What happens to our bodies after death is a process that begins within minutes and unfolds over hours, days, and weeks. Mortician Holly Williams, who has worked on around 1,000 bodies at a family-run funeral home in north Texas, describes the early stages: “Usually, the fresher a body is, the easier it is for me to work on.” She explains that bodies collected from nursing homes are often fresher than those found alone days or weeks after death, which are already decomposing.
Decomposition starts with autolysis, or self-digestion, soon after the heart stops. Cells become deprived of oxygen, acidity increases, and enzymes begin digesting cell membranes. This process typically begins in the liver and brain, which are rich in enzymes and water. Damaged blood cells spill out, settling in capillaries and small veins, discolouring the skin. Body temperature drops to match the surroundings, and rigor mortis sets in—starting in the eyelids, jaw, and neck, then spreading to the trunk and limbs.
Rigor mortis occurs because muscle cells are depleted of energy, locking the protein filaments actin and myosin in place. This causes muscles to become rigid and joints to lock. During these early stages, the body's ecosystem is dominated by bacteria that lived in and on the living human. The gut alone hosts trillions of bacteria from hundreds or thousands of species.
In August 2014, forensic scientist Gulnaz Javan of Alabama State University published the first study of the thanatomicrobiome—the microbial community that emerges after death. “Many of our samples come from criminal cases,” says Javan, including suicides, homicides, drug overdoses, and traffic accidents. This research views a rotting corpse as the cornerstone of a vast ecosystem that evolves as decomposition progresses.
