Lazarus is a name that has become shorthand for coming back from the dead. It originates from the biblical story of Lazarus of Bethany, whom Jesus raised from the grave four days after death. But in modern science and medicine, “Lazarus” appears in several distinct contexts: a rare medical syndrome where a person’s heart restarts on its own after resuscitation efforts have stopped, a neurological reflex seen in brain-dead patients, a term in paleontology for species that reappear after being declared extinct, and a genetics project attempting to literally bring an extinct frog back to life.
The Biblical Origin
The original Lazarus appears in the Gospel of John. He was a man from Bethany, near Jerusalem, who fell ill and died. Jesus arrived four days after Lazarus had been placed in a tomb, ordered the stone removed, and called him out alive. The story became one of the most recognized miracle narratives in Western culture, and “Lazarus” evolved into a universal metaphor for resurrection or unexpected return from apparent death. That metaphor is why scientists and physicians across multiple fields independently adopted the name.
Lazarus Syndrome: Hearts That Restart on Their Own
Lazarus syndrome, formally called autoresuscitation, is the spontaneous return of circulation after CPR has been stopped and a patient has been declared dead. It is rare but real. A study published in the journal Resuscitation found an incidence of roughly 6 per 1,000 cases where CPR was terminated in the field. In those cases, the heart began beating again on its own between 3 and 8 minutes after resuscitation efforts ceased.
The mechanisms behind it are poorly understood, but several physiological explanations have been proposed. One of the most discussed involves air trapping in the lungs. During aggressive manual ventilation, air can enter the lungs faster than it escapes, gradually building pressure inside the chest. That rising pressure acts like a clamp on the heart, reducing blood flow back to it and eventually causing cardiac arrest, even when the heart itself still has an electrical rhythm capable of producing a heartbeat. Once CPR stops and the ventilation pressure releases, blood flow may return to the heart, allowing it to restart.
Another proposed mechanism involves potassium levels in the blood. When potassium is too high, heart muscle cells become electrically unresponsive and the heart stops. As potassium slowly redistributes through the body after CPR ends, the heart may regain the ability to fire. Delayed drug effects also play a role in some cases: medications given during CPR may not reach the heart until after resuscitation has stopped, particularly when chest pressure was slowing circulation.
Because of this phenomenon, medical protocols now include a mandatory waiting period after stopping resuscitation. UCSD Health’s standardized procedure, for example, requires a 5-minute observation period after diagnosing death to confirm that no spontaneous return of cardiac or respiratory function occurs.
The Lazarus Sign: Movement After Brain Death
The Lazarus sign is something different entirely. First described in 1984 by neurologist Allan Ropper, it refers to a complex involuntary movement seen in patients who have been declared brain-dead. The movement typically involves both arms flexing up toward the chest, the shoulders pulling inward, and the hands crossing or coming together in a posture sometimes compared to praying hands. The entire sequence lasts about 10 to 30 seconds before the arms return to their resting position.
It most often occurs when a ventilator is disconnected or during an apnea test (a standard part of confirming brain death). Despite how unsettling it looks, the Lazarus sign does not indicate any brain activity. It is a spinal reflex, meaning the movement originates from nerve circuits in the spinal cord that can still function even when the brain has completely and irreversibly shut down. Studies have found it in only about 2% of brain-dead patients, making it uncommon but well-documented enough that medical teams are trained to recognize it for what it is.
Lazarus Taxa: Species Back From Extinction
In paleontology, a Lazarus taxon is a species that vanishes from the fossil record for millions of years, appearing to have gone extinct, only to show up again in later rock layers or, in some cases, alive today. The term was coined in 1986 by paleontologist David Jablonski to describe what he called “the disappearance and apparent extinction of taxa that later reappear unscathed.”
The most famous example is the coelacanth, a large, lobe-finned fish that disappeared from the fossil record around 65 million years ago, right alongside the dinosaurs. Scientists assumed it had been extinct for tens of millions of years until 1938, when a live coelacanth was pulled from a fishing trawl off the coast of South Africa. Populations were later found near the Comoro Islands in the Indian Ocean, and a second species was identified near Indonesia in 1997.
Lazarus taxa don’t literally come back from the dead. The explanation is usually that small populations survived in isolated refuges, such as deep ocean habitats or remote islands, where they left no fossils. Some ancient corals and sponges, for instance, were eventually found in rock formations from oceanic islands far from the continental shelves where paleontologists had been looking. The gap in the fossil record reflects the limits of fossilization and discovery, not actual extinction and return.
The Lazarus Project: Cloning an Extinct Frog
The name Lazarus has also been given to a modern genetics effort that took the resurrection metaphor literally. The Lazarus Project is an Australian research initiative that attempted to bring back the southern gastric-brooding frog, a species that went extinct in 1983. This frog had one of the strangest reproductive strategies in nature: the female swallowed her fertilized eggs, brooded them in her stomach, and gave birth to fully formed froglets through her mouth.
Using tissue samples collected in the 1970s and preserved in a standard deep freezer for 40 years, researchers extracted cell nuclei from the extinct frog. They then used a cloning technique called somatic cell nuclear transfer, taking fresh eggs from a living relative (the great barred frog), removing the egg’s own genetic material, and replacing it with the nucleus from the extinct species. Some of those eggs began dividing and grew to an early embryo stage. Genetic tests confirmed the dividing cells carried the extinct frog’s DNA.
None of the embryos survived beyond a few days, and a living gastric-brooding frog has not been produced. But the project demonstrated that genetic material from a long-dead, frozen specimen could be reactivated into living, dividing cells. The research team described the remaining challenges as technological rather than biological, and the project generated fresh cryopreserved cells that could be used in future cloning attempts.