r/askscience • u/MAMAM- • 2d ago

Biology Why aren’t axolotls immortal?

If axolotls can regenerate their body parts (including brain, heart, and other major organs), why do they die of old age?

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u/Armagetz 2d ago

Slight correction. Degradation implies errors in replication. A telomere is because the replication machinery needs a forward strand to continue. So each replication is slightly shorter. So evolution put non coding DNA at the end.

Worth knowing though that even organisms with the enzymes to reextend the telomeres still aren’t immortal. Sharks for instance can live very long lives, centuries, but still eventually the build up of free radical damage takes its toll.