**2.1 Hair profile**

*Forensic Analysis - Scientific and Medical Techniques and Evidence under the Microscope*

of these techniques are discussed in the proceeding sections.

to the identification of hairs of moles and shrews [14].

**2. Microscopy in wildlife forensics**

In this scenario, it becomes the need of the hour to develop wildlife forensics with the changing paradigms of wildlife crime. Some of the important techniques that have made a strong impact in the field of wildlife forensics are microscopy, DNA analysis and elemental analysis, especially the study of isotopes. The aspects

The spectrum of types of physical evidence in wildlife forensics is very wide and so are the techniques. Microscopy is one of the most useful tools in wildlife forensics, especially while dealing with hair evidence. Hair is one of the important physical evidence found in wildlife crime cases about mammals. Mammals form one of the largest groups of poached species and a large number of wildlife crime cases require identification of species from hair. The history of examination of hair for species identification can be traced back to the nineteenth century, but the first significant contributions in this field were the works of Hausman [5–7] in America. Numerous studies related to species characterization from hair reported in the first half of the last century [5–10]. Microscopic hair characteristics have also been widely used in biological sciences for studying food habits, prey, predator relationships and mammals inhabiting a den or a tree [11–13]. In 1938, Mathiak produced a key to the identification of hairs of mammals of Southern Michigan [11]. In the same year, Williams produced a key

A key for the identification of Californian mammals from hair characteristics was published by Mayer [12]. The entire key was based on a consideration of dorsal guard hairs that had been taken from one small area of the pelage. In all, around 392 species and subspecies were considered. Thoroughly descriptive guides on microscopic hair characteristics of some important mammalian species in certain geographic regions have been worked out by several prominent workers. Guide on hair structure of some selected mammals of Ontario was provided by Adorjan and Kolenosky [15]. Similarly, a guide for species identification from the hair of some selected mammals of Australia was provided by Brunner and Coman [16]. Moore et al. [17] provided a guide for the identification of hair of some mammals of North America (Wyoming). Later guides on species identification from hair were provided by Appleyard [18] and Teerink [19]. Statistical evaluation of quantifiable hair characteristics was also reported. Sato et al. performed a statistical comparison of dog and cat guard hair using numerical morphology [20]. They were able to distinguish between species based on discriminant function analysis. Similarly, Sahajpal et al. used discriminant function analysis to characterize hair from four mongoose species of India, based on the banding pattern of the hair [21]. Sahajpal et al.

further reported the guard hair characteristics of four Indian bear species and bovid species listed under Schedule I of Wildlife (Protection) Act 1972 of India [22, 23]. Scanning electron microscopy (SEM) also finds great use in the study of surface morphology of hair and has also been used by several investigators. Rollins and Phan et al. used SEM for the studies of scale patterns in the wool hairs of Ibex, Cashmere/ Pashmina and Shahtoosh/Tibetan antelope wool [24, 25]. They were able to show the usefulness of scale patterns of wool fibers for species characterization. A scanning electron microscopy (SEM) study on the cuticular pattern of guard hair of Tibetan antelope (*Pantholops hodgsonii*) was reported by Bahuguna and Mukerjee [26]. It is apparent from the aforesaid facts that examination of hair can provide valuable information on species identification in wildlife forensics. For species characterization of hair, the following aspects are necessary to understand.

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The general shape or profile of the hair has pertinent value in species identification from hair. The hair can be divided into root and shaft. Most of the mammal species have guard hair that flattens toward the distal (away from the skin) end. This flattened region is often referred to as the shield.

### **2.2 Cuticle**

The outer layer of the mammalian hair is made up of scales and is called the cuticle. The layer is very thin and almost transparent. This layer can be considered analogous to the paint on the surface of a pencil. There are three parameters for describing the cuticle:


There are further subclassifications that are beyond the scope of this chapter.

#### **2.3 Cortex**

The thick solid layer under the cuticle is called the cortex of the hair. The thickness of the cortex varies across species, and for simple understanding, it can be considered as analogous to the wooden part of the pencil. The cortex is made up of dead cornified cells, packed on to a rigid and homogenous hyaline mass [8]. The pigments that impart a color to the hair are present in the cortex region. Though the cortical region does not have much importance in species identification, the pigment granules present in the cortex do find use in species characterization from hair.

#### **2.4 Medulla**

The innermost core of the hair is called the medulla. It can be considered analogous to the graphite lead of the pencil. Medullae have been classified into four basic groups, unbroken, broken, ladder and miscellaneous, based on the general shape, arrangement of cells and air spaces [16, 27]. These four major groups can be further divided into more descriptive categories that cannot be covered in the current chapter.

#### **2.5 Hair cross-section**

As discussed in the Section 2.1, hair shows a significant variation in shape across its length. This variation gets very clearly revealed by the outline of their cross-sections. A cross-section of hair shall essentially be circular if the hair has a cylindrical shape. However, for complex shapes, the cross-sections are of very distinct shapes. The cross-section shape and their dimensions are of significance in species identification. For calculating the ratio of medulla and cortex concerning hair thickness, cross-sections are best suited. Cross-sections from the widest portion of the shield are most informative for species identification [19].
