“Fingernails and toenails are made of the same material as hair”

It's a common observation that our hair and nails share a certain resilience and texture, leading many to wonder if they are, in fact, composed of the same fundamental stuff. This curiosity likely stems from their similar appearance as dead tissue that grows from the body, can be cut without pain, and possesses a tough, somewhat flexible quality. The visual and tactile similarities make it easy to assume a shared material basis, prompting a widespread belief that they are essentially identical in composition. Both hair and nails are specialized parts of our skin and protect our body from the outside world.

Scientifically, this common assumption is largely accurate. Both the hair on our heads and the nails on our fingers and toes are predominantly constructed from a remarkable protein called keratin. Keratin is a fibrous structural protein that forms the main constituent of hair, skin, and nails in humans and many other animals. While there are numerous types of keratin, the primary difference lies in their arrangement and specific chemical bonds, leading to variations in hardness and flexibility. For instance, nails are made of a harder, more densely packed alpha-keratin, whereas hair contains a mix of alpha-keratins, giving it more flexibility. Despite these minor structural nuances, the foundational building blocks are indeed the same.

The persistence of this belief is understandable, given that most people aren't regularly dissecting their cells or studying biochemistry textbooks. The visual evidence of hair and nails growing from follicles and nail beds, respectively, and their similar resistance to wear and tear, strongly suggests a common origin and material. It's a testament to the body's efficient use of materials that one robust protein can be adapted to serve such diverse yet structurally demanding roles, from protecting our fingertips to insulating our scalps. This shared molecular foundation (Review) is why the claim that hair and nails are made of the same material is, in essence, confirmed.