1. Human vs. Animal Hair

2. HUMAN MEDULLA A human medulla is different from an animal medulla.
The medulla is the center part of the hair shaft.

3. The human medulla may be fragmented, absent or continuous.

4. Medullary Index
The index is calculated by measuring the diameter of the medulla and dividing it by the diameter of the hair.
The Medullary Index for animal hair is usually greater than 1/2.
The Medullary Index for human hair is generally less than 1/3.

5. Animal hairs are classified into three basic types.
Guard hairs: form the outer coat of an animal and provide protection
Fur or wool hairs: form the inner coat of an animal and provide insulation
Tactile hairs: (whiskers) found on the head of animals and provide sensory functions

6. Comparison Human Animal
Consistent in color and pigmentation throughout the length of the hair shaft.
May exhibit radical color changes in a short distance called banding.
Evenly distributed, or slightly more dense toward the cuticle.
More centrally distributed, more dense toward the medulla.
The medulla is generally less than one-third the overall diameter of the hair shaft.
The medulla is generally more than one-half the overall diameter of the hair shaft.
The root is commonly club-shaped.
The roots are highly variable between animals.
The scale pattern of the cuticle in human hairs is most commonly imbricate.
The scale pattern is highly variable between animals.
The shape of the hair shaft is most often cylindrical.
The shape of the hair shaft is also more variable in animal hairs.

7. Human Hair

8. Cat Hair

9. Bat Hair

10. Rat Hair

11. Dog Hair

12. Horse Hair
Human Hair
Horse Hair

13. Rabbit Medulla
uni-serial ladder
(in guard hair)
multi-serial
Medullas are different depending on the type (location) of hair.