Rana sylvatica, the only amphibian found north of the arctic circle, has a very unique survival strategy: it pumps its body full of glucose and hormones just before freezing so that ice crystals don't cause irreversible damage to the creature's body. Then, when it comes time to thaw, the frog thaws slowly. The membranes around the heart begin to stretch, somehow causing a sort of energy discharge that constricts the heart muscles in an odd twitch that "wakes up" the dead frog.

I recognize that humans are far more complex than frogs, but perhaps the frogs' innovation is in the right direction. What is keeping the frogs' approach from working on more complex organisms?

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    $\begingroup$ I think that's just it: more complex $\endgroup$ Apr 15 '17 at 3:08
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    $\begingroup$ Actually there is case where human hibernate (or at least similar to). It just needs the correct conditions for the brain to start hibernation signal. However, we don't have the instinct and knowledge to do this correctly (not yet) $\endgroup$
    – Vylix
    Apr 15 '17 at 3:28
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    $\begingroup$ Google "not dead till warm and dead" $\endgroup$
    – apaul
    Apr 15 '17 at 4:16
  • $\begingroup$ @TheNate No sweat. I have flaggged this question to have the notice removed, too, but since an actual human has to do that, it may take a while longer. $\endgroup$
    – user
    Apr 15 '17 at 6:34
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    $\begingroup$ I'll try to get back and answer this when I get a bit, provided a good answer hasn't appeared. In the meantime: Glycol and glycerin can be used to preserve mammalian tissues and organs because it smooths out the freezing. I did forget to mention one factor: Yes, too slow freezing leads to ice crystal aggregation (which pierces cell walls and such), but too fast leads to shearing of cells and certain other things to similar effect. $\endgroup$
    – The Nate
    Apr 15 '17 at 6:46

The use of Cryoprotetants such as ethylene glycol is already part of the cryopreservation of humans. These chemicals are used to protect tissue from damage associated with freezing, primarily the formation of ice crystals.

Preventing the formation of ice crystals is only one of many obstacles to success of cryonics.


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