Topic
Longevity
The science of extending healthy lifespan — the biology of aging, the interventions claimed to slow it, and the evidence that separates the two.
Longevity is where careful science and confident marketing collide most often. This hub collects our coverage of the biology of aging and the interventions — pharmacological, behavioral, and nutritional — that claim to influence it, with a consistent emphasis on what has actually been demonstrated in humans versus what remains hypothesis.
Publications on this topic
What Is Autophagy?
Autophagy is the cell's recycling system: it packages up worn-out and damaged parts, digests them in the lysosome, and returns the raw materials as building blocks and fuel. This explainer covers what it is, its three types, how Ohsumi's yeast work won a Nobel Prize, how nutrient sensors control it, why its failure is a hallmark of aging, and what the fasting, exercise, rapamycin, and spermidine evidence does — and does not — show in humans.
Lifespan vs Healthspan
Lifespan measures how long you live; healthspan measures how long you live in good health. This explainer defines both, quantifies the gap between them with population data, and explains why closing that gap — not simply adding years — is the goal.
Mitochondrial Dysfunction
Mitochondria make most of a cell's ATP, and their function declines with age — one of the recognized hallmarks of aging. This explainer covers what 'mitochondrial dysfunction' means, the mtDNA-mutation and free-radical mechanisms proposed for it (and how the free-radical theory has been substantially revised), mitochondria as signaling hubs linked to senescence and inflammation, the disease associations, and the honest human evidence for exercise, NAD+ precursors, and urolithin A.
What Is mTOR?
mTOR is the enzyme that decides whether a cell should build or maintain itself, and one of the central levers in the biology of ageing. This explainer covers what mTOR is, the two complexes it runs as, how reduced signalling extends lifespan in animals, why rapamycin lengthens the lives of mice, and why a proven human longevity effect does not yet exist.
Muscle Is a Metabolic Organ
Skeletal muscle does far more than move you: it absorbs most of the glucose in your blood after a meal, secretes hormone-like myokines, and serves as the body's amino-acid reserve. This explainer covers muscle's metabolic jobs, why losing it with age matters, what the GLP-1 lean-mass debate does and does not show, and which exercise evidence is strong enough to stand on.
Why We Age
Why does aging happen at all? This explainer separates the two great families of theory — stochastic damage (wear, mutation, free radicals, failing proteostasis) and evolutionary explanation (why selection permits aging once reproduction is done) — shows how they combine into a proximate 'how' and an ultimate 'why', and reviews the evidence that aging rates are not fixed.
What Is Cellular Senescence?
Cellular senescence is a stable state in which a stressed cell stops dividing, resists death, and secretes an inflammatory signal its neighbours can hear. This explainer covers what triggers it, how it is identified, why it protects early in life yet harms when senescent cells accumulate, and what clearing them with senolytics does — and does not yet — show in humans.
What Is Insulin Resistance?
Insulin resistance is a reduced response of the body's tissues to insulin. This explainer covers what it is, the ectopic-fat mechanism behind it, how it is measured, why it precedes diabetes by years, what it predicts, and what has been shown to improve it.
The Hallmarks of Aging
The hallmarks of aging are a proposed framework that organizes the biology of getting old into a small set of recurring processes — nine in the original 2013 paper, twelve after a 2023 update. This explainer covers what the hallmarks are, how they are grouped, what qualifies as a hallmark, the critiques of the framework, and why most of the hard causal evidence still comes from worms, flies, and mice rather than people.
What Is Longevity Science?
Longevity science studies healthspan — years lived in good health — and asks whether aging itself can be slowed. Its evidence is a ladder: strong for unglamorous lifestyle factors, weaker for the drugs that make headlines, and weakest of all for what supplements promise.
What Is Metabolic Health?
Metabolic health is not one test result but a cluster — how the body manages glucose, insulin, blood fats, blood pressure, and where it stores fat. This explainer covers what the cluster is, how it is measured, why it matters, and how much of it is modifiable.