The question of whether hair decomposes after death is common. Many people wonder if hair continues to grow or if it simply endures indefinitely. Understanding the science behind decomposition reveals that hair does not grow post-mortem, but its unique composition makes it remarkably resilient compared to other tissues. This resilience contributes to its presence long after other parts of the body have broken down.
The General Process of Human Decomposition
Human decomposition is a biological process that begins shortly after death, involving the breakdown of tissues by internal enzymes and external microorganisms. The initial stage, known as autolysis, involves the self-digestion of cells as oxygen ceases and cellular enzymes are released. Following this, putrefaction begins, driven primarily by the body’s own bacteria, which proliferate and break down tissues. These bacteria produce gases, leading to bloating, and contribute to the liquefaction of organs and soft tissues.
Different tissues and organs decompose at varying rates, influenced by their composition and the presence of moisture and nutrients for microbial activity. Softer tissues, rich in water and readily digestible proteins, typically break down more quickly. The overall process progresses through stages, from fresh to bloat, active decay, and finally, skeletonization, where most soft tissues have disappeared.
Hair’s Unique Resistance to Decay
Hair exhibits strong resistance to decomposition due to its structural component, keratin. This protein is highly insoluble and forms a robust structure reinforced by disulfide bonds. These strong linkages make keratin resistant to degradation by most proteolytic enzymes produced by bacteria and fungi. This stability allows hair to persist for extended periods, even centuries, under favorable conditions.
A common misconception is that hair and nails continue to grow after death. This is inaccurate, as growth requires metabolic processes and nutrient supply, which cease when the body dies. The apparent lengthening of hair and nails is an optical illusion caused by the dehydration and retraction of the skin around the hair follicles and nail beds. As the skin dries and shrinks, it exposes more of the hair shaft or nail plate that was previously embedded, creating the impression of continued growth.
Environmental Factors Affecting Hair Preservation
While hair is highly resistant, its preservation is influenced by environmental conditions. Temperature, moisture, and oxygen levels play a role in how long hair remains intact. Extreme cold (e.g., glaciers) or dryness (e.g., deserts) can inhibit microbial activity and enzymatic breakdown, leading to remarkable preservation. For instance, hair has been found on mummified remains thousands of years old.
Conversely, high moisture and moderate temperatures can accelerate hair degradation, though it still decomposes much slower than other soft tissues. The pH level of surrounding soil or water also affects hair’s integrity, with acidic or alkaline conditions potentially contributing to its breakdown. In some rare instances, hair can even undergo fossilization, where organic material is replaced by minerals over vast geological timescales, although this is far less common than the fossilization of bones.