Key Points:
- Cryonics is the practice of freezing and storing a deceased person’s body at low temperatures with the hope that future scientific advancements will allow them to be revived.
- Cryonics faces significant legal and ethical hurdles, with varying regulations across countries and concerns about its recognition as a legitimate form of body preservation.
- The economic sustainability of cryonics companies is questioned, highlighting their struggle to stay operational over the long durations necessary for the promise of future revival.
In the new Netflix sci-fi series “The Three-Body Problem,” one of the characters (Thomas Wade) proposes a plan to participate in a moment 400 years in the future when invading aliens are expected to arrive. The solution proposed isn’t time travel but, instead, something perhaps much more feasible—suspended animation.
Suspended animation, also known as “cryosleep,” “hypersleep,” or “hibernation,” is used numerous times during space travel in films such as 2001: A Space Odyssey, Planet of the Apes, Alien, James Cameron’s Avatar, and Christopher Nolan’s Interstellar.
In films, there’s no shortage of imaginative conceptions of how to perform suspended animation on humans. Oftentimes, bodies are lying horizontally in a tube filled with gas or are floating in a standing position within some sort of magical liquid. Then there’s the simplest depiction of cryopreservation, where characters are just good ol’ frozen in ice.
But besides being a fascinating concept that shows up in fictitious stories, suspended animation is actually something that can happen in real life.
Suspended animation in nature
Suspended animation is an umbrella term for all kinds of pausing of biological processes. It refers to the stoppage of life that doesn’t have negative effects on the organism itself—on the contrary, life in this state is protected.
Frozen and dried worms
Nematodes buried in Siberian permafrost may be able to stay in a state of suspended animation indefinitely, according to recent findings. In 2023, scientists revived a 46,000-year-old nematode from Siberian permafrost. The microscopic roundworm was revived and began reproducing in a laboratory dish.
Russian scientists found that, in response to freezing temperatures, the worms produce a naturally occurring sugar called trehalose that somehow transforms the worms into a desiccant-resistant state. This gooey state serves to protect cells and their contents, stabilize proteins, and prevent the formation of damaging ice crystals within cells.
Another method also shows up in “The Three-Body Problem” called anhydrobiosis—when organisms lose almost all water and enter a state of essentially non-existent metabolism and activity that is reversible. In the story, people desiccate with the intention of being rehydrated in a more favorable future.
Anhydrobiosis isn’t just a sci-fi fantasy. There’s a type of roundworm called Panagrolaimus superbus that enters suspended animation via anhydrobiosis. This ability gives P. superbus a tolerance for various extreme environments, having been shown to withstand immersion in liquid metal (gallium) and tolerate 400,000 times the Earth’s gravitational force (g-force), which is what it would be like to be blasted by a supernova.
Torpor: the deepest of sleep
Torpor, a state of deep sleep, can occasionally induce suspended animation without completely drying out or freezing the subject. Torpor is, in many ways, a less intense version of cryptobiosis in that it involves decreased breathing and heart rates and a lower metabolic rate.
Torpor can last for a few hours, as in daily torpor, or it can last for months. For example, hummingbirds use daily torpor during the night to reduce their metabolic rate and save energy. Wintering chickadees also use torpor to preserve their fat reserves and save energy.
The eastern long-eared bat uses torpor during the winter and can arouse and forage during warm periods. Some animals, particularly those living in unpredictable habitats, use torpor during their reproductive cycle. While this prolongs the reproduction period, it ensures their survival and ability to reproduce at all.
To freeze, desiccate, or sleep?
So, do any of these methods—cryptobiosis, anhydrobiosis, and torpor—apply to humans?
The study of tardigrades and nematodes has been a rich source for understanding forms of suspended animation. From the study of phenomena like cryptobiosis and torpor, a new idea crossed the minds of scientists: cryonics—the practice of freezing and storing the remains of a deceased person at low temperatures with the hope that they can be brought back to life in the future.
Early cryonics efforts in humans melted away
In April 1966, the first human body, or corpse, was frozen—though it had been embalmed for two months—by being placed in liquid nitrogen and stored just above freezing. Family members soon thawed out and buried the middle-aged Los Angeles woman, whose name is unknown.
The first body to be cryonically preserved with the hope of future revival was that of James Bedford within around two hours of his death from cardiorespiratory arrest (secondary to metastasized kidney cancer) on January 12, 1967. Bedford’s corpse is the only one frozen before 1974 and still preserved today. In 1976, Ettinger founded the Cryonics Institute; his corpse was cryopreserved in 2011.
Robert Nelson, “a former TV repairman with no scientific background” who led the Cryonics Society of California, was sued in 1981 for allowing nine bodies to thaw and decompose in the 1970s.
Gregory Fahy and Brian Wowk, two cryobiologists, created the first cryoprotectant solutions in the late 1990s for the purpose of banking transplantable organs that could vitrify at very slow cooling rates while still being compatible with whole organ survival. This has allowed animal brains to be vitrified, warmed back up, and examined for ice damage using light and electron microscopy. No ice crystal damage was found; cellular damage was due to the dehydration and toxicity of the cryoprotectant solutions.
I will revive
Though cryonics—freezing and reviving—in humans remains to be seen, one challenge that remains largely unexplored is revival.
