The concept of death has constantly changed over the centuries, becoming more accurate as our knowledge and technologies advance. For example, in the 19th century, a person was pronounced dead after simply ceasing to breathe. A hundred years ago, someone was officially dead once their heart stopped beating. And today, we believe that death occurs when our bodies suffer irreversible cell damage—that is, our vital functions can no longer be reactivated.

But even after a person dies and their body begins to decompose, that does not mean he or she is entirely dead. In fact, new research indicates that some processes occurring in a corpse challenge our understanding of death. A group of American and European scientists discovered in 2017 that after certain animals die, many of their cells are still fighting to survive. And they not only remain alive for days after death, but in some types of cells, their activity increases.

Everything points to the fact that, in an attempt to repair themselves, the cells in a dead body accelerate the process by which they transform DNA into instructions to make new proteins. And stem cells in particular are able to continue living not for hours or days but for weeks after the death of the creature. It is understandable if we take into account that every animal is a being composed of multiple populations of different cells. For this reason, some cells are more resilient than others, even after the apparent death of the body. And the same researchers state that this behavior occurs in all multicellular beings, including us. So it is clear that the line between life and death is much more blurred than we thought.