The changes a body undergoes after death are part of a natural biological process called taphonomy, which begins the moment life ceases. This progression involves the breakdown of complex organic matter into simpler components through physical and chemical reactions. While the process follows a specific sequence, the rate of change is highly variable and dependent on numerous internal and external conditions. The “one-week” appearance described is an average based on a moderate, temperate environment.
The Initial Stages (First 48 Hours)
The first two days following death are characterized by three distinct physical changes that occur as the body loses its ability to maintain homeostasis. The body begins to cool in a process known as algor mortis, where the internal temperature drops until it matches the ambient temperature. This cooling is an early indicator of time since death, though it is influenced by clothing, body mass, and air temperature.
Simultaneously, livor mortis, or post-mortem lividity, develops as blood settles in the lower parts of the body due to gravity. This pooling creates a purplish-red discoloration on the skin that begins within 30 minutes to two hours after death. It becomes fixed, meaning it will not blanch when pressed, after about eight to twelve hours.
The third change is rigor mortis, the stiffening of the muscles caused by chemical changes in the muscle fibers. This rigidity typically begins in the face and neck within two hours and becomes complete throughout the body around 12 hours. It then gradually disappears as the muscle proteins break down, typically resolving after 36 to 48 hours.
The Mechanisms of Early Decomposition
The macroscopic changes defining the appearance of a body after several days result from two parallel biological mechanisms: autolysis and putrefaction. Autolysis, or self-digestion, begins immediately at the cellular level, driven by the body’s own hydrolytic enzymes. When circulation stops, oxygen levels drop, leading to an acidic environment inside cells.
This acidity causes cell membranes to rupture, releasing internal enzymes that break down surrounding tissues. These early autolytic changes are most noticeable in enzyme-rich organs like the pancreas and liver, but they are generally microscopic and do not cause significant visible alteration to the body’s exterior.
Putrefaction is the second, more visually impactful mechanism, involving the proliferation of bacteria, primarily those originating from the large intestine. These gut flora invade surrounding tissues and blood vessels, feeding on the body’s proteins and carbohydrates. This microbial activity produces the characteristic gases and chemical byproducts that result in the major visible signs of decay.
Physical Appearance at the One-Week Mark
By the one-week mark in a moderate environment, the body is typically well into the “bloat” or “active decay” stage, dominated by the visual effects of advanced putrefaction. The most striking change is the significant swelling of the torso, face, and limbs due to the accumulation of internal gases. Bacteria produce large volumes of gases like methane, hydrogen sulfide, and carbon dioxide as they consume the tissues, sometimes causing the body to nearly double in size.
Externally, the first visible sign of putrefaction, often appearing around two to four days, is a greenish discoloration in the lower right quadrant of the abdomen. By seven days, this coloration has typically spread across the abdomen and chest as bacteria-produced sulfhemoglobin permeates the tissues. A pattern known as marbling may also be visible, where the superficial veins appear dark red or black due to the breakdown of blood within the vessels.
The pressure from the internal gases often forces putrefactive fluids, or purge fluid, out of the mouth and nose. The epidermis, the outermost layer of skin, begins to separate from the underlying dermis, a phenomenon called skin slippage. This can cause large, fluid-filled blisters to form, and the skin may easily peel away, sometimes like a glove from the hands. The decomposition process at this stage generates a distinctive odor from volatile organic compounds such as putrescine and cadaverine.
Environmental Factors That Alter the Timeline
Temperature is the single most influential factor, with heat significantly accelerating the rate of autolysis and bacterial growth. Conversely, cold temperatures dramatically slow or can even halt decomposition, which is why bodies preserved in freezing conditions can remain intact for centuries.
Moisture is also a determinant, as bacterial growth requires water. High humidity and water exposure generally speed up decay, but overly saturated conditions can sometimes slow the process by limiting the oxygen needed by aerobic bacteria. In contrast, very arid conditions can lead to mummification, where tissues dry out rapidly, effectively stopping putrefaction.
The accessibility of the body to insects and scavengers also impacts the timeline. Insect activity, particularly by blowflies, can accelerate soft tissue loss, moving the body into the advanced decay stage much faster than microbial action alone. Location also matters, as a body exposed to air decomposes faster than one submerged in water or buried in soil, due to differences in temperature, oxygen availability, and insect access.