Introduction: Aging Starts at the Cellular Level

What causes aging? Is it just the result of time passing, or does something deeper drive it?

In the field of comparative aging biology, scientists are uncovering that aging is not simply a matter of “wear and tear.” Instead, it’s governed by molecular and cellular mechanisms—and these mechanisms vary dramatically across animal species.

By comparing how different organisms age on a cellular level, researchers can identify the root causes of aging—and develop interventions to slow or even reverse it. Our animal biology research services are designed to help uncover these mechanisms in both model and non-model species.

The Molecular Hallmarks of Aging

Across species, several conserved biological processes are associated with aging:

1. DNA Damage Accumulation

Errors and breaks in DNA accumulate over time, leading to mutations and cellular dysfunction. Long-lived animals often show enhanced DNA repair capacity.

2. Telomere Shortening

Each cell division trims the protective telomere caps on chromosomes. In many species, telomerase activity delays aging by replenishing these caps — a mechanism active in zebrafish but limited in humans.

3. Oxidative Stress

Reactive oxygen species (ROS) damage proteins, lipids, and DNA. Animals with long lifespans (e.g., rockfish, bats) often show enhanced antioxidant defenses and mitochondrial efficiency.

4. Stem Cell Exhaustion

With age, regenerative capacity drops due to the decline in adult stem cell populations. Some animals like hydra and zebrafish can sustain regeneration for much longer.

5. Epigenetic Drift

Aging cells lose control over gene expression due to changes in DNA methylation and histone marks—a field rapidly advancing with cross-species epigenomic analysis.