When our ancestors learned how to wrap pieces of animal skin around their feet to protect them from stones and thorns, they were able to walk faster. When they found out that food could be transported in a bag made of animal skin, they could walk farther. And when they learned to cover their bodies with hides, they were protected from the elements. Once they learned to tan the untreated hides to keep them from getting as hard as wood or rotting away, they produced flexible and long-lasting leather for the first time.
One of the earliest trades of our ancestors, the craft of tanning uses three primary methods—fat, plant-based, and mineral-based tanning—that are still in use today. The search for methods of preserving hides started in the early Stone Age, around 8,000 BCE. To create waterproof leathers, humans began to rub fatty substances into the rawhides. Around five thousand years later, the people of Egypt and Mesopotamia are said to have invented plant-based tanning, using the bark of Acacia nilotica, or the gum arabic tree. Plant-based tanning is a slow process that uses tannins occurring naturally in the bark and leaves of plants, most commonly mimosa, chestnut, and bark and results in a stiff leather. Plant tanning was not the only method known to the Egyptians. Craftsmen already knew much about tanning methods based on sesame oil and the mineral alum. The Romans circa 800 BCE tanned a variety of leather—tough corium leather for sandals as well as a supple leather they named aluta—using the process now commonly known as alum tanning.