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

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Non-human root structures are highly variable


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Referred to as “banding”
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).
(Right) The
Angora goat,
source of
mohair.
The Peruvian
alpaca (above), a
camel relative
whose wool
comes in 22
natural colors
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?
Non-Human Hair
Its an Angora RABBIT.
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 chainlike 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 nonhuman medulla scale
structures.
Cuticle Scale Structures in Non-Human Hair

3 Basic Structures

Coronal or “crownlike”



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 “petallike”


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.