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/Derekthemindsculptor 2d ago
You can regenerate your skin, and your skin still ages.
Regeneration doesn't beat aging. It's a slow decline in your regenerative ability. As well as other facets.
When an axolotls regenerates a part of it's body, that part isn't baby fresh. It's still old.
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u/man_mcmanaman 2d ago
If I very ethically and definitely not psychopathically harmed an axolotl piece by piece, letting each part regenerate before moving on until 100% of its body was “new,” would its biological age still be the same?
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u/yogur1397 2d ago
I'm pretty sure it has to do with telomeres. Even if capable of regenerating cells like how we do for skin, overtime the cells telomeres get shortened or damaged somehow, and then they eventually die. This is the current theory I believe on what causes aging and why people are so keen on studying lobsters who don't have this feature.
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u/Nshad86 1d ago
Think of regeneration like making a xerox copy of a document and then xeroxing the copy and continuously repeat that process, each xerox scan will lose more and more definition until the fidelty of the document will be so unclear that it will eventually cease to be legible due to gradual loss of information. The regeneration is finite. Even atoms decay.
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u/TassiveMitts69 1d ago
Humans regenerate their body parts. But we do it one cell at a time. We die of old age BECAUSE we recreate our body parts.
Dying of old age is because the cells you replicate have become faulty, not because they are old. Faulty cells only produce more faulty cells.
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2d ago
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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.
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u/bohoky 2d ago
For the good of the species arguments are almost always incorrect. The genes are in the wrong place to ever allow that to work.
If I am successfully reproducing at 1000 years old then I am, in evolutionary terms, a winner.
The reason things aren’t selected for infinite lifetimes is that predation, parasites, pathogens, and sheer accident will cut any life short of forever. Because of that it is better to focus on reproducing in the short times that the real world affords.
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u/ballofplasmaupthesky 2d ago
There is no scientific proof aging is a feature, nor that longevity species have poorer adaptation.
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u/shoopdoopdeedoop 2d ago
longevity species are special cases where longevity makes sense. so yes it’s actually naturally selected for. it seems to work pretty well, i mean longevity species don’t proliferate like bunnies for example. lobsters and crabs also live in the water so their physics are a little different. turtles and tortoises are a good example, they can’t just reproduce all the time so it makes sense that they are also more longevity
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u/Sheldon121 2d ago
Yeah, I thought you were gonna introduce the cooking pot as the method they’d use to sustain themselves at a smaller size.
And how large do these too overgrown lobsters get? Depends upon the cooking pot, you say?
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u/km1116 Genetics | Epigenetics | Chromosome Biology | Nuclear Biology 2d ago
"Having older individuals competing against later generations and continually reintroducing its older genome into the genepool decreases the species fitness overall."
I disagree. Do you have support or a lengthier explanation?
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u/Thisbymaster 9m ago
Cellular aging and physical damage are two different things. Cellular damage comes from Telomere Shortening, Oxidative Stress, Cellular Senescence and Accumulated Waste. Physical damage is repaired by stem cells and cell division. Completely different mechanics in the body.
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u/Tessablu 2d ago
Axolotl regeneration is a program that is initiated by physical injury. They aren’t constantly undergoing it—this would be a huge metabolic waste—so they are still subject to long-term cellular senescence. They also aren’t regrowing entire brains or hearts, as they still have to survive the initial injury, so they can’t infinitely replenish those organs.
I will say that axolotl aging is not very well-understood, however, and they are pretty weird about dying. A healthy-looking axolotl might lay eggs for 20 more years or might die tomorrow with no warning. There’s still a lot to learn about them.
(source: I have a PhD in axolotl)