Bears may have evolved natural mechanisms to prevent blood clots during hibernation, an important development, since inactivity typically leads to blood clots in other animals.

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...

Over 200 known species hibernate, allowing them to lie dormant and survive harsh periods when water and food become scarce, such as frigid winter months or scorching summer periods.

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.

Polar bears have black skin to better absorb warmth from the sun, but their transparent, hollow hairs scatter and reflect light so that they appear white.

Blood has evolved many times over hundreds of millions of years, resulting in different blood colors and compositions—and there are even some organisms that don't need blood at all.

To survive underwater hibernation, some freshwater turtles perform cloacal breathing—blood vessels absorb dissolved oxygen from water drawn into the organism's cloaca, or rear orifice.

Fish in polar waters contain proteins in their blood that act as antifreeze, and some manufacturers have used lab-grown versions of these proteins to help keep ice cream smooth.

Tardigrades’ intrinsically disordered proteins may help preserve biological matter

Researchers have attempted to create more drought-resistant crops by introducing proteins that help protect tardigrades in their dehydrated tun state. The proteins’ ability to stabilize molecular degradation may allow scientists to develop refrigeration-free storage for vaccines, insulin, and blood.

Studying the circadian clock of a tiny swimming polar creature may help forecast polar ecosystem health

A 2025 study found that Antarctic krill, a food chain staple in the Southern Ocean, have an internal biological clock that helps regulate its swimming patterns and helps the tiny shrimp-like animals adapt to daily and seasonal environmental changes. Better understanding of how the clock and light cues interact may help scientists understand how well the species will respond to pronounced climate change in the polar region.

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

Can humans delay or reverse old age?

We're not sure yet. Researchers at the University of California San Francisco are studying why some conditions and behaviors, such as low-oxygen environments and exercise, benefit the aging process, hoping to reveal potential health applications. Some of this research focuses on klotho, a naturally occurring age-regulating hormone named after the Greek Fate Clotho. Animal studies on klotho brain injections found subjects had improved memory recall and age-related degeneration resistance.

The US military, concerned about potential deployments worldwide, has long funded experimental hantavirus vaccines and therapies.

Collaborations between the military, biotech, and academic researchers led to an experimental antibody treatment for the Andes hantavirus strain—the one that more readily passes between humans. As of spring 2026, it had only been tested in animals. The US Army has also tested a potential hantavirus vaccine in people. It published early findings in 2023 that seemed promising, eliciting some immune system response. (Some users may encounter a paywall.)

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.

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.

Cold-blooded reptiles seek heat, and that behavior may help combat fungal infections

This Radiolab podcast episode takes on the idea that though our human bodies are too warm for the majority of fungal species to effectively replicate inside our bodies, that's not the case for reptiles. Yet when those species warm their bodies by basking in the sun on rocks, they can soak up heat and may also help keep fungal infections in check.

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.

Skull bone marrow may be playing a key role in chronic pain.

Polar bears find refuge in an abandoned Russian village

Russia's Wrangel Island hosts one of the world’s largest seasonal gatherings of polar bears. Hundreds of females come ashore to den and raise cubs, often entering abandoned homes for protection. See videos and pictures of the endangered species mingling on the island.

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.

Studies suggest when you sleep is as important as how much you get.

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.

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.

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.

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.)

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.

Lack of sunlight during Arctic winters can fuel a winter slump and a circadian disconnect.

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.

Supplements ahead of exertional heatstroke helped protect mice against brain damage

In the lab, mice dosed with probiotics prior to inducing exertional heatstroke, had better cognitive outcomes. This evidence underscores the links between the gut microbiome and the brain, at least in rodents.

Poor sleep increases the risk of developing Alzheimer's, and a main reason appears to be that the brain disposes of toxic protein buildup during high-quality sleep.

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.

How sea ice decline threatens polar bears

This two-minute video discusses a recent study warning that arctic polar bears are at risk of near-extinction by the end of the century due to the rapid melting of the sea ice they rely on for survival. The study used models based on satellite data...

A 'buffy coat' is the roughly 1% of blood that includes multiple types of white blood cells and plays a key role in fighting off disease.

Genetic blood test offers an estimated clock on when Alzheimer's symptoms may appear

The 2026 research finding from researchers at Washington University School of Medicine in St. Louis—if validated in broader populations—suggests that an already available blood test could estimate when Alzheimer's symptoms may begin within a margin of several years. The test detects a protein called p-tau217 found in blood plasma and the researchers incorporated the findings from that blood test into a statistical model to come up with the symptom timeline predictions.

Large animals like giraffes and elephants have evolved unique cancer defenses.

Rodent research suggests goose bumps may play a role in hair growth—raising questions about if this knowledge could be used to reactive sympathetic nerves in hair follicles to boost hair growth in people.

Relax to a livestream of brown bears chilling in Katmai National Park in Alaska.

The economics of horseshoe crab blood

Horseshoe crabs are older than dinosaurs and have survived five mass extinctions that wiped most life from the planet. But it's only now that their future as a species is in danger. This blood, worth about $60,000 per gallon, is hyper-sensitized to certain bacteria that are fatal to humans. This 17-minute podcast dives into humanity's pursuit of horseshoe crab blood, a "somewhat magical" mixture heavily relied on by the pharmaceutical industry.

In 2026, University of Cambridge researchers reported that a group of gut bacteria called CAG-170 may be a key marker of good health, occurring far more often in healthy individuals and less commonly in people with chronic diseases.

Scientists may have discovered why gene-edited pig kidneys are rejected in humans

In November 2025, researchers studying how a brain-dead donor’s body responded to the transplantation of a genetically engineered pig kidney, published that they’ve identified immune system reactions that may explain why these pig organs get rejected. What’s more, they were able to reverse the rejections with an already available drug combination and the kidney functioned well. They also pinpointed a way to detect a potential rejection up to five days sooner.

Blood color differs across the animal kingdom, with some animals producing blood that appears green (a group of lizards in New Guinea) or blue (horseshoe crabs).

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.

As immobile animals, corals and the organisms that live on them have evolved a suite of chemical compounds to prevent disease and ward off predators they cannot outrun.

Early peptide research focused on isolating the substances from animal tissue

In the first half of the 20th century, peptides including insulin and adrenocorticotropic hormone were isolated from animals to provide life-saving medicines. ACTH was isolated from the pituitary glands of cows and pigs and insulin was isolated from the pancreas of dogs and cows.

Herd behavior has been seen in 193-million-year-old dinosaur fossils

Scientists excavated eggs, juveniles, and adult remains in Patagonia, all arranged by age group. The organization into structured groups may have contributed to evolutionary success by consolidating eggs in one location to make defending them easier.

One Canadian town operates a polar bear jail

The town of Churchill has a population of 850 humans and just as many polar bears. In an effort to prevent hungry bears from breaking into homes or attacking residents, the town began imprisoning them for 30-day stints.

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.

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.

To prevent floating away from others while sleeping, sea otters may wrap themselves in kelp or hold paws, using physical contact to form groups known as 'rafts.'

From glands beneath their skin, hippos produce their own sunscreen in the form of a fluid containing hipposudoric and norhipposudoric acids, which absorb sunlight in the ultraviolet and visible range.