What determines maximum animal lifespan?

Lifespan varies enormously across species — from days for mayflies to centuries for bowhead whales and clams. The molecular determinants of this variation are only partly understood.

Candidate mechanisms include telomere maintenance, DNA-repair fidelity, mitochondrial physiology, and the activity of pathways such as mTOR and IGF-1. Whether human lifespan has a hard biological ceiling is debated.