Hair Analysis and Species Recognition Hair and Fiber 2

Forensic Importance of Non-Human Hair  Can link a suspect or location to a crime  Humans often interact with other mammals  Hairs can be “transferred” from suspect to victim or location Can be transferred to almost anything  Used directly in specialty animal cases

Forensic Importance of Non-Human Hair  Vitally important to identify species with any hair evidence  Related species will often have similar hair structures Most important study involves examination of cuticle scales and medulla structure Cuticle similarities of human hair (left) with orangutan hair (right)

Non-Human Hair  Like humans, other mammals have distinctive hair types Guard hairs  Outer hairs used for protection  Usually thick, coarse or even spiny Fur or “wool hairs”  Inner coat for insulation  Shorter, often softer hairs  Down-like

Non-Human Hair  Mammal Hair (cont.) Tactile  Whiskers  Used for communication and sensory purposes

Non-Human Hair  Non-Human vs. human hair Non-human hair can have wildly different pigmenting through the shaft  Referred to as “banding” Non-human root structures are highly variable  Does not often have the “club” appearance Pigmenting often more centrally distributed rather than throughout cortex Very wide medulla  Usually clearly defined

Non-Human Hair Samples  Recall humans have less than 1/3 medulla, most other animals at least ½  When discovered, microscopy compares hair with known exemplar to identify species Can not usually prove individual characteristics  Sources Combs, brushes, beds, pens, cages

Non-Human Hair  Identification processes are essentially the same as with human hair  Will usually contain medulla and/or scale pattern that will help identify species  Identification of less common animal hairs has increased significance

Non-Human Hair  Wool Most common animal fiber Usually originate from sheep  Other species include goats (Mohair/cashmere), camels, llamas, alpaca Commercial use dictates characteristics  Clothing - Fine fibers  Carpeting – Coarse fibers

Non-Human Hair Sheep wool fibers that have been artificially colored. Note the medulla in the hairs at lower right.

Non-Human Hair Two sources of cashmere wool; the endangered Tibetan antelope (top) and the Cashmere goat (left). The Peruvian alpaca (above), a camel relative whose wool comes in 22 natural colors (Right) The Angora goat, source of mohair.

Non-Human Hair This slide really has no purpose other than the fact I couldn’t believe it when I saw it. What is it?

Non-Human Hair Its an Angora RABBIT.

Medullary Index of Non-Human Hairs Note the clear difference between the medullary index of a human hair (right) and a dog hair (left).

Medulla Structures in Non-Human Hair  4 General Types Uniserial Ladder  Resembles a ladder-like appearance Multiserial Ladder  Resembles a series of uniserial ladders side by side

Medulla Structures in Non-Human Hair Typical uniserial (left) and multiserial (right) ladders. In this case, both types were removed from rabbits.

Medulla Structures in Non-Human Hair  Cellular or vacuolated Resembles a chain- like shape composed of many vacuoles Cellular medulla structure.

Medulla Structures in Non-Human Hair  Lattice Speckled or honeycomb appearance Common in deer and deer relatives Lattice medulla structure in this case from a deer.

Medulla Structures in Non-Human Hair Representative sample of various common non- human medulla scale structures.

Cuticle Scale Structures in Non-Human Hair  3 Basic Structures Coronal or “crown- like”  Resemble stacked paper cups  Common in many rodents and bats  Extremely rare in humans Diagram of coronal scales and hair from a free-tailed bat.

Cuticle Scale Structures in Non-Human Hair  Spinous or “petal- like” Triangular scales shape and often protrude from hair shaft Common in seals, mink and especially cats Diagram of spinous scales and hair from a mink.

Cuticle Scale Structures in Non-Human Hair  Imbricate or “flattened” Overlapping scales with narrow margins “Brick-like” Includes humans and other primates Diagram of imbricate scales and hair from a human.