Keratin protein is the perfect evidence of how all life on Earth is related and shows just how intricate evolution can be. Keratin is one of the most dynamic, vital proteins in the world. Even more astounding is the fact that all animals on Earth have some form of keratin protein in their body. Regardless, what is keratin protein and where can it be found?
Keratin is a structural protein that has evolved in animals to make up key structural components and is found in reptiles, birds, amphibians, fish, and mammals. However, keratin proteins for birds and reptiles slightly differ from mammals. Different functional groups can be added or removed from keratin, which allows it to be such a dynamic protein.
In humans, keratin is the structural protein that makes up the outer layer of the skin. Keratin is also the main component that makes up peoples hair and nails. It is easy to see how dynamic this protein can be since it makes up hair, nails, and skin in just one animal.
On other mammals, the keratin protein is the main structural protein in hooves, horns, and claws, as well as skin, hair, and nails. If humans were not closely related to other mammals, then other mammals would have different structural proteins that made up the same body parts as humans. However, this is not the case, but what about other animals, such as birds and reptiles?
Birds and reptiles both evolved from the dinosaurs. In fact, the Tyrannosaurus Rex closest living relative is the chicken. While scientists cannot be sure, the beaks and armor of dinosaurs probably made up of keratin. One-reason dinosaurs probably had keratin proteins are because both birds and reptiles have different structures where keratin protein is the key component. The scales and claws of reptiles are made out of keratin, as well as turtle shells. Where birds have feathers, beaks, and claws that are made up of keratin proteins.
When going back further in time, before the evolution of dinosaurs there was only fish and amphibians, which started to take over land for the first time. Keratin proteins do not play as large of a role in these animals, but it is present. In frogs, for example, keratin is located in the skin that gets exposed to wear and tear. Nevertheless, the frog’s skin is not entirely made of keratin. Frogs would not be able to absorb oxygen and water through their skin if their skin was entirely made of keratin, according to the Office of Environment and Heritage. Fishes of certain classes only have teeth that are made up of keratin.
It is remarkable how one protein can have so many uses, and be used by almost every animal on Earth. This gives people more evidence that all life is connected, and we all came from the same ancestor so many billions of years ago.
Hickman, Cleveland Pendleton; Roberts, Larry S.; Larson, Allan L. (2003). Integrated principles of zoology. Dubuque, IA: McGraw-Hill.