Aging & Longevity

What Determines Human Lifespan?

Human lifespan reflects both intrinsic biology and extrinsic risks. Genetics matters, but environment, disease, and public health shape how longevity plays out in real populations.

3 min read

Intro

Human lifespan is shaped by two broad forces:

  • Intrinsic biology (the aging process and inherited risk)
  • Extrinsic risk (infection, trauma, environment, and social conditions)

Understanding lifespan means understanding how these forces interact across a lifetime.

Key Points

  • Lifespan is not “genes vs lifestyle” — it’s biology plus exposure and risk.
  • Public health primarily extends lifespan by reducing extrinsic mortality.
  • As extrinsic mortality falls, intrinsic aging becomes more visible.
  • Healthspan is often the more actionable target. (See: [/guides/healthspan-vs-lifespan])

The Big Determinants

1) Early-life conditions

Nutrition, infection burden, stress, and access to care in childhood can influence lifelong risk.

2) Cardiometabolic risk

Blood pressure, glucose, smoking, obesity, and lipids strongly influence survival.

3) Socioeconomic conditions

Income, education, housing, and access to care shape exposure to risk and chronic disease management.

4) Genetics

Genetics can influence risk pathways (lipids, inflammation, dementia risk, etc.). Effects often become more noticeable at older ages.

5) Intrinsic vs extrinsic mortality

See: [/guides/intrinsic-vs-extrinsic-mortality]

FAQ

Q: If lifespan is partly genetic, can you “outrun” your genes?
A: Often you can reduce risk substantially by changing exposures and managing modifiable risk factors.

Further Reading

  • WHO: life expectancy and healthy life expectancy resources
  • PubMed: “lifespan heritability” review papers
  • [/guides/intrinsic-vs-extrinsic-mortality]
  • [/guides/healthspan-vs-lifespan]
  • [/guides/biological-age-vs-chronological-age]