The key difference between human and animal hair is that the human hair does not stop growing; hence, it is longer while the animal hair stops growing when it reaches a certain length; therefore, it is shorter.
Presence of hair is one of the most gripping features in mammals, and it varies within species or mostly among animal groups. In forensic studies, hair is one of the most important sources to identify an individual. Katz (2005) defines the hair as an appendage of the skin that grows out of a hair follicle. It is a complex chain of proteins, mainly keratin, interconnected and formed fibrils. The cuticle is the outermost layer of a hair shaft. The cuticle is scaly, and it differs within species. Inside or the cortex of a hair shaft is also different in both inter and intra species as the medulla and pigmentation vary according to the localities. When differentiating human and animal hair, it is necessary to look at these features in detail.
CONTENTS
1. Overview and Key Difference
2. What is Human Hair
3. What is Animal Hair
4. Similarities Between Human and Animal Hair
5. Side by Side Comparison – Human vs Animal Hair in Tabular Form
6. Summary
What is Human Hair?
Hair grows everywhere on the human body except mucus membranes and glabrous skin (lips, penis, labia minora, palms, and feet). There are four types of human hair; they are the primordial, lanugo, vellus and terminal hair. Primordial and lanugo hairs develop at three and six months in the baby during of gestation period before the birth. Vellus hairs are fine and lack medullae inside cortex, and are present all over the body. Terminal hairs are prominent in appearance and hard in structure, and are present on the scalp/head, eyebrows, eyelashes, face, armpits, and around genital organs.
Moreover, mongoloids have the thickest terminal hairs among all the human races (90 – 120 µm). Caucasian hairs measure the diameter between 70 and 100 micrometres while in Negroid race, it is from 60 to 90 micrometres.
Figure 01: Human Hair
There are two types of pigments, the eumelanin and pheomelanin, which result in different hair colours according to the concentrations inside the cortex. In red hair, pheomelanin is prominent while eumelanin is dominant in black, blond, and brown hairs. Grey hair is a result of lowering or disappearing of pigments from the hair cortex. A hypothesis is that the straight hair in human evolved later in Caucasians and Mongoloids.
What is Animal Hair?
Hair is one of the exclusive features of all the mammals to overcome heat and sometimes to win sexual mates but, some animals such as Aardvark prefers scales over hairs. The animal hair is of three types; vibrissae, bristle, and wool. All those three types are very important for their lifestyles as they involve with different functions. Vibrissae make the whiskers to function in tactile and sensitivity. Bristle hairs act as the coat or guard hairs.
Figure 02: Animal Hairs
Moreover, colours of bristle hairs vary within animal species and other taxonomic groups, giving the animals a distinctive appearance. Since the bristle colour inherits from previous generations to offspring, the coat colour patterns could vary among individuals (e.g. dogs and cats). Wool hairs are fine that make the fur of an animal, functioning as insulators (e.g. sheep, goat). The cuticle and the medullar patterns vastly differ among animals. The tail and mane hairs in horses are more like human terminal hair.
What are the Similarities Between Human and Animal Hair?
- Both human and animal hair are made of a protein called keratin.
- Also, their hair contains a pigment called melanin that gives the black colour.
- Moreover, both human and animal hair consists of the same three parts; they are the cuticle, medulla, and cortex.
What is the Difference Between Human and Animal Hair?
Hairs in mammals vastly vary in structure, colour, location on the body, present period of the life stages, and function, etc. When considering human hair and animal hair, there are several differences. The key difference between human and animal hair is the ability to grow. The human hair does not stop growing while the animal hair stops growing at a certain stage. Hence, the human hair is much longer than the animal hair.
Furthermore, unlike the human hair, the animal hair provides a protective function. Hence, the medulla of animal hair is thicker than the human hair. Moreover, human hair has a consistent colour from root to tip while the colour of animal hair may vary to several colours. Hence, this is another key difference between human and animal hair. Structurally, the human hair is imbricated while animal hair is coronal or spinous. Thus, it is also a difference between human and animal hair.
The following infographic illustrates more information on the difference between human and animal hair.
Summary – Human vs Animal Hair
Human and animal hair are structures that have a similar appearance. But, structurally they differ. In summarizing the difference between human and animal hair, the key difference is that the human hair grows continuously and naturally without stopping the growth while the animal hair stops growing at a certain stage. Hence, the human hair is much longer than the animal hair. Furthermore, the human hair has a consistent colour while animal hair often has several colours. Also, the medulla of the animal hair is much thicker than the human hair.
Reference:
1. “Animal Hair.” NeuroImage, Academic Press. Available here
Image Courtesy:
1.”HUMAN HAIR 07″By IUPinhumanhair – Own work, (CC BY-SA 4.0) via Commons Wikimedia
2.”3728492″ by Ruwadium (CC0) via pixabay