained by studying the science of snow. After nine students died on a hiking trip in the Ural Mountains, Soviet investigators found six had perished from hypothermia while three others died from blunt force trauma. The mystery confounded officials for years, and rumors of yeti attacks and similar theories abounded until researchers proposed a new potential culprit: an avalanche.

Stuffy nose congestion occurs because of swelling of the inferior turbinates

These structures in the nose above the nose hairs swell and shrink constantly and are affected by head position. They can fill with blood during illness, causing the feeling of congestion, but also when a person changes position, especially when lying down. Medications can be used to shrink them, providing temporary relief.

Explaining why animals don't cross this invisible line in Indonesia

Although the distance separating the two regions is small, East and West Indonesia have starkly different species, puzzling scientists for decades. Biogeographers use the theory of plate tectonics to explain the phenomenon, arguing the two regions...

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

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

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

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.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

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

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

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.

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.

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.

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

Despite being favored by 87% of Americans, Congress does not have term limits.

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

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

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

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

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

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