Hair Analysis and Species Recognition

1. Hair Analysis and Species Recognition Hair and Fiber 2

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

3. 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)

4. 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

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

6. 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

7. 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

8. 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

9. 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

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

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

12. 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?

13. Non-Human Hair Its an Angora RABBIT.

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

15. 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

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

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

18. 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.

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

20. 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.

21. 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.

22. 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.