Hair

1. Hair

2. Objective: SWBAT identify the various parts of a hair. SWBAT describe the variations in the structure of the medulla, cortex and cuticle. Do Now: • How are the layers of hair similar to the layers of a pencil • How can hair be used in a forensic investigation *If students are talking during Do Now – pop quiz (click here)

3. From hair, one can determine: If the source is human or animal Race (sometimes) Origin of the location on the source’s body Whether the hair was forcibly removed If the hair has been treated with chemicals If drugs (or poisons) have been ingested Introduction

4. Form and Structure of Hair • Morphology – form and structure of hair • Average human body has about 5 million hairs • Blondes average 120,000 strands of hair on their head • Redheads have about 80,000 • Black and brown hair people have about 100,000 • Hairs are continuously shed and renewed at a rate of about 100 each 24-hour period from the scalp alone!

5. Hair Shaft Composed of: Cuticle— clear outside covering of hair shaft, made of overlapping scales (pattern is used to determine species) Cortex—inner layer made of keratin and embedded with pigment; also contains air sacs called cortical fusi Medulla—inside layer running down the center of the cortex

6. The cuticle is the outermost layer of hair which is covered with scales. animals and are named based on their appearance. The three basic patterns are: The Cuticle Coronal- mouse Spinous- cat Imbricate- human

7. The cortex gives the hair its shape. Melanin—give hair its color Contains keratin – a tough protein makes hair so resistant to chemical and biological degradation. The Cortex

8. The Medulla • Hair Core • Most humans have no medulla or one that is fragmented (except Native Americans and Asians, where medulla is usually continuous) Types: Intermittent or interrupted Fragmented Continuous Stacked Absent—not present

9. Human Medulla Human medulla may be continuous, fragmented, or absent.

10. Hair Classification Activity

11. Exit Ticket1. What are the three parts of the hair?2. Can the hair cuticle get you to an individual person? Why or why not?

12. Medullary Index Determined by measuring the diameter of the medulla and dividing it by the diameter of the hair. Medullary index for human hair is generally less than 1/3. For animal hair, it is usually greater than 1/2. mouse

13. Can be straight, curly, or kinky, depending on the cross-section, which may be round, oval, or crescent-shaped. Hair Shape and Cross Section Crescent moon (Kinky) Oval (Curly) Round (Straight) • Human hair ranges in diameter from 25-125 µm

14. Racial Characteristics of Hair • Risky, but generally… • Asians & Native Americans – round cross section with no twisting • American & European whites, Mexicans, and people of Middle Eastern background – oval cross section, rarely with a twist or undulation. • African heritage – flat to crescent-shaped cross section with twist, undulation and dense, clumped pigmentation. Undulation – (in hair morphology) slight waviness Undulated Twisted

15. Terminology Anagen—hair is actively growing; lasts up to 5 years; includes 80-90% of hair follicles Catagen—hair is not growing; a resting phase Telogen—follicle is getting ready to push the hair out; lasts two to six months; about 8-10% of hair follicles Grows about 0.4 mm per day, or 1 cm per month; approximately one-half inch per month Replaced about every 3-5 years with new hair Coarser hairs grow at slower rate and fall out less frequently Hair Growth

16. The Root Human roots look different based on whether they have been forcibly removed or they are telogen hairs and have fallen out. Animal roots vary, but in general have a spear shape. Fallen out Forcibly removed

17. The Tip Tip of mature hair will taper to a point Recently cut hair is squared off at the tip, but within 2-3 weeks the tip becomes rounded Frayed hair tip results from over-processing (bleach, coloring, straighteners, blow dryer) or age

18. Color Length Diameter Distribution, shape, and color intensity of pigment granules Scale types Presence or absence of medulla Medullary type Medullary pattern Medullary index Hair Comparison • Dyed hair has color in cuticle and cortex • Bleaching removes pigment and gives a yellow tint

19. The root contains nuclear DNA. If the hair has been forcibly removed, some follicular tissue containing DNA may be attached. The hair shaft contains abundant mitochondrial DNA, inherited only from the mother. It can be typed by comparing relatives if no DNA from the body is available. This process is more difficult and more costly than using nuclear DNA. DNA from Hair

20. Questioned hairs must be accompanied by an adequate number of control samples. Collection of Hair • From victim • From possible suspects • From others who may have deposited hair at the scene Control sample • 50 full-length hairs from all areas of scalp • 24 full-length pubic hairs

21. Advantages: Hair Toxicology • Easy to collect and store • Is externally available • Can provide information on the individual’s history of drug use or evidence of poisoning Collections must be taken from different locations on the body to get an accurate timeline.

22. Hair as Chemical Indicator • Metabolite – a specific product of a substance, formed by chemical processes in the body • Drugs and their metabolites, vitamins and poisons can be detected with just a few mm of hair. • Provides back up to urine and blood testing • Drug metabolites only detectable in urine for approx. 3-5 days from last use. • Hair grows at approx. 1 cm per month and will record drug use over a longer period of time. • Can establish dietary deficiencies and diseases • Oils on scalp can deposit onto hair and will leave evidence of environment • Smoke from crack cocaine can be deposited this way • May provide a false positive

23. Hair Toxicology, continued Napoleon died in exile in 1821. By analyzing his hair, some investigators suggest he was poisoned by the deliberate administration of arsenic; others suggest that it was vapors from the dyes in the wallpaper that killed him.

24. For additional information about hair and other trace evidence, check out truTV’s Crime Library at: www.crimelibrary.com/criminal_mind/forensics/trace/1.html More about Hair