The liver is the one organ that seems built to survive. Cut half of it away and it regrows to full size in a few months. Age it and it keeps near-full strength. Give it to someone else and it works again. Nearly every other part of the body fails in some way that feels avoidable.
A recent online post titled “Why is the liver so weirdly regenerative?” argues that this contrast has a single explanation: cancer. The post makes the case that most of the body is fragile by design to stop cancer from taking hold.
What the Body Does Wrong
The post lists a series of failures that seem unnecessary:
- Kidneys start to decay once adulthood begins, damaged by ordinary things like vitamin D overdose or ibuprofen taken while dehydrated.
- Gums retreat down teeth and never return if brushing is too harsh or flossing is skipped.
- Menopause is almost unknown outside humans. Other great apes stay fertile almost their whole lives, with only six known exceptions: killer whales, pilot whales, beluga whales, false killer whales, narwhals, and one specific group of chimpanzees in Uganda.
- If a leg is chopped off, it’s gone forever. Salamanders grow a new one.
- Telomeres shorten each time cells divide, until they stop dividing entirely after 50-70 divisions.
- Transplanted kidneys face a 30% rejection rate within ten years, thanks to the body’s own attack on foreign tissue.
- Brain injuries leave dead neurons behind, never replaced.
- Blood vessels can clog with plaque, but the body maintains high levels of inhibitors that tell cells not to sprout new blood vessels.
The Liver’s Case
The liver stands apart because it heals without scars and regenerates fully after injury. The post asks why the body isn’t built like this everywhere.
Cancer Is the Answer
The post’s central claim is that the body sacrifices durability to prevent cancer. Telomeres shorten deliberately because the body stops using telomerase after embryonic development, except in stem cells, reproductive cells, and parts of the immune system.
Cells with a mutation that makes them reproduce too fast are usually killed by the immune system. But sometimes those cells stop growing and sit there. The post explains the pause as part of its reasoning.
The Fragile Body
The list above shows how the body sacrifices strength across nearly every system. Some organs fail under ordinary use. Others fail under neglect. Some fail simply by existing. Each failure seems avoidable on its own terms.
The Trade-Off
The post admits the answer is only semi-correct, with several caveats. It also notes that the reason for linear DNA over circular DNA is disputed.
The trade-off is simple: fragility elsewhere buys protection against cancer. The liver is an exception because it doesn’t present the same risk.
What This Means for You
The post offers no practical advice. It is a speculative look at biological design, not a guide to staying healthy.
But the wonder remains. The liver heals itself without scars, unlike nearly everything else in the body, and the post argues that cancer is the reason why.
Source material: “Why is the liver so weirdly regenerative?,” dynomight.substack.com.
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