Tokyo, May 25 -- Scientists have uncovered a surprising twist in how cells behave when division goes wrong. Sometimes a cell successfully copies its DNA but fails to split into two, leaving it with double the genetic material, a mistake linked to ageing, cancer, and other major diseases.

Researchers discovered that not all of these failures are equal. Every second, countless cells in the human body divide to create new cells.

It is one of the most important processes in biology, and it depends on thousands of molecules working together with incredible precision. But sometimes the process breaks down in unexpected ways.

Before a cell can divide into two separate cells, it first has to copy all of its DNA so each new cell receives a full...