Biological aging tests assess the breakdown of physiological systems

Doctors use three key physical markers to determine biological aging

The length of the ends of chromosomes (known as "telomeres"), the gradual change in collections of DNA molecules called "methyl groups", and the secretion of inflammatory proteins are all used as indicators of biological age.

Epigenetic clock: DNA alterations on cells that predict biological age

Epigenetics refers to a biological process that controls whether certain genes are expressed or not. With a rising interest in the concept of biological age, researchers have discovered a cellular change known as DNA methylation that leaves a fingerprint on our genome as we age.

Chronological versus biological age

Science has come to understand different types of aging. What we call age is simply the number of years since birth, or chronological age. At the cellular level, biological aging happens at different rates for different people, and explains why some seem to age more quickly (or slowly).

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.

Aging results from the cumulative breakdown of cellular and tissue processes

A cumulative breakdown of cellular and tissue processes combines to result in decreased organ function, disrupting the systems driving normal human physiology. This five-minute video provides a primer on the subject, complete with a discussion of risk factors, cellular changes, and potential future treatments in the fight against aging.

DNA damage and chemical stress causes cellular aging

While outward signs of aging, like gray hair and wrinkles, are easy to spot, aging changes at the cellular level are less obvious. The decline within cells stems from numerous sources, including DNA damage, oxidative stress, and accumulated waste.

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.

Genetics play a role in the reliability of the body's biological clocks

Growing evidence suggests genetics influence when, how long, and how well one sleeps, meaning insomnia may have a genetic component. While exact insomnia biomarkers have yet to be determined, some genes, including those related to psychiatric disorders, have been implicated.

The Dog Aging Project uses information from over 50,000 dogs to explore longevity

The study gathers health, lifestyle, and genetic data to understand what helps dogs live longer, healthier lives. Findings could also provide human health insights due to our shared surroundings and biology.

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.

Polygenic scores aim to predict traits based on the contributions of many genes

These novel tests for multifactorial conditions evaluate the probability of traits like elevated blood pressure, diabetes, or high cholesterol based on what researchers currently know about different gene variants and their links to various traits. The tests are predictive, not definitive, partly because environmental factors influence the expression of genes. What's more, knowledge about cumulative effects from individual genes continues to evolve. The American Society for Reproductive Medicine states that these tests are too unreliable and nascent for clinical use.

Most things you would get tested for at the doctor’s office are influenced by circadian rhythm

In this video, a Salk Institute Researcher offers daily habit tips focused on aligning with your circadian rhythms. She notes heart rate and blood pressure are highest in the afternoon, for example, and there’s a triglyceride peak in the morning. Generally, she says, it’s a good idea to schedule your doctor’s checkups at the same time of day each year so there’s consistency across your data.

Ancestry testing matches DNA to known genetic variants found in specific ancestries

After a lab receives a person's sample, the DNA is separated into single strands, which are chemically cut into smaller fragments. The fragments are then fed into an array of variants of known origins, and technicians observe if a person's fragments bind to specific variants.

Single-cell organisms have circadian clocks that direct daily biochemical routines

Cyanobacteria, a type of light-sensitive bacteria, use this clock to signal when to alternate between making organic compounds through photosynthesis and when to convert atmospheric nitrogen into usable ammonia. Upregulating photosynthetic machinery before dawn helps ensure efficient photosynthesis.

How atomic clocks have been used to measure the universe's fundamental constants

Atoms behave according to a set of parameters that scientists have determined give reality its properties. For example, the fine-structure constant, α, quantifies the strength of interactions between charged particles. Since the light emitted by atoms as they move between energy levels is affected by α, analyzing these emissions—the basis of atomic clocks—using different atoms helps calculate α.

Despite privacy risks, scientists are using DNA in the air to assess ecosystem health

While DNA in soil and water samples has long been used for such analyses, airborne DNA is being incorporated into such efforts to monitor individual species abundance, detect invasive species, measure biodiversity, and determine the success of conservation actions. Future work may include detecting attacks from biological weapons.

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

Model organisms like yeast, mice, and flies help scientists decode the human body

Some species are used to quickly study the effects of human diseases and treatments because they are short-lived and have similar systems to those found in humans. Bacteria, like E. coli, have been used as human proxies given their rapid growth and ease of genetic manipulability.

There's no definitive test for inflammation, or a baseline for what's considered normal

Existing tests can pick up proteins that indicate an immune response—in particular C-reactive protein, which the liver produces when the body's stressed—but that won't tell you why there's inflammation nor if it's chronic or acute inflammation. (Some users may experience a paywall.)

Pregnancy at older ages increases the chances of fetal abnormalities

Chromosomal irregularities are more likely at older maternal ages so genetic testing for a fetus of mothers-to-be at age 35 and older is often recommended. Conditions that can be screened for in utero include cystic fibrosis, Tay-Sachs disease, sickle cell disease, Down syndrome, spina bifida, Duchenne muscular dystrophy, and more.

Learn the differences between mild cognitive impairment and age-associated memory loss

Mild cognitive impairment is a condition in which people experience more thinking and memory problems than expected for their age. It's often associated with depression and anxiety. Daily routines, writing things down, and healthy lifestyle choices can help cope with the condition, but there's no cure. The condition elevates the risk of developing dementia and Alzheimer's.

Take a 360-degree look at biochemical activity from within a human cell

In this tour, users can observe the dynamic processes that occur within the basic units of the human body, including the production and transport of proteins and the assembly and disassembly of microtubules—thin, cylindrical structures that provide structural support and a means of moving material within the cell.

What is biohacking? An overview

Biohacking is a broad collection of self-improvement techniques meant to enhance a human's health, lifespan, or ability. There are basic biohacks, like the use of caffeine, and more extreme ones, like under-the-skin implants. The difference between biohacking and standard medicine is that biohacking is primarily a do-it-yourself approach and is mostly unregulated.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

ConsumerLab is a watchdog site reviewing supplements for quality and recalls

The group purchases supplements and tests them for accuracy. When it tested 26 popular B vitamin supplements, it found five failed their tests because they provide either significantly less or much more of the ingredients than listed. This type of product-label mismatch can occur because the FDA does not regulate these products as it would a drug.

Using fitness wearables to track muscle wasting in astronauts

All that exercising, and astronauts still are likely to lose a large amount of muscle mass while in microgravity. Astronauts can lose up to 20 percent of their muscle in as little as five days in space. Currently, tracking muscle loss means waiting until astronauts land to remeasure their muscle density post-trip. This article explains a NASA-backed fitness wearable that may be able to track muscle atrophy as it happens.

Mortality tables help determine the probability of death for specific populations

A mortality table is a diagram that helps predict a specific population’s likelihood of death within a particular time period. Life insurance companies often use them to help figure out pricing for their insurance products. They’re sometimes known as actuarial tables or life tables.

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

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

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

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.

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

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

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

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

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

A century of Billboard issues documenting the evolution of popular music.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

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

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

Frank Lloyd Wright's houses are historically hard to sell because they're old, subject to local landmark commissions, and often unfashionable