Revival would require repairing damage from lack of oxygen, cryoprotectant toxicity, thermal stress (fracturing), and freezing in tissues that do not successfully vitrify, finally followed by reversing the cause of death. In many cases, extensive tissue regeneration would be necessary. This revival technology remains speculative and does not currently exist.
You’re nothing more than a brain
Going back to “The Three-Body Problem,” there’s one other situation that’s proposed for suspended animation. This method that makes an appearance has to do with preserving a human brain dissected from a living human (at least at the start of the procedure) to endure flying through space at speeds that aim to reach 1% lightspeed and eventually reach aliens, which some of the characters think may be able to used by the aliens to recreate a human given their far superior technology.
Indeed, cryonics of the brain involves preserving a brain at subzero temperatures to potentially revive it in the future. The goal is to regrow a healthy body around the brain, which is a whole other problem beyond just freezing and reviving organs to function. Even using the best methods, cryonic preservation of whole brains and bodies is very damaging and irreversible with current technology.
For obvious reasons, the method is fatal and is performed as euthanasia under general anesthesia. But the hope is that future technology will allow the brain to be physically scanned into a computer simulation, neuron by neuron.
Some cryonics advocates hold that in the future, the use of some kind of presently nonexistent nanotechnology may be able to help bring the dead back to life and treat the diseases that killed them.
Short-term suspended animation by cooling
The idea of suspended animation for interstellar human spaceflight has often been posited as a promising long-term solution for long-duration spaceflight. A means for full freezing and revival by cryogenics remains a long way off. However, recent medical progress is quickly advancing our ability to induce deep sleep states (i.e., torpor) with significantly reduced metabolic rates for humans over extended periods of time.
This process has been considered for reducing the metabolism of astronauts during long space missions. To enter this state, astronauts would need to lower their internal body temperature by about 9 ºF, which could be done by cooling the surrounding air.
Perhaps the best-studied version of this involves the rapid cooling of trauma victims. The idea here is for rapid cooling to reduce brain activity to a near standstill and to slow the patient’s physiology and it is being explored to give surgeons precious extra minutes, perhaps more than an hour, to operate. Known formally as emergency preservation and resuscitation, or EPR, the procedure is being trialed on people who sustain such catastrophic injuries that they are in danger of bleeding to death and who suffer a heart attack shortly before they can be treated. The patients, who are often victims of stabbings or shootings, would normally have less than a 5% chance of survival.
The process involves rapidly cooling the brain (but not freezing it) by replacing the patient’s blood with ice-cold saline solution. Typically, the solution is pumped directly into the aorta, the main artery that carries blood away from the heart to the rest of the body. Once the patient’s injuries have been attended to, they are warmed up and resuscitated.
If science prevails, what stands in the way?
Let’s say science finds a way to figure out cryonics—the freezing and revival components—or how to get astronauts to enter a deep sleep for interstellar travel. What would stand in the way of anyone wanting to freeze themselves with hopes of coming back to life in the future?
In addition to the scientific challenges of cryonics, there are a slew of non-scientific ones as well. For example, most countries legally treat preserved individuals as deceased because of laws that forbid vitrifying someone who is medically alive.
French law only permits three forms of final disposition: burial, cremation, or official donations to science; none of these options include cryonics. The sale of cryonics-based arrangements for body preservation has been illegal in the Canadian province of British Columbia since 2015. In Russia, cryonics falls outside both the medical and funeral services industries, making it easier than in the United States to get hospitals and morgues to release cryonics candidates.
Can you afford cryonics?
As of 2014, about 250 corpses have been cryonically preserved in the US, and around 1,500 people have signed up to have their remains preserved. As of 2016, four facilities exist in the world to retain cryopreserved bodies: three in the US and one in Russia.
Cryonics is not cheap. Payment for on-call medical staff, vitrification, dry-ice transportation to a preservation facility, and a trust fund to cover indefinite storage in liquid nitrogen and future revival costs are all possible expenses.
The price tag for cryonics-based body preparation and storage was $28,000 to $200,000 in 2018. KrioRus, which stores bodies communally in large dewars, charges $12,000 to $36,000 for the procedure.
About 1,500 individuals have registered to have their remains preserved, and as of 2014, approximately 250 corpses have been cryogenically preserved in the US. There are currently four facilities worldwide that store cryopreserved remains; three of these are located in the United States and one in Russia.
The Berlin-based Tomorrow Biostasis GmbH has just emerged as a new player in the cryonics industry, providing standby and transportation services across Europe. They will collaborate with the European Biostasis Foundation in Switzerland to store corpses for an extended period of time. Their facility is scheduled to be finished in 2022.
Taking into account the average lifespan of a company, it is highly unlikely that any cryonics company can remain operational for the 100 years needed to reap the alleged benefits. The odds of even the most powerful companies lasting that long are one in a thousand. Failures abound in the cryonics industry; by 2018, every single batch that existed before 1973 had already defrosted and been disposed of due to bankruptcy.
While these technologies seem far off, the invention of the lightbulb was almost 150 years ago, and look how far we’ve gotten. In 150 years, it is possible that cryonics will be solved scientifically and all that may remain is a personal choice of whether or not you’d want to live again sometime in the future.
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