This combination of images provided by the Yale School of...

This combination of images provided by the Yale School of Medicine in April 2019 shows stained microscope photos of neurons, green; astrocytes, red, and cell nuclei, blue, from a pig brain left untreated for 10 hours after death, left, and another with a specially designed blood substitute pumped through it. Credit: AP/Stefano G. Daniele, Zvonimir Vrselja

The report last week read like science fiction.

Researchers at Yale University restored some cellular functions to the brains of pigs decapitated in a slaughterhouse four hours earlier.

Let that sink in.

The brains were dead by any conventional measure. But after being infused with a solution of synthetic fluids that functioned as a substitute for blood, some brain cells regained metabolic activity. Brain tissue absorbed oxygen and glucose. Some neurons exhibited electrical activity.

The brains never regained anything that could be termed consciousness. The experiment as reported in the journal Nature was designed to ensure that would not happen, by using a chemical in the fluid that would inhibit the recovery of full brain activity. Just in case, an anesthetic was on hand.

Nevertheless, enough happened to give us a new reason to examine an old question:

Where is the line between life and death?

The answer has long been definitive. Brains are fragile. Depriving one of oxygen will quickly and irreversibly lead to brain death. And that’s the end.

And now?

“We had clear lines between ‘this is alive’ and ‘this is dead,’  ” Duke University bioethicist and law professor Nita Farahany told The New York Times. “How do we think about this middle category of ‘partly alive’? We didn’t think it could exist.”

This new ethical quandary arrived in a week during which Christians contemplate life and death, and life after death, and what it means to be reborn. And it came in a season in which rebirth is all around us, from the flowers that spring like magic out of barren ground to the chirping of chicks making their way into the world.

The work by the Yale researchers addresses a different sense of rebirth: Is it possible that someone who has suffered a severe brain injury from a heart attack or stroke could recover that brain function? Is it possible, in other words, that the brain is not as fragile as thought? Is it possible a brain can be reborn?

This once was the realm of sci-fi storytellers and B-movie plots featuring brains in jars and other mad scientist concoctions. Now that it’s edging toward reality, the ethics of these experiments must be debated.

Does a “partly alive” brain feel pain? If so, does the goal of relieving a profound human condition justify that suffering? As the technology of restoring brain function improves, and it will, what are the implications for organ donation, which depends on the defined moment of death of the donor?

This new work is one more variation of the life-after-death themes that humans always have found powerful and alluring. They’re in our religions, to be sure, but really are present in almost every facet of life.

At their root, they animate every comeback story, and we do love a good comeback. The athlete, the politician, the inventor. The career, the idea, seemingly dead. Then the triumphant return — the resurrection, if you will.

That’s why we thrilled at the Masters victory of Tiger Woods, whose career was once thought to be dead. It’s why we mourned the fire at Notre Dame cathedral, unsure that it could ever recover. It’s why we refuse to leave the ballpark, hoping to see our team rise up.

We cling to life. We yearn for its return. Medicine gets ever more successful at helping us avoid death and prolong life. Often, we are immensely fulfilled. Sometimes, the trade-off for a renewed lease on life is a diminished quality of that life.

The ethical questions are endless. But they must be asked. And we shouldn’t shy away from the progress that forces them to be asked.

If the Yale researchers are blurring the line between life and death, that’s OK. Boundaries are meant to be tested, and knowledge is meant to be learned.

Michael Dobie is a member of Newsday’s editorial board.

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