Tearing one's clothing on hearing devastating news is depicted repeatedly in the Hebrew Bible well before rabbinic law formalized it into a fixed mourning rite: Jacob tears his garments on being shown Joseph's bloodied coat and concluding his son is dead, and Job tears his robe on learning of the deaths of his children, both passages rabbinic sources later cite as evidence that the gesture is an old and instinctive expression of grief rather than a rabbinic invention needing separate justification.
What the Talmud and later codes added was structure: fixing which side of the garment is torn for which relative, specifying that the tear for a parent is never fully mended in a way it may be for other relatives, and timing the obligation to the moment the mourner first learns of the death rather than to the funeral itself, so that a tear performed immediately on hearing news can precede burial by hours or days. Because the classical rite involves damaging real clothing, many contemporary and non-Orthodox communities, along with some Orthodox ones for practical reasons, have adopted a substitute: a black ribbon, pinned to the mourner's clothing and torn in the same manner as the fabric itself would have been, preserving the symbolic act and its specific rules about side and repair while sparing the garment underneath, an adaptation that keeps the ancient gesture legible without its original cost.