By Scott A. Rowan
Keratin is a fibrous protein that is the basic structural component of hair, horns, claws, fingernails, hooves, and other epidermal growths in humans and animals.
Insoluble and tough, the keratin protein structure can be thought of as Mother Nature’s all-purpose plastic. Found in mammals (humans and other species) as well as reptiles, birds, and even fungi, keratin is one of the most resilient and durable biological structures known. The outermost layer of the epidermis is coated in keratin, making humans and animals alike waterproof.
Though keratin can be soft as skin or flexible as your fingernail, it can also create some of the hardest materials in the animal kingdom. The scutes of crocodiles, alligators and caimans are made from keratin, as are the carapace and plastron of turtles, tortoises and terrapins, and the horns found on cattle.
Keratin is divided into two major categories: alpha keratin is in humans and the softer of the two; beta keratin is much harder and used to form the horns, claws, hooves, and dermal plates omnipresent in mammals, birds and reptiles.