As an animal grows, it adds more cells—and each cell has some baseline chance of turning cancerous. That means larger organisms with more cells should, in theory, be more likely to develop cancer.
Elephants and other large animals face a trade‑off: being big and long‑lived comes with higher risk if each cell has a fixed chance of becoming malignant. Yet elephants seem to have partially overcome this problem.
> Peto's Paradox: The observation that species with vastly more cells (like elephants or whales) do not have correspondingly higher cancer rates - wikipedia 
So why do elephants live as long as they do with so little cancer? That question is fascinating—and it’s the one we’ll explore.
# Elephants’ cancer resistance:
- African elephants have an estimated tumor‑related mortality rate of about **4–5 %**, compared to around **11–25 %** in humans - utah.edu
- A major finding is that elephants possess **many extra copies of the tumor‑suppressor gene TP53** (which encodes the p53 protein). Humans have just **one TP53 gene** (two alleles), while elephants have **around 20 copies**, meaning up to **40 alleles** in total - scientificamerican
- These extra TP53 variants produce multiple p53 protein versions. Some of these variants **evade inactivation** by the regulatory protein MDM2, making damaged cells more likely to be eliminated via **apoptosis** rather than repaired or left to mutate further - ox.ac.uk
- In lab experiments, elephant cells exposed to DNA‑damaging agents initiate cell death much more readily than human cells—about **twice the rate** compared to normal human cells and **five times that** of cells from individuals with familial TP53‑deficiency syndromes (Li‑Fraumeni) - utah.edu
- Additionally, elephants have extra copies of other anti‑cancer genes, including **LIF6**, which induces programmed cell death under DNA damage (“zombie gene”) - science.org
# Beyond TP53 – Other contributing factors: - Many large, long‑lived animals (such as bowhead whales) rely on different mechanisms—enhanced **DNA repair**, slowed **cell division**, or larger **cell size**, which reduces division frequency and oxidative damage per unit mass.
- In particular, some of these species show **superior DNA repair capacity**, especially for double-strand breaks, supporting cancer resistance in whales - thetimes.co.uk
# Why elephants live as long as they do? Because evolution selected genetic adaptations—chiefly the **TP53 amplification** and robust apoptosis responses—elephants can safely carry far more cells over a long lifespan without a corresponding rise in cancer incidence. Their cancer rate remains under **5%**, even though they have about **100 times more cells** than humans and live similarly long lives. These adaptations mitigate the per-cell mutation risk that would otherwise doom large, long-lived animals.