Presentation on theme: "Hair Analysis and Species Recognition Hair and Fiber 2."— Presentation transcript:
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?
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.