Cell lines can be immortal. Why aren’t bodies?

[Hook with striking examples] How can individual cells be immortal?

[Establish contrast with multicellular mortality] Why do multicellular organisms age and die?

[Pose the core evolutionary puzzle] Why do multicellular organisms suppress cellular immortality?

[Pose provocative question that hits reader in gut] Are immortalized cells always parasitic?

[Challenge reader’s assumptions about evolutionary design] Why design easily accessible dormant immortality?

[Set up the central thesis question] What makes cellular immortality incompatible with cooperation?

Peto’s paradox: cancer incidence vs body size

Larger species evolved stronger anti‑cancer surveillance despite more cells.

[Establish mathematical prediction] Why should big animals be impossible?

[Reveal the paradoxical reality] But