The hallmarks of aging

The biology of aging, in twelve parts

Aging is not one thing. Scientists split it into connected processes called the hallmarks of aging: twelve from the field's 2023 review, plus one candidate we track. Tap a tile to see what each one is and whether it can be measured.

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Where the damage starts

DNA damage builds up

DNA is damaged every day. Repair slows with age, so mutations pile up.

Measurable todayMostly research, some specialist tests

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Where the damage starts

Chromosome tips wear down

The protective tips of your chromosomes shorten each time a cell divides.

Measurable todayTests sold, results vary a lot

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Where the damage starts

Gene settings drift

The chemical tags that switch genes on and off drift with age, and cells work less well.

Measurable todayClock tests sold, meaning still unproven

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Where the damage starts

Protein upkeep falls behind

Cells fold, fix, and clear out proteins. With age this slips, and damaged proteins clump.

Measurable todayNo routine test yet

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Where the damage starts

Cell recycling slows

Cells recycle their worn-out parts. With age this slows, and junk builds up.

Measurable todayNo routine test yet

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The body's responses

Growth signals stay on

Cells sense food and choose growth or repair. Always fed, they get stuck on growth.

Measurable todayCommon blood tests, indirectly

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The body's responses

Cell energy fades

Mitochondria make your cells' energy. With age they make less and leak more harmful byproducts.

Measurable todayFitness tests, indirectly

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The body's responses

Damaged cells linger

Damaged cells stop dividing but do not die, and their signals inflame nearby tissue.

Measurable todayNo reliable test yet

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Whole-body effects

Repair cells run low

The cells that replace worn-out tissue get fewer and work less well with age.

Measurable todayResearch labs only

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Whole-body effects

Cell messages get distorted

Hormone and immune signals between cells get distorted and tilt toward inflammation.

Measurable todaySome blood tests, indirectly

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Whole-body effects

Inflammation that won't stop

Low, constant inflammation with no infection behind it. It feeds other aging drivers.

Measurable todayCommon blood test, partial picture

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Whole-body effects

Gut microbes lose balance

Gut microbes lose variety with age, a shift linked to inflammation and metabolism.

Measurable todayConsumer tests unreliable so far

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A candidate we track

The thymus shrinks

The thymus trains immune cells. It shrinks from puberty on, so fewer new ones are made.

Measurable todaySpecialist tests, mostly research

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Plus one candidate

The thymus is not on the 2023 list. We track it because evidence that it shapes how the immune system ages keeps growing, and we label it a candidate wherever it appears.

The Longevity Intelligence Report

See how your own routine lines up

Enter what you take and do: supplements, medications, exercise, sleep. The report maps each item to these hallmarks and grades the human evidence behind it, so you can see what your routine covers, where items overlap, and which parts of aging nothing touches. Early access opens in December.

Get early access

New research

Three new studies worth knowing

Picked for how much they move the biology of aging forward, and written in plain words. Research checked October 1, 2026.

DNA damage

Eating less slowed the buildup of DNA mutations in mice

Mice · Cell · September 9, 2026

What they foundMice on a calorie-restricted diet built up fewer DNA mutations in liver, kidney, and brain cells than normally fed mice, counted with a very accurate DNA-reading method.

What it does not showMice only. It does not show the mice lived longer because of it, or that people would respond the same way.

Why it mattersMutations piling up in body cells is one of the most upstream drivers of aging. This shows the pace can change, at least in mice.

Read the study on PubMed ↗
Caloric restriction modulates genome-wide somatic mutation in mice.

Nutrient sensing

A GLP-1 drug started late in life extended lifespan in female mice

Mice · Nature · September 2, 2026

What they foundOld female mice given semaglutide did better on physical, memory, and blood-sugar tests. Mice kept on it had a median lifespan about 12 percent longer, with many changes resembling calorie restriction.

What it does not showFemale mice only. It does not show the drug slows aging in people.

Why it mattersIt is a lifespan result for a drug millions of people already take, tied to the same nutrient-sensing systems calorie restriction works through.

Read the study on PubMed ↗
Late-life semaglutide treatment slows ageing and extends lifespan in female mice.

Epigenetic drift

Which aging clocks actually move when people change something

People, 51 intervention studies pooled · Nature Medicine · August 21, 2026

What they foundResearchers ran 16 well-known epigenetic aging clocks on data from 51 human intervention studies. Clocks built to predict death risk or the pace of aging responded most consistently.

What it does not showA clock moving is not proof that anyone will live longer. These clocks are still being tested as stand-ins for real health outcomes.

Why it mattersClock tests are sold to consumers today. This helps show which clocks can tell whether an intervention is working.

Read the study on PubMed ↗
Responsiveness of epigenetic aging biomarkers to longevity interventions in humans.

Follow the science

Follow the hallmarks you care about

Pick the ones you want to follow. Starting in December, we'll email you every two weeks when new studies or new tests come out on them. Longevity Intelligence Report members also get the plain-English read on each one: why it matters, and whether it should change what you're doing.

How the evidence gets graded, and where the grades stop: the methodology.