Could I make a bridge out of human hair?
Meera Mahesh
We’ve all had situations, where someone has accidentally (or in the case of my brother and I, purposefully), pulled your hair. It sometimes feels like a miracle that all your hair wasn’t pulled off! Your hair is one of the strongest materials in the world. When it is stretched it is even stronger than steel.
What is human hair made of?
You have about 5 million hair follicles all over your body, and these are made before you are born. There are only some places without hair, like the palms of your hands, your lips, and the soles of your feet. Your hair is mostly made of a protein, called keratin, which is wound in a helix shape (like DNA). There are different bonds (disulphide, hydrogen, and ionic) between the strands of keratin and other proteins, which form a very strong structure. It is from the follicle that the hair pushes out, through the skin, until you can see it. You will grow enough hair over your life for it to be laid out from London to Prague, which is over 1000km! You will also lose 50-100 strands of hair every day, as they come to the end of their four years of service.
The reason that your hair does not hurt when you cut it is that after the hair is out of the follicle, the hair contains dead cells. That’s why you can only feel someone touching your hair if they move it enough to stimulate the follicles on your head.
Why do we have hair?
Your hair does different jobs in different places:
- Your eyebrows are tasked with protecting your eyes, and not letting many substances, including sweat, into them.
- Your eyelashes decrease the light and dust that goes into your eyes.
- The hair on your head protects your skull.
- The hair around your body, on your legs, arms, and tummy is important for protecting you, and regulates the temperature of your body by rising and trapping air to keep you warm or lying flat when you are too warm.
How strong is human hair?
It’s estimated that all the hairs on your head when combined could carry the weight of two elephants and not snap. A single strand is strong enough to hold 100g, which is about as heavy as an apple.
The reason that hair is so strong is because of its structure. The keratin fibres stretch very easily, and the several layers making up hair make it resistant to different types of forces, helping it protect us in everyday life.
Could you make a bridge with human hair?
Since human hair is so strong, why aren’t we building more structures out of it, for example, bridges? Well, bridges are very strong structures and require two components. Firstly, they need strong materials, like steel and aluminium. Secondly, they require clever designs, which help make sure these bridges can take the heavy load of hundreds of people, cars, and trains every day.
Although hair is very strong, there are a few issues that would arise when using hair as the sole bridge-making material. The difficulties of sourcing high quantities of hair, the bendy, flexible nature of hair, and its texture, which isn’t suitable for car tyres, would make hair an undesirable material for bridge making.
Don’t be disheartened by the inability of our hair to carry automobiles, however – scientists are using the structure of hair as a template for new materials. Soon, ropes, bridges, and buildings will be made of materials that are modelled after the hair on your head!