Live·Open questions in longevity research
Research perspectives

Research directions

Evolutionary biology of ageing

Ask why some species live so much longer than others. Compare long-lived species, their environments and the evolution of ageing mechanisms.

A carved branching tree ending in a bat, rodent and tortoise, printed in green and ochre.
Conceptual illustration

Who lives how long, and why

Animal lifespans range from a few hours to five centuries. Species that rarely die from predators and accidents tend to evolve bodies that last longer.

  1. Engraved plate of an adult mayfly above water, with its nymph on a river stone below

    Mayfly

    Ephemeroptera

    Hours to daysadult stage; the larva lives in water for many months

    The adult cannot feed: its mouthparts are reduced or absent. It lives on reserves stored by the larva and spends them on reproduction.

  2. Engraved plate of a house mouse beside scattered grains and an owl feather

    House mouse

    Mus musculus

    4 yearsrecord in the laboratory

    A small animal in the open has many predators. Selection favours breeding early and fast; investment in long-term repair pays off poorly.

  3. Engraved plate of a naked mole-rat walking through an underground burrow

    Naked mole-rat

    Heterocephalus glaber

    37 yearsreported record in captivity

    It lives in underground colonies, sheltered from predators. Its risk of dying stays flat even at ages 25 times beyond sexual maturity.

  4. Engraved plate of Brandt's bat in flight beneath a cave ceiling

    Brandt's bat

    Myotis brandtii

    41 yearsbanded male in the wild

    It weighs about 7 grams. Flight lets it escape most predators, and selection has favoured a body built to last.

  5. Engraved plate of a giant tortoise with a domed shell on island grass

    Galápagos giant tortoise

    Chelonoidis niger

    177 yearsrecord in captivity

    Its shell protects it from predators. In a study of 52 turtle and tortoise species, about three quarters aged slowly or negligibly.

  6. Engraved plate of a bowhead whale swimming beneath Arctic sea ice

    Bowhead whale

    Balaena mysticetus

    211 yearsage estimate for a wild whale

    Its cells repair DNA breaks more accurately than other mammals' cells and accumulate fewer mutations.

  7. Engraved plate of a Greenland shark gliding through cold water

    Greenland shark

    Somniosus microcephalus

    About 400 years392 ± 120 years, radiocarbon estimate for the largest female

    It grows no more than a centimetre a year and reaches sexual maturity at about 156 years.

  8. Engraved plate of an ocean quahog shell with dense growth lines, beside a cut shell

    Ocean quahog

    Arctica islandica

    507 yearsthe clam Ming from the North Atlantic

    It shows almost no signs of ageing, and its proteins are unusually stable.

  9. Engraved plate of a hydra polyp with extended tentacles and a budding daughter polyp

    Hydra

    Hydra

    No ageing detectedby projection, 5% of laboratory hydras would still be alive after 494-3,376 years

    Stem cells divide constantly and keep renewing its tissues. In the laboratory its risk of death stays the same at any age.

Lifespan on a logarithmic scale from one day to a thousand yearsHuman record, 122 yearsNo age limit detected

Questions for comparisons between species

  1. Long-lived species. Which features of tissue repair and cell protection distinguish naked mole-rats, bats and other long-lived animals from shorter-lived relatives?

  2. Selection and age. How do reproductive timing and external causes of death alter selection on traits expressed late in life?

  3. Evolution of ageing. Which observations distinguish late-acting mutation accumulation, early benefits with late costs, and hypotheses of adaptive ageing?

Why species differ in lifespan

Why do some species live for a few years while others live for decades or centuries? Comparative biology describes these differences and identifies traits of long-lived species. Evolutionary biology asks how selection shaped them. Explanations concern reproduction, bodily maintenance, external hazards and the effects of inherited changes at different ages.

What to investigate

  1. Compare related species while accounting for ancestry, ecology and the age at reproduction.

  2. Measure the early benefits and late costs of the same genetic or physiological change.

  3. Test how protection from external hazards and different reproductive schedules alter selection on longevity.

Evidence to build on

Cagan and colleagues compared somatic mutations in intestinal crypts across 16 mammalian species. Annual mutation rates were strongly inversely related to species lifespan. The observation offers a comparative constraint for theories linking investment in genome maintenance with longevity.

What remains unresolved

A cross-species association leaves causality open. Evolutionary explanations address why a trait was shaped by selection; identifying a useful therapeutic target also requires a physiological mechanism and an intervention test.

The next useful experiment

Compare a maintenance mechanism in closely related species with different lifespans, then test the predicted early-life and late-life consequences of altering it.

Proposed experiments

The wider strategy

The presentation distinguishes evolutionary causes from cellular mechanisms and clinical interventions. Keeping these levels explicit makes their predictions easier to connect.

The Death-Fighting Spectrum presentation

Related work on Eternal Search