Unsung Heroes of Hygiene: How Accidental Soap Discoveries Shaped Our Cleansing Habits

There’s nothing more satisfying than washing away the dirt, sweat and grime after a long day. Today, soap and suds help us stay clean, but how did people wash themselves before modern soap was invented?

Soap has a straightforward formula and a long history. However, for many centuries, people relied mainly on water for bathing. For instance, during the Indus Valley Civilization, which flourished between 2600 BC and 1900 BC in regions that are now Pakistan, India and Afghanistan, the Great Bath at Mohenjo-Daro is seen as one of the earliest examples of a public steam bath.

Before soap became widely accessible for personal hygiene, many people probably had unpleasant body odours, as noted by Judith Ridner, a historian at Mississippi State University who studies material culture, in Live Science. While today’s soap often has various additional ingredients, the basic formula for soap is quite simple.

Soap’s Simple Science

Soap is essentially a salt made from a fatty acid, created by mixing a water-soluble compound, or alkalis, such as sodium hydroxide (lye), with fat, such as animal fat or vegetable oil, according to Kristine Konkol, a chemist at Albany State University, says Live Science. When you mix a water-soluble compound (alkali) and fat together, a chemical reaction occurs that produces soap. So, the alkali helps break down the fat, allowing them to combine and create soap.

Soap’s Dual Action

A soap molecule has two key parts:

-  Water-attracting head: This part loves water, which allows it to dissolve in it easily

- Grease-and-oil-loving tail: This carbon chain side is attracted to oils and fats

When you use soap, the water-attracting heads grab onto water, while the grease-loving tails attach to dirt and oil. This helps surround the dirt particles, allowing them to be washed away with water. Essentially, soap acts like a bridge between water and grease, making it easier to cleanse surfaces.

Degradation Problem

This simple formula was essential for soaps used in ancient cultures. Early cleansers commonly included such ingredients as plants, animal bile, oils and exfoliants, such as sand and wood ash.

It is difficult for historians to track ancient soaps due to one main reason: According Seth Rasmussen, a chemistry historian at North Dakota State University, soap breaks down, or degrades. Chemical dating and archaeology are used to study ancient soaps, but this only works if samples have lasted from their time of creation till the present day.

Mesopotamian Origins

The oldest written evidence of soap-like substances goes back to about 2500 BC in Mesopotamia—modern-day Iraq, along with parts of Syria and Turkey. Clay tablets show that the Sumerians—an ancient people who lived in southern Mesopotamia—cleansed themselves using water and sodium carbonate, a powdery salt made from plant ash. They also used beer and hot water to clean wounds.

A few hundred years later, the Akkadian Empire in Mesopotamia used a blend of plants for cleansing. This included such materials as date palm, pine cones and a bushy plant called tamarisk. This mixture matches the basic ingredients of today’s soap: an alkali like tamarisk, an oil, such as date palm and an abrasive such as pine cones. Konkol and Rasmussen explained this in their paper on soap of ancient times.

Soap’s Ancient Roots

How can that be true if modern science was not around in ancient times? Konkol suggested that people likely made soap by accident. For instance, cleaning a greasy pan with plant ash at high heat could create soap, just like boiling animal fats with wood ash. Plant ash refers to the leftover material that remains after burning plant matter, such as wood or other vegetation. It often contains minerals and can be used for various purposes, including as a natural alkaline ingredient in soap-making, cleaning and even as a soil amendment in gardening.

Historians have found these methods date back to Babylon and ancient Egypt. Such ingredients as natron (a type of salt), clay and a soapstone made of talc have been found in Egyptian artefacts, possibly used in their bathing practices. Alternatively, these ingredients could have “resulted from decomposing bodies”, according to Rasmussen, meaning that the ingredients could have come from the natural breakdown of bodies after death. So, these materials may also be found as a byproduct of decay.

An Alternative Method

The ancient Greeks and Romans had a different way of bathing. After washing with water, they covered themselves in fragrant olive oils. After applying the olive oils, often containing aromatic plant extracts, they used a special curved tool known as a strigil to remove any remaining dirt or impurities from their skin. The strigil helped them clean themselves more effectively by scraping off grime, according to Rasmussen.

But most of these soapy mixtures were used to clean fabrics instead of people making them more suited to industrial purposes than personal hygiene, according to Rasmussen explained. Historians are unsure exactly when using soap for bathing became common, but, in the Western world, it, possibly, did not happen until the early- to the mid-1800s, according to Ridner.

Several factors contributed to this. One, says Ridner, is that cheaper fats became more easily available. The Industrial Revolution shifted soap-making from a home industry to the factories. City engineers and reformers also focused on improving cleanliness in immigrant communities, which helped drive the change. Additionally, the Civil and Crimean wars increased the focus on sterilization in hospitals and healthcare. Ridner explained that all these factors combined to create a large demand for soap, which companies like Procter & Gamble in the US began to capitalize on.

(The author of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany)

(Disclaimer: The views expressed above are the author's own and do not reflect those of DNA)