1. Chapter 3 The Study of Hair By the end of this chapter you will be able to:
Identify the various parts of a hair
Describe variations in the structure of the medulla, cortex, and cuticle
Distinguish between human and nonhuman hair

2. Chapter 3 The Study of Hair By the end of this chapter you will be able to:
Determine if two examples of hair are from the same person
Explain how hair can be used in a forensic investigation
Calculate the medullary index for a hair

3. Hair Expert Testimony – Anthony Trial

4. History of Hair Analysis
1883: Alfred Swaine Taylor and Thomas Stevenson covered hair in a forensic science text (The Principles and Practice of Medical Jurisprudence)
1910: Victor Balthazard and Marcelle Lambert published a comprehensive study of hair
(The Hair of Man and Animals) This text includes numerous microscopic studies of hairs from most animals.
: Dr. Sydney Smith, analyzed hairs side by side (comparison microscope)
4. Today: chemical tests, neutron activation analysis, and DNA analysis

5. Studies Bradford research into ancient human.wmv
Anderson Cooper 360 The CSI Effect.wmv

6. The Function of Hair Regulates body temperature Decreases friction
Protects against sunlight
Sense organ
*Birth – 5 million hair follicles, of which 2% are on the head.
- density decreases with age

7. The Structure of Hair
A follicle embedded in the skin produces the hair shaft
There are two parts to a hair – follicle and shaft
When a hair is removed with the follicle, it should be referred to as a follicular tag.
Three layers (illustrated above):
the inner medulla
the cortex
the outer cuticle

8. The Structure of Hair

9. Cuticles, Cortex, and Medulla

10. Types of Cuticle and Cortex
the outermost layer
over-lapping scales that protect the inner layers
Cortex:
Thickest layer
Contains most of the pigment
Distribution of pigment varies
Usually denser nearer the cuticle

11. Types of Medulla

12. Medulla Index— Animals vs. Humans
The medullary index measures the diameter of the medulla relative to the diameter of the hair shaft.

13. Types of Hair
Buckled Blunt Double Medulla
A cross section: circular, triangular, irregular, or flattened
Shape: influences the curl of the hair
Texture: coarse or fine

14. Hair Colors
Blonde Brown Red

15. Six Types of Hair Human hair varies on the body Head
Eyebrows and Eyelashes
Mustache & Beard
Underarms
Body hair
Pubic

16. The Life Cycle of Hair Hair proceeds through 3 stages as it develops:
Anagen stage:
hair actively grows
cells around the follicle rapidly divide and deposit materials in the hair
Catagen stage:
hair grows and changes
Telogen stage:
follicle becomes dormant

17. Treated Hair Bleaching Dyeing colors the cuticle and the cortex
disturbs the scales on the cuticle and
removes pigment
leaves hair brittle and yellowish
Dyeing colors the cuticle and the cortex

18. Racial Differences
Broad, racial groups do exhibit some shared physical characteristics
But NOT applicable to all individuals in these groups
Therefore,
Individual hairs CANNOT be assigned to any of these groups

19. Animal Hair and Human Hair
Pigmentation:
animal hair is denser toward the medulla
human hair tends to be denser toward the cuticle
Banded Color Patterns:
possible in animals
not in humans
Medulla: much thicker in animals

20. Human vs. Animal
Cat
Sheep
Horse
Human with and without Medulla

21. Animal Hair and Human Hair
Spinous Coronal Imbricate
Animals: cuticle scales resemble petals (spinous) or a stack of crowns (coronal)
Humans: commonly flattened and narrow (imbricate)

22. Microscopic Observation
Imbricate Scales

23. Using Hair in an Investigation
Macroscopic investigations indicate
length
color
curliness
Phase contrast microscopy shows
presence of dye or other treatments
Electron microscopes yield yet more detail

24. Using Hair in an Investigation
Note the overlapping scales and the pigment granules in the cortex

25. Testing for Substances in the Hair Shaft
Chemical tests-Gas Chromatography
Spectrometer
presence of various substances
Examining a hair shaft
timeline for exposure to toxins
Neutron Activation Analysis (NAA)
concentrations of substances

26. Testing the Hair Follicle
Microscopic assessment
Cost effective and quick
Blood test
Determine blood type
DNA analysis
Identification with a high degree of confidence

27. Microscopic Assessment
Preparation

28. Can you identify the animal hairs shown?B C D G E F H I
Teacher Note: I challenge students to identify each hair sample pictured on this slide as they examine the sets of animal hairs I have prepared for them. An observation worksheet is available on my website which requires students to draw an image of what they see and add a description that highlights unique characteristics of each specimen. A key for the animal hairs is available on the next to last slide of this presentation!
Think About It …
In which samples are we viewing the cuticle? How do they compare?
(2) In which samples are we viewing the medulla? How do they compare?
(3) What characteristics can be used to identify hair samples?

29. Types of Animal Hairs - Key
Cat
Horse
Pig
Human A B C D G E F H I
Deer
Dog
Rabbit
Rat
Human

30. Summary
Hair functions to regulate temperature, reduce friction, protect from light, and produce sensory data.
Hair consists of a (a) hair shaft produced by a (b) follicle embedded in the skin.
The shaft consists of an outer cuticle, a cortex, and an inner medulla.
Hair characteristics vary depending on location on the body.

31. Summary
Hair development has three stages: anagen, catagen, and telogen.
Various hair treatments produce characteristic effects useful to forensic experts.
Some characteristics can be grouped into general racial categories.
Forensic experts examine hair using chemicals, light, electrons, neutrons, and DNA sequencing.