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Cryonics is the idea of freezing someone for a long period of time until the cause of death is curable (including general old age). This is not really the vision of immortality most people want and there was evidence presented on sci.longevity that freezing and thawing produces so much cellular damage that all you end up with is a person shaped pile of meat product. It's also a tempting target for fraud, since your customers pay in advance and don't complain.

There is a species of frog I read about that, because of a higher sugar content in its cells, formed ice crystals with more sides that humans. Because there were more sides the points were less pronounced and the crystals for the most part did not damage the frogs cells. The frog could be completely frozen for an period and be thawed and still live.

I am not sure how long the frog could freeze for though. I'm sure if it was frozen for too long when it thawed it would not resume living.
There are two main strategies for protection from low temperatures; one is cryoprotectants, the other is ice binding proteins. The frog mentioned by no comply uses a sugar (glucose) as its cryoprotectant, as do many insects. The 'arctic willow gall insect' (which uses glycerol, not glucose) can withstand temperatures down to -66 degrees centigrade. Chilly.

However, the frog's story is a little more complicated. You may be thinking "if the frog has cryoprotectants, why does it freeze" (you may be thinking something else entirely - if so, piss off!)). The strategy this creature has adopted is to actually promote freezing in the extracellular space (outside the cells) but supress ice formation inside the cell. So it produces proteins that make crystals in the blood while raising glucose levels to 200 times normal. The small ice-crystals that form are less damaging than larger ones (as no comply mentioned they are also 'rounded' crystals) and the cells are protected from the inside by syrup.

The question of whether a) this could be extended to humans and b) this could work indefinitely is tricky. Certainly metabolism in such frogs (and other freeze-tolerant organisms) slows but does it stop? Is there some slow decay in this state - and can all cell types survive equally?

Solution? Participate in your own manipulation!

All information in this node was messily ripped from the heart of : H2O A Biography Of Water by Philip Ball (ISBN 0 75381 092 1) published by Pheonix. Which I highly recommend (read it - if you know what's good for you...).

Joke of the day - "Cryonics: Death, on the rocks."

The procedure follows these steps:

  1. When a person is pronounced medically dead, but before the structure of the brain starts to degenerate, the body is attached to a heart-lung machine and their heart started again as it is packed in water ice.
  2. Blood is flushed out and the body is progressively infused with anti-freeze or a "cryoprotectant" and other cellular stabilisers with the goal of evacuating as much water as possible from the corpse. This is to eliminate icicles which will form inside cells and rupture them upon thawing. The exact composition of this cryoprotectant fluid differs between each unique organisation, but the main ingredient is the same: glycerol, which like automobile anti-freeze has a much lower freezing point than plain water.
  3. The body temperature is lowered until it is at liquid nitrogen temperatures. (Different cryonics organisations employ different methods to get patients the rest of the way to -179 degrees Celsius. While some companies prefer to use a thoracic surgeon to crack open the rib cage for access to the heart, the better to use the body's circulatory system to flush the cryoprotectant solution from head to toe, others prefer to use veterinarians or licensed morticians, and make do with the femoral arteries in the groin).
  4. At this point all molecular change stops indefinitely and the body is then preserved in liquid nitrogen at -196 degrees C or -320 degrees F.
  5. Later, when nanotechnology cell repair devices become available, the fatal disease that caused "death" is reversed, the anti-freeze toxicity is removed, and the body is warmed back up alive and well.


Leaders of the "esteemed" Alcor Life Extension Foundation and other cryonics organisations estimate that frozen patients may be repairable and declared "potentially alive" in sooner than one hundred years.

This procedure without doubt preserves cellular life. Sperm, skin, corneas, and human embryos are routinely frozen in LN2, thawed, and transplanted. More other individual tissues can also be treated this way, resulting in viable cells; but today's resuscitation methods are not yet entirely successful on whole organs or animals. However, since the frozen individuals are not changing further, they can afford to wait until better thawing procedures and cell repair treatments (through nanotechnology) are available in the future.

A major question must be raised however: Do today's cryonics techniques reliably preserve memories and the identity of a frozen individual? Neuroscience cannot yet show us what specific structures in the brain encode memory or identity (or even provide us with a decent working definition of "identity"), so we can't examine brain tissue to look for the presence of those structures. And the basic principles of nanotechnology are still so new that we don't have a firm understanding of its technical and practical limitations. Since many experiments and clinical evidence show that long-term memory has to be something physical (or made of molecules), it seems that a technology capable of moving molecules and repairing cells should be able to repair memory structures, if the information itself has not been lost to brain destruction.

But what of the human after he is awakened? Technology is advancing so rapidly that people born fifty or so years ago are finding it hard to keep up, to cope. What will the world be like in three hundred years? Will we be able to navigate it at all? One would have a frighteningly primitive nature, socially and technologically, if not biologically and intellectually.

Regardless of the inescapable ethics involved, the fact is that many 20th and 21st century citizens are opting for this type of immortality. The cost for this "suspension" procedure alone can range from US$28,000 to US$150,000 depending on which organisation freezes you. For those who cannot spare the big bucks, there is a less expensive route, the route of neuro-suspension. This is just a euphemism for "head only". This is a service which the ALCOR Life Extension Foundation will provide for a slight US$50,000, which lovingly includes cremation and a burial at sea of your non frozen remains.

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