Human Cryonics

What is human cryonics?

Human cryonics is the practice of preserving human bodies or brains at ultra-low temperatures after legal death, with the hope that future medical technology may enable revival and repair. The field rests on two key premises: that current preservation methods can maintain sufficient biological information, and that future advances in nanotechnology and medicine could reverse the preservation process and treat the original cause of death ^[1].

How vitrification works

Modern cryonics uses vitrification rather than simple freezing. This process rapidly cools tissue while replacing water with cryoprotectant chemicals, transforming biological structures into a glass-like solid without ice crystal formation. Ice crystals are the primary enemy of preservation—they rupture cell membranes and destroy the delicate synaptic connections that encode memory and personality ^[2].

In 2016, researchers at 21st Century Medicine demonstrated aldehyde-stabilized cryopreservation, successfully preserving a rabbit brain with cellular structures, synapses, and intracellular components intact. The Brain Preservation Foundation awarded this work their Small Animal Brain Preservation Prize, noting the preservation quality achieved ^[3].

Current scientific status

The mainstream scientific community remains skeptical about cryonics. The Society for Cryobiology has stated that cryonics is "an act of speculation or hope, not science" ^[4]. No human has ever been revived after cryopreservation, and significant technical barriers remain.

However, some researchers argue the theoretical case deserves attention. Studies show that brain injury from stopped blood flow progresses over hours, not minutes, suggesting a larger window for intervention than previously assumed ^[1]. Others point to the precedent of cryopreserving and successfully thawing sperm, embryos, and simple tissues as evidence that biological information can survive freezing under the right conditions.

Challenges and limitations

Revival faces formidable obstacles. Even with perfect vitrification, rewarming without damage proves difficult. Cryoprotectant chemicals carry toxicity. Large organs tend to fracture during cooling. And revival would require technologies that do not yet exist—likely advanced molecular nanotechnology capable of repairing structures cell by cell ^[2].

Approximately 250 bodies have been cryopreserved in the United States, with another 1,500 people signed up for future preservation. Costs range from $28,000 to $200,000, typically funded through life insurance ^[4].

Ethical and legal considerations

Cryonics raises complex questions about identity, consent, and resource allocation. Most countries legally treat cryopreserved individuals as deceased, though a 2016 English High Court ruling allowed a terminally ill teenager's wish for cryopreservation against a parent's objections. The court urged ministers to develop proper regulation for the practice ^[4].