The Study of Hair

Mitochondrial DNA (mtDNA)

DNA from mitochondria, inherited maternally, can provide family relationships but not individual evidence.

Cuticle

The transparent outer layer of the hair shaft; dissolved during analysis.

Anagen stage

The growth stage of hair that lasts about 10-100 days.

Catagen stage

The transitional stage when hair stops growing and the follicle recedes.

Telogen stage

The dormant stage of hair growth where the follicle is inactive and hair is easily lost.

Medullary index

The ratio of the diameter of the medulla to the diameter of the hair, used to distinguish animal hair from human hair.

Types of Medulla Patterns

Patterns include continuous, interrupted, fragmented, solid, and none, which can help identify species.

Cuticle types

There are three types of hair cuticles: imbricate, coronal, and spinous, which help distinguish human hair from animal hair.

History of Hair Analysis

Key milestones include contributions from Alfred Swaine Taylor, Victor Balthazard, and the development of standard procedures for hair analysis.

Functions of Hair

Hair regulates body temperature, decreases friction, protects against sunlight, and acts as a sensory organ.

Treated Hair

Hair that has undergone chemical processes such as dying, which can alter its color and structure.

Human Hair Characteristics

Human hair varies from person to person and exhibits distinct traits based on body location.

Electron Microscope

A tool that provides magnification of 50,000 times or more for detailed examination of hair samples.

Chemical tests on hair

Can reveal the presence of drugs, toxins, heavy metals, and nutritional deficiencies.

Hair Examination Process

Involves PCR amplification of DNA and automated profiling to establish or exclude genetic relationships